Bell X-1 Variants

Aerofax Datagraph 3

BeIIX-1 Variants •

By Ben Guenther and Jay Miller ISBN 0-942548-40-X

X-1 SECOND GENERATION GENERAL ARRANGEMENT ©1988

Aerofax, Inc. P.O. Box 200006 Arlington, Texas 76006 ph. 214 647-1105

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1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20.

De-icing Fluid Tank 22. Canopy 23. Oxygen Filler 24. Lox Tank 25. Nitrogen Filler 26. External Power Receptacle 27. Hydrogen Peroxide Filter Hydrogen Peroxide Tank Lox Filler Fuel Tank Fuel Filler Turbine Pump Pick-Axe Antenna XLR11·RM-S Motor ANfAPN-60 Antennas AN/APN-60 Radar Installation Pitol Tube Tube Bundles (Nitrogen) Main Wheel Door Actuator Air Bollie Main Wheel Door Actuator Air Bottle Filler 21. AN/AAC-5 Radio Installation

Stor.k No. 0303

ABBREVIATIONS AND ACRONYMS: AAF AB AF AFB AH ARDC ASD g.

NACA NASA PARD PSI RMI tIc tho

USAF VHF X

Army Air Force Air Base Air Force Air Force Base Amp Hour Air Research and Development Command Aeronautical Systems Division Gravity National Advisory Committee for Aeronautics National Aeronautics and Space Administration Pilotless Aircraft Research Division Pounds per Square Inch Reaction Motors, Inc. Thickness/Chord Ratio Thrust United States Air Force Very High Frequency Experimental

THE BELL X·1 VARIANTS STORY

The second X-I, 46-063, during final assembly inside Bell's Niagara Falls, New York facilily, during late 194~. The wing~ with a thickness/chord ratio of 8%, and its associated center section, later were swapped with the 10% wmg of the flfsl X-I, 46-062, pnor to the latter s hlslonc flfst supersonic flight on October 14, 1947. With the exception of their wings and serial numbers, when compfeted, 46-062 and 46-063 were externally, Virtually Identical.

leading edge and all changes in velocity and pressure take place quite sharply and SUddenly. The airflow ahead is not influenced until the air molecules SUddenly are forced out of the way by the concentrated pressure wave set up by the actual object. Simply stated, compressibility anomalies occur at those speeds which approach or exceed the speed of sound. This velocity, in turn, is defined as the speed at which small pressure disturbances will be propagated through the air-which in turn is solely a function of air temperature. The accompanying table illustrates speed of sound variations in the standard atmosphere:

CREDITS: The authors and Aerofax, Inc. would like to express our thanks to the many individuals who contributed to this detailed description of the Bell X-1 research aircraft family. Three people who were particularly helpful in 3ssisting us under the auspices of Bell Aerospace [extron include Eddie Marek, Stanley Smolen, and Bob 3herwood. Eddie's Willingness to pull and file rare original legatives, and Bob's willingness to let him do it, provided the final contribution assuring the publication of this book. Stan's support and assistance gave Eddie the boost needed to persevere while digging. Because of the efforts of these three individuals, much of the imagery seen on the pages of this book has been released for pUblic consumption for the first time. Others whose efforts on our behalf won't soon be lorgotten include David Anderton, Bill Beavers, 'Joe Cannon, Bob and Gloria Champine (the latter of NASA Langley), Robert Cooper, Richard Forest (special thanks), Elaine Heise (Bell Aerospace Textron), Wes Henry (USAF Museum), Cheryl Hortel (Office of History, Edwards AFB), Alvin "Tex" Johnston; Helen Lapp (special thanks); Dave Menard; Robert Perry (RAND Corp.); Terrill Putnam (NASA Dryden); Michael Rich (RAND Corp.); Mick Roth; Sue Seward, Stanley Smith (special thanks); Tom Vranas (NASA Langley); and Lucille Zaccardi (retired from the Edwards AFB History Office). For another perspective on the X-1 story, Aerofax, Inc. highly recommends Richard Hallion's Supersonic Flight (the MacMillan Co., NY, 1972). And for a detailed description of the rest of the X-series aircraft, the pUblisher also recommends author Jay Miller's The X-Planes, X-I to X-31 (Aerofax, Inc., TX, 1988).

PROGRAM HISTORY: As an object moves through the air mass, velocity and pressure changes occur which create pressure disturbances in the airflow surrounding the object. Traveling at the speed of sound, these pressure disturbances are propagated through the air in all directions, extending indefinitely. If the object is traveling at low speed, the pressure disturbances primarily are propagated ahead of Ihe object and the oncoming airflow thus is influenced by the pressure field being generated. Once an object approaches sonic velocity, this scenario dramatically changes. There now is no warning for oncoming air molecules that the object is about 10 pass through. The oncoming air molecules cannot be influenced by a pressure field because none exists ahead. Thus, as flight speed nears the speed of sound, a compression wave (shock wave) is formed at the

Variation of Temperature and Speed of Sound With Altitude in the Standard Atmosphere Altitude

Ft. Sea level 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 50,000 60,000

Temperature

• F. 59.0 41.2 23.3 5.5 -12.3 -30.2 -48.0 -65.8 -69.7 -69.7 -69.7

·C. 15.0 5.1 - 4.8 -14.7 -24.6 -34.5 -44.4 -54.3 -56.5 -56.5 -65.5

Speed of Sound Knots 661.7 650.3 638.6 626.7 614.6 602.2 589.6 576.6 573.8 573.8 573.8

Thus it is that all compressibility effects depend upon the relationship of airspeed to the speed of sound. It is important to note that Ernst Mach (pronounced "Mahk"), a nineteenth century Austrian physicist and mathematician, became the first to enunciate the mathematical theory dealing with airflow. This theory assigned a numerical value to the ratio between the speed of a solid object through a gas (or space) and the speed of sound through that same medium. This became known as "Mach number"-with Mach 1 being equivalent to the speed of sound and with anything more or less than Mach 1 being given in terms of a percentage (i.e..85 Mach would be 85/100ths the speed of sound; Mach 2 would be twice the speed of sound; etc.). Today, Mach is the generally accepted term used to quantify supersonic speeds. By the beginning of WWII, aerodynamicists, structural engineers, powerplant designers, and numerous pilots had concluded that the science of flight was faced with an insidious aerodynamic hurdle of truly staggering implications. For the first time ever, compressibility phenomenon (also later referred to as the "transonic barrier" or "sound barrier"), a dynamic gaseous event wherein air molecules compress into a seemingly im· penetrable wall in front of an aircraft's wings and fuselage (and, as it were, spinning propeller blade leading edges) when it nears Mach 1, had raised its serpentine head. During the late 1930s and very early 1940s, new high·

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Rarely seen view of all three first-generation Bell X-I s under construction inside the Bell plant during late 1945. The aircraft on the left is 46-062, the one m the middle IS 46-064, and the one on the far nght IS 46-063. The forward fuselage section of 46-062 has been rotated 90° in its support crade.

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One of the first Bell design studies, dated early 1945, illustrating what was to become the Model 44, and later, the X-I. Noteworthy are the dual-wheel-and-tire main landing gear, the side-opening canopy, and the unfaired XLRII combustion chambers.

Rocket

A I/Bth-scale subsonic wind tunnel model representing the X-I as it eventually would be built. Of particular interest is the extended landing gear configuration and the diminutive, rarely-seen, lift dumping upper-wing-surface spoilers.

performance pursuit (as they then were called) aircraft, such as the U.S. Army Air Force's Lockheed P-38 Lightning and Republic P-47 Thunderbolt, capable of achieving Mach numbers approaching. 75 in a dive, had begun to enter the operational inventories of the world's military flying services. Their speed capabilities were close enough to sonic velocity and its associated compressibility phenomenon to cause serious, and sometimes irreversible buffet, structural overload, control, and stability problems. Already compressibility's associated loss of control and resultant occasional catastrophic structural failures had led to the deaths of several pilots. It had become painfully obvious to the world aviation community that, unless something was done to eliminate or circumvent the problem, more deaths soon would follow. Because research tools during the 1930s and early 1940s were limited in capability and technology, compressibility was not an easily understood phenomenon. Wind tunnel data, so commonplace as a means of predicting aircraft performance and flight characteristics today, almost was non-existent in the speed and dynamics regime encompassed by transonic and supersonic aircraft design, and only bullets then were known to be capable of stabilized "flight" at speeds in excess of sonic velocity. Supersonic phenomena, which occurred beyond the speed of sound, also were little understood. Such things as wave drag, high-speed flutter, "shock stall", centerof-pressure shift, the affect of supersonic speeds on interference drag, and the static and maneuvering load anomalies associated with supersonic flight were mysterious, and at times frightening unknowns. There even was concern over the possibility that something beyond prediction might occur-no human being had flown supersonically and lived, and no one knew for certain what strange and potentially disastrous' surprises awaited the first to explore. Over a period of several years, the phrase "sound barrier" came to describe the invisible gaseous wall generated in front of an object moving at or near the speed of sound. On paper, some aerodynamicists had predicted that at supersonic speeds, because of this "wall", drag and lift would reach infinite proportions and

2

thus create a barrier that literally could not be penetrated. The first serious thrust in the direction of conquering compressibility had come during the SeptemberlOctober 1935 Fifth Volta Congress on High Speeds in Aviation, held in Campidoglio, Italy. Attended by a large number of the world's leading aerodynamicists and aviation engineers, it proved a historic milestone due to its emphasis on supersonic flight. Among the American representatives attending was Theodore von Karman, who later would have a decidedly influential effect on the birth of the X-plane program in the U.S. von Karman's reaction to the meeting was immediate and significant; he became convinced that supersonic flight was possible, and he became adamant the U.S. should initiate a research program quickly that would explore this monumental leap forward in aircraft performance. During approximately this same time period, another engineer, Ezra Kotcher, who then was an instructor at the Air Corps Engineering School at Wright Field near Day1on, Ohio, also had become enamored with the proposition of supersonic flight. Having attended a lecture by fellow engineer Lt. Col. H. Zornig on the dynamics of supersonic ballistics, Kotcher had come away convinced that flight at supersonic velocities was within the realm of possibility. Over the following several years, Kotcher reviewed what he had gathered at the Zonig lecture and by mid-1939, was prepared when asked to write a report describing his views on the subject of problems confronting future aeronautical research and development. Completed during August, the paper was circulated through several engineering offices, eventually finding its way onto the desk of Maj. Gen. H. H. "Hap" Arnold, and into the offices of the NACA (National Advisory Committee on Aeronautics). Kotcher's paper was progressive and far-sighted. He placed heavy emphasis on the need for an extensive series of full-scale flight test programs to be complemented by related wind tunnel studies. He also placed heavy emphasis on the development of gas turbine and rocket propulsion systems, already noting that the conventional piston engine and its associated propeller propulsion systems would not be sufficient to explore truly

high speeds. Though appearing quite reasonable from perspective, Kotcher's ideas proved too radical fa The rumblings of war now were becoming quite ( and the momentum being gathered in the aircraft i was strictly production oriented. Compounding th lem, while at the same time adding to its validity, \ fact that wind tunnel data was extremely limite( critical area of transonic flight. Technically the regime approximately encompa: the speeds between Mach .7 and Mach 1.3, the tr, envelope was important because it was in this range that the most radical changes took place a~ ject translated from subsonic to supersonic vel Without wind tunnel data to verify events in this al only way to explore it was with full-scale hardw The basis for the wind tunnel anomaly was the tion of shock waves off wind tunnel walls and ba the model being tested. From Mach .7 to Mach angles of shock wave reflection were such that it' tually impossible to eliminate the reflection difficult then-state-of-the-art tunnel design. Known as "ch, the problem foiled attempts at accurate data acq and prevented aerodynamicists from acquiring into events in the transonic zone. Because of this dilemma, new impetus was pia the Kotcher proposal calling for a full-scale re vehicle to explore transonic phenomena. Kotch not, of course, the very first to conceive the idea 01 sonic research aircraft. His proposal, in fact, ha preceded by the until-1940 generally unheralded fellow aerodynamicist John Stack who, as early a had begun conceptualizing rudimentary aircraft ( optimized for studying transonic phenomena. By 1941 , aircraft such as the aforementioned Lo P-38 Lightning and Republic P-47 Thunderbo, beginning to enter the Army's inventory for the fir: These were the first U.S. aircraft fully capable a in the "compressibility zone" on a routine basis, at the first to confront the realities of its affects. The exigencies of war overshadowed the n thoroughly explore the undesirable affects of tra speeds on extant aircraft design technique, so th, lem was sidestepped:temporarily by limiting aircr<

(Bot" I, to r) Dick Frost (fit. tst, proj. eng); Jerry? (chi. proj. insp); Harold Dow (B-29 co-pit); unknown: Benson Hamlin; Clarence Quillan (exp, shop man); (top I, to r) George White (exp, hang, man); Bill Smith (chf, rock, eng); Steve Elgren; Julius Domonkos (v,p" Mfg); Jack Strickler (asst. chI. eng,); Larry Bell (pres); Leston Faneuf (pres, asst); Harvey Gaylord; Ray Whitman (1st, v,p,); Stanley Smith (pro}, eng); Bob Woods (ch, desJch. prelim, des); Roy Sandstrom (ch, eng); Paul Emmons (ch, aero); ? Devine (compt.).

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speeds to safe velocities and by beefing up structures to withstand the loads imparted by flying at relatively high subsonic velocities, Propulsion limitations eliminated concern in level flight as no piston engine aircraft then flying was even marginally affected by compressibility in that attitude, The infusion of money and manpower into the war machine that was mandated by WWII proved fertile ground for technology, Among its many offspring were several monumental advances in aircraft propulsion, not the least of which were viable and routinely reusable rocket engines and functional turbojet propulsion units, The advent of such powerplants placed a heavy burden on then-extant aerodynamic and structural design techniques as suddenly it was possible to propei an aircraft or missile to transonic velocities in level flight on a routine basis, The power-to-weight ratios of these new propulsion systems were many times that of their piston-andpropeller predecessors, Unfortunately, this propulsion leap was not easily mirrored in the aerodynamic progress of the day, In the U,S" Robert Wolf, an engineer with Bell Aircraft Corporation of Buffalo, New York, began like Stack, von Karman, and Kotcher, during 1943 to conceptualize the idea of a high-speed research aircraft, Attending a special NACA conference in Washington, D,C, during December of that same year, he proposed that the power advantages of the new turbojet engines then under development in Britain and the U,S, be integrated into the design of a transonic research aircraft, Coupling this proposal with a suggestion that development responsibilities be undertaken by a multi-faceted team consisting of Army, Navy, and NACA personnel, he went on to suggest that the military fund it, the aircraft industry develop it (with input from the military and the NACA), and the NACA night test it Information and data generated by the NACA program would be disseminated throughout the U,S, aviation industry, Parallelling Wolf's rather timely proposal, which eventually found its way into the upper echelons of the NACA, was a growing sentiment within the confines of the War Department that a serious transonic research program be undertaken, Kotcher's 1939 proposal now resurfaced, and with the January 1944 issuance of Confidential

Technical Instruction 1568, calling for "the initiation of a study of the possible development of an experimental article for the purpose of investigating aerodynamic phenomena in the range of 600 to 650 mph", the Development Engineering Branch of the Materiel Division at AAF Headquarters in Washing!on, D,C, finally elected to move forward with a legitimate research effort, With the blessing of the Air Force, a small cadre of aerodynamicists and engineers began studies optimized to meet the new requirement Among these was Kotcher, who now decided to investigate the respective advantages and disadvantages of rocket (specifically an Aerojet unit of 4,000 Ib, th,) and jet propulsion (specifically the General Electric TG-180 of 4,000 Ib, th,) systems for what soon was to be known as the Wright Field "Mach 0,999" study, The comparison was completed during April 1944, by the Wright Field Design Branch of the Aircraft Laboratory and the results led to the conclusion that a rocketpropelled design offered the greatest performance, The high thrust-to-weight ratio of the rocket engine, coupled with its expected superior operation in level flight at high altitudes, far outweighed any advantages provided by jet propulsion systems-which were expected to require dives from high altitude to achieve the research aircraft's velocity objectives, Along with the Design Branch's proposal was a prospective aircraft design, Not surprisingly, it superficially resembled the hardware that would eventually be built by Bell Aircraft Corporation as the X-1, Its fuselage was circular in cross section with a faired canopy, the wings were mid-fuselage-mounted and of essentially conventional straight-wing planform, and the vertical fin also was straight The only major variation was the placement of the horizontal tail surfaces which on the Design Branch aircraft, were fuselage-empennage-section-mounted, rather than vertical fin mounted, Kotcher and von Karman now joined forces in an attempt to push the transonic research aircraft proposal through to the hardware stage, Concommitantly, the NACA began studying alternative transonic exploration methods, eventually working with their British counterparts on a series of test projects that included the use of scale models (called "falling bodies") dropped from

full-scale aircraft flying at very high altitudes (the resulting supersonic free-fall dives being documented both photographically and with radar), and the use of "bump models" attached to the upper wing surfaces of highperformance aircraft such as the North American P-51 Mustang (during a dive from high altitude, the localized flow over the upper surface of the Mustang's laminar flow wing could be made to exceed sonic velocity, thus exposing the small' 'bump model" to sonic airflows for short periods of time), This work, coupled with ground launched, rocket-propelled model tests conducted by the NACA's Pilotless Aircraft Research Division (PARD) at Wallops Island, Virginia, added significantly to the basic transonic data base without undermining the existing need for a full-scale testbed aircraft, While these various efforts were on-going, the Army Air Technical Service Command, the Navy Bureau of Aeronautics, and the NACA gathered at the NACA's Langley Laboratory, Virginia, on March 15, 1944, and during the course of two conferences, devoted significant time to the problem of the transonic research aircraft The meetings proved quite productive, not only in bringing together for the first time the Army (Air Force), the Navy, and the NACA, but also in initiating the first steps toward the development of actual hardware, As it were, the two meetings also permitted for the first time a dichotomy to surface that eventually would lead to two different approaches to the transonic aircraft project The NACA and the Navy, because of these two meetings, eventually would join forces to develop a conservative jet-propelled aircraft of somewhat limited performance potential (thus giving birth to the Douglas D-558-1 and D-558-2 research aircraft family), The Air Force and the NACA would join in a less balanced relationship that would result in a somewhat more radical rocket-propelled design (the Bell X-1 family), The latter was the product of a May 15, 1944, meeting with NACA representatives requested by the Air Forcewhich was represented by Ezra Kotcher. The NACA, during the course of the discussion which centered around the aforementioned "Mach 0,999" study, asked for additional time to respond with a design of its own, Two months later, on July 10, the NACA proposed a more conservative (and thus potentially safer) aircraft that was

3

Three key personnel in the design and preliminary flight test stages of the X-I program included (from I. to r.) Alvin "Tex" Johnston, Robert Stanley, and Richard Frost. Johnston later would become one of Boeing's most accomplished test pilots.

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In preparation for its static structural load test program, the first X-I was rolled inverted via an elaborate hoist assembly and then lowered onto a special dolly. Via the dolly, it then was moved into Bell's structural test stall.

The static structural test program was the first of its kind for a manned, supersonic aircraft. The X-I easily met its specified 18 g load limit, making it perhaps the strongest aircraft in the world at the time of its manufacture.

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The X-I 's fuselage cross-section was almost perfectly round and was marred only by the dorsal and ventral fairings housing propellant lines and control cables. Sweptwing L-39 testbed, one of two built by Bell, is visible in the background.

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In order to accommodate 8-29 loading requirements, a special pit was dug next to the Bell plant permitting the 8-29 to straddle the aircraft during the uploading process. A similar pit also later was dug at Muroc.

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sonic desigr quentl fective ed in c consel 0-558· Witt lookin! Karma mind. reache leap fl The first X-I, 46-062, during the occasion of its informal roll-out on December 12, 1945 Thre A more formal event took place on December 27, after the aircraft had been painted the pr< and minor detail work had been completed. Small transport dolly is noteworty. ductee object exped

Ezr< persol ing as propo: mentl given later, ---"-- with tt numel With the X-I in the pit, the 8-29 could be maneuvered into position by a tow tractor and in with little difficulty. A hoist assembly then was attached to the X-I to raise much it into position. Snubbers then helped hold the X-I firmly in place. Kote

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The lirst X-I, 46-062, shortly alter roll-out at Bell during early 1946. The aircralt has yet to be painted and detail assembly is not yet complete. VHF radio mast on top 01 the lorward luselage is noteworthy as it later was removed.

The first X-I, 46-062, during weight-and-balance tests at Betl, and 10110 wing painting. When empty, the X-I's center-ai-gravity was virtually neutral, thus requiring the shot-bag weights seen on the tow bar attached to the nose gear.

Initial glide flight trials 01 the first X-I took place at Pinecastle Field near Orlando, Ftorida during late January 1946. A toading pit, to accommodate B-29 ctearance requirements was built there, but was utilized on only a lew occasions.

powered by a turbojet engine. Air Force representatives were quick to reject the proposal, and within a short time, had agreed to endorse Kotcher's original "Mach 0.999" design as the one most likely to meet the Air Force transonic research aircraft requirement. The Navy, conse· quently, elected to forge ahead with its own design, ef· lectively blessed by the NACA, and eventually succeed· ed in consummating a relatively successful, but decidedly conservative flight test program with the Douglas D·558-1/-2 aircraft series. With Air Force approval now in hand, Kotcher began looking for a contractor to build the aircraft he, von Karman, and a host of other curious engineers had in mind. It now was the end of 1944, the war in Europe had reached its zenith, and the time was ripe for the next great ieap forward in aviation. Throughout 1944, design and engineering studies for the proposed compressibility research aircraft were con· ducled by the NACA, the Air Force, and the Navy. The objective was to determine the most sensible and expedient means of development.

sonic aircraft and began a study that compared the merits of rocket versus jet (and ramjet) propulsion. Eventually he concluded that the rocket·prop'elled research aircraft offered superior performance and greater versatility. With Kotcher looking over their shoulders, an engineering team at Wright Field, consisting of Capt. F. D. Orazio and Capt. G. W. Bailey, proceeded to design an aircraft that, it was hoped, could explore the transonic speed envelope. Kotcher took this design and presented it to several Army Air Force and NACA teams. The latter needed little convincing as to the merits of the project as NACA engineer John Stack, long a proponent of highspeed research aircraft, had been pushing for transonic research aircraft program support for well over a decade. Stack, in fact, had been instrumental in calling together a conference on high-speed flight in which the Army Air Force and the Navy had been asked for the first time to build a transonic aircraft for research. At the time, the NACA was not in the political or financial position to back such a project, but it was stated unequivocally that if either or both the Army and Navy would fund construction, the NACA would be happy to conduct the flight test

THE DEVELOPMENT AND FLIGHT TEST PROGRAMS:

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program.

Ezra Kotcher was perhaps the single most important personality in the U.S. transonic aircraft program. Working as an engineer at Wright Field during 1939, Kotcher proposed that the Army Air Corps sponsor the development of a transonic flight research aircraft. This was not given serious consideration at the time, but four years later, following the advent of compressibility problems with the Lockheed P-38 and RepUblic P-47 (and, by now, numerous other high·performance aircraft, both foreign and indigenous) strong interest in transonic flight led to much needed government and industry support. Kotcher, during early 1944, renewed his work on tran-

rocket propulsion. NACA engineers considered turbojet propulsion a safer, albeit admittedly more conservative proposition and they asked that Kotcher reconsider his stance to accommodate their wishes. While Kotcher and the Army Air Corps worked on their proposal, the Navy initiated work on a totally independent Navy-sponsored transonic research aircraft project. This eventually gave birth to the Douglas D-558-1

Skystreak, which proved a successful testbed, but one

of only minor importance in the field of transonic research.

BELL X·1 (The First Generation): By the summer of 1944, Kotcher had received approval

and permission from his superior, Dr. Theodore von Karman, to find a contractor and begin development of project MX-524, a rocket-propelled transonic research air· craft. Finding a contractor, however, proved significant· Iy more difficult than expected. During 1944, the U.S. aviation industry was in the middie of an incredibly massive wartime production program that eventually would result in the delivery of several hundred-thousand aircraft. Virtually every aircraft manufacturer and sub-contractor in the country was booked solid with prime and sub-contract work. By the fall of 1944, Kotcher had become somewhat frustrated: though quick to acknowledge the need for a transonic research aircraft, none of the major contractors had expressed serious interest in building it and all questioned the project's economics and timing. Every1hing changed on November 30,1944. Bell Air. craft Corporation design engineer (and one of the Bell founders) Robert Woods, while at Wright Field on Bell business, stopped in to visit with Kotcher at his Wright Rield office. As it were, both engineers maintained a strong interest in transonic aerodynamics, and Woods had elected to visit with Kotcher to discuss recent advances and related news. Kotcher was not long in working the ensuing conversation around to his transonic 'research aircraft. It was with some surprise that he discovered Woods was a serious listener, and better yet, one who supported Kotcher's enthusiasm for the development of full-scale transonic hardware. After hearing from Kotcher that the Air Force would require only that the air· craft be guaranteed safe and controllable up to a Mach number of 0.8, Woods committed Bell Aircraft Corporaiion to build the aircraft of which Kotcher had dreamed for almost five years. Woods returned to Beli's plant near Buffalo, New York several days later and with the assistance of chief engineer Robert Stanley, immediately began assembling the engineering team that would create the world's first manned supersonic aircraft. Among the members chosen were Paul Emmons, Benson Hamlin, Roy Sand-

5

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There was /ittle in the way 01 sophistication involved during the Pinecastle trials, including the use 01 a civilian "woody" to serve as a tow truck! Noteworthy, though barely discernible, is the Bell logo just alt 01 the cockpit hatch.

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Support personnel examine the minor wing damage that occurred lollowing the collapse 01 the left main gear during landing at Pinecastle on February 8, 1946. Pilot Jack Woolams is visible in his flight suit as the second person Irom the right.

strom, and Stanley Smith. Stan Smith later became chief project engineer. During his initial meeting with Kotcher, and later preliminary design meetings at Bell, Woods had requested that the MX-524 aircraft be visualized in terms of turbojet propulsion. Later, however, following a review of notes and several engineering team studies, he acceded to Kotcher's recommendations and redirected the team to concentrate on rocket powered designs only. By December 1944, the Air Force, Bell, and the NACA had completed the final specification draft. ConsequentIy, an NACA team submitted instrumentation requirements, and Bell engineers met with Wright Field representatives to formalize initial configuration concepts and basic performance and controllability objectives. The official X·1 contract (W33·038-ac-9183) was signed on March 16, 1945. Three aircraft were to be built. They would be assigned Air Force serial numbers 46-062, 46-063, and 46-064. Originally these aircraft were designated XS-1. By late 1947, due to changes in the Air Force designator system, the "S" (for "Supersonic") had

By the summer of 1945, the new aircraft was known in-house at Bell as the Model 44 and the Wright-Patterson people had assigned it a new project designator. Now referred to as the MX-653, it was given a high priority status and classified secret. Even at this late stage of development, controversy continued as to whether the X-1 should be ground- or air-launched. Woods, a proponent of the ground-launch (conventional) method felt that by designing the X-1 for ground-launch, it would be possible to eventually develop it into a point defense interceptor. Stanley, on the other hand, felt that the aircraft's performance would be seriously degraded by the wasting of fuel required to get to test altitude from ground level. As it turned out, Woods' argument proved in vain, as the powerplant's turbopump, required to move fuel and oxidizer from the fuel and oxidizer tanks to the rocket engine combustion cnambers, became seriously delinquent in meeting its availability schedule. Accordingly, air-launching became the only alternative that would permit the X-1 to achieve its performance objectives. The loss of the turbopump dictated the use of pressurized

been officially dropped. Because of the scarcity of supersonic aerodynamics data available during 1945, it was necessary for the Bell engineering team to make important decisions concerning airfoil sections, pilot safety, propulsion, landing gear, windscreen design, structural integrity, and wing configuration based on estimated performance. The X-1 's fuselage configuration, for instance, was very much the end product of a study of the conventional .50 calibre bullet. This was the result of research conducted by two of Woods' engineering team members, Benson Hamlin and Paul Emmons, who had concluded that the only way to accommodate their data gap was to observe actual objects known to be capable of traveling at supersonic velocities. Discussions with ballistics experts and armaments specialists soon led to the conclusion that little actually was known about the aerodynamics of the .50 calibre slug. However, there was no question that it was a stable configuration while moving at sonic velocities.

nitrogen gas to force the fuel and oxidizer from the aircraft's tanks. Additionally, the nitrogen tanks added significant weight while taking up considerable internal volume. The X-1 full-scale mock-up was inspected on October 10, 1945, by representatives from the Air Force and the NACA. As no major changes ensued, the design was approved for construction. Concommittantly, ongoing 6000C4 (Air Force designation was XLR11) powerplant work by the small Reaction Motors, Inc.. engineering team was given renewed support, though already it was becoming apparent that delivery of the first flightworthy engine would not be on schedule. The first X-1, 46-062, was completed during late 1945, and rolled out of Bell's Wheatfield, New York plant doors on December 27. On January 19, 1946, it was flown by B-29 (45-21800) carrier aircraft (piloted by Harold Dow and Joseph Cannon and crewed by Ivan Hauptmann, William Means, and Herman Schneider) to Pinecastle Field near Orlando, Florida, where preliminary flight

testing was to take place. The first glide flight, with ballast in place of the sti, delayed powerplant, was completed successfully 0 January 25, 1946 (some controversy remains concerni~ this first glide flight date, as various sources state Janual 19 as the actual day; however, research by the co-autha Ben Guenther, has determined the January 25 datea correct). The launch, from 27,000 feet, was relative! problem free and with Bell company test pilot Jao Woolams in the cockpit, the X-1 returned to Pinecas Field, safely. In part, Woolam's post flight report stated: "The break with the 8-29 was clean as the XS·l dropped with an initial force of approximately one negative g with the tail slightly low. The research airplane drifted aft approximately one foot for six feet of drop. Aerial observers unanimously agreed that the dropping characteristics were ideal. No discomfort was experienced by the pilot of the XS-l during the initial stages of the release. 8-29 crew members reported that they felt hardly any reaction to the release of the research airplane. "Once in free flight, the XS-l glided absolutely noiselessly at quite a flat gliding angle, as was to be expected of such a clean design. At speeds up to 275 observed mph, which was the highest reached on this flight, the airplane fell as solid as a rock, experiencing absolutely no vibration or noise. At the same time, it felt as light as a feather during maneuvers due to the lightness, effectiveness, and nice balance between the controls. Longitudinal stability is quite positive; slick force versus g satisfactory up to 3 g's (the highest attained on this flight); directional stability positive, with fair dampen. ing and lateral stability about neutral, although satisfac· tory for normal conditions. "The stall with the landing gear and flaps retracted is preceded by center section buffeting and occurs at an observed airspeed of 120 mph. There is no tendency to drop off on a wing and some aileron control is maintained to the end giving support to the possibility that the wing does not completely stall. The stall with the landing gear and flaps extended is preceded by a little less buffeting than the clean configuration stall, and occurs at an observed airspeed of 110 mph. The stall is complete and satisfactory. The tendency for the airplane to drop off on one wing or the other to a slight degree is readily corrected by the rudder. A slight amount of lateral instabili· ty, requiring correction by use of the ailerons, manifested itself as the stall occurred, but is not considered to be

no air

Ten Iy wen sion t< been I and th bed. Unf make was ki Cobr£' nickn: comp, "Tex' would $19.4' Ch, chief I the Xalso 0 ect er Frost. engin and a notori ThE to Mu time I to hal tic ral origin tail SL the SE tion e ThE flight, follow a thin two V powe Bel secor modil

of serious magnitude.

5, wa

"The spoilers are very effective with the clean con· figuration. When the landing gear and flaps are extended, the angle of descent of the airplane is very steep and it was difficult at high altitude to determine the magnitude of the increase in rate of descent due to raising the spoilers. It appeared, however, that their relative effec· tiveness was only about one-half of what it was with the airplane in the clean configuration. "Due to a miscalculation on the part of the pilot, the airplane was landed somewhat short of the runway prop· er and on the hard grass shoulder of the runway, without damage. The flaring characteristics of the airplane for

Chair cessf SOl contr dition stane manE to the contr cond imurr

landing were normal.

"Visibility in flight, while not good, is adequate, although the pilot must bank the airplane to see the landmarks below within a radius of about five miles. Landing visibility is good due to the steep glide angle, and ground visibili· ty is adequate. "Of all the airplanes the writer has flown, only the xp-n and the Heinkle 162 compare with the XS-l for

Du tative totaf From toexi

maneuverability, control relationship, response to control

trans In ore jectiv differ Th

movements, and lightness of control forces. Although The lirst X-1 immediately 10110wing launch at altitude over Muroc during 1947. Shock diamonds are visible in the engine exhaust and the aircralt is just beginning to accelerate. In order to preserve propellants, ascent to mission altitude usually was undertaken with only one or two 01 the XLR11 's lour chambers functioning.

6

these impressions were rather hastily gained during a flight which lasted only 10 minutes, it is the writer's opi·

nion that due to these factors and adding to them the security which the pilot feels due to the ruggedness,

usin~

The first X-l on June 4, 1946. Side-view invites comparison with standard .50 cal. bullet. With the exception of the dorsal and ventral spines, the landing gear, and the vertical and horizontal tail surfaces, the shape was virtually identical.

noiselessness, and smoothness of response of this airplane, it is the most delightful one to fly of them aiL" Ten glide flights by the the first X-1, 46-062, eventualIywere completed at Pinecastle, though by March, a decision to move to Muroc Air Force Base in California had been made based on the remoteness of the latter facility and the expansive landing areas provided by its dry lake bed. Unfortunately, Bell test pilot Jack Woolams would not make it to Muroc with the X-1. On August 30, 1946, he was killed in a special race-configurated P-39 nicknamed Cobra I. This heavily modified aircraft, and a sister ship nicknamed Cobra II, had been created specifically to compete in the 1946 Thompson Trophy race. Alvin M. "Tex" Johnston, Woolams partner in the project, later would win the race in Cobra II, turning over half the $19,400 winnings to Woolams' wife shortly afterwards. Chalmers "Slick" Goodlin now replaced Woolams as chief Bell test pilot and accordingly, took over his slot in the X-1 program. During this same time period, changes also occurred in the X-1 engineering team, with X-1 project engineer Stanley Smith being replaced by Richard Frost. Smith now was moved into the position of project engineer for the upcoming X-2, and Frost, a Bell test pilot and aeronautical engineer of significant skill and some notoriety, was named to replace him. The second X-1, 46-063, now was delivered by B-29 to Muroc on October 7, ahead of the first aircraft (by this time having been returned to Bell from Florida in order to have new 8% thickness/chord (tic) ratio wings and 6% Vc ratio horizontal tail surfaces installed in place of the original 10% tic ratio wings and 8% tic ratio horizontal tail surfaces-which had been removed and installed on the second aircraft), in order to initiate the powered portion of the X-1 flight test program. The second X-1 successfully completed its first glide flight on October 11 with Goodlin at the controls. This was followed by a second successful flight on October 14, and athird on October 17. A fourth glide flight followed some two weeks later, and finally, on December 9, the first powered flight was logged. Bell continued contractor-required flight testing of the second X-1 until the middle of 1947. During March, the modified first aircraft was completed at Bell and on April 5, was flown by B-29 to Muroc. There on April 11, with Chalmers Goodlin at the controls, it completed successfully its first powered flight. Some 20 powered flights, as required in the original contract, were completed by Bell through May 1947. Additionally, the aircraft proved easily capable of withstanding the required 8 g dynamic loading during maneuvers, and handling proved virtually faultless out to the specified Mach .8. This effectively concluded Bell's contractor obligations and accordingly, the first and second aircraft were turned over to the Air Force for maximum performance flight trials. During June 1947, Air Force and NACA representatives met at Wright Field to discuss what best approach to take to accomplish several mutually beneficial goals. From this meeting came a decision to allow the Air Force to explore the transonic and supersonic speed envelope using the first aircraft, and to allow the NACA to explore transonic stability and control using the second aircraft. In order to accomplish these two somewhat different objectives, the aircraft would be equipped with decidedly different instrument packages. Three Air Materiel Command personnel were assign-

Rarely seen together, the first two X-Is, 46-062 (I.) and 46-063, pose between flights at Muroc during 1947. The 8-29 launch aIrcraft, 45-21800, IS In the background The second X-I SItS Just In front of the Muroc loading pIt ramp

ed the task of heading up Air Force X-1 operations. These were James Voyles, project engineer; Paul Bikle, head of the Flight Test Division's Performance Engineering Branch; and Col. Albert Boyd, chief of the Flight Test Division. Boyd would shortly afterwards playa key role in the Air Force pilot selection process. Three pilots, Capt. Charles E. "Chuck" Yeager, Lt. Robert A. Hoover, and Capt. Jack Ridley, all volunteers, eventually would be picked by Boyd from among a select group, these three shortly afterwards being sent to Bell's Niagara Falls facility where they were introduced to the X-1 and its various idiosyncrasies. The NACA also moved forward with its part of the X-1 program, assigning agency test pilots Herbert Hoover and Howard Lilly to the project and seeing to it that they were exposed to all facets of the program through Bell project engineer Richard Frost. Shortly after the Air Force's X-1 team members were selected, the program officially got underway. On July 27, 1947, everyone assembled at Muroc for the beginning of Air Force flight trials. It took nearly a week for actual Air Force flight testing to begin, but finally, on August 6, following a series of ground tests to verify powerplant performance, the first X-1, with Yeager at the controls, was dropped from its B-29 carrier aircraft for the first time over Muroc. Two more familiarization flights, with Yeager in the cockpit, followed, and finally, on August 29, the first powered flight was successfully completed. Like his Bell predecessors, Yeager found the X-1 to be exceptionally docile. • A second powered flight followed on September 4, and a third on September 18. Slowly, with the successful completion of each flight, the speed envelope was expanded

to higher and higher Mach numbers. On September 12, the fifth powered Air Force X-1 flight was successfully completed with a speed of Mach .92 being attained. The aircraft now was temporarily grounded in order to allow time for the installation of a quicker responding horizontal tail surface actuator, and at the same time, Yeager was sent to Wright Field to be fitted for a pressure suitwhich was considered a necessary safety precaution at the altitudes being reached. By the eighth flight, Yeager had flown the first X-1 (nicknamed "Glamorous Glennis" in tribute to his wife) out to Mach 0.997-not only a world's speed record, but also the closest anyone had come yet to penetrating the mysterious transonic barrier. It now was time to take the big plunge. The transonic mission was scheduled for October 14. A thorough check of the X-1's powerplant and airframe was made in the interim, and additional checks were run on the carrier aircraft and various pieces of test gear. Finally, on the scheduled morning of the flight, Yeager, quietly hiding the fact that he had suffered two broken ribs during a surreptitious fling the night before, boarded the aircraft and prepared for the flight. At approximately 10:00 a.m., the B-29 and its bright orange rocketpropelled payload headed down the main Muroc strip and into the cool desert sky. Twenty minutes later, they were at the predetermined launch altitude of 20,000 feet. The drop went smoothly. Igniting two chambers for the initial acceleration and climb, Yeager pulled back on the X-1's yoke and headed for 40,000 feet where the speed run was scheduled to be made. Shortly before assigned altitude was reached, Yeager began nosing over the X-1 so that 40,000 ft. would not be exceeded. Leveling off moments later, he flipped on

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The second X-I, 46-063, folfowing completion, in the static load testing jig at 8ell. Unlike the first X-I, 46-062, which was inverted during tests, 46-063 was tested in a conventional, up-right attitude. National insigne and company logo have been covered with wrapping paper for protection, indicating the aircraft had been painted.

7

a third rocket chamber and watched as the Mach mete§ needle rapidly progressed round the dial to the Mach ~ indicating point. Seconds later, with little if any physie~ indication that something historically significant halt occurred, it moved to the Mach 1.06 (700 mph) positiore and stopped. . ~ Yeager now flipped off the powerplant switches a~ allowed the X-1 to decelerate down to subsonic speec Ten minutes later, he and the orange research aircra' touched down on Muroc Dry Lake. With little fanfare, tn first manned supersonic flight in history had been safe~ completed .. Yeager, later would summarize the flight in part a follows:

The second X-I, 46-063, at the time of roll-out during the fall of 1946. Like its stablemate, 46-062, the second aircraft also was painted bright orange overall and given only conventional national insigne on its wings and fuselage. Wingtip and nose booms accommodated static pilot and pitch/yaw data requirements.

--~~

All three X-Is had conventional horizontal stabilizers and elevators. Unlike most conventional aircraft, however, the horizontal stabilizer was adjustable in flight, thus permitting what then were considered critical trim changes as the aircraft accelerated into the transonic speed regime.

-----~

The second X-I as viewed from the rear underscored the extreme simplicity of the basic X-I design. The circular fuselage cross-section and mid-fuselage-mounted wings were textbook perfect. Though the X-I had a very narrow main landing gear tread, pilots found landings generally provided few difficulties.

The second X-I shortly after roll-out during late 1946. Like 46-062, it was painted bright orange over-all, with standard national insigne on the fuselage and wings. The Bell Aircraft Corporation logo appeared on both the vertical fin (under the horizontal stabilizer) and the nose.

8

"With the stabilizer selting at 20 the speed was allowed to increase 'to approximately .98 to .99 Mach number where elevator and rudder effectiveness were regained and the airplane seemed to smooth out to normal flying characteristics. This development lent added confidence and the airplane was allowed to continue to accelerate until an indication of 1.02 on the cockpit Mach meter was obtained. At this indication the meter momentarily stopped and then jumped to 1.06 and this hesitation was assumed to be caused by the effect of shock waves on the static source. At this time the power units were cut and the airplane was allowed to decelerate back to the subsonic flight condition. When decelerating through approximately .98 Mach number a single sharp impulse was experienced which can best be described by comparing it to a sharp turbulence bump."

The mission's achievement remained secret for In following two months but finally, in Its December 22, 194 issue, Aviation Week leaked the news, the story mad headlines across the country and around the world-a~ caught the Air Force completely by surprise. Rumorse legal action, based on what was considered aver serious security breach, persisted for weeks, but nothi~ came of them, The flight now was public knowledge an a lawsuit could not put it back under wraps. Air Force testing of the first X-1 proceeded at a bril pace following Yeager's momentous flight. Furtne aerodynamic studies were conducted during the spri~ of 1948, and on March 26, during the 22nd Air Force mil sion, Yeager reached a speed of Mach 1.45 (957 mph: In OJ An This was to become the highest speed attained by an th of the first generation X-1 s and was, in fact, represer. tative of the aircraft's true maximum speed potential: Once the speed envelope had been thoroughly eli plored, further tests were conducted to determine t~ X-1's more mundane aerodynamic characteristics, ~ number of pressure distribution survey and low altitud! missions were flown to ascertain controllability in dens~ atmosphere, and a variety of high-speed and low-speel stability trials were undertaken. One of the first X-1 's (46-062) more unique flight occurred during early 1949. The Air Force long had bee! curious to know what kind of performance the X-1 couk achieve using a conventional ground takeoff, Accordi"! Iy, on January 5, a test was conducted from Muroe'l Rogers Dry Lake. With Yeager at the controls and will the first X-1 equipped with new tires, tubes, and brakl pads, and specially fueled and balanced in order to 8C commodate its rather fragile landing gear, ignition of a four XLR11 chambers qUickly moved it down the takeli strip. Just over a mlnute-and-a-half later, an altitudeo 23,000 ft. had been reached, Engine power now was em and a glide path back to Muroc was taken, FollOWing t~ jettisoning of remaining propellants, Yeager completa a smooth landing and what was to become the one an only ground launch ever conducted by a manned, rocke! propelled X-designated aircraft. During the spring of 1949, several new Air Force pilo~ assigned to the Air Force X-1 program arrived at Muroo Among them was Maj. Frank Everest, who soon w~ tasked with exploring the first X-1's maximum altitu~ capability. The first of these altitude flights, following I short familiarization flight series, was conducted on Apli 19,1949. During the mission, powerplant problems CUI tailed reaching maximum performance, though m altitude of 60,000 ft. was attained. Another mission on May 2 ended with even mon serious difficulties when an explosion seriously damaga an engine combustion chamber section and at the sam time, jammed the base of the rudder. A relatively unevenl ful landing followed, but the aircraft was grounded fo almost six weeks while repairs were made. Following the repairs, which were undertaken at Wrig Field under Air Force supervision, the first X-1 was f! turned to Edwards and prepared for further altitu~ Iv. flights. On July 25, It again was launched with Everes ) in the cockpit, this time reaching an X-1 record altitudl of 66,846 ft.

The second X-I, 46-063, was the first to arrive at Muroc. Equipped with the first X·I's 10% thickness/chord ratio wings, it was air-transported to California on October 7, 1946. The first X-I, 46-062, followed on April 5, 1947.

The second X-I during early 1947 static tests of its XLRII rocket engine. All four chambers have been ignited and maximum thrust is being generated. Noteworthy is the fact the aircraft is unchocked and tied down only by a single cable.

In order to facilitate X-I loading, a special pit was dug into the Muroc south base ramp. An incline permitted the aircraft to be rolled backwards into the pit. The carrier aircraft then was maneuvered into position by tow tractor, and the X-I raised into position.

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Moments after release, the second X-I is seen over Muroc at the beginning of a test flight. Engine ignition has yet to take place and the aircraft is free falling without power. At this point, while stabilizing the aircraft in a slight nose down attitude, the pilot usually was experiencing light negative g's while reaching for the engine ignition switches. Consequently, chase aircraft were monitoring external events frorT) several differerJI angles. Photo camera was mounted in carrier aircraft bomb bay.

9

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The second X-I moments before touchdown on the Muroc runway. Normally, landings took place on the vast expanse of the base's hard-surfaced dry lake bed. Slight flap deployment visible in this view is noteworthy.

[ The X·ls were well known for their propensity to break nose gears. The cause was a lack of elevator authority at low airspeeds; as the aircraft rotated into a conventional stall landing, the elevator tended to lose effectiveness prematurely.

Following its Air Force career, the second X-I, 46·063, was turned over to the NAGA on September 25, 1947. Painted white over-all and bearing a small NAGA logo on its vertical fin, it was released for initial flight tests during October.

The second X-I following transfer to the NAGA. The aircraft was painted white over-all, with conventional insigne visible on the wings and fuselage. The vertical fin carried a conventional NAGA logo which was black on an orange background. the horizontal stripes were apparently in red. The wing roots were given black walkway to allow access to nitrogen bottles and the test equipment bay located behind the removable panels on either side of the fuselage center section.

10

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NACA X-1 Test Equipment SIXTY·CAPSULE RECORDING MANOMETER FOR PRESSURE DISTRIBUTION - - - - ,

FIVE·CHANNEL TELEMETER TRANSMITTER (TRANSMITS AIRSPEED, ALTITUDE, NORMAL ACCELERATION, AND AILERON AND ELEVATOR POSITIONS)

TWELVE·CHANNEL OSCILLOGRAPH FOR STRAIN GAUGES - - - - - - - - - - , CONTROL BOX FOR OSCILLOGRAPH THREE·COMPONENT RECORDING ACCELEROMETER ~-------GUNSIGHT CAMERA TO PHOTOGRAPH INSTRUMENTS ON PILOT'S PANEL SIDESLIP ANGLE, FUEL PRESSURE, CONTROL POSITION (RUDDER) RECORDER CONTROL POSITION RECORDER (STABILIZER, AILERON, AND ELEVATOR) [

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PEDAL FORCE TRANSMITTERS AIRSPEED HEAD FOR PILOT'S INSTRUMENTS RATE OF TURN RECORDER

PRESSURE DISTRIBUTION ORIFICES (COMPLETE INSTALLATION INCLUDES 400 ORIFICES ON WING AND TAIL SURFACES WHEEL AND PEDAL FORCE RECORDER CONTROL BOXES FOR CONTROL FORCE AND CONTROL POSITION RECORDERS SIDESLIP ANGLE TRANSMITTER

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X-I, 46-063, during static powerplant tests at Bell's Niagara Falls facility. The tests, for acoustical reasons were conducted inside a hangar.

The large X's painted on the side of 46-063 apparently were for photo interpretation purposes. Visible on the upper wing surfaces were what appeared to be a row of small vortex generators stretching from wingtip to wingtip. On the left wingtip is a vertical surface that might possibly have been a mechanically actuated aerodynamic exciter. The nose boom mounted pitch and yaw vanes which normally were not seen on the X-Is following initial flight trials.

11

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The third, and last, 01 the first-generation X-Is, 46-064, undergoing final assembly at Bell. Though the fuselage is virtually complete, the wing has yet to be installed. Noteworthy is the fully-fuhctional XLRII engine which already is in place.

Unpainted, the third X-I undergoes static ground tests of its liquid-oxygen oxidizer tank and associated jettison systems at Bell following completion. This aircraft was immediately recognizable by its strapless windscreen and canopy assembly.

Externally, the third X-I differed only in minor details from its two stablemates. Visible in this view are the turbopump propellant dump ports on the aft fuselage and plate peculiar to its more advanced powerplant configuration.

The third X-I sat slightly higher on its main landing gear than its stablemates and the gear appeared slightly less splayed. Forward visibility from the cockpit was modeslly improved through the elimioation of the anachronistic restraining straps.

In its gleaming white paint, the third X-I was perhaps the most attractive of the three first-generation aircraft. In this view, the elevator mass balances, added to offset a tendency toward flutter, are readily visible.

By the time of the third X-I's availability, Bell had installed a hydraulic lift system to accommodate loading requirements. This system rapidly replaced the pit used previously. Similar hydraulic lifts also were installed at Edwards AFB.

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The third X-I immediately prior to departing Bell on its delivery flight to Edwards AFB during April 1951. Large strap-like shackles can be seen holding the aircraft firmly in place in the B-29 carrier aircraft's modified bomb bay.

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The third X-I 's high-performance turbopump propellant transferral system, seen undergoing static testing at Bell during early 1951, was considered a significant improvement over the compressed nitrogen systems found in the first two aircraft.

12

The third X-I is seen receiving a load of liquid oxygen and nitrogen prior 10 a static ground test. Extraordinarily low propellant (oxidizer) temperatures caused condensation to form on hoses, even in the hot California desert.

Hydraulic lift system installed at Edwards south base permitted the research aircraft to be towed directly underneath. Carrier then was lowered onto the research aircraft with the final attachment occurring after it was hoisted into the bomb bay.

/

Because of cockpit pressurization requirements, the first two X-Is, 46-062 and 46-063, had straps across the windscreen to prevent any possibility of catastrophic blow-out. The third aircraft, because of improvements in windscreen materials technology and basic design advances, was able to do away with the windscreen straps. This permitted improved vision for the pilot, a slight reduction in drag, and a modest weight savings.

~

The third X·I proved to be the shortest-lived of the three first-generation aircraft. Only one glide flight was completed before it was lost on November 9, 1951. The cause later was traced to the use of Ulmer leather gaskets.

The fire that followed the explosion destroying the third X-Ion November 9, 1951, not only totalled the research aircraft, but also its Boeing B-50 carrier aircraft, 46-006. X-I test pilot Joseph Cannon almost lost his life in this accident.

r The November 9, 1951 mission had not been planned as a drop flight for the third X-I, but rather as a captive flight to permit rehearsal for a forthcoming first powered flight. Following return to Edwards AFB, the mated aircraft were moved into the defueling area at the base where off-loading at the lox and water/alcohol was initiated. An explosion followed shortly afterwards, this leading to an intense fire which quickly destroyed both aircraft.

13

NAC, itiate, view throu tunat, April nose No plagl

lem~

During development, concern arose over the placement of the X-I's horizontal tail surfaces and how such placement could alleviate perceived difficulties relating to the shock wave being generated by the wing. Many solutions were considered, including, perhaps most importantly, the "butterfly" or "V" tail. Variations to the X·I "V" tail theme are seen in these three photos. The first and second are front and rear views of the same model, whereas the third shows one with increased dihedral.

A fourth altitude mission was flown on August 8, this setting yet another X-1 record. Post flight examination of recording instrumentation indicated that an altitude of 71,902 ft. had been achieved. This would become the absolute altitude record for the first generation X-1 series. Further tests using the first X-1 were conducted during the fall of 1949 and the spring of 1950. Finally, on May 12, 1950, with Yeager again in the cockpit, the aircraft was launched on its 59th and final mission. On August 19, the first X-1, 46-062, was flown by B-29 to Wright-Patterson AFB (at the time, recently re-named from Wright Field), and there refurbished for permanent display in the Smithsonian Institution. Official transfer ceremonies took place one week later in Boston, Massachusetts, when Air Force Chief of Staff Hoyt

Vandenberg turned over the aircraft to Alexander Wetmore, Ph.D., then Smithsonian Institution Secretary. While flight testing of the first X-1 under the auspices of the Air Force had been conducted at a near feverish pace, the second X-1 (46-063) also had been conducting missions at a high rate under the auspices of the NACA and its program directors, Hartley Soule, Gerald Truszynski, and Walter Williams. This aircraft officially had been accepted by the NACA on September 25,1947, immediately following an Air Force test flight conducted by Yeager. Its first un powered glide flight had been completed on October 11, 1946, at Muroc AFB, with Chalmers Goodlin at the controls. The first powered flight occurred on December 9, 1946, again with Goodlin as pilot. The first NACA-piloted glide flight followed on October

21, with Herbert Hoover handling the controls for the II time. A nose landing gear failure occurred on touchdow however, and it wasn't until December 16, that a secor NACA mission, the first to be flown with power, \IIi completed. Additional NACA tests followed throughout the r. mainder of 1947, these slowly exploring the transon potential of 46-063. Throughout the spring of 1948, II speed envelope was expanded, eventually resulting flights to Mach numbers of just over 0.94. Finally, ( March 10, with Hoover at its controls, the second X· went supersonic for the first time. A speed of Mach 1.1X was achieved, this making Hoover the first civilian e~ to fly faster than sound. Once sonic velocity was successfully achieved byll

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As full-scale flight test operations with the X·ls began to accelerate at Muroc Air Base, the NACA initiated a follow-on wind-tunnel model program calling for the exploration of sweptwing attributes in the transonic regime. Accordingly, a quarter-scale transonic X-I tunnel model was modified during mid-1947 at the NACA's Langley facility to accommodate the basic X-I wing (with suitably modified tips and center section) at various angles of sweepback.

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Though the initial sweptwing X-I studies were related directly to the preliminary design effort resulting in the Bell X-2, ongoing studies continued to explore more abstract configurations including the chine-like leading edge extensions seen on the left, and the forward swept wing seen on the right. The latter proved somewhat premature as it would not reach true feasibility until the late 1970s with the advent of composites and computer analysis of load dynamics.

14

tualit) norm they, gear simul comr assel Th, catas side, quire' for all was, On the c, folloY pilot, Nove Ad the a strun span, agair WI begir that ElevE in th, supe well Th Dece be in tiona Or May to its were due i durin of its Ur cider and ~ now· Augl Fa X-1 e progl disc( majo Ye no Ie ofa r craft anAl follov The PoW! An gram chec probl sphe madE and, first: Th plagl it suf pearl byR, a f XLR earli! oxidi: volur syste techr As

NACA aircraft, a stability and control program was initiated which, it was hoped, would give a more detailed view of what was happening to the X-1 as it plowed through the atmosphere at supersonic velocities. Unfortunately, this program was slowed considerably when on April 16, NACA pilot Howard Lilly touched down and the nose gear again collapsed. Nose gear failures in the first-generation X-1 s would plague them throughout their flight test lives. The problem was only partially due to pilot technique, being in actuality the result of limited elevator control at the aircraft's normal stall speed. Pilot's tended to discover too late that they were running out of elevator-thus allowing the main gear and nose gear to contact the ground almost simultaneously. When this happened, it was not uncommon to overload the nose gear fork and mount assembly-with the inevitable result. The damage caused during Lilly's landing was not catastrophic, but it was serious. The landing gear, underside of the fuselagf> and empennage, and left wingtip required extensive rebuilding and the aircraft was grounded for almost six months. It was not until October that it again was declared f1ightworthy. On November 1, 1948, with Herbert Hoover again in the cockpit, the second X-1 completed its first check flight following the April accident. Later, a new NACA X-1test pilot, Robert Champine, took over the controls and, on November 23, completed his first familiarization flight. Additional flights followed and during early December, the aircraft was grounded in order to install special instrumentation and recording equipment for the NACAsponsored stability and control program. It was not flown again until some five months later. When it was declared airworthy again, the second X-1, beginning on May 6, embarked on a series of test flights that consumed most of the summer and fall of 1949. Eleven missions were flown successfully, these resulting in the accumulation of rather substantial transonic and supersonic data that would serve the aerospace industry well for many years to come. The second X-1 again was grounded during early December 1949 so that recording instrumentation could be installed. It wasn't until the following May that additional missions were undertaken. On May 26,1950, following two flights on May 12 and May 17, NACA pilot John Griffith piloted the second X-1 to its highest speed ever, Mach 1.20 (792 mph). As it were, this aircraft was somewhat slower than the first X-1 due in part to its 10% Uc ratio wing. The speed it attained during the May 26 flight was considered representative of its maximum performance potential. Unfortunately, the May 26 flight did not end without incident. Following touchdown, the nose gear collapsed and significant damage was incurred. Another grounding now followed, this resulting in no further flight testing until August 1950. Following its return to operational status, the second X·j embarked on a pressure distribution survey flight test program. Some nine flights were conducted before it was discovered the fuel tank had begun to rust and that a major overhaul would be required to correct the problem. Yet another grounding followed, this one consuming no less than six months and leading to the installation of anew fuel tank and new test instrumentation. The aircraft was flown for the first time following refurbishment on April 6, 1951, and again on April 20. Two more flights followed, with a month-long break occurring during June. The latter allowed time for the installation of a new powerplant. An additional nine flights completed the NACA's program with the second X-1. Several different pilots checked out in the aircraft in the interim, and by October, problems with battery acid leaks and weak nitrogen spheres had led to another grounding decision. This was made permanent following further analysis of the spheres and an attempted replacement by using spheres from the first X·1-which proved fruitless. The third X-1 (46-064) unquestionably was the most i11~agued aircraft of the original three. From the beginning, lsuffered numerous setbacks including what at first appeared to be a temporary delay in its delivery date caused by Reaction Motors' failure to complete and deliver to Bell a f1ightworthy sample of its steam-driven XLR11-optimized turbopump. The latter, as explained ea~ier, was for transferring propellants from the fuel and oxidizer tanks to the powerplant. Lighter and less volumetrically invasive than its predecessor nitrogen system, the turbopump was considered a significant technological step forward for the X-1 series. As noted, development of the new turbopump did not

occur as rapidly as originally planned. Additionally, problems with funding and a lack of sustained Air Force interest eventually caused the third X-1to fall no less than three years behind its original flight program schedule. It was delivered eventually to Edwards AFB (as Muroc AFB was renamed on January 25, 1950) during April 1951, and on July 20, with NACA pilot Joseph Cannon (by now, retired from Bell) at the controls, it completed its first glide flight. The next attempted flight of the third X·1 proved to be its last. On November 9, 1951, the aircraft had undertaken a captive flight of approximately one hour. This had been scheduled as a rehearsal for the forthcoming first powered flight as well as a test of the rocket propellant and hydrogen peroxide (the latter, which was carried by the third aircraft only, and utilized to power the turbo· pump, was simulated with distilled water) jettisoning system. Jettisoning of fuel and liquid oxygen had been aborted due to loss of X-1 nitrogen source pressure. At 18,000 ft., X-1 pilot Cannon had inadvertently tripped the hydrogen peroxide and fuel jettison switches while struggling to fasten the X-1's door. Since at that time the peroxide tank was pressurized and contained only nitrogen, this could have been the cause of the loss of jettison source pressure. A crew decision now was made to land with the X-1 still in the B·50's bomb bay and still containing most of its liquid oxygen and fuel complement. The landing was completed without incident and the still-mated aircraft were taxied to the propellant loading area to obtain nitrogen source pressure for the purpose of on-theground jettisoning of the liquid oxygen, and to attempt to locate any possible leaks in the nitrogen pressure system. Source pressure was obtained with no difficulty and the aircraft were towed to the east end of the ramp and swung around SO that they faced into the wind. A standard procedure for jettisoning then was begun; i.e., the area to the rear of the aircraft was cleared, fire trucks and firemen were moved into position, and an operator, in this case, pilot Joseph Cannon, was placed in the X-1 's cockpit. Following a visual check, the "all clear" signal was given and Cannon began the normal liqUid oxygen jettisoning procedure. He pressurized the liquid oxygen tank pressure regulator dome until the indicator reached its red line at 52 psi. He then turned his attention to the liquid oxygen tank pressure guage. This pressure was rising slowly, and when it had reached approximately 42 psi, an explosion occurred. All witnesses later agreed that the first explosion was a dull thud, or contained explosion, quickly followed by a "hiss" and a small cloud of white vapor rising from the X-1 center section. Some witnesses reported small flames; the majority remembered none. Within one to five seconds, a sharp, violent explosion occurred, immediately followed by yellow flame and black smoke. This was followed closely by numerous other explosions, varying in intensity from minor to very violent. Additional fire trucks now arrived at the scene and the fire was extinguished in approximately 8 minutes. Unfor-

EARLY 0-37 STUDY

tunately, the X-1 was demolished totally and the B-50 center section, except for the wing, was burned away. At the outset of the explosions and ensuing fire, everyone was evacuated from the premises and there were no fatalities. Cannon, who still was inside the B-50 at the time of the initial explosion, was rescued, though not before receiving serious injuries. Liquid oxygen had spread everywhere following the explosion, and Cannon, in an attempt to extricate himself from the B-50 bomb bay, had had to crawl on his hands and knees through a pool of the cryogenic liquid in order to escape. Freeze burns eventually cost him parts of several fingers and left scars of significant proportions. He would not have made it without the help of several fellow Bell employees who happened to be on hand at the time of the explosion. A lengthy investigation followed the accident. Various conclusions were reached as to its cause and cure, but it was not until the demise of the X-1A, nearly four years later, that the real problem was discovered. As research later would verify, the problem lay with the aircraft's Ulmer leather gaskets.

The interim design between the Bell X-I and the later Bell X·2 was the Bell 0-37 (Design #37), seen in wind tunnel model form .. Essentlally.a compromise configuration utilizing the basic X-I fuselage with swept wings and swept vertical and honzontal tall surfaces, It proVided Bell With a stepping stone to the totally new X·2.

15

THE BELL X·1 A, X-1 B, X~1 C, AND X·1D (The Second Generation)

The second of the second-generation X-Is to be completed, X-lA, 58-1384, was rolled out from Bell's Niagara Falls, New York plant doors during late 1952. Originally painted bright orange over-all, this scheme was replaced by bare metal, (standard for all second-generation X-Is), prior to the aircraft's delivery to Edwards AFB.

0[1 November 14,1947, exactly one mOr'\th after Chud Yeager achieved sonic velocities in the first X-1, theA Force authorized Bell Aircraft Corporation to formall undertake a study calling for the development of a secon generation X-1 aircraft that would offer significant pa formance improvements over its predecessors. Th resulting design was the Bell Model 58 (assigned theA Force project designator MX-984), which utilized th basic wing, horizontal taii surfaces, and powerplant ofth first generation aircraft, but which had an almost tota~ new fuselage featuring increased capacity fuel tanks, revised and much improved cockpit and associate canopy, a low-pressure turbopump powerplant fuel fee system, and improved airframe and powerplar The) maintenance features. Following contract initiation on December 11, 1947, formal contract, W33-038-ac-20062, for four aircraft, w, consummated on April 2, 1948, and less than a year lale a full-scale mock-up was ready for inspection. Th' passed Air Force scrutiny following numerous minor rm. sions and changes, and by the end of 1950, under tn direction of project engineer Richard Frost, the firslr three second generation X-1s (X-1A, 48-1384; X-II 48-1385; X-1 D, 48-1386) approved for construction, tn X-1D, was nearly complete (a fourth aircraft, the X-II was cancelled; to have been a propulsion system tel bed, it is assumed to at one time have been assigm the 48-1386 Air Force serial number). ._The X-1 D, the first of the second generation aircra "to roll from Bell Aircraft Corporation's Buffalo, New y~ plant doors, made its debut at Edwards AFB suspendl from the bomb bay shackles of EB-50A, 46-006A, durin July 1951 . On the 24th of that month, with Bell compa! test pilot Jean Ziegler at the controls, it was launched 01 Rogers Dry Lake on what was to become the only su cessful flight of its career. The unpowered glide was cor Ma pleted after a nine-minute descent, but upon landing, II to nose gear failed and the aircraft slid somewhat ungrao fully to a stop. Repairs took several weeks to compie and it wasn't until mid-August that a second flight cou be scheduled. This mission, on August 22, with the X-1 D attachedl the EB-50A, at first went routinely. However, as the mall aircraft ascended through 7,000 ft., Lt. Col. Fra' Everest, the X-1 D's Air Force pilot, noted upon enterir the cockpit that the nitrogen source pressure indica! was giving a very low reading. After discussing the prd lem with Bell engineers aboard the bomber, the decisir was made to abort the mission and jettison the X-tD propellants. Shortly after Everest initiated the jettison pi cess, an explosion rocked the aircraft's aft end. ThisWi followed immediately by flames visible from the char aircraft following in close trail underneath the EB-5~ Everest now hurriedly egressed the X-1 D's cockpit a! moments later, an engineer onboard the EB-50A, Jat Ridley, pulled the drop handle which released II shackies holding the X-1 D in place. Less than a minu later, the once highly advanced multi-sonic research a craft lay a twisted pile of wreckage on the desert floc some two miles west of the south end of Rogers Dry Lai The X-1 D was followed to Edwards by the similar X·I S. re, which arrived on January 7, 1953, shackled to the san EB-50A carrier aircraft that had transported the X-10t protn its fateful last mission. Just over four weeks later, II X-1 A, on February 14, with Bell company test pilot Jer Ziegler at the controls, successfully completed its fil glide flight. This was followed by a second glide son six days later, and by a first powered flight, also Yn Ziegler, on February 21. The X-1 A originally haa been scheduled for a serH of stability and control test flights under the auspices Cornell Aeronautical Laboratories following completir of Bell's required contractor (Phase I) test flights. 01 to the untimely demise of the third X-1 and the X·II however, the Cornell program was cancelled and shq ly afterwards, the Air Force confirmed that the aircrafti stead would be delivered directly to the NACA. In the meantime, contractor X-1A flights continul through April, at which time the aircraft temporarily~ grounded and returned to Bell's Buffalo plant I modification. At the same time, an elevator flutter anon Iy was examined and the aircraft's nitrogen-tube-buna Land pressurization system was replaced with one consistil fin of simple spherical containers. The decision to incorporate the latter was the resull

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In bare metal, the X-IA is seen at Bell shortly before being delivered to Edwards AFB. The cockpit transparency remains covered in protective paper to prevent scratching and the wing upper surface has a protective mat in place to permit access to the center section equipment bay. Vertical fin tip has just been painted.

Prior to completion, the X-IA was check fitted to confirm compatibility with B-29 carrier aircraft. The second-generation X-Is required significantly different bomb bay fittings, snubbers, and attachment assemblies, and therefore represented a totally new entity. Noteworthy is the X-I A's unpolished aluminum skin.

In order to accommodate powerplant test requirements, the X-I A was loaded aboard a flatbed trailer and moved to Bell's engine test facility several miles from the main Bell plant. The aircraft sill was painted bright orange over-all. Interestingly, littfe was done to secure the aircraft from inquisitive eyes.

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The X-IA originally was rolled out in a bright orange over-all scheme. This was to be short lived as it was concluded erosion and the temperatures involved with cryogenic propellants would create a constant maintenance headache.

Mass balances were added to the elevators of the second-generation X-I s in order to alleviate a flutter concern. Flush exhaust nozzles for the turbopump propellant system later were modified to incorporate protruding extensions.

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The turbopump exhaust nozzle extensions are readily discernible in this view of the X-I A. Also visible are the small open hook bay doors on the top of the dorsal spine. There actually were two sets of doors with one pair for each hook.

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The conventional markings applied to the orange-scheme for the X-I A, including the national insigne and serial number, were completely standard. Besides being a maintenance headache, the orange paint also added weight.

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Small hatch, visible on top of X-IA dorsal spine, just ahead of aircraft center section, covered forward attachment hook and electrical umbilical. Aircraft is seen at Bell after removal of orange paint and probably prior to delivery to Edwards AFB. Lox jettison system fairing is visible on ventral spine, just to the rear of the nose landing gear. Small protrusions visible just aft of ventral spine end are AN/APN-60 antennas. Except for white ventral spine and wing undersurfaces, and black anti-glare panel, aircraft was unpainted.

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landing gear tread and related aircraft stance were essentially the same between the first- and second-generation aircraft. Though narrow, the gear provided excellent stability after touchdown and pilots rarely noted handling difficulties.

During late 1952, the X-lA, 48-1384, is seen being prepared for a practice mating with its B-29 carrier, 45-21800. Winters in Buffalo, New York, though often bitter, rarely hampered X-plane flight test operations.

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The X-IA is seen being maneuvered into position under its B·29 carrier aircraft during a practice mating session. Noteworthy are the small dollies used to move the X-Is during icy weather conditions. The smaller footprint provided better traction.

the loss of Bell X-2, 46-675, which had exploded mysteriously during a mated test hop over Lake Ontario. At the time, it was thought the accident had been caused by leaking liquid oxygen and its subsequent accidental ignition by an electrical spark. In turn part of the leak problem was though1 to have been the result of using the complicated nitrogen-tube-bundle assembly then found in all Bell-designed rocket-propelled research aircraft. Later, as noted earlier, the real explosion cause was traced to the use of Ulmer leather gaskets. Following its return to Edwards AFB on October 16, 1953, the X-1 A was declared flightworthy and almost immediately moved into preparation for its next mission. The aircraft resumed flight operations with a powered flight on November 21, 1953, at the hands of Chuck Yeager; another mission was undertaken eleven days later. Though several control system problems now surfaced, a decision was made by the Air Force to move ahead as rapidly as safety would allow with plans to fully explore the maximum speed potential of the aircraft. On December 8, Yeager took the X-1 A out to Mach 1.9 at 60,000 ft. while gingerly exploring the aircraft's stability and control envelope. With confidence increasing rapidIy in the aircraft's ability to perform as designed, another

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d Th e t akeoff wen t smoothl y craft were fue Ied an d chec ke. and launch of the X-1 and ignition of its XLR11 powerplant proved problem-free, as did the climb to pitch-over altitude. After attaining an altitude of 70,000 ft., Yeager

leveled the X-1 A and began to accelerate. In a matter of seconds, Mach 2 had been exceeded and the Mach meter needle continued to move. As the X-1A passed through Mach 2.4, Yeager noticed with some concern that the aircraft had begun a gentle roll to the left. Corrective action in the form of right aileron and mild rudder damping followed, but this resulted in an exaggerated roll to the right. Moments later, Yeager and the X-1A were completely out of control. Though the throttle had been cut, violent tumbling followed the initial roll series and continued for no less than 36,000 ft.

Tolerances were minimal in terms of ventral fairing and wingtip clearances due to the size of the second-generation X-Is. B-29, 45-21800, warming up for flight, is seen with the X-IA suspended in its bomb bay.

During the wild ride down, Yeager was thrown about the cockpit and knocked into a state of semi·consciousness. It was not readily apparent he would survive. Once the X-1A had entered the denser atmosphere around 35,000 ft., it stabilized in a subsonic inverted spin. Yeager came-to some 6,000 ft. later and within a matter of seconds, groggily determined his predicament and initiated standard inverted spin recovery procedures. The X-1A rolled upright and shortly afterwards was banking back towards Edwards AFB, some 60 miles distant. The X-1A, as it was uncovered. through post-flight analysis, had experienced a high-speed phenomenon known as roll-coupling at 1,612 mph and an altitude of 74,200 ft. The possibility of this happening to aircraft f1ying at high speeds 10ng had been predicted by a number of aerodynamicists, but Yeager's flight was the first actually to encounter it. Following Yeager's December 12 mission, the Air Force declared that no further high-speed flights (above Mach 2) would be undertaken and that the X-1 A now would be used to explore flight at very high altitude. As a result of this, the NACA was asked to postpone its forthcoming accession so that the Air Force could complete its proposed high altitude program.

Returning to Edwards during mid-1955, the X-1Aqu Iy was placed on f1ightworthy status and scheduled a series of exploratory missions. The first NA( sponsored flight, which resulted in a speed of Machi and an altitude of 45,000 ft., took place on July 20, ¥ agency pilot Joseph Walker at the controls. The second NACA flight was undertaken just overl weeks later, on August 8. Just prior to launch fron B-29 carrier, however, an internal explosion ruptured liquid oxygen tank, blew off the center section aoo panels and main landing gear doors (thus causing gear to extend), and caused generally massive Inter damage. . . . Fortunately, no personnel '!"ere Injured, but the e~ Slon made It Impossible to glide the X-1A to Edwards recovery. Addlltonally, the explosion made It hazard: to attempt to land the B-29 with the X-1A mated beea, theX-1A's landing gear extended some 8 in. below main gear of the B-29. X-1A gear extension was ao shot, mtrogen actuated and gravity assisted system wi afforded no prOVISion for manual retraction. . To complicate matters even further, all attempts to tlson the fuel aboard the X-1A failed. The Jettison s~ had apparently been serrously damaged and therer g: the highly volatile propellants fromf no way/o

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Maj. Arthur Murray now was chosen to fly the altitude missions. As it turned out, no less than fourteen flights proved necessary to accommodate the altitude program . . . requirements, with only four of these being su,ccessful. T~e m?st Important of the four ,:"as ~urray s r~cordsetting flight of August 26, 1954, In which a maximum altitude of 90,440 ft. wasachieved .. ThiS was a ~ecord not bettered by a manned aircraft until Kincheloe s Bell X-2 flight to 126,200 ft. some two years l a t e r . . . Durrng September 1954, follOWing the completion of ItS altitude program, the Air Force turned over the X-1 A to the NACA. The aircraft then was flown by EB-50A back to Bell for installation of an ejection seat (a reaction to the aircraft's now readily-acknowledged stability and contro.1 failings at high Mach) and to accomplish several addltlonal, though minor modifications. ~

Bell's Niagara Falls facility, during the early I 950s, was remote enough from the main Buffalo population core to permit static ground testing of the X-lA's powerful four-chamber XLRII rocket engine. Shock balls are readily visible in the exhaust. Only three of the four chambers are functioning.

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respec Ive an s . . I . On the day of. the explosion, the personne asslg· to the X-1A misSion Included B-29 crew members Sta: Butchart (pilot); John McKay (co-pilot); Rex Cook (ff engineer); Richard Payne (X-1A crew chief); Jack Me (X-1 A launch crew member); Charles Littleton (X launch crew member); Merle Woods (scanner); Riel DeMore (scanner); and Joseph Walker (X-1A pilot). Additionally, three chase aircraft were assigned, t~ consisting of a North American F-86 piloted by Maj. Art Murray; a North American F-100 piloted by Capt. Lc Schalek, Jr.; and a North American P-51 piloted by~ unknown NACA test pilot Neil Armstrong. Following normal procedures, pilot Walker had enll the X-1A cockpit at an altitude of about 8,000 ft. She afterwards, the canopy was closed and the cockpili pressurized. Topping-off procedures of the X-1 A's Ik oxygen system were started when the aircraft reaa an altitude of about 22,000 ft. During this period, the f. with Maj. Murray, was flying close to and slightly be the right wing tip of the B-29. The P-51, with Armslrc was also flying chase on this side, though somel further away. At the instant of the explosion, Maj. Murray obser a white cloud erupting from the lower center sectio the X-1A. He was momentarily enveloped in this cit and debris struck his aircraft, cracking the canopyr damaging the wing tip light. When the vapor cleared a Maj. Murray reported "a slight explosion", but I everyth ing appeared all right otherwise. Requesting the B-29 crew to help Walker into the S Maj. Murray then flew close to the X-1A and obser that the landing gear doors and access panels mediately forward of the doors were gone, and that main landing gear was extended. No smoke was vi· but Maj. Murray observed a small, dull red fire in the ward part of the fuselage center section which 1m about 30 seconds. He also reported that the liquid oX¥, tank was ruptured, enabling him to see into the tao The above items were the only external damage vii to Maj. Murray, but the center section where the dr

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Shortfy after its arrival on January 7, 1953, the X-1A, 48-1384, sits on the ramp at Edwards AFB south base. Markings were minimal and the right wingtip test boom has yet to be installed. This aircraft would have a highly successful flight test program.

The X-IA became one of the first aircraft ever to experience inertia coupling phenomenon (sometimes called roll coupling) at high Mach. A speed limit was placed on the aircraft afterwards, preventing further uncontrollable flights.

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By the time it was delivered to Edwards AFB on January 7, 1953, the X-IA had been static tested thoroughly by Bell and consequentfy had been quickly cleared for full-scale flight test operations. Several world speed and altitude records would result before the aircraft was purposefully jettisoned to destruction on August 8, 1955, following an internal explosion that forced the main landing gear into the down-and-Iocked position. The latter prevented the carrier aircraft from landing safely.

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Ground clearances, as notedearlier, were minimal wIth the entire X-I family, but were particularly acute with the second-generation aircraft. The X-I A is seen following uploading but prior to being filled with propellants.

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Fully loaded with propellants, the second-generation X-Is proved a heavy cargo for the venerable B-29 carrier aircraft, particularly at higher altitudes. The X-IA is seen shortfy before launch. Condensation around lox tank is noteworthy.

Chase aircraft remained with the X-Is for as long as possible following launch, and re-formated with them as early as possible following their return from altitude and high Mach. A North American F-86D, 50-509, is seen off the left wing of the X-IA.

19

Jean "Skip" Ziegler, one of Bell's most experienced test pilots, was at the X-lA's controls during the course of its first flight. He is seen at a later date with the aircraft following landing on the dry lake bed at Edwards AFB. Ziegler would be killed during a test of the Bell X-2 on May 12, 1953.

Posed photo of Chuck Yeager and Bell founder Larry Bell in front of the KIA following Yeager's speed record-setting flight in the aircraft.

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Snubbers, visible protruding from the bomb bay and contacting the upper wing surface and fuselage sides, prevented lateral oscillations of the aircraft.

Almost at the moment of release, the X-IA is seen descending from the B-29's bomb bay. Engine ignition still is several seconds away and a small puff of residual lox from the exhaust is visible at the aft end of the aircraft. Dump tubes from the B-29, preventing fume accumulation in the bomb bay, are easily discerned.

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Nearing the end of a high altitude mission, the X-IA is seen in level gliding flight on its final approach to Edwards AFB. Visible are camera ports in the ventral fairing, and an externally mounted camera on the nose (below the windscreen).

All three gear invariably touched the landing surface at almost exactly the same time. Narrow tread of the main gear necessitated good piloting technique. Once on the ground, speed was bled off gradually via mild use of the main gear brakes.

Missions were logged on the nose of the X-I A along with pilot, crew chief, crew, inspector, and foreman names. Powered ffights were indicated with exhaust plumes; unpowered flights had no exhaust plume.

Following completion of its Air Force ffight test program, the X-tA was turned over 10 the NACA during September 1954. The NACA promptly painted it white (leaving natufO metal the area around the lox tank), and added a NACA logo to the vertical fin.

had been blown off was filled with debris indicating considerable internal damage. The scanners in the rear compartment of the B-29 noted that the rear portion of the X·1A dorsal fairing was split just forward of the sealed firewall separating the engine and turbopump compartment from the forward part of the dorsal fin. The X-1A also appeared to have dropped a few inches so that the drag braces which fit into each wing from the B-29 were cleared. No other damage was visible. Moments after the explosion, activity inside the B-29 went into high gear. The bomb bay had immediately filled with white vapor which, just as quickly, had disappeared. X·1A pilot Walker, who was by this time already belted into the research aircraft's cockpit, immediately noted Ihat his radio was inoperative and the instrument power and ready-to-drop lights on the X-1 A instrument panel were out. He also noted that the liquid oxygen tank pressure was zero and the nitrogen source pressure was falling rapidly. He shut off all electrical equipment and depressurized the cockpit preparatory to opening the canopy. The X-1A launch crew members assisted Walker into the B-29 crew compartment. No smoke or flames were observed by any member of the B-29 crew during this time. A small quantity of vapor, possibly liquid oxygen, was seen rising around the electrical plugs located in the dorsal fin above the X-1 A center section. The B-29 pilots had started a descent immediately following the explosion, and continued to descend to 11,000 ft. At this time, Richard Payne, the X-1A crew chief, entered the bomb bay and examined the X-1A's cockpit. He noted that all the major nitrogen, liquid oxygen, hydrogen peroxide, and water/alcohol tank pressures were at zero. He also noted that the landing gear handle was still in the up position. He attempted to jettison the remaining fuel and peroxide using the small emergency nitrogen supply to open the jettison valve. When he did so, the pressure dropped from 1,200 psi to about 500 psi in the normal manner, but Maj. Murray, in the chase plane, observed only a very small flow. Even Ihis stopped after a short while. When it was determined that the fuel and peroxide could not be jettisoned, and that the X-1 A main landing gear could not be retracted, communication with the NACA ground station was established and it was decided to jettison the X-1 A. Furthermore, there were indications of leaking and decomposing hydrogen peroxide. The X-1A was therefore dropped from about 6,000 ft. and crashed 3/4 mi. south and a little east of PB-3 (Practice Bombing Range 3), on the Edwards AFB bombing range. The time was 14:15 PDT. The B-29 crew, Maj. Murray, and Armstrong observed the X·1 A enter a tail-down flat spin and crash and explode in the desert. A USAF fire truck sped to the scene of the crash and extinguished a small brush fire that followed. Soon 'afterwards, NACA and USAF personnel arrived to examine and photograph the remains. The following afternoon a USAF crew moved the wreckage by truck to the NACA High Speed Flight Station hanger for inspection and damage analysis. The X-1A was a total loss, primarily as a result of hitling the California desert at over a hundred miles per hour. Thorough analysis of the wreckage revealed, however, that the following damage was a result of the initial explosion rather than ground impact: 1. Blowing-off of the upper main gear doors with the consequent lowering of the gear to the down-and-Iocked position. The gear-up locks were attached to the doors, therefore the lowering of the gear could have been by gravity aided by the force of the explosion. 2. Blowing-off of the non-structural fuselage panels adjacent to and forward of the gear doors. It was later calculated that a pressure of about 20 psi would have been required to blow off these panels and the gear doors. The desert area where these doors presumably would have landed was searched by helicopter, but the doors

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Bearing its mission record be/ow its right canopy rail, the X-IA sits next to the X-IB on the baked floor of the Edwards dry lake bed. This photo would become one of the (nost often reproduced of this dynamic pair, and one of the few to show them together.

The X-I B, lacking its empennage section and vertical and horizontal tail surfaces, is seen nearing final assembly at Bell during early 1954. Forever overshadowed by the X-lA's accomplishments, the X-IB eventually would draw consolation from being the only second-generaton X-I to survive.

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The X-IB at Bell's Niagara Falls facility shortly after completion. With a calculated gross weight of 16,816 Ibs., it was determined to weigh II pounds more than either the X·IA or X-1D. Otherwise, it was essentially identical to its stablemate.

were never found. 3. Rupturing of the dorsal fin cover and tearing open a bolted seam in the dorsal fin cover. The dorsal fin was

sealed from the tail section because of fire hazards, but there were several sizable openings from the fin area into

the center section of the fuselage whereby the force of an explosion in the center section could pass into the dor-

al

sal fin. 4. Rupturing of the liquid oxygen tank. The escort pilots could see that the fiberglas insulation used to cover the liquid oxygen tank rear bulkhead had been pushed back and the bare tank metal exposed. Maj. Murray thought he was looking into the inside of the tank. Further evidence of this rupturing was the fact that the tank was emptied of liquid oxygen within a few seconds, since after the initial blast of vapor cleared away, there was no further

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Static ground testing of the X- t 's 6,000 lb. tho XLRII-RM-5 rocket engine was undertaken at Bell shortly before delivery to the Air Force. Shock balls can be seen in the exhaust efflux. Visible in the background are North American F-5IDs of the New York Air National Guard.

21

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The X-I a, before being turned over to the NAGA, served primarily to familiarize new experimental aircralt pilots with the idiosyncrasies 01 rocket-powered aircralt. A total 01 seven familiarization /lights were flown.

As originally conceived, the X-I a was to have been an armament systems testbed. Later, this task was assigned the X-I G (originally to have been a propulsion system testbed), and as such; was stillborne belore the hardware could be completed.

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The propellants carried by all the X-Is consisted of liquid oxygen and a mixture of specially denatured alcohol (Specification MIL-A-6091) and water, having a specific gravity of .860 + or - .020 at 15.6°G (60°F).

The x-Ia completing a mission initiates a base leg turn following its down wind leg over the runway at Edwards AFa. Recent rains have yet to dry from the lake bed as the large pond beneath the aircraft testifies.

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evidence of oxygen coming from the tank and the frost which was normally present on the outside of the fuselage at the tank location, immediately began to melt. Also the flanged sleeve and the doubler plate, which conducted the liquid oxygen through the door, were not found in the wreckage. It was possible they were blown out of the aircraft at the time of the main explosion. 5. Loss of nitrogen pressure. Nitrogen source pressure lines were located immediately behind the liquid oxygen tank and could have been ruptured simultaneously with the liquid oxygen tank or the pressure could have been bled off through the liquid oxygen tank. The pressurizing valves on the fuel and hydrogen peroxide tanks vented the tanks to the atmosphere when the source pressure dropped to zero. This depressurization effectively prevented jettisoning most of the contents of the two tanks by gravity because of the level of the jettison lines and the internal baffles in the fuel tank. The emergency jet-

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=~ Following completion of its Air Force mission objectives, the x-Ia was turned over to the NAGA. Dudng mid-December 1954, it was flown by carrier aircraft to the NAGA's Langley facility and there, over a period of eight months, modified to include an ejection seat, dedicated NAGA test instrumentation, and a hinged canopy.

opening the jettison valve in the event of an electrical failure and was not designed to overcome a loss of source pressure. 6. Loss of electrical communication and electrical power. The radio transmitter and receiver were located

adjacent to the rear bulkhead of the liquid oxygen tank and were subject to damage if this bulkhead ruptured. There was sufficient electrical wiring in the center fuselage section to cause the blowing of most of the electrical circuit breakers if an explosion occurred in that area. 7. Dropping of the X-1A away from the drag braces. Normally, braces extended from the 6-29 with pads resting on the wing of the X-1 A and pins projected from these pads into holes in the upper surface of the X-1 A wing to absorb most of the drag forces. After the explosion, observers reported several inches clearance be-

tween the pads and the wing surface on both sides of the X-1 A aircraft. The X-l A attached to the bomb shackle of the 6-29 by means of two rods extending from the X-1A wing up through the fuselage. Each rod was in two parts connected by a hydraulic snubber and the two snubbers were connected by a hydraulic line to equalize the pressure on the forward and rearward bomb shackle hooks. If the hydraulic lines were broken, the X-1A aircraft would drop about 2 in. with respect to the 6-29. Presumably, this is what happened.

NAGA pilots flew the X-I a during all of its final test flight series. The aircraft is seen shortly after being transported back to Edwards AFa following modification at Langley. Distinctive external canopy hinges are visible just aft of the canopy transparency. The NAGA logo on the vertical fin is noteworthy.

22

Damage to the B-29 was minimal. In fact, the on~ damage of any note was to the drag braces. The force of the explosion was sufficient to bend the 3/4-i~ diameter pins that extended into the X-1A wing and to shear most of the 1/4-in. bolts of the forward brackets~ both the right and left braces on the B-29. Most of the remaining bolts were partially sheared. Calculations showed a total force of from 25,000 to 40,000 Ibs. was required to shear the bolts. The momentum force of the liquid oxygen leaving the tank through a completely ru~ tured rear bulkhead would have amounted to more than

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100,000 Ibs. The exact force would depend on the degree of rupturing that actually occurred. Damage to Maj. Murray's F-86 chase aircraft (sin ,2·5528) consisted of a cracked left-hand windshield and adamaged left-hand wing-tip light assembly. Cost of repairs amounted to $212.20, including parts and labor. Close examination of the X-1A's twisted and burned parts quickly led examiners to the conclusion that something out of the ordinary had caused the destructiveexplosion. Wendell Moore, a Bell engineer involved in the post-accident investigation decided to do some experimenting on his own. On August 18, some ten days alter the X-1A was lost, he made the following notation mhis engineering diary: "Exploded Ulmer feather in lox with small hammer! This apparently answers many unknowns concerning the X-1D, X-1 #3 , and X-2 accidents, as Ulmer leather lox tank gaskets were common to al! four aircraft including the aft lox tank vent strut on the X·2 which was known to be banging and vibrating in mght prior to the explosion over Lake Ontario. The only ~ing now remaining is to find the source of shock in the "D", X-1 #3, and the "A"-called Dick Smith tonight and informed him of the results." Based on the results of Moore's experiment, the Air Force and the NACA began experiments of their own. What fo!lows is the final accident report for the X-1 A, and ~s inevitable conclusion: "Liquid oxygen will unite chemically with explosive violence with most organic substances, but such detonations generally require a triggering impact. The only known organic substance in contact with the liquid oxygen in the X-1A aircraft would be the Ulmer leather gaskets used to seal the doors in two of the inner bulkheads and the rear bulkhead. In the course of removing the access door of the rear bulkhead in the liquid oxygen tank of the X-I B aircraft to examine it for welding defects and signs of fatigue cracks in the material, a considerable amount of combustible oily substance was found within the tank and within the liquid oxygen SUppllline from the tank to the oxygen compartment. A chemicai anaiysis of this substance and of the leather gasket material from the X-IB aircraft was made by the Edwards AFB Chemical Laboratory and aiso by the Truesdail Laboratory in Los

Angeles. Additionai tests were made by the Edwards AFB Chemical Laboratory on gasket material from the X-1A aircraft, the X-2 #1 aircraft, and the stock materials. The results of the analysis of these materials are presented in the following: 1. Ulmer leather consists of leather impregnated with an approximately 50/50 mixture of tricresyl phosphate and carnauba wax. About 1.04 Ibs. of this mixture is used to

impregnate 1 lb. of untreated leather. 2. The liquid found in the X-I B tank was principally tricresyl phosphate. 3. Tricresyl phosphate was present in the gasket material from the X-IA wreckage, as well as in the gasket material removed from the X-I Band X-2 #1 aircraft. Assuming the gaskets in the liquid oxygen tank of the X-1Awere the same as the stock material obtained from Bell Aircraft Corporation, then approximately 1.75Ibs. of the leather was used to seal the tank, and this amount of leather would have contained approximately 0.45 Ibs. (almost a cupful) of tricresyl phosphate. Experiments showed that heating samples of the leather to about 200 0 F. would cause the mixture of tricresyl phosphate and carnauba wax to run out of the

leather, and when collected and cooled, to solidify. in experiments the leather was compressed between flanges and allowed to stand at room temperature overnight. The tricresyl phosphate separated from the leather and the wax in appreciable quantity. Thus, the liquid present in the X-1 Band X-2 aircraft can be explained. Concerning using the leather in liquid oxygen service,

Mr. George Patch, Assistant to the Vice President in charge of distribution at the Linde Products Company, was consulted. He stated that Ulmer leather could be used for gaseous oxygen at room temperature and moderate pressures, and is used by the Linde Air

Products company for pump and valve packing. However, he further stated that in contact with liquid oxygen, a comparatively low impact, 40 to 50 foot-pounds, with a halfinch diameter hammer, can detonate the Ulmer leather.

This is a result of laboratory tests which Linde conducted approximately 4 to 5 years ago. Mr. Patch further stated that, as a result of these tests, his company would not recommend using Ulmer leather for liquid oxygen service."

As point of interest, it should be mentioned that in Air Force tests, "It was also demonstrated that frozen drops

of pure tricresyl phosphate would detonate when placed alone on an anvil and struck with a weight". Based on the results of the investigation into the cause of the X-1A explosion, all Ulmer leather gaskets were removed from the remaining rocket propelled aircraft still in the Air Force inventory. Affected were the X-1 B, the X-2 #1, and the X-1 E. No further catastrophic explosions were recorded among these aircraft. Thus, at long last, was discovered the cause of the explosions that had destroyed the X-1 #3, the X-1D, and the X-2 #1. The third and final member of the second generation X-1 family, the X-1B (48-1385), arrived at Edwards on June 20,1954. By this time, the X-1A already had demonstrated the type's maximum speed and altitude capabilities and it therefore was decided by Air Force program directors to use the X-1 B primarily for pilot familiarization flights. Following this, it was to be turned over to the NACA. The first X-1 B glide flight (it originally was scheduled to be a powered flight-but became a glide flight following a fuel system turbopump malfunction) was completed with Lt. Col. Jack Ridley in the cockpit on September 24, 1954. This was followed by a second glide flight on October 6 and a first powered flight with Maj. Arthur Murray at the controls, on October 8. The first of the scheduled familiarization flights took place on October 13. Five additional familiarization flights took place during the following six weeks, these ending with two flights by the scheduled pilot of the forthcoming Bell X-2, Lt. Col. Frank Everest. On December 3, 1954, the Air Force turned over the X-1 B to the NACA. Shortly afterwards, it was loaded aboard its B-29 carrier aircraft (the original carrier aircraft scheduled for X-1 B launch duties, a B-50, had been lost with the third X-1) and flown to NACA's Langley, Virginia facility for the installation of dedicated NACA test instru mentation. The Langley stay lasted almost eight months and it was not until August 1, 1955, that the X-1 B was returned to Edwards. Renewed flight testing of the aircraft with an initial hop to verify the X-1 B's flightworthiness fol!owing

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The original second-generation full-scale mock-up served as the basis for the X-I BIG armament systems testbed nose section mock-up. Important element in study was flooring in nose compartment and versatility of mounting options.

Nose section could be separated from rest of mock-up, which was essentially conventional. As wing and vertical and horizontal taif surfaces were basically those of the firstgeneration aircraft, they were not included in second-generation mock·up study.

23

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The X-1D nears final assembfy at Bell during early 1951. Though sequentially the last in designation, it was to be the first of the second-generation X-Is to be completed. During July it would be delivered to Edwards AFB.

Prior to completion, the X-ID was subject to several propellant tank pressurization tests to verify tank integrity. Visible in this view is the routing of the lox plumbing through the dorsal fairing back to the turbopump compartment.

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The X-ID, because it was the first of the second-generation aircraft completed, was subject to intense scrutiny when it came time to test mate it with the B-29 carrier aircraft. As it were, the B-29's bomb bay dimensions had played a critical role in the design of the second-generation aircraft as the dimension between the B-29's fore and afr pressure bulkheads effectively dictated their over-all length and vertical fin height. '

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The basic idea leading to the decision to take the first-genera ton X-I fuselage design and scratch it in order to improve performance came from Bell project engineer Richard Frost. The stretch permitted greater propellant capacity and consequently, greatly increased engine operating times, With power available over a longer period, higher speeds and altitudes became possible. Additionally, the new design permitted a more conventional cockpit and canopy configuration which improved emergency egress survivability.

24

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initial hop to verify the X-1B's f1ightworthiness following modification got underway on August 14. NACA test pilot John McKay was in the cockpit on this flight and would remain the X-1 B's assigned pilot for the following twelve missions. Eventually, he would pass the reins on to NACA test pilot Neil Armstrong. Armstrong would fly the last four X·1B missions and would have the honor of making the last landing ever in a second generation X-1 aircraft. Most of the NACA X-1 B flights up to this point had been conducted for purposes of aerodynamic heating research. The instrumentation installed at Langley had consisted of thermal sensors and associated recorders, and the several flights flown from August 1956 to July 1957, had been primarily for purposes of accumulating data in this segment of the flight envelope. Due to the instability problems encountered by the X-1 A, flights to speeds of Mach 2 or greater were prohibited. However, on several occasions speeds of Mach 1.8 or better were achieved. The last three X-1 B missions were flown with extended wingtips and a rUdimentary hydrogen peroxide-fueled reaction control system in place. The latter never actually was used in exo-atmospheric flight, but the technology base generated by its development and preliminary testing proved of great value in designing a similar system for the forthcoming North American X-15. Following the completion of the X-1B's 17th NACA flight, a decision was made to temporarily ground the aircraft in order to install a small set of ventral fins to improve directional siability at high speeds and altitudes, and to equip it with a new XLR11 powerplant. Unfortunately, during an inspection conducted while the grounding was in effect, fatigue cracks were discovered in the X-1 B's liquid oxygen tank. An attempt to repair Ihes~ with welds failed, and d4ring June 1958, a deci· sion was made to cancel the remainder of the X-1B's flight test program. Fo!lowing this, the reaction control system was removed and installed in an Air Force Lockheed NF-104A and some six months later, on January 27,1959, the X-1 B was turned over permanently to the Air Force Museum at Wright-Patterson AFB, Ohio, for preservation and public display. The unbuilt X-1 C was to have served as a supersonic propulsion syst(lm testbed exploring the performance increases provided through the use of improved turbopump and combustion chamber designs. As there was no fullscale aircra,ft available to accommodate this requirement atthe time of the second generation X-1 program's birth, il was proposed that one .of the four second generation X·ls be optimized for a propulsion system test program. Parallelling this was a decision to utilize the X-1 B for armament systems testing in a: supersonic environment. Various weapon types were plann(ld for testing, and it is known from photographs of the mock-up and available qocumentation, that many different types of machine gun a~d cannon armament were to have been mounted in the nose. The X-1 B as an armament testbed would have incorporated a number of modifications not seen on any of its sister ships, the most notable being large, vertical dorsai and ventral yaw-stability surfaces on the tops and botioms of each wing, and a retractable ventral fin underneath the fuselage. The concurrent and rapid development of operational fighters such as the North American F-1 00 and Lockheed F·l04, with sustained supersonic flight capabilities, eventually negated the need for the armed X-1 B, and the program was cancelled. Some sources later stated the X-1 C was the aforementioned armament systems testbed, but recently located records now verify the X-1 B to have been the intended armed version. At least one study conducted by Bell refers to a reconnaissance capability for the aircraft. Apparently, it was proposed at one time to carry an "RX-1" to a target area, launch it, and later retrieve it following its intelligence gathering pass over the target. Little information has surlaced concerning the aircraft configuration, its optical sensors, or the proposed means of retrieval.

The X-10 being examined during ground testing of the propulsion system. The center section bay panels were hinged to open vertically in order to provide access to test instrumentation and a nitrogen tank. Electrical connection, located between open panels, was dorsally mounted for carrier aircraft compatibility.

Propellants were loaded into the X-1 s at a special Edwards AFB site. Large water/alcohol, nitrogen, and lox tanks accommodated all daily needs. Propellant uploading could be accomplished with the aircraft or unmated. Off-loading usually was achieved either by running the e,.~n~g:in:~e~_:o~lr:~s~i::.m~p~/Y:"'~;j'~~t~:o~~~,

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The second-generation X-1 s, like their first-generation stablemates, periodically suffered from nose gear failures follOWing touchdown. The X-tO is seen on the dry lake bed at Edwards AFB following its first, and only, successful flight (ul1powered) on July 24, 1951. Jean "Skip" Ziegler was the pilot.

THE BELL X·1 E: The X-1 E was born as much out of desperation as out oflegitlmate need. During early 1951, the second X-1 still was flying for the NACA. The Air Force, at this point, was expecting the new X-1 0 (48-1386) to arrive at any time, and accordingly, had retired the first X-1 (46-062) to the Smithsonian Institution. The NACA also was expecting 10 receive a new aircraft, the third X-1 (46-064), with its new turbopump and increased fuel capacity. The arrival of this aircraft was expected to allow the NACA to retire the second X-1 (46-063).

The X-10 was destroyed lollowing a near catastrophic in flight explosion while still attached to its carrier aircraft. Because the explosion forced the X-10's main landing gear into the down-and-Iocked position, and because the landing gear hung some 8 in. below the carrier aircraft's main gear, the crew was forced to jettison it.

25

The X-IE at Edwards AFB during late 1956. The Douglas D-558-II-style canopy and windscreen are readily apparent. This configura1ion provided proper clearances and mechanics for the installation of a rudimentary rocket-propelled ejection seat. The NASA had elected to install the ejection seat out of considera1ion for the pilot's safety. Prior to this, egressing any of the first-genera1ion X-Is required the pilot to remove the side door and fall out-directly in front of the right wing.

With its changes, the X-IE was somewhat more appealing, aesthetically, than its stablemates. Both the wing and horizontal tail surfaces incorporated the extremely thin 4% thicknesslchord ratio airfoil. This was, at the time, the thinnest airfoil section ever flown on a manned, supersonic aircraft; and in terms of technology, a major achievement in structural design. Flap and aileron actuating mechanisms set new standards in cross-sec1ional area and mechanical assemblies.

26

When empty of propellants, the X-I E, and in fact, all aircraft in the X-I family, had a very neutral center of gravity. The X-I E, however, was the only one to have a true tail skid to protect the empennage from over-rotation during landing. As can be seen in this view, there was little room for error as the aircraft pitch angle was extremely limited during flare. Only two pilots, Joseph Walker and John McKay, both with the NACAINASA, ever were to fly the X-IE during the course of its 26 flight program at Edwards AFB.

The X-IE (seen statically displayed during a 1957 airshow at Edwards AFB), on November 6, 1958, became the last X-I, of either generation, to fly when NASA test pilot Joseph Walker landed the aircraft at Edwards AFB following its final research mission. Throughout its flight test program, the X-I E's ailerons, rudder, and elevators remained unpainted. And when ventral fins were added during mid-1958, they a/so were left unpainted.

All of these plans fell by the wayside when the X-1D ind third X-1 were destroyed in accidents before their respective flight test programs could be consummated. !ocompound the NACA's problems, during 1951 it was lscovered that the high-pressure nitrogen spheres in the 1maining second X-1 were prone to explode after 700 b800 cycles (one fill-up and emptying was considered I cycle). In the hope of correcting this, three nitrogen \1ieres were removed from the first X-1 which already ras residing in the Smithsonian Institution. Two of these ~rst in tests after a few hundred cycles. There now were no flyable X-1 s. A hurried decision to :ssure the NACA's continued participation in high-speed '~earch thus gave birth to a program to modify the ~cond X-1 (46-063) into what was effectively a new air~a~. As part of the project, it would be equipped with Ilurbine pump powerplant fuel system similar to that in nenever-tested third X-1. Additionally, a new wing, with mincredibly thin 4% thickness/chord ratio, would replace .Ie original 8% wing. In ils original configuration, and still suffering from the torementioned nitrogen sphere problem, the second X-1 liS retired from the NACA high-speed flight stable follow'gits 54th and last NACA mission on October 23, 1951. Air Force, in collaboration with the NACA, in the 'eantime, had begun research into the use of very thin ·iI thickness/chord ratio airfoils and had concluded that ~ improved performance potential of these experimeni surfaces merited full-scale testing. Concommitantly, the NACA also had been conducting :search associated with rocket powerplant im'Iovements. During 1951, work had begun on the lvelopment of a new low-pressure engine turbopump ,Iii that, it was hoped, would replace the somewhat

The X-I E's ejection seat forced NACAINASA and Belf engineers to incorporate a more conventional windscreen and canopy. Interestingly, the latter were built as a single, integral unit removable for pilot ingress and egress. The X-IE was nicknamed "Little Joe" and the moniker was painted on both sides of the forward fuselage.

27

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Loading lox into "Little Joe" at Edwards. Barely visible in the cloud of lox surrounding the aft end of the aircraft are the combustion chambers of the XLRII, which appear to be equipped with expansion nozzles. The latter improved exhaust efficiency and thus provided an incremental increase in thrust. This modification, coupled with the use of a new fuel (Hidyne or V-deta) in place of the standard water/alcohol mixture, was expected to give the aircraft near Mach 3 capability.

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Apparently following the June 10, 1958 landing accident that incurred only minor damage, the X-IE is seen being raised from the Edwards dry lake bed surface for transport back to the NACNNASA hangar for repairs. Damage to the ventral fuselage fairing appears to indicate a landing gear failure. The X-I E was suspended by its twin dorsal hook apparatus that normally served to support the aircraft when mounted in the bomb bay of its carrier aircraft. The retrieval vehicle is nicknamed "Big Bertha ".

28

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the X-IE periodically was ground tested to check propulsion and miscellaneous aircraft sub-systems. Such tests involved a ground tie-down and numerous tJi partial- and full-throttle static engine runs, when necessary. Safety precautions, during these relatively early days of high-performance rocket-propelled research ~ aircraft operations, were minimal. Noteworthy is the lack of hearing protection utilized by attendant ground personnel during this static engine run.

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dangerous, space consuming, and heavy, high-pressure nitrogen pressurization systems then in use. In order to accommodate concurrently two major research objectives, the NACA, following contract signing during April 1952, began exploring the possibility of modifying the second X-1 into a full-scale thin wing and turbopump-engine testbed. NACA engineers quickly concluded that the modification effort was worthwhile and shortly afterwards, began revamping 46-063. During March 1954, the "new" X-1 officially was designated X-1 E, and by mid-1955, most of the modification work, which included a new cockpit and canopy configuration (required to accommodate the NACA-specified ejection seat) in addition to the new wing, had been completed at the NACA facility at Edwards AFB. Several months were spent ground checking the aircraft and by late November, it had been cleared for flight test. It is germane at this point to mention that development of the X-1 E's special wing was a rather significant undertaking. Stanley Aviation Corporation, founded by ex-Bell Vice President of Engineering Robert Stanley (and ably essisted by another ex-Bell chief engineer, Richard Frost), had won the NACAIAir Force contract to build the new high-technology wing. With a span of 22.79 ft., a root chord of 7.62 ft., and a tip chord of 2.81 ft., it used a modified NACA 64A-004 symmetrical airfoil section which gave a maximum thickness at the root of 3-3/8 in. Aeroelasticity, which was -the wing's flexibility factor in adynamic load situation, was the item of most concern due to the thinness of the airfoil section and the associated severe limitations placed on structure. Accordingly, maximum torsional stiffness was acquired by using multiple rectangular cross-section spars and tapered milled wing skins. The latter literally were bolted to the spars and rips. Complicating matters was the NACA requirement that the wing be equipped with over 200 orifices for pressure distribution studies and 343 gauges for structural loading and aerodynamic heating measurements. FolloWing an abortive first launch attempt on December 3,1955, the first X-1E glide flight, with NACA test pilot Joseph Walker in the cockpit, was completed successfuliyon December 15. Walker would remain the X-1E's pilot lor the following twenty missions.

The X-1 E now explored its performance envelope in a steady train of test flights. On June 7, 1956, the airplane reached a speed of Mach 1.55. This was the first X-1 E flight over 1,000 mph (which also was the aircraft's first supersonic flight since modification). Additional flights culminated in the first X-1E Mach 2 flight on August 31, 1956, and a maximum speed flight of Mach 2.24 (approximately 1,480 mph) on October 8, 1957. Following the installation of twin ventral fins during December 1957 (to improve directional stability), the X-1 E was again declared flightworthy. On May 14, 1958, it successfully completed its eighteenth mission. A minor landing accident following a flight on June 10, 1958, gave NACA engineers a chance to incorporate a performance improving engine modification (allowing engine combustion chamber pressures to be increased from 250 psi to 300 psi). This, coupled with an experimental and significantly more powerful propellant known as Hidyne or U-deta (60% unsymmetrical dimethylhydrazine and 40% diethylene triamine), was expected to give the X-1 E near-Mach 3 speed potential. On September 17, Walker made his last X-1 flight and two days later turned over the X-1 E's contois to NACA test pilot John McKay. Mckay successfully completed the remaining four X-1 E flights, at which time, the aircraft again was grounded, this time for replacement of the pilot emergency egress system. During this grounding, X-ray-inspections of the fuel and oxidizer tanks were undertaken. When the negatives were returned from the lab, they revealed a serious crack in the fuel tank. This, coupled with the imminent arrival of the new North American X-15, resulted in a final NACA decision to terminate X-1 E flight test work.

CONSTRUCTION AND SYSTEMS: THE BELL X·1 (The First Generation): The three original X-1 s were of conventional aluminum

stressed skin construction but built to extremely high structural standards. They were, in fact, stressed to plus or minus 18 g's-which was about half again the known g capability of any other aircraft then being flown. The X-1s had nitrogen-actuated and gravity assisted retractable tricycle landing gear. Gear limit speed was 300 mph. The main wheel tires were 24 x 7.7 in.; and the nose wheel tire was 16 x 5.8 x 8.5 in. The wheels were of magnesium allby. The nose wheel, though equipped with a hydraulic shimmy damper, was not steerable but there was differential disc braking available on the main gear. Nose gear swivei angle was 40° to either side of the aircraft centerline. The wheel base was 100.7 in. and the tread was 51 in. The first and third X-1s were built with a NACA 65-108 airfoil wing section of 8% thickness/chord ratio. The second X-1 was built with a NACA 65-11 0 airfoil wing section of 10% thickness (the 8% wing was significantly more difficult to manufacture than the 10%; the 8% wing, due to structural requirements, had wing skins that tapered from 1/2-in. thickness at the root to approximately 1/32-in. at the tip). The taper ratio for both wing types was 2:1. Root chord length was 74.2 in. and tip chord length was 37.1 in. Incidence atthe root was + 2-1/2°; incidence at the tip was + 1° 30 minutes. Dihedral was 0° and leading edge sweepback was 5° 2 minutes and 52 seconds. The aspect ratio was 6.03. The controls and control surfaces were not boosted, but the horizontal stabilizer (26 sq. ft. in area) could be electrically trimmed (5° up to 10° down from neutral). For the first time in a transonic-capable aircraft, an allmoving stabilizer was utilized. The latter was in fact a somewhat unconventional version of this now-standard device as in the X-1 the elevators (and rudder) could be locked in position so that trim control served as total vehicle pitch control. This system had been developed and flown on a Curtiss XP-42 at NACA Langley during the 1943/1945 period. During the X-1 design stage, the NACA insisted that an all-moving horizontal tail surface be included in the aircraft's control surface complement. The NACA believed this would provide the needed trim ability for the piiot. The X-1, of course, later proved the viability of this concept. Shortly afterwards, production military aircraft

The X-I E flew its finat nine missions with ventral fins attached to its empennage section. Additionalty, an over-rotation skid was mounted at the aft end of the fusetage ventral fairing. The ventral fins increased the aircraft's vertical surface area and thus helped counter an inherent instability problem that had affected alt members of the X-I family at high Mach-inertia coupling. Unfortunately, the X-I E's rarely seen combustion chamber expansion nozzles have been covered for protection in this view.

29

capable of transonic performance began emerging from the various aircraft production facilities with all-moving horizontal stabilators as standard equipment. The control surfaces were conventional, consisting of wing ailerons (6.3 sq. ft. in area; angular movements of 12° up and 12° down), and elevators (5.2 sq. ft. each in area; angular movements of 15° up and 10° down). The wing also had 11.6 sq. ft. of flap area (angular deflection upon deployment, 60°). A mechanically activated spoiler was installed on the upper surface of each wing and was found to be very effective as a landing aid. However, during the course of the flight test program, most pilots elected to utilize only the more conventional flaps-which proved sufficient for landing. The spoilers eventually were sealed over. The aircraft was equipped with a conventional vertical tail and rudder. The vertical tail total effective area was 25.6 sq. ft., and the rudder area was 5.2 sq. ft. (with an angular movement of 15° left or right). The cockpit was pressurized with a maximum pressure differential of 3 Ibs.lsq. in. Additionally, the pilot was provided with a personalized oxygen system (this unit underwent several changes during the course of the X-l 's flight test program). A control yoke for aileron and elevator actuation was provided along with conventional rudder pedals. The pilot was not furnished an ejection seat (though studies for an ejection seat were undertaken, it was concluded that it would be of little use at high speeds and that the weight penalty would be too severe). In an emergency, he was expected to remove a pin from the hinged control column and displace it, remove the door panel located on the right side of the cockpit, and manually bailout. He was equipped with a conventional backpack type parachute which was expected to suffice for emergency egress purposes. The windshield was a doubie glazed surface configured to minimize condensation formation. The external surface was constructed of laminated glass panes, and the internal surface was of methyl methacrylate. Defrosting was provided. The fuselage was basically a tapering semimonocoque cylinder comprising transverse frames, longitudinals, and stressed skin. Inside the fuselage were two large stainless steel propellant tan ks for fuel and oxidizer. One was mounted behind the wing center section and one in front. The forward tank was capable of holding 311 gal. of liquid oxygen and the aft, 293 gal. of diluted ethyl alcohol. The third X-l had an increased fuel capacity and could carry 437 gal. of liquid oxygen and 498 gal. of diluted ethyl alcohol. This aircraft also carried 31 gal. of hydrogen peroxide to provide power for its propulsion unit's advanced turbopump. The X-l also was equipped with several communication and radar beacon type antenna. Other than conventional communications radios, there was nothing unusual about its avionics complement. The aircraft was, however, equipped with a wide variety of dynamic sensors which in turn were interfaced with a variety of recorders.

THE BELL X.1A, X.1B, X·1C, AND X·1D (The Second Generation): All three second generation X-l s had turbo-driven propellant pumps which were essentially the same as that utilized in the ill-fated third X-l (46-064) and described in the preceeding chapter, increased fuel capacity (limited by the B-29/B-50's bomb-bay dimensions which allowed only a 4 ft. 6 in. increase in fuselage length over that of the first generation X-ls), a stepped windscreen and canopy (for improved pilot ingress and egress, and improved pilot visibility), an ejection seat (not installed until the type already had undertaken part of its flight test program), cockpit pressurization, and a fighter-type control stick (the first generation X-l s used an H-shaped yoke for improved control system leverage). Aluminum construction was used throughout. There was little unconventional about the airframes except that, like their predecessors, the second generation X-l s were stressed to plus and minus 18 g's. Propellant capacity was 500 gal. of liquid oxygen and 570 gal. of diluted ethyl alcohol. This was contained in two tanks (oxidizer forward and fuel aft) separated by the wing center section. Additionally, 37 gal. of hydrogen peroxide were provided as fuel for powering the engine turbopump.

30

The landing gear was simiiar to that used on the first generation aircraft, though modified slightly to accommodate heavier empty weights. The free-castoring (equipped with a shimmy damper) nose wheel could be steered through the use of differential braking of the main gear disc brakes. The flight control system, which was virtually identical to that of the first generation X-l s (with the exception of the use of a control stick rather than a control yoke), re·mained un-boosted and consisted of dynamically balanced ailerons, a dynamically balanced elevator, and a conventional rudder. The horizontal stabilizer was adjustable in pitch for trim control from the cockpit. Perhaps the only distinctive change of note was the slight reduction in flap area from 11.6 to 11.46 sq. ft. All other control surface areas remained essentially the same. In general, the X-lA, X-l B, and X-l D were quite similar. However, the X-l D differed in having a new low-pressure fuel system, a slightly increased fuel capacity, and minor changes in cockpit instrumentation. The X-l B later was modified to accommodate the aforementioned highaltitude reaction controi system. This led to the addition of slightly extended wingtips-thus giving the X-l B a greater total wingspan than any of the other first or second generation X-ls. Related modifications were required to accommodate the hydrogen peroxide propellant system and the cockpit-mounted reaction control system indicators, function lights, and stick modifications. All three aircraft utilized a NACA 65-108 airfoil section wing with an 8% thickness/chord ratio that was similar, in almost every respect, to that of the first generation X-l s (46-062 and 46-064, specifically).

THE BELL X·1E: During April 1959, X-l, 46-063, was grounded in order to modify it into what was to become the X-l E. A number of significant modifications were incorporated, not the least of which were the addition of a turbopump-equipped XLRll, a stepped windscreen and hard canopy, an ejection seat (the surplus seat from the second Northrop X-4, 46-677), and an extremely thin 4% thickness/chord ratio wing. The latter, a product of the Stanley Aviation Corporation of Denver, Colorado, was perhaps the most important modification. Under the direction of Stanley project engineer Gordon Valentine, the wing was built and stresstested, and then transported to Edwards AFB for installation. It was a mUlti-spar layout with tapered milled skins attached by bolts tapped into solid ribs and spars. The rectangular section spars had no capstrips. Maximum inside clear depth at the root was 2-1/8 in., and maximum wing thickness at the root was a mere 3-3/8 in. Inside the wing surfaces were 343 baked-on plastic gauges to measure structural strain and temperatures. More than 200 pressure pickup orifices had to be imbedded in the wing surfaces and connected with remote manometers by more than 1,500 ft. of 5/32 o.d. aluminum tubing. No modifications were made to the landing gear or the tail surfaces. The last nine flights of the X-l E program were conducted with ventral fins installed; these improved directional stability at high-Mach.

POWERPLANTS: THE BELL X·1 (The First Generation): The three X-l s were powered by a single four-chamber Reaction Motors, Inc. bifuel XLRll-RM-3 ('6062 and '6063) or XLRll-RM-5 ('6064) rocket engine (the Reaction Motors designation was Model 6000C4). Fuel was liquid oxygen and diluted ethyl alcohol. Maximum thrust rating was 6,000 Ibs. at sea level. The engine weighed 345 Ibs. dry. The XLR11 was not throttleable, but the combustion chambers could be fired either individually or in groups. Each chamber was rated at 1,500 Ibs. thrust. At maximum thrust settings, the engine was expected to provide full power for approximately 5 minutes before fuel depletion. The third X-l, when finally completed, differed from its two stablemates in being equipped with a steam-driven turbopump that served to transfer propellants from their respective tanks to the powerplant. Hydrogen peroxide was passed over a manganese dioxide catalyst to provide the superheated steam necessary to drive the turbo-

pump turbine. Engine dimensions included a length 57 in. a width of 13.5 in. and a height of 18 in.

THE BELL X·1A, X·1B, X-1C, AND X·1D (The Second Generation): The X-lA, X-l B, and X-1D each were powered bl single four-chamber Reaction Motors, Inc., bill XLRll-RM-5 (Reaction Motors, Inc. designation I E6000D4) rocket engine which weighed 345 Ibs. dry.1 sea level thrust rating was 6,000 Ibs. with all II chambers operating. Each chamber was rated at 1,~ Ibs. thrust. Like the XLRlls used in the first generati X-l s, the RM-5 had no throttle and was controlled byt niting one or more of the thrust chambers at will. Theil was diluted ethyl alcohol and the oxidizer was liqUid 0: gen. Engine dimensions included a length of 57 in. width of 13.5 in., and a height of 18 in. Midway through its flight test program, the X-181 equipped with an XLRll-RM-9 engine (Reaction Moto Inc. designation was E-6000C4-1) which differed onll haVing an electric spark, low-tension interrupter type nition in place of the older high-tension type.

THE BELL X·1 E: The X-l E was powered by a Reaction Motors, Inc. R LR-8-RM-5 (advanced XLR11) four-chamber ro~ engine rated at 6,000 Ibs. tho at sea level. As with alII rocket engines, this powerplant was not throttleable,1 instead, depended on ignition of anyone chamber group of chambers to vary the thrust rating. The LR·81 the same type and model RMI engine used in the DouS D-558-11 research aircraft for the Navy.

DISPOSITION: THE BELL X-1 (The First Generation): The first X-l, 46-062, is on permanent display in! main hall of the Smithsonian Institution's National M Space Museum, Washington, D.C. Before being tum over to the NASM on August 6, 1950, the aircraft co pleted a total of 78 glide and powered flights. The second X-l, 46-063, in X-l E configuration, is permanent display in front of the National Aeronau: and Space Administration's Dryden Flight Resea' Facility building at Edwards AFB, Cali!ornia. Beforel ing converted to the X-l E, this aircraft completed atl of 74 glide and powered flights. The third X-l, 46-064, was destroyed on Novembe' 1951, during static ground operations at Edwards AI California immediately following a mated test hop un: its B-50 carrier aircraft. The explosion eventually I determined to have been caused by the incompatib' of Ulmer leather gasket material and liquid oxy~ Before the accident the third aircraft had "COmpleted I successful glide flight.

THE BELL X·1A, X-1B, X·1C, AND X·1D (The Second Generation): The X-l A was jettisoned to destruction following an flight explosion over Edwards AFB, California on Aug 8, 1955. This aircraft had completed a total of 25 g' and powered flights prior to the accident. The X-l B is displayed permanently at the Air Fo Museum, Wright-Patterson AFB, Ohio. This aircraftl completed a total of 27 glide and powered flights bel retirement and delivery to the Museum on January 1959. The X-l D was jettisoned to destruction following an flight explosion and fire on August 22, 1951,0 Edwards AFB, California. This aircraft had completedl glide flight prior to its loss.

THE BELL X·1 E: Sans ventral fins, today it can be seen mounted 0 pylon in front of the National Aeronautics and Space I ministration building, Dryden Flight Research Cer facility, at Edwards AFB, California.

------------------

~-_._-

FLIGHT LOGS The following is a complete listing of all X·l glide and powered flights conducted between January 25,1946, and October 23,1951 (#1 = 46·062; #2 = 46·063; #3 = 46·064; first flight implies first flight by pilot as well as first flight of aircraft): MACH/MPH (MPH est.)

MAX. ALT. (FT.lMSL)

REMARKS

?I?

First glide flight.

?I? ?I?

? 7 ? ?

Woolams

?I?

?

1 1 1 1 1

Woolams Woolams Woolams Woolams Woolams

?I?

?I? ?I? ?I?

? 7 7

2 2 2 2 2

Goodlin Goodlin

.39/230 .39/230

Goodlin Goodlin Goodlin

.39/230

DATE

A/C PILOT NO.

1 2 3 4

1/25/46 2/5/46 2/5/46 2/8/46

1 1 1 1

Woolams Woolams Woolams Woolams

5

2/19/46

1

6 7 8 9 10

2/25/46

11 12 13 14 15

10111/46 10/14/46

SEQ. NO.

2/25/46 2/26/46 2/26/46 3/6/46

10117/46

12/3/46 12/9/46

?I?

?/?

.391230 .751510

? ?

25,000 25,000 25,000 25,000 35,000

Second flight of the day. Wing damage incurred following landing gear collapse Nose gear collapse on landing.

11

Jt 1

Jt lr

LS

tS

1e &

3d

m-

12/20/46 1/8147 1/17/47

2 2 2 2 2 2 2 2 2 2 2

Goodlin Goodlin Goodlin Goodiin Goodlin Goodlin Goodlin Goodlin Goodlin Goodlin Goodlin

?I?

27 28 29 30 31 32 33 34 35 36 37

4/10/47

1 1 1 1 1 1 1 1 2 2 1

Goodlin Goodlin Goodlin Goodlin Goodlin Goodlin Goodlin Goodlin

.371250

38 39 40 41 42 43 44 45 46 47 48 49 50

8/6/47

1 1 1 1 9/4147 1 1 9/8/47 1 9/10/47 1 9/12/47 2 9/25/47 10/3/47 1 1018/47 1 10/10/47 1 10/14/47 1

Yeager Yeager Yeager Yeager

51 52

10/21/47

2 1

53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71

10/28/47

1 1 1 1 1 1 2 2 2 2 2 2 1 2 1 2 2 1 1

1/22/47 1/23/47 1/30/47 1/31/47 2/5/47 2/7/47 2/19/47

2/21/47

4/11/47 4/29/47 4/30/47 5/5/47 5/15/47 5/19/47

5/21/47 5/22/47 5/29/47 6/5/47

Johnston Goodlin Goodlin

.80/540 .82/554 .76/515 .761515 .751416 .701473

?I? ?I? ?I? ?I?

.77/476

.77/476 .751478

?I? ?I? ?I? ?I?

.72/487 .721487 7/?

27,000 37,000 30,000 31,000 30,000 32,000 7 7 7 7 7 25,000 20,000 35,000 35,000 7

Second flight of the day. Last flight at Pinecastle AAF, Florida. First flight of #2 aircraft.

First powered flight of the

?

on cs ch

le·

,taI

r9

=s

de r

vas ility

en

)n e

1 in ~u st

llid e

)rc e

had ,fo re

r2 7,

n'Inov er

10ne

on a

lAdIn ter

8/7/47 8/8/47 8/29/47

10/27/47

10/29/47

10/31/47 11/3/47 11/4/47 11/6/47 12/16/47

12/17/47 1/6/48 1/8/48 1/9148 1/15/48 1/16/48 1/21/48 1/22/48

1/23/48 1/27/48 1/30/48 2124/48

?I? 71? 71?

.85/570 89/596

? 7 7 7 7 7 7 7 30,000 7 40,000 41,000 45,000

Yeager Yeager Yeager Yeager Yeager Yeager Yeager Yeager

71? 71? .925/620 .9971668

Yeager

1.06/700

Hoover Yeager

.84/568

24,000

?I?

7

Yeager Yeager Yeager

?I?

Yeager Yeager Yeager Hoover Hoover Hoover Hoover Lilly

?I?

? 7 7 ? 7 48,600 7 7 7 7 7 7 38,000 7 7 31,000 7 36,000 40,000

Lilly Yeager Hoover Yeager Hoover Hoover Yeager Fitzgerald

.89/596 .91/610

.92/616

71? 71?

?I?

1.35/905 .84/568 .80/541

.74/500 .83/561 ?I? .761514

1.05/703 .82/554 1.20/804

.89/596 .925/620 1.20/815 1.10/744

Glide flight due to engine malfunction. First glide flight for Goodlin . First powered flight.

?

7 7 7 ?

DATE

AlC PILOT NO.

MACH/MPH (MPH est.)

MAX. ALT. (FT.lMSL)

REMARKS

2/25/48 3/4/48

Fitzgerald Hoover Hoover Yeager Hoover Yeager

?/? .943/622

?

Glide flight to check repairs

1.065/703

1.451957

40,000 45,000 ? 50,000

72 73 74 75 76 77

3/26/48

1 2 2 1 2 1

78 79

3/30148 3/31148

2 1

Hoover Yeager

.901594 ?I?

36,000 ?

80 81

3/31/48 4/4/48

2 2

Lilly Lilly

1.1/726 71?

40,000 ?

82 83 84 85 86 87 88

4/6/48 4/7/48 4/7/48 4/9/48 4/9/48 4/16148 4/16148

1 1 1 1 2 1 2

Fitzgerald Lundquist Fitzgerald Lundquist Lilly Lundquist Lilly

89

4/26/48

1

90 91 92 93 94 95

4/29/48 5/4/48 5/21/48

3/10/48 3/11/48 3/22/48

1.25/845 1.12/739

?

Second flight of the day.

X·l program. 16 17 18 19 20 21 22 23 24 25 26

SEQ. NO.

Demo flight for the Aviation Writers Association. First AF flight.

96 97 98 99 100 101 102 103 104 105 106 107. 108 109 110 111

5/25148 5/26148 6/3148

11/1/48 11/15/48 11/23/48 11129/48 11/30/48 12/1/48 12/2148 12/13/48 12123/48

1/5/49 3/11/49 3/16/49

3/21/49 3/25/49 4/14/49 4/19/49

.94/620

45,000 7 37,000 7 30,000 7 41,000

Fitzgerald

.9/608

28,000

1 1 1 1 1 1

Lundquist Fitzgerald Lundquist Fitzgerald Yeager

1.181798 1.15/777 .921622 1.081731 1.101745

Lundquist

71?

40,000 40,000 32,000 30,000 64,000 27,000

2 2 2 2 2 1 2 1 1 1

Hoover Hoover Champine Champine Champine Yeager Champine Yeager Yeager Yeager

1 1 1 1 1 1

Ridley Boyd Everest Everest Ridley Everest

1.431927 1.45/972 ?I?

51,700 50,000

1.11744 71? 1.0/676 71?

.89/587 ?I?

.945/624

.98/647 .70/462 .88/581 ?I? 1.05/710 1.01/667

.95/642 1.091737

?f?

1.23/831 1.04/703 1.22/825 1.24/838 1.07/723 71?

40,000 40,000 30,000 43,000 40,000 28,000 40,000 22,000 60,000 7 7 7 7 ?

40,000 7

First NACA supersonic flight.

Fastest flight in original X·l series ale. Engine malfunction caused flight to be completed as a glide. Engine failed to light; flight completed as a glide. First flight; glide flight.

Nose wheel down lock broke causing aircraft to skid on nose. Aborted due to engine difficulties.

Landing gear problems led to premature termination of flight.

First flight.

First conventional ground takeoff. First flight; small engine fire. First flight; small engine fire. First flight. Pressure suit check.

Engine problems curtailed altitude record attempt.

First supersonic flight by manned aircraft. First flight. Glide flight due to electrical system failure.

112 113 114

5/2/49 5/5/49

1 1 1

Ridley Yeager Everest

115 116 117 118 119 120

5/6/49 5/13/49 5/27/49 6/16/49 6/23149 7/11/49

2 2 2 2 2 2

Champine Champine Champine Champine Champine Champine

.92/607 .91/601 .94/620 1.06/700 .97/640 .91/601

40,000 35,000 38,000 40,000 47,000 43,000

7/19/49

2 1 2 2 1 1

Champine Everest Champine Champine Everest Everest

.911605 1.21804

42,000 66,846 40,000 7 71,902 69,000

2 1 1 1 2 1 1 1 1

Griffith Fleming Johnson Everest

121 122 123 124 125 126

4/29/49

7/25149

7/27/49 8/4/49 8/8/49 8/25/49

.881581 1.12/739 71? 71?

?

First flight

First flight; engine fire caused competion as glide flight.

127 128 129 130 131 132 133 134 135

9/23/49 1016/49 10/26/49 11/29/49 11/30/49 12/2/49 2/21/50 4/25/50 4/7150

Griffith Everest Everest Yeager Ridley

.99/653 1.2/811

?I?

41,500 7 7 7 7 7

71? 71? 71?

7 7

71?

?I?

.93/614

New engine. Engine explosion caused emergency landing.

Cockpit camera broke loose causing minor interior damage. Altitude record attempt.

Altitude record attempt. Loss of pressurization during alttiude record attempt forces use of partial pressure suit in emergency for first time; Everest survived . First flight. First flight. First flight.

?

Continued next page.

31

FLIGHT LOGS continued ... AlC PILOT SEQ. DATE NO. NO. 136 1 Ridley 5/8/50 137 1 Yeager 5/12/50

138 139 140 141 142 143 144 145 146 147 148 149 150 151

5/12/50 5/17/50 5/26/50 8/9/50 8/11/50 9/21/50 10/4/50 4/6/51 4/20/51 4/27/51 5/15/51 7/12/51 7/20/51 7/20/51

2 2 2 2 2 2 2 2 2 2 2 2 2 3

Griffith Griffith Griffith Griffith Griffith Griffith Griffith Yeager Crosstield Crosslield Crossfield Crossfield Crossfield Cannon

152 153 154 155 156 157 158

7/31/51 8/3/51 8/8/51 8/10/51 8/27/51 9/5/51 10/23/51

2 2 2 2 2 2 2

Crossfield Crossfield Crossfield Crossfield Walker Crossfield Walker

MACH/MPH (MPH est.)

MAX. ALT. (FT.lMSL) ? ?

?I? ?I? .95/627 1.13/746 1.20/792 .98/647 .92/607 .90/659

?/?

?I?

45,000 45,000 45,000 45,000 ?

.89/587 .90/594.90/594 .90/594 1.16/766 ?/? ?I?

45,000 45,000 45,000 45,000 ? ? ?

AGENCY

FLIGHTS

Air Force NACA NACA NACA Air Force Air Force Air Force Bell NACA

1 1 13 10 10 7 1 26 9

Last tlight of #1 aircralt; made for purposes of tootage for movie Jet Pilot.

First flight.

1.07/706 1.12/739 1.12/739 1.12/739 1.12/739

Col. Albert Boyd Joseph Cannon Robert Champine Scott Crossfield Maj. Frank Everest Capt. James Fitzgerald Lt.Col. Patrick Fleming Chalmers Goodlin John Griffith

SEQ. NO. 35

40,000 45,000 45,000 45,000 44,000 46,000 45,000 ?

?I?

PILOT

REMARKS

First flight; glide flight; only flight of #3 X-I.

Engine and flap problems led to premature termination of flight; completed as a glide; last f1igh1 of 1st X-1 series.

Herbert Hoover Maj. Richard Johnson Alvin Johnston Howard Lilly Maj. Gustav Lundquist Capt. Jack Ridley Joe Walker Jack Woolams Capt. Charles Yeager

NACA Air Force Bell NACA Air Force Air Force NACA Bell Air Force

14 1 1 6 6 5 2 10 35

The following is a complete listing of all X-1A, X·1B, and X·1D flights conducted between July 24,1951, and January 23,1958 (first flight indicates first flight by pilot as well as first flight of aircraft): SEQ. NO.

2 3

DATE

A/C NO.

7/24/51

X·1D Ziegler

?/?

2/14/53 2/20/53

X-IA Ziegler X-IA Ziegler

?I?

PILOT

4 5 6 7 8 9 10

2/21/53 3/26/53 4/10/53 4/25/53 11/21/53 12/2/53 12/8/53

X-1A X-1A X-1A X-1A X-1A X-1A X-1A

11

12/12/53

X-IA Yeager

Ziegler Ziegler Ziegler Ziegler Yeager Yeager Yeager

MACH/MPH (MPH est.)

MAX. ALT. (FT./MSL)

First glide flight; nose gear failed on landing; only flight completed by this aircraft. First glide flight. Though planned as a first powered flight, this flight was completed as glide due to propellant system problems. First powered flight.

?I?

?I? ?I? .93/614 .93/614 1.15/759 1.5/990 1.9/1,254 2.44/1,650

REMARKS

75,000

First attempt at high Mach flight. Speed record; but aircralt

encountered inertia coupling phenomenon and went out of control; Yeager recovered at 25,000 ft. Fourteen Air Force flights were attempted during the first half of 1954. Three of these flights were successful in achieving their objective-which in most instances was to achieve the highest altitude possible with the X-I A aircraft. These flights were: 5/28/54

X·1A Murray

?I?

87,094

6/4/54

X-1A Murray

1.97/1,300

89,750

8/26/54

X-1A Murray

?I?

28

7/20/55 9/24/54

X-1A Walker X-1B Ridley

1.45/957 ?I?

29

10/6/54

X-1B Ridley

?I?

30

10/8/54

X-1B Murray

?I?

31 32 33 34

10/13/54 10/19/54 10/26/54 11/4/54

X-1B X-1B X·1B X·1B

?I?

32

Stephens Childs Hanes Harer

?/? ?/? ?/?

90,440

Unofficial world altitude record. Unofficial world altitude record. Unofficial world altitude record. First and last NACA flight. First flight; ,1irst glide flight by this aircraft. Glide following lox fank problems. First flight; first powered flight by this aircraft. First flight. First flight. First flight. First flight.

DATE 11/26/54

A/C PILOT NO. X-1B Holtoner

?I?

36 37 38

11/30/54 12/2/54 8/14/56

X-1B Everest X-1B Everest X-IB McKay

?I?

39 40 41 42 43 44 45 46 47

8/29/56 9/7/56 9/18/56 9/28/56 1/3/57 5/22/57 6/7/57 6/24/57 7/11/57

X-IB X-1B X-1B X-1B X·1B X·1B X-1B X-1B X-1B

?I?

48 49

7/19/57 7/29/57

X-IB McKay X-IB McKay

1.65/1,089 1.55/1,023

50 51

8/8/57 8/15/57

X-1B McKay X-1B Armstrong

?I?

52

11/27/57

X-1B Armstrong

?/?

53 54

1/16/58 1/23/58

X-1B Armstrong X-1B Armstrong

?/? 1.5/990

McKay McKay McKay McKay McKay McKay McKay McKay McKay

MAX. ALT. (FT.lMSL) ?

MACH/MPH (MPH est.)

? 65,000 ?

2.3/1,541

?I? 1.8/1,188 ?/? ?/? 1.94/1,280 1.45/957 1.5/990 1.5/900

56,000 ? 60,000 ? ? ? ?

?I?

~

REMARKS

~

First flight; first officer of General rank to fly any X·l aircraft.

~

p" .~ ~ ~

Nose gear failed on landing.

~

~ ~

~ Glide flight.

Glide flight due to landing gear difficulties. Extended wingtips for reaction control system simulation installed.

1.5/990

60,000 ?

First flight, nose gear failed on landing. First flight in which the new reaction control system was used. Last flight of second generaion X-1 series.

PILOT

AGENCY

FLIGHTS

Neil Armstrong Maj. Stuart Childs Lt.Col. Frank Everest Col. Horace Hanes Capt. Richard Harer Brig. Gen. Stanley Holtoner John McKay Maj. Arthur Murray Lt.Col. Jack Ridley Maj. Robert Stephens Joseph Walker Maj. Charles Yeager Jean Ziegler

NACA Air Force Air Force Air Force

4 1 2 1 1 1 13 15? 2 1 1 4 7

Air Force Air Force NACA Air Force Air Force

Air Force NACA Air Force Bell

The following is a complete listing of all X-1 E flights between December 12, 1955 and Novembel 6, 1958 (first flight indicates first flights of pilots): SEQ. NO.

DATE

AlC NO.

PILOT

MACH/MPH (MPH EST.)

1 2 3 4

12/12/55 12/15/55 4/3/56 4/30/56

X-1E X-1E X-1E X-1E

Walker Walker Walker Walker

?I? ?I?

5 6 7 8 9 10 11 12 13

5/11/56 6/7/56 6/18/56 7/26/56 8/31/56 9/14/56 9/20/56 10/3/56 11/20/56

X-1E X-1E X-1E X-1E X-1E X-1E X-1E X-1E X-1E

Walker Walker Walker Walker Walker Walker Walker Walker Walker

.84/554 1.55/1,023 1.74/1,148 ?/? 2.0/1,320 2.1/1,386

14 15

4/25/57 5/15/57

X-1E Walker X-1E Walker

1.71/1,129 2.0/1,320

16 17

9/19/57 10/8/57

X-1E Walker X-1E Walker

?I?

REMARKS First flight; first glide flight

.85/561

?I?

Glide flight due to engine ~ malfunction. ~

?I? ?I? ?I?

'~

Minor landing damage. Engine problems. 60,000+ 60,000+ ? ?

67,000+ 73,000+

2.24/1,478

18

5/14/58

X-1E Walker

?I?

19

6/10/58

X-1E Walker

?/?

20 21 22 23 24 25 26

9/10/58 9/17/58 9/19/58 9/30/58 10/16/58 10/28/58 11/6/58

X-1E X-1E X-1E X-IE X-1E X-IE X-1E

?I? ?I? ?I? ?I? ?I? ?I?

Walker Walker McKay McKay McKay McKay Walker

MAX. ALT. (FT.lMSL)

I

'"

Engine problems. Engine problems. Glide flight due to engine problems. Landing accident caused serious damage. Engine problems. Fastest flight of X-1 E program. First flight with ventral fins in place. Landing accident caused minor damage.

First flight.

?/?

U-Deta fuel test flight; la. flight of X-1 E program; a. last X-1 flight.

PILOT

AGENCY

FLIGHTS

John McKay Joseph Walker

NACA NACA

5 21

7

"Chuck" Yeager's involvement in the X-I program resulted in the first nose markings seen on the aircraft. Informally named after Yeager's wife, Glennis, the first X-I, 46-062, was given the nickname "Glamorous Glennis" and adorned with appropriate nose art. Other items noteworthy in this view include the small nose bump which effectively fa ired over the dual static pitot lines that ran around the right side of the nose mounted nitrogen tank, aft. There was no bulge on the left side of the aircraft.

;1

nd

The first X-I, 46-062, on the ramp at Muroc Army Air Field During 1947. Static tests of the Reaction Motors, Inc. XLRII four-chamber regeneratively cooled rocket engine were taking place at the time, and shock balls, caused by the exhaust gas's sonic velocity, barely are visible exiting one of the engine's four combustion chambers. Safety was not a primary concern during these early days; note the absence of landing gear chocks, ground crew protection, and monitoring equipment.

33

The second X-1, 46-063, following roll-out at Bell's Niagara Falls, New York facility during 1946. Bright orange scheme over-all, typical of the period, was thought to make the aircraft more visible to chase pilots and ground tracking teams. Fuselage generally was symmetrical in contour with few straight lines. X-1 's .50 cal. bullet ancestry was readily apparent from almost any angle. Fairings on fuselage top and bottom covered efectrical wiring, propellant lines, and control cables.

One of the few visible features distinguishing the first X-I from the second (46-063, shown) was the pressurization vent on the hatch door. The second aircraft had only one, and the first aircraft had two. Otherwise, the two aircraft were almost identical. Throughout most of their respective flight test programs, the first generation X-1s remained painted orange. At Ii later date, the ventral and dorsal spines and vertical fin on 46-062 were painted white.

34

SELECT MARKINGS - - - - - - - - - - - - - Scale: 1/72nd Drawn by Mike Wagnon Bell X-1, 46-062, in F.S. 12243 gloss orange over-all, as seen during initial tests at Muroc AS during 1947. The aircraft carried the standard star-and-bar U.S. national insigne on both sides of the aft fuseiage and on the upper left and lower right wing surfaces. Note the Bell iogo appearing on both the nose and under the horizontal stabilizer on both both sides of the aircraft.

,

''--..-/'

Bell X-1, 46-063, as it apeared shortly after roll-out from Bell's production facility at Niagara Falls, New York. The national insignia was part of WWII vintage and the aircraft, like 46-062, was painted F.S. 12243 gloss orange over-all.

,

Bell X-1, 46-064, in its over-all gloss white paint scheme. Positions and scale of the national insigne were similar to those on all first generation X-1 s. Even with the white paint, the Bell logo still appeared on both the nose and tail of the aircraft (almost certainly in black). Noteworthy are the deleted windscreen restraining straps removed only from this aircraft.

,

Bell X-1E, 46-063, in its over-all white paint scheme with bare metal control surfaces and ventral fins. The NACA insigne was yellow and black and the anti-glare panel ahead of the windscreen was flat black. The "rescue" placard on the forward nose panel was painted in red with white lettering, while "X-1E" was painted in red with black shadow lines. A portion of the pitot boom was painted flat black, but can be seen at other times in bare metal. The ventral fins, which initially were left bare metal, eventually were painted white.

,

''--..../.

35 \

Bell X-1B, 48-1385, in bare metal displaying the yellow and black NACA insigne. The "r'1ls~ue" arrow below the cockpit was painted red with white lettering. "X-1S" was stenciled in red with black shadow lines. Data and warning placards appeared in red stenciling, as well.

,

Bell X-1C depicted in bare metal, over-all scheme. As this aircraft only was completed in full-scale mock-up form, its actual markings are unknown.

,

Bell X-1D, 48-1386, in bare metal with a white vertical fin tip. The short life of this aircraft left few resources for marking references. One variation on the basic theme was a white painted ventral spine and the Bell logo on the nose and tail.

,

Bell X-1A, 48-1384, while in NACA service in over-all gloss white paint with bare metal control surfaces. The NACA insigne was on a yellow field with black borders and a black winged shield. The fuselage skin near the tank was left unpainted in consideration of the deleterious effect on paint caused by the extremely low temperatures of liquid oxygen.

,

BELL X-1, 46-062

-~~r-

Scale: 1/100th ,. .....- ....mUJ;

Drawn by Mike Wagnon

feature: Bell X-; lIowr

() Bell X-1A, 48-1384, in over-all bare metal with black anti-glare panel and white lin tip. The Bell logo appeared on both sides of the nose and tail. The national insignia was located in proper positions while USAF appeared on the upper-left and lower right wing surfaces. Note that the USAF appeared as an abbreviation rather than an acronym. "X-1 A" was in gloss red with gloss black shadow lines.

SPECIFICATIONS AND PEl Length Wingspan Wing Area (Inc. fuselage center section)

Leading edge sweep Dihedral Wing Wing Wing Wing

root chord tip chord root Incidence tip incidence

Wing aspect ratio Mean aerodynamic chord Total aileron area Aileron angular movements

Total flap area Height Total vertical fin area Rudder area (aft of hinge line)

Total horizontal tail area Total elevator area (aft of hinge line)

Wheel track Wheelbase Empty weight (lb•.) '6062 w/8% wing '6063 w/10% wing '6064 w/8% wing Gross weight (Ibs.) '6062 w/8% wing '6063 w/10% wing '6064 w/8% wing Maximum speed (Mach/mph) '6062 and '6063 '6064 Maximum altitude (ft.) Endurance (at max. power)

',---,,' ..

X-1AiE

X-1 30'11"

35' 28'

28'0" 130 sq.'

1305

5° 3' 0° 6'2.2" 3'1.1" +2° 30' +1° 30' 6.03

5° 6'2. 3'1. +2° : +1° :

6. 57.7 6.425 up 1 dn 1 11.46 s 10' 25.6 s 5.25 265

57.71" 6.42 sq.' up 12°

dn 12° 11.6 sq.' 10'10" 25.6sq.' 5.2 sq.' 26 sq.' 5.2 sq.'

5.25

4'3" 8'5"

4' 9'

7,000 6,750 6,847

6,8

12,250 12,000 14.751

16,4

1.45/957 2.44/1,612 70,000+ 5 min.

2.44/1,6

90,000 4m 40 SE

Bell X-1E, is shown with right side illustrated. Painting was over-all gloss white on 46-063, with ba surfaces and gloss white ventral fins. The pitot boom was bare metal. The "rescue" arrow .. in gloss red with gloss white lettering, and "X-1 E" appeared in gloss red with gloss black lines. The NACA logo was in standard colors, as were the national insignia,

37

5·062, in F,S, 12243 gloss orange over-all with F.S, 17925, gloss white trim, Aircraft was this scheme only lor a short while, late in its career, All other markings, such as national insigne, were standard for type,

,

AVAILABLE SCALE MODELS AND DECALS: MODELS: Airvac (Bell X-l): 1/72nd Airvac (Bell X-l E): 1/72nd Revell (Bell X-l): 1/32 nd Strombecker (X-1B[A,C,D)) wlpilot bust: 1/48th Strombecker (X-1B[A,C,D)) w-o/pilot bust: 1/48th

VAC VAC

DECALS: No decals other than those with kits are available at this time,

:ORMANCE: x-,c 35' + 28'0" 130 sq.'

X·1E 30'11" 22"0" 115 sq.' approx.

o·

5° 3' O·

6'2,2" 3".1" + 2° 30' + 1° 30' 6,03 57,7'" 6.42sq.' up 12° do 12° 11.46 sq.' 10'8" 25.6 sq.' 5.2 sq,' 26 sq.' 5.2 sq,'

? ? ? ? ? ? ? ? ? ? '0"0" 25.6sq.' 5,2 SQ.' 26 SQ.' 5.2 SQ.'

4'3" g'g"

4'3" 8'5"

6,880

6,850

16,487

14,750

2.44/1,612

2.24/1,450

90,000 + 4 min.

75.000+

40 sec.

45 sec.

5° 3'

4 min.

Scale: 1/72nd netal control ?ainted !dow

Drawn by Mike Wagnon

Rarely seen color image of the first second-generation X-I, X-lA, 48-1384, in its original, bright orange wraparound scheme worn only during the first few weeks following its late-1952 roll-out. This paint was removed from the aircraft apparently before it was shipped to Edwards AFB. The X-lA, though to claim an exceptional list of speed and altitude records, eventually would fall victim to the same Ulmer leather culprit that destroyed the X-1D and later, the third first-generation X-I.

The X-IA was, by far, the most successful of the three second-generation X-Is. It is seen in flight over Edwards AFB during the mid-1950s. The frozen condensation around the liquid oxygen tank (located in the fuselage section just ahead of the wing center section) occurred on almost every powered flight. Noteworthy in this view is the rarely seen all-white wing undersurface which supposedly increased the aircraft's trackability at altitude.

0,...-------. .. e

"

~

i

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. . .y,;<'-,

Test mating the X-IA at Bell. The large hydraulic lifts replaced the old-style pit loading system. Readily discernible in this view is one of two beef-up straps riveted to the lower fuselage sides just above the bomb bay. These straps corrected the loss of fuselage rigidity that occurred when the aft bomb bay cut-outs dictated the removal of select stringers and the bomb bay door assemblies. Note, too, the B-29's missing main landing gear doors.

39

The X-IA and X-1B, though being flown. at Edwards during the same time period, rarely were photographed together. With the exception of serial numbers, pitot and test boom placement (which changed regularly), and miscellaneous markings, differences were few. Visible on the side of the X-IA fuselage, just below the canopy, is the aircraft's flight record. The small black rectangles on the fusefage sides are contact points for the anti-sway snubber pads.

The ill-fated third, second-generation X-I, X-·lD, 48-1386. This aircraft would complete only an unpowered glide flight on July 24, 1951, before falling victim to the Ulmer leather gasket. Like its two stablemates, the X-IA (48-1384), and the X-IB (48-1385), the X-lD was flown unpainted except for the long white ventral fairing underneath the fuselage, the white vertical fin cap, the white wing undersurfaces (for improved trackability), and the standard national insignia.

The X-l0, though sequentially the last of the three second-generation X-Is, actually was the first to be completed and flown. The aircraft is seen at Bell shortly after roll-out and immediately prior to delivery to Edwards AFB during July 1951. The X-l0's short life caused it to be one of the feast photographed of the entire X-I family. Noteworthy in this view is the lack of lox, hydrogen peroxide, and water/alcohol dump tube extensions normally seen next to the combustion chamber nozzles.

40

IN DETAIL:

Ii

I

I

The completed cockpit of X-I, 46-062. In the foreground is the peculiar H-shaped yoke found in all three of the first-generation aircraft. This configuration was designed to give the pilot more leverage if additional effort was required for controf at sonic velocities. Rotating the upper portion of the yoke provided roll control, and moving the entire assembly back and forth provided pitch control. The aircraft also was equipped with conventional rudder pedals.

41

The left "console" area of X-I, 46-062. Nitrogen pressure gauges are visible on the upper left panel, and the oxygen regulator can be seen immediately to the left of the control yoke. The oxygen hose ran from the regulator to the pilot's face mask.

The back side of the instrument panel installed in X-I, 46-062. All instrumentation was analogue, and much of it was dependent upon pneumatic power for actuation. Test jig installation ,belies complexity of plumbing problem.

Aft cockpit bulkhead provided space for 34 AH battery, a gyro platform (for instrumentation), some communications equipment, and the seat back. This bulkhead was, in turn, mounted just ahead of the liquid oxvqen tank.,

The main instrument panel of X-I, 46-062, was painted in black "crackle"-like paint All instrument faces similarly were painted black. The Mach meter, then a unique feature, was the top instrument in the center row..

_Q~

The left sub-console was angled at approximately 40° off the main instrument panel. It accommodated oxygen regulator indicators, on/off switches for the radar beacon, a camera, strain gauges, miscellaneous powerplant systems, and radio equipment.

42

The right sub-console, also angled at approximately 40° off the main instrument panel, accommodated the fuel and lox jettison switches, nitrogen pressure gauges, and the associated nitrogen control knobs.

~

~

The left "console" area of the cockpit of X-I, 46-064, supported a voltage inverter, various powerplant and propellant system control switches, and gauges for monitoring propellant supplies and nitrogen gas quantities and pressures.

The right sub-console panel of X-I, 46-063, served to support on/off switches for the battery, cockpit camera, radio, pitot heat, and various NACA test instruments. Additionally, it support the switch for changing the ARC-S radio bands.

The cockpit of X-I, 46-064 differed only in detail from those of its stablemates. Readily discernible in this view was the peculiar "H"-shaped control yoke seen in all three first-generation aircraft.

The X-I E was the only one of the first-generation X-I airframes to be equipped with an ejection seat (retrieved from an X-4)-and this did not take place until the NACA modified the aircraft into the unique X-IE configuration.

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The surplus ejection seat from the second Northrop X-4, 46-677, was commandeered for use in the X-IE. Its addition to the cockpit led to a major nose section redesign effort that included sealing off the original cockpit ingress/egress hatch, removing the original windscreen, and the replacement of the latter with a totally new hatch and wind-screen assembly. The changes, which permitted an improved view forward, also forced the pilot to sit higher in the cockpit.

43

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One of the few discernible differences marking external physical variations between the first X-I, 46-062, and the second, 46-063, was the number of pressurization vent holes in the cockpit hatch door. The former had two, and the latter had only one. Otherwise the two aircraft were virtually identical.

~

Famous Bell test pilot, Chalmers "Slick" Goodlin demonstrates the large size of the ingress/egress hatch found only on the first-generation X-Is' right sid!

While transporting the X-I s (46-063, shown) cross-country, the aircraft were secured in position using heavy canvas shackles in addition to the normal twin-hook dorsal attachment unit. When an actual mission was being flown the entrance hatch door was left off to permit pilot ingress in flight. A small retractable ladder assembly, barely discernible protruding from the bomb bay, was lowered into position to facilitate pilot entry. The door then was installed after him.

44

____J

mt

The main instrument panel of the X-I A. The familiar T-shaped arrangement generally was conventional, though several of the indicator gauges, such as the turbine governor pressure, fuel (tank and dome) and lox (tank and dome) pressure, and first stage line pressure gauges were not. The flight instruments were centrally mounted with the propulsion system related indicators on either side. The missing gauge in this view appears to be the Mach meter.

The cockpit sides of the second generation X-Is generally were devoid of accouterments. The left side wall served as the mounting surface for the very simple throttle quadrant (which, when moved forward, basically ignited either one, two, three, or all four of the XLRII rocket chambers), and the right side wall served as the mounting surface for the oxygen regulator (removed in this view). Interior colors were medium green on the walls and flooring and a black instrument panel.

45

X-1 SECOND GENERATION INSTRUMENT PANEL

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.

Cabin Altimeter Aircraft Altimeter Windshield Defroster Control Valve Tank Vent and Pressurizing Switches landing Gear Warning Lights Fuel and Lox Shut-Off Valve Switches Accelerometer HlO l Line Temperature Gauge HlO l Line Temperature Warning Light HlO: Temperature Relay Reset Button H 20: Tank Temperature Gauge HlO: Tank Temperature Warning Light Chamber Pressure Indicators Emergency Jettison Valve Jellison Switches Chamber Selector Switches

17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32.

Oxygen Blinker Oxygen Cylinder Pressure Gauge Lox Quantily Reset Button Source pressure Gauge Windshield De·icing Pump Fuel and Lox Quantity Gauge Fire Warning Lights Fuel Quantity Reset Bulton Pump Outlet Pressure Indicator H10! Tank Pressure Gauge Attitude Gyro Turbine Overspeed Warning Light Clock Turn and Bank Indicator Stabilizer Position Indicator Turbine Overspeed Reset Bulton

33. Turbine Governor Balance Pressure Indicator 34. Turbine Governor Balance Pressure Regulator and Spill Valve 35. Machmeter 36. Lox Tank and Dome Loading Regulator and Spill Valve 37. Fuel Tank and Dome Loading Regulator and Spill Valve 38. First Stage Dome Loading Regulator and Spill Valve 39. First Stage Dome Pressure Gauge 40. Lox Tank and Dome Pressure Gauge 41. First Stage Line Pressure Gauge 42. Fuel Tank and Dome Pressure Gauge 43. Gyro Vent Selector Switch 44. Airspeed Indicator 45. Drop Light and Switch

X-1 SECOND GENERATION SWITCH PANEL

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

Aileron Trim Tab Switch Lox Auxiliary Vent Switch Radio Switch Battery Switch Pitot Heat Switch Radar Switch Interphone Switch Inverter Switch Igniter Test Switch Circuit Breakers Fire Extinguisher Selector Switch Radio Output Control Radio Channel Selector Switch

...k.. / 1

~

_ _Ln,..

The main instrument panels of the KI8 (left), X·IC mock·up (center), and X·IO (right). The general layouts of the X·18 and X·IO were quite similar to that found in the X·IA, and thus conventional for the second·generation X-I family, but the X-IC, as a propulsion system, and later, weapon systems testbed differed in having major

___4_6

ad_d_'_.t'_.0_n_s_in_t_h_e_~_or_m_O_f_a_s_p_e_r _y_A_-I_2_a_u_tO_P_il_o_t_a_n_d_t_e~s_t_e_q_U_iP_m_e_n_t_c_o_n_t_ro_'_s_, _T_h_e_a_u_t_OP_'_"o_t_s_e_r_v_e_d_t_o_s_t_ab_'_'fi_Z_e_t_h_e_a_ir_c_r_a_ft_d_u_r_in_g_w_e_a_p_o_n_~_ir_in_g_ru_n_s_.

~

The right cockpit console area essentially was the insulated metal wall of the aircraft with accouterments hungwhwe needed. Occupying the right wall of the X-1A (left) and X-tO (right) were the oxygen hoses, the oxygen system regulator, and the pilot's flight suit heater controls. Combined with the oxygen system hoses were the umbilicals for the oxygen-mask-mounted communications system. AS is apparent, the(/~ were no armrests ,on the cockpit sides.

.

.

.

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Left (left) and right views of the X-lA's main instrument panel. The panel was mounted directly to the flat side walls of the cockpit, with shock cushions residing between the mounting brackets and the actual panel. Though essentially simple in concept, the panel, which was typical of second generation X-l panels, was crowded and, typical of its era, painted black. Flight instruments were centrally located, with propulsion system monitors surrounding the central cluster.

'..':-JX.-tSEC6"N5' GENERATION~ COCKPIT (Left Side)··

1. Radio Leads

4. Stabilizer Manual Control Lever

7. Canopy Lock Indicator

2. Landing Gear Control Lever 3. Harness Release

5. Flap Switch

8. Canopy Locking Lever 9. Canopy Emergency Release

6. Thrallie

Handle

1. Canopy Locking Lever 2. Canopy Pressure Seal Valve 3. Canopy Lock Indicator

4. Emergency Jettison Tank

Pressure Gauge 5. Cabin Pressure Dump Valve

6. Stabilizer Actuator Switch 7. Emergency Cut·Off Switch 8. Oxygen Regulator

Control Lever

47

During static ground testing and related maintenance, the cockpit was accessed via a special side-mounted ladder. Pins hooked the ladder via small holes.

Nitrogen lines were rouled through the right headrest assembly which also served as the mounting point for the control system bellcranks and levers.

The revised cockpit configuration of the second-generation X-Is dictated a more conventional seating arrangement and the installation of a rather blocky and robust integral headrest assembly. This also housed the nose landing gear shock strut mount and related nose gear retraction unit.

The left side of the headrest assembly served as a mounting point lor additional control system bellcranks and a pressure indicator, and several related plumbing lines. None of the X-Is were manufaclured with ejection seats (though the X-18 later was modified by the NACAINASA to incorporate one).

The second-generation X-Is had canopies that were manually installed and removed before and after each flight. On a typical mission, the canopy was installed after the pilot had entered the cockpit from the carrier aircraft bomb bay.

48

The canopy was a laminated plexiglass bubble mounted rigidly in an aluminum frame (a cracked transparency is shown). The X-I B later was modified by the NACAINASA to have a hinged, vertically opening canopy.

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The first-generation X-Is had a simple, free-castoring nose wheel that when retracted was covered by a single-piece gear well door hinged on the right side.

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2


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The main gear axle and disc brake assembly of the first-generation aircraft retracled upward and into the main gear well located under the wing center sectipn. I

'

The main gear were small and rugged and designed to withstand very high vertical loads. Main gear failures were rfj/atively few in number, The basic design pioneered on the first-generation aircraft (shown) later was utilized in' the design of the main gear for the second-generation aircraft.

~

~

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View looking forward of a first-generation aircraft main landing gear. The doors were pneumatically opened and closed in concert with the main gear strut.

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View looking aft of a first-generation aircraft main landing gear. The pneumatic strut permitted extremely rapid extenision and/or retraction.

The second-generation X-I nose gear assembly was essentially the same as that used on the first-generation aircraft. Minor changes were incorporated in the wheel design, but otherwise, it was unchanged. Visible to the right of the nose gear is the lox fill vent exhaust, with its peculiar plumbing fairing.

Main wheel and tire assembly of a first-generation X-I. The U.S. Royal tire was a code A, 8-ply nylon, 24 x 7.7 unit. Inflation pressure was 115 psi.

The nose gear strut of the second-generation X-Is was a typical free-castoring yoke assembly. A mechanical linkage sequenced door opening and closing.

49

The gear well door (second-generation aircraft, shown) was piano hinged to the fuselage structure just below the wing center section. A mechanical strut opened and closed the door in concert with the gear retraction/extension sequence.

There were few changes visible in the basic design of the main gear of the secondgeneration X-Is when compared to the first-generation. Gear well door warning states the tire shoufd be inflated to 135 psi for towing at speeds of 20 mph.

The main gear each were equipped with separate hydraulic disc brakes. Differential use permitted steering and sequential use provided braking.

The main landing gear assemblies were rugged units designed to accommodate the relatively high landing loads incurred during the X-I 's high sink rate landings. The main load bearing carry-through structure is visible as the centerpiece between the gear strut assemblies.

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View of first-generation gear well looking forward. Main strut axle assembly is visible, along with pneumatic lines for braking, and actuator for retraction/extension. Barely visible to the far right is part of a nitrogen tube bundle.

50

~

View of first-generation gear well looking aft. Main strut axle mount, near aircraft centerline, is visible protruding from bulkhead. Cutouts in bulkhead provide excellent view of complex nitrogen bundle assembly.

A small nitrogen sphere was mounted in the extreme forward nose of all three firstgeneration X-Is. Nose boom sensor lines were routed around it on the right side, thus causing the distinctive small bulge visible in many photos.

Second-generation X-I fuselages were built in three primary sections. The nose section of the X-IA (apparently) is shown during assembly. The ffat ffoor of the nose compartment served as a mounting point for test instrumentation.

Another nose bay package, consisting of accelerometers and miscellaneous sensors, probably in the X-IA. Again, the mounting platform is a sheet of plywood. This material was easy to drill and attach test equipment to.

There were many variations to the second-generation X-I nose cone configuralion. Boom lengths and locations were particularly variable and highly dependent upon test program objectives. Boom purposes varied with requirements.

51

The center section test equipment and nitrogen tank bay of a second-generation X-I. Two piano hinged panels opened vertically to permit access. Strut assembly visible in this view was attached to support hook assembly for carrier aircraft.

The hydrogen peroxide tank, for energizing the turbopump, was mounted in the center section bay on the right side of the aircraft. Like the lox and water/alcohol tanks, it was filled from the right side of the aircraft, only.

View looking aft of the wing center section and fuselage center section of the X-1A as the aircraft was nearing final assembly. Visible on the left is the hydrogen peroxide tank for the turbopump. The finned rectangular devices in front are batteries. Noteworthy is the actual wing center section with its seemingly endless bolt and load-bearing plate assemblies. The wing, like the rest of the aircraft, was stressed to take a load of up to 18 gs.

52

Some propulsion system plumbing lines, electrical systems, and connectors were routed through the bay located in the area above the wing center section. Accouterments found in this bay varied considerably from aircraft to aircraft. The hydrogen peroxide tank provided gas for the turbopump-which served to speed delivery of the lox and waterlalcohol mix on to the XLR11 's four combustion chambers. The latter could be operated singly, in pairs, or all at once.

A ventral bay area just in front of the main gear well on the right side of the aircraft served to house two 24 voltl35 amp batteries and their associated connectors. Mounted just above that on a separate shelf was an MO-7/ARC-5 radio.

. When the NACNNASA initiated its X-1a modification program, one of the many noteworthy changes included the installation of hundreds of pressure pickups in each wing. The left wing, with panels removed for accessibility, is shown.

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The wing trailing edge (second-generation aircraft shown) consisted of ffaps, ailerons, and a right aileron trim tab. Trese surfaces were simple one-piece units with simple hinges to permit movement within prescribed limits. The ailerons were equipped with mass balances to alleviate ffutter anomalies, and the trim tab, located on the inboard end of the right aileron, was electro-mechanically actuated via an arm/piano hinge assembly. All surfaces were tightly toleranced to prevent air leakage.

53

Both first- and second-generation (shown) X-Is used essentially the same airfoil (NACA 65-108) and what was, to all intents and purposes, essentially the same wing. The airfoil was an excellent transonic design with good thickness/chord ratio numbers and enough internal volume to permit extremely rugged construction. The wing was, in fact, stressed to 18 g's, which at the time of the birth of the X-I program, was almost certainly the strongest ever installed on an aircraft. ~

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The X-I 's (second generation, shown) vertical fin and its associated rudder were simple, rugged, singlepiece units with very high strength factors.

Both first- and second-generation (shown) X-Is used a very simple, single-piece trailing edge flap assembly that was electro-mechanically deployed. Maximum deployment angle was approximately 60°. The flaps were used almost exclusively as high drag devices to promote rapid speed decay during landing.

A large array of pressure pick-ups and thermocouples were installed in almost all the X-Is at one tinie or another (X-IB horizontal stabilizer, shown). These sensors generated data that was relayed back to recording units mounted in either the nose or the center section equipment bay. Post-flight examination of the information generated by these units provided a data base for measuring the dynamics of flight at transonic velocities and varying altitudes.

54

A fairing covered the stabilizer hinge and actuator assembly which was mounted inside the vertical fin root section. In the event of an electrical failure, the actuator control valve could be operated by a lever on the left side of the cockpit.

The horizontal stabilizer on both first- and second-generation (shown) X-Is was adjustable from neutral to 4 (+ or -) 1/2 0 down to trim the aircraft longitudinally. A switch on the control stick energized the stabilizer actuator.

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Mass balances were installed on the elevators of both first- and second-generation aircraft when it was discovered that flutter could be induced at transonic speeds. Four such balance weights were installed on each elevator.

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The single-piece rudder was equipped with four cantilevered mass balances and a ground adjustable trim tab (not shown). It was hinged at three points. Rudder pedal movement was imparted via an arm assembly at its base through a set of tensioned steel cables. The aerodynamic form of the rudder (and ailerons, and flaps) was determined by proper shaping of a series of pressed aluminum ribs (and a spar assembly) which then were riveted to the external aluminum skin.

55

Loading of propellants and gases was accomplished through a series of connectors located on the upper right side of each X-I. Required were lox, a water/alcohol mix, nitrogen gas, and hydrogen peroxide (turbopump-equipped aircraft only).

The dorsal (top) and ventral spine fairings enclosed plumbing which routed propellants from their respective tanks to the powerplant. Control cables, push-pull tubes, and some electrical cables were simifarly routed.

The spiral-shaped nitrogen tube bundles utilized only on the first two first-generation aircraft saved significant space but proved extremely difficult to manufacture. The bundles were placed at the respective rear and front ends of the lox and water/alcohol tanks at either end of the fuselage center section. Additional nitrogen was carried in miscellaneous tanks in the nose. Nitrogen contained in these bundles was utilized to force propellants to the engine.

56

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In the second-generation X-Is, the dorsally-mounted lox line was sheathed in a zippered thermal blanket. Offset routed around carrier aircraft attachment hooks.

The third first-generation X-I, 46-064 (left), was the first to be equipped with a turbopump. The specific model utilized on the second-generation aircraft was the 6M325CF-l consisting of a fuel pump, an oxidizer pump, a turbine, a governor, an overspeed control, a gas generator, valves; tubing, and necessary wiring and switches. By passing pressurized hydrogen peroxide through a manganese dioxide catalyst in the gas generator, oxygen and steam were generated which powered the pump's turbine wheel.

The XLRll was a bipropellant liquid rocket engine utillizing an alcohol/water mixture as fuel and liquid oxygen as the oxidizer. The fuel and oxidizer were forced either by pressurized nitrogen or a turbopump to the engine combustion chambers.

The XLRll's four Chambers were closely stacked to provide minimal asymmetric thrust anomalies. Regenerative cooling, wherein the propellants were circulated around the combustion chambers before being combusted, was utilized.

57

The XLRII fit neatly into the X-l's empennage section. Regenerative cooling lines are visible as ribbed tubes running forward into the engine compartment.

XLRII combustion chambers in a first-generation X-I. Visible inside each chamber is the propellant injector unit for mixing the lox and water/alcohol.

The four XLRII combustion chambers fit flush against the aft end of the fuselage. Three dump tubes for lox, water/alcohol, and nitrogen are visible.

The configuration of the lox, water/alcohol, and nitrogen dump tubes varied considerably from aircraff to aircraft, and also from modification to modification.

Plastic extensions are seen as the intermediate tubing to ensure that residual lox, water/alcohol, and nitrogen gas are routed into the dump tubes attached to the carrier aircraft. These dump tubes prevented dangerous propellant accummulations in the carrier aircraft bomb bay during the ascent to launch.

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A single dump tube installed on the aft lower fuselage section of the 8-29 carrier aircraft. This particular tube appears to be optimized to accommodate the X-l's nitrogen gas dump tube. The plastic extensions routing the residuals into the dump tubes normally burned away during engine operation.

58

Cameras, for photo documentation purposes, on occasion, were mounted externally on the X-I s. One is shown, though its exact purpose remains unidentilied.

There were many different test boom configurations utilized on the various X-Is, including this pitch and yaw vane installation on the right wing tip of the X-I A. Size and placement varied with the requirement. On some flights, no nose booms or pitot tubes were carried at all.

Boeing B-29, 45-21800. was by far the most-used of the two carrier aircraft eventually assigned to the X-I program. This aircraft served the needs of both the first- and second-generation aircraft. The only other X-I transport was Boeing EB-50A, 46-006, which was lost with the third generation X·I, 46-064.

A ladder was designed for the second-generation X-I s

for use on the ground. Pilot accouterments, including the seat-pack type chute, were standard.

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The X-IA during mating compatibility checks with B-29, 45-21800, at Bell during late 1952. B-29 modifications were numerous and included the installation of lox top-off tanks, dump lines for residual propellants, bomb bay cut-outs to accommodate the X-I 's horizontal stabilizers and elevators, and structural beef-up straps on each fuselage side just aft of the wing trailing edge. The latter served to compensate for the loss of rigidity suffered with the removal of skin and stringers at the aft end of the bomb bay.

59

The X-IA at the moment of launch. B-29, 45-21800, was serving as the carrier aircraft. Visible under the B-29 are the lox, nitrogen, and hydrogen peroxide dump tubes as well as the externa/lines attached to the empennage of the aircraft to handle residual propellants from its own top-off tanks. Noteworthy, and easily ascertained in this view, is the fact the B-29's main gear well doors were removed for most of the X-I carrier missions.

The only other aircraft to carry any member of the X-I family was Boeing E8-50A, 46-006. This was to have become the preferred transport due to its more powerful engines and consequently better performance, but loss of the aircraft, along with the third first-generation X-I, 46-064, on November 9, 1951, ended any plans for it to replace 8-29, 45-21800. Like the 8-29, the EB-50A had had its main landing gear well doors removed.

The bomb bay modifications to 8-29, 45-21800, were numerous and extensive. Visible on the right is the rarely seen ladder/elevator assembly that could be lowered into position while the mated aircraft were in flight, thus permitting X-I cockpit access.

60

In order to accommodate the second-generation X-Is as well as the first-, 8-29, 45-21800 was modified and updated a second time. Discernible is the special cutout at the forward end of the bomb bay designed to accommodate the X-I noses.

Bell test pilot Chalmers "Slick" Goodlin demonstrating ladderlelevator ass(1mbly installed on t(le right forward end of the bomb bay of 8-29,45-21800. Goodlin is entering the cockpit of X-I, 46-062. The hatch was locked in place after entry.

Another view of the forward pressure bulkhead modification of B-29, 45-21800, required to accommodate the second-generation X-Is. A walkway permitted cockpit access, thus allflviating the need for the ladderlelevator assembly.

The wing center section seriously limited the amount of recess available to accommodate the X-Is. Such clearances later would dictate several important physical aspects of the second-generation aircraft. Visible in this view are the aft (nearest camera) and forward anti-sway snubbers, the support hook assembly (center), and the forward bulkhead cut-out to accommodate the X-I noses. To the right of center is the unextended ladderlelevator assembly.

61

View looking aft in the bomb bay of 8-29, 45-21800. Early snubber configuration is shown. These later were deleted and replaced with steel tube snubbers that could be more easily adjusted to accommodate X-l fuselage shape variables.

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The anti-sway snubbers were hinge-mounted to beam structure on each side of the 8-29/8-50 bomb bay. As can be seen in this view, the snubbers had to be moved to accommodate either the first- or second-generation X-ls.

Detail of second-generation X-l in up-and-Iocked position. Visible are the forward hook assembly, the lox top-off line and connect point, and the electrical umbilical. Small, spring-loaded doors faired-over these openings at the moment of X-l release.

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The dorsal spine contained three small openings covered by spring-loaded doors to accommodate the two lift hook assemblies and the lox top-off connection.

Checking the X-lA's compatibility. A single anti-sway snubber can be seen protruding down just behind the lift cables. Note marked contact point on fuselage.

62

The fuselage length of the second-generation X-ls essentially was dictated by the length of the 8-29's bomb bay. Additional factors included the aircraft's gross take-off weight limitations, and vertical clearances. Visible in this view is the forward snubber with its rubber padded foot.

The B-29 control panel for monitoring propellant top-off and on-board propellant quantities. Included were lox, nitrogen, and hydrogen peroxide supplies. Noteworthy are altimeter and airspeed indicator on the right side of the panel.

Older verson of B-29 sub-panel to the left of the primary X-I panel. At the time, this unit contained navigation system indicators, an altimeter, and an airspeed indicator. Later, this area would be utilized lor crew member oxygen equipment.

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Crew oxygen tanks were somewhat haphazardly mounted in the aft end 01 the B-29's fuselage. Lying on its side in the center is the primary nitrogen gas supply bottle. Visible in the far background are the lox top-off tanks.

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The rack-mounted lox top-off tanks were completely encased in thermal blankets to keep to a minimum lox loss due to temperature decay. Pumping equipment and plumbing are visible between the two, which were accessible in flight.

The permanent lox (left) and nitrogen (right) tanks installed at Edwards AFB for use during the course of the various rocket-powered research aircraft programs conducted there. Aircraft were pre-flight loaded near the tanks and then, as was the case of the X-Is, moved into position for loading aboard their respective carrier aircraft. Because lox literally boiled off over time, the X-I 's lox tank was constantly replenished by the on-board top-off tanks prior to launch.

63

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Muroc Army Air Field on October 10, 1946, just a few days less than a year before "Chuck" Yeager's historic first supersonic flight. This later would be referred to as "south base", becoming a secondary installation to the significantly newer and larger main base that would be built to the immediate northwest. "South base" would, for years, be the facility assigned the various rocket aircraft research teams including those for the Bell X-I family.

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Looking southeast, this view of the main base during the early 1950s shows Boeing B-29s, Boeing B-47s, and a single North American T-28 active on the ramp. The large hangars in the far background remain in use to this very day. Almost due north of this area, though several miles distant, was a third Edwards installation referred to as "North base". In later years, this would be occupied by the Central Intelligence Agency and several similar government entities, and utilized for highly classified programs.

64

Concerning references: Aerofax, Inc., in a conscientious effort to provide readers with the most accurate and authentic monographic aircraft histories available in their price range, does not print bibliographies in its Minigraph or Datagraph series. This measure is taken only to preserve precious space in books that are optimized to offer a maximum amount of information at minimal expense. In general, however, our primary references are official, unclassified government documents, official, unclassified private sector (company) documents, and authoritative civilian publications such as Jane's All The World's Aircraft and" Aviation Week & Space Technology". Our photo sources consist primarily of contributions by professionals and amateurs from around the world, various government agencies, the aerospace industry, and our own in-house morgue. Specific requests from Aerofax customers for titles utilized as information sources in our books will be provided as time permits. Photos from our negative files also will be provided based on availability and the willingness of the requestor to pay reproduction charges. Thanks for your consideration,

Jay Miller, Publisher

AEROFAX, INC. is pleased to announce the release of the initial titles in its new DATAGRAPH monographic aviation history series. These books are designed to accommodate aircraft histories and related subject areas that are either too large for the smaller MINIGRAPH series or too small for the larger, definitive AEROGRAPH series. Like the MINIGRAPHS and AEROGRAPHS, the DATAGRAPH titles are designed to provide exceptional subject coverage via numerous well-reproduced photographs, an extremely detailed and comprehensive text, and extraordinary quality. Each of these authoritative references has been created for the serious enthusiast and modeler and is designed to provide unparalleled textual and pictorial detail not usually found in other readily available books of this type. Each DATAGRAPH contains over 150 photos, fOld-out-type multi-view drawings, color scheme information, systems drawings, and related reference material. If you find the new DATAGRAPH series to your liking and would like to have your name added to our mailing list to receive, free of charge, our quarterly AEROFAX NEWS, please drop us a line at P.O. Box 200006, Arlington, Texas 76006. We would like to hear from you and would particularly appreciate comments, criticisms, and suggestions for future titles. AEROFAX also is in need of interesting, previously unpublished photos of aircraft for use in forthcoming MINIGRAPH, DATAGRAPH, and AEROGRAPH titles. If you have such items in your files, please cclnsider loaning them to AEROFAX so that others can see them, too. You will, of course, be credited if your photo is used, and a free copy of the publication in which it is used will be sent. AEROFAX looks forward to hearing from you. Thanks for you interest, Jay Miller and the AEROFAX, INC. Staff

Radar track ApproxiJDate course N

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ApproxiJDate location

ot io1 tial explosion

PLOT OF X-1 A ACCIDENT ROUTE The loss of the X-1A, 48-1384, on August 8, 1955 eventually led to the discovery that Ulmer leather when in contact with liquid oxygen created a highly volatile gasket assembly. This scenario also led to the destruction of the second Bell X-2, 46-675, the X-1D, 48-1386, and the third Bell X-1, 46-064. Details of this anomaly can be found on page 18.

X-lA released

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H = 11,500 tt t = 1407 br

X-1A CUTAWAY