Misplaced Pages

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72-575: The Bell X-2 was developed to provide a vehicle for researching flight characteristics at speeds and altitudes in excess of the capabilities of the Bell X-1 and D-558 II , while investigating aerodynamic heating problems in what was then called the "thermal thicket". The Bell X-2 had a prolonged development period due to the advances needed in aerodynamic design, control systems, materials that retained adequate mechanical properties at high temperature, and other technologies that had to be developed. Not only did

144-642: A "bullet with wings", its shape closely resembling a Browning .50-caliber (12.7 mm) machine gun bullet, known to be stable in supersonic flight. The shape was followed to the extent of seating its pilot behind a sloped, framed window inside a confined cockpit in the nose, with no ejection seat. For the design of the XS-1 the many unknowns relating to transonic and supersonic flight meant seeking every available source of information from governmental agencies, powerplant manufacturers and research institutions. Foreign information became available in early 1946, shortly after

216-438: A banking turn while the aircraft was still above Mach 3 (lagging instrumentation may have indicated he was flying at a slower speed or perhaps he feared he was straying too far from the safety of his landing site on Rogers Dry Lake ). The X-2 tumbled violently out of control and he found himself struggling with three sequential coupling modes, control coupling, inertial roll coupling and supersonic spinning. " Inertia coupling " and

288-399: A captive flight intended to check the aircraft's liquid oxygen system. A B-50 crew member, Frank Wolko, was also killed during the incident. The wreckage of the aircraft fell into Lake Ontario and was not recovered. Lt. Col. Frank K. "Pete" Everest completed the first powered flight in the #1 airplane (46-674) on 18 November 1955. By the time of his ninth and final flight in late July 1956

360-558: A flight on 27 September 1956, killing pilot Captain Mel Apt . Although simulators had predicted that Apt's maneuvers would produce an uncontrollable flight regime, at the time most pilots did not believe that the simulators accurately modeled the plane's flight characteristics. The first two production aircraft to experience inertial roll coupling were the F-100 Super Sabre and F-102 Delta Dagger (both first flown in 1953). The F-100

432-554: A glide-flight over Pinecastle Army Airfield , in Florida , on 19 January 1946. Woolams completed nine more glide-flights over Pinecastle, with the B-29 dropping the aircraft at 29,000 feet (8,800 m) and the XS-1 landing 12 minutes later at about 110 miles per hour (180 km/h). In March 1946 the #1 rocket plane was returned to Bell Aircraft in Buffalo, New York for modifications to prepare for

504-518: A hypersonic test program was not approved. The aircraft was scrapped. The subsequent investigation into the X-2's fatal flight raised numerous contributing factors into the crash—largely focusing on Apt's decision to turn the aircraft while still above Mach 3. Some cited his lack of experience with rocket planes, but, as historian Chris Petty notes, "he had in fact flown the complex profile almost perfectly, but this, combined with additional seconds of thrust from

576-473: A leather treatment, which was used in the liquid oxygen plumbing. TCP becomes unstable and explosive in the presence of pure oxygen and mechanical shock. This mistake cost two lives, caused injuries and lost several aircraft. The changes included: The X-1E first flew on 15 December 1955, a glide-flight controlled by USAF test pilot Joe Walker . Walker left the X-1E program during 1958, after 21 flights, attaining

648-545: A liquid propellant (alcohol and oxygen) two-chamber Curtiss-Wright XLR25 2,500 to 15,000 lbf (11 to 67 kN) sea level thrust, continuously throttleable rocket engines, the swept-wing Bell X-2 was designed to probe the supersonic region. Following a drop launch from a modified B-50 bomber, Bell test pilot Jean "Skip" Ziegler completed the first unpowered glide flight of an X-2 at Edwards Air Force Base on 27 June 1952. Ziegler and aircraft #2 (46-675) were subsequently lost on 12 May 1953, in an inflight explosion during

720-694: A maximum speed of Mach 2.21 (752 m/s, 2,704 km/h). NACA research pilot John B. McKay took his place during September 1958, completing five flights in pursuit of Mach 3 (1,021 m/s, 3,675 km/h) before the X-1E was permanently grounded after its 26th flight, during November 1958, due to the discovery of structural cracks in the fuel tank wall. Data from Bell Aircraft since 1935, The X-Planes: X-1 to X-45 General characteristics Performance Aircraft of comparable role, configuration, and era Related lists Inertia coupling In aeronautics, inertia coupling , also referred to as inertial coupling and inertial roll coupling ,

792-510: A new airspeed record of Mach 2.44 (equal to 1620 mph, 724.5 m/s, 2608 km/h at that altitude). Unlike Crossfield in the Skyrocket, Yeager achieved that in level flight. Soon afterwards, the aircraft spun out of control, due to the then not yet understood phenomenon of inertia coupling . The X-1A dropped from maximum altitude to 25,000 feet (7,600 m), exposing the pilot to accelerations of as much as 8g, during which Yeager broke

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864-443: A rapid roll. Techniques to prevent inertial roll coupling include increased directional stability ( k ) and reduced roll rate ( ω r ). Alternatively, the unstable aircraft dynamics may be mitigated : the unstable modes require time to grow, and a sufficiently short-duration roll at limited angle of attack may allow recovery to a controlled state post-roll. In 1948, William Phillips described inertial roll coupling in

936-410: A shockwave was preventing a deflected elevator from altering the pressure distribution and pitching force on the tailplane. In September 1946 a DH 108 tail-less jet aircraft was practicing for an attempt on the world speed record when it experienced violent pitching oscillations at Mach 0.875 and broke up. The Bell XS-1 would have a conventional horizontal tail which provides pitch damping not present in

1008-1192: A small one on each wing. The inertia tensor that this distribution generates has a large yaw component and small pitch and roll components, with the pitch component slightly larger. Euler's equations govern the rotation of an aircraft. When ω r , the angular rate of roll , is controlled by the aircraft, then the other rotations must satisfy I y ω y ˙ = ( I p − I r ) ω r ω p + T y I p ω p ˙ = − ( I y − I r ) ω r ω y + T p {\displaystyle {\begin{aligned}I_{\text{y}}{\dot {\omega _{\text{y}}}}&=(I_{\text{p}}-I_{\text{r}})\omega _{\text{r}}\omega _{\text{p}}+T_{y}\\I_{\text{p}}{\dot {\omega _{\text{p}}}}&=-(I_{\text{y}}-I_{\text{r}})\omega _{\text{r}}\omega _{\text{y}}+T_{p}\end{aligned}}} where y, p, and r indicate yaw, pitch, and roll; I

1080-412: A specific speed, this wouldn't have happened." One point that became clear even before the investigation was that the X-2's escape mechanism was woefully inadequate. According to The New York Times reporting on the event, Everest had criticized the relatively new detachable capsule, maintaining that "some safety had been sacrificed in preference to delaying the X-2 flight tests while the escape mechanism

1152-407: A straight-wing supersonic aircraft surprised many American experts, who like their German counterparts during the war believed that a swept-wing design was necessary to break the sound barrier. On 10 June 1948, Air Force Secretary Stuart Symington announced that the sound barrier had been repeatedly broken by two experimental airplanes. On 5 January 1949, Yeager used Aircraft #46-062 to perform

1224-450: A subsonic inverted spin had overtaken Chuck Yeager in the X-1A nearly three years before. Yeager, although exposed to much higher vehicle inertial forces, was able to recover. Apt attempted to recover from a spin, but could not. The rudder lock was still on in the attempted spin recovery. He fired the ejection capsule, which was itself only equipped with a relatively small drogue parachute . Apt

1296-713: A system of small reaction rockets used for directional control, making the X-1B the first aircraft to fly with this sophisticated control system, later used in the North American X-15 . The X-1B is now at the National Museum of the United States Air Force , Wright-Patterson Air Force Base at Dayton, Ohio , where it is displayed in the museum's Maj. Gen. Albert Boyd and Maj. Gen. Fred Ascani Research and Development Gallery. ( Bell Model 58C ) The X-1C (serial 48-1387)

1368-521: A tail-less aircraft. The XS-1 was first discussed in December 1944. Early specifications for the aircraft were for a piloted supersonic vehicle that could fly at 800 miles per hour (1,300 km/h) at 35,000 feet (11,000 m) for two to five minutes. On 16 March 1945, the U.S. Army Air Forces Flight Test Division and the National Advisory Committee for Aeronautics (NACA) contracted with

1440-463: A test flight on 22 May 1947, after complaints about the slow progress of flight tests. According to Johnston, "The contract with the Air Corps defined the tests by Bell as onboard systems verification, handling characteristics evaluation, stability and control, and performance testing to Mach 0.99." After Johnston's initial flight at 0.72 Mach, he thought the airplane was ready for supersonic flights, after

1512-523: A toy version in the Arthur episode "Arthur's Big Hit". In that episode, D.W. tries to let it fly out the window, but it ends up falling to the ground and breaking. This resulted in a classic moment in which Arthur clenches his fist and punches D.W.; the classic moment of Arthur clenching his fist has since become a meme. Later variants of the X-1 were built to test different aspects of supersonic flight; one of these,

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1584-456: Is a rocket engine–powered aircraft , designated originally as the XS-1 , and was a joint National Advisory Committee for Aeronautics – U.S. Army Air Forces – U.S. Air Force supersonic research project built by Bell Aircraft . Conceived during 1944 and designed and built in 1945, it achieved a speed of nearly 1,000 miles per hour (1,600 km/h; 870 kn) in 1948. A derivative of this same design,

1656-399: Is a potentially catastrophic phenomenon of high-speed flight in a long, thin aircraft, in which an intentional rotation of the aircraft about one axis prevents the aircraft's design from inhibiting other unintended rotations. The problem became apparent in the 1950s, when the first supersonic jet fighter aircraft and research aircraft were developed with narrow wingspans , and caused

1728-500: Is the moment of inertia along an axis; T the external torque from aerodynamic forces along an axis; and dots indicate time derivatives . When aerodynamic forces are absent, this 2‑variable system is the equation of a simple harmonic oscillator with frequency (1- ⁠ I r / I p ⁠ )(1- ⁠ I r / I y ⁠ ) ω r : a rolling Space Shuttle will naturally undergo small oscillations in pitch and yaw. Conversely, when

1800-583: The Bell X-1A , having greater fuel capacity and hence longer rocket burning time, exceeded 1,600 miles per hour (2,600 km/h; 1,400 kn) in 1954. The X-1 aircraft #46-062, nicknamed Glamorous Glennis and flown by Chuck Yeager , was the first piloted airplane to exceed the speed of sound in level flight and was the first of the X-planes , a series of American experimental rocket planes (and non-rocket planes) designed for testing new technologies. In 1942,

1872-537: The United Kingdom 's Ministry of Aviation began a top secret project with Miles Aircraft to develop the world's first aircraft capable of breaking the sound barrier. The project resulted in the design of the turbojet -powered Miles M.52 , with a maximum speed of 1,000 miles per hour (870 kn; 1,600 km/h) (over twice the existing airspeed record ) in level flight, and able to climb to an altitude of 36,000 ft (11 km) in 1 min and 30 sec. The fuselage

1944-498: The X-3 Stiletto , first flown in 1952, was extremely short but produced valuable data. Abrupt aileron rolls were conducted at Mach 0.92 and 1.05 and produced "disturbing" motions and excessive accelerations and loads. In 1953, inertial roll coupling nearly killed Chuck Yeager in the X-1A . Inertial roll coupling was one of three distinct coupling modes that followed one another as the rocket-powered Bell X-2 hit Mach 3.2 during

2016-484: The Bell Aircraft Company to build three XS-1 (for "Experimental, Supersonic", later X-1) aircraft to obtain flight data on conditions in the transonic speed range. Bell built a rocket plane after considering the turbojet alternative. Turbojets could not achieve the required performance at high altitude. An aircraft with both turbojet and rocket engines would be too large and complex. The X-1 was, in principle,

2088-493: The Navy. Providing adequate stability and control for aircraft flying at high supersonic speeds was only one of the major difficulties facing flight researchers as they approached Mach 3. For, at speeds in that region, they knew they would also begin to encounter a " thermal barrier ", severe heating effects caused by aerodynamic friction . Constructed of stainless steel and a copper - nickel alloy called K-Monel , and powered by

2160-550: The X-1A, with Yeager at the controls, inadvertently demonstrated a very dangerous characteristic of fast (Mach 2 plus) supersonic flight: inertia coupling . Only Yeager's skills as an aviator prevented disaster; later Mel Apt would lose his life testing the Bell X-2 under similar circumstances. ( Bell Model 58A ) Ordered by the Air Force on 2 April 1948, the X-1A (serial number 48-1384)

2232-463: The X-2 push the envelope of manned flight to speeds, altitudes and temperatures beyond any other aircraft at the time, it pioneered throttleable rocket engines in U.S. aircraft (previously demonstrated on the Me 163B during World War II) and digital flight simulation. The XLR25 rocket engine, built by Curtiss-Wright , was based on the smooth variable-thrust JATO engine built by Robert Goddard in 1942 for

Bell X-2 - Misplaced Pages Continue

2304-659: The XLR25 [engine], had carried the X-2 well beyond the envelope of knowledge and into the uncertain stability predicted by the GEDA [Goodyear Electronic Differential Analyzer computer]." In short, Petty suggests that Apt did his job too well and may have been pushed to exceed Mach 3 by the AFFTC and conflicting priorities within it. Petty quotes Base commander General Stanley Holtoner: "I think that every supervisory guy from me on down has criticized himself, because if we had told this boy [Apt] to stop at

2376-511: The aircraft descended to 15,000 feet (4,600 m), where all four chambers were briefly tested. After Woolams died while practicing for the National Air Races in August 1946, Chalmers "Slick" Goodlin was assigned as the primary Bell Aircraft test pilot for the X-1. Goodlin made the first powered flight on 9 December 1946. Tex Johnston , Bell's chief test pilot and program supervisor, made

2448-419: The airplane would encounter very severe stability problems as it approached Mach 3. Captains Iven C. Kincheloe and Milburn G. "Mel" Apt were assigned the job of "envelope expansion" and, on 7 September 1956, Kincheloe became the first pilot ever to climb above 100,000 ft (30,500 m) as he flew the X-2 to a peak altitude of 126,200 ft (38,470 m). Just 20 days later, on the morning of 27 September, Apt

2520-1435: The body are then of two damped , coupled harmonic oscillators : 0 = θ y ¨ − ( 1 + J y ) θ p ˙ + ( k y − J y ) θ y 0 = θ p ¨ + ( 1 − J p ) θ y ˙ + ( k p − J p ) θ p {\displaystyle {\begin{aligned}0&={\ddot {\theta _{\text{y}}}}-(1+J_{\text{y}}){\dot {\theta _{\text{p}}}}+(k_{\text{y}}-J_{\text{y}})\theta _{\text{y}}\\0&={\ddot {\theta _{\text{p}}}}+(1-J_{\text{p}}){\dot {\theta _{\text{y}}}}+(k_{\text{p}}-J_{\text{p}})\theta _{\text{p}}\end{aligned}}} where J y = I p − I r I y J p = I y − I r I p {\displaystyle {\begin{aligned}J_{\text{y}}&={\frac {I_{\text{p}}-I_{\text{r}}}{I_{\text{y}}}}\\J_{\text{p}}&={\frac {I_{\text{y}}-I_{\text{r}}}{I_{\text{p}}}}\end{aligned}}} But if k ≈ J in either axis, then

2592-459: The canopy with his helmet before regaining control. On 28 May 1954, Maj. Arthur W. Murray piloted the X-1A to a new record of 90,440 feet (27,570 m). The aircraft was transferred to NACA during September 1954, and subsequently modified. The X-1A was lost on 8 August 1955, when, while being prepared for launch from the RB-50 mothership, an explosion ruptured the plane's liquid oxygen tank. With

2664-465: The context of missiles in an NACA report. However, his predictions appeared primarily theoretical in the case of planes. The violent motions he predicted were first seen in the X-series research aircraft and Century-series fighter aircraft in the early 1950s. Before this time, aircraft tended to have greater width than length, and their mass was generally distributed closer to the center of mass . This

2736-969: The craft does not roll at all ( ω r =0 ), the only terms on the right-hand side are the aerodynamic torques, which are ( at small angles ) proportional to the craft's angular orientation θ to the freestream air. That is: there are natural constants k such that an unrolling aircraft experiences I y ω y ˙ = T y = − k y I y θ y I p ω p ˙ = T p = − k p I p θ p {\displaystyle {\begin{aligned}I_{\text{y}}{\dot {\omega _{\text{y}}}}&=T_{y}=-k_{\text{y}}I_{\text{y}}\theta _{\text{y}}\\I_{\text{p}}{\dot {\omega _{\text{p}}}}&=T_{p}=-k_{\text{p}}I_{\text{p}}\theta _{\text{p}}\end{aligned}}} In

2808-502: The damping is eliminated and the system is unstable . In dimensional terms (that is, unscaled time), instability requires k ≈ Jω r . Since I r is small, J y J p ≈ 1 {\displaystyle J_{\text{y}}J_{\text{p}}\approx 1} In particular, one J is at least 1. In thick air, k are too large to matter. But in thin air and supersonic speeds, they decrease, and may become comparable to ω r during

2880-415: The dangerous dynamical regime. But at high speeds or thin air, the wing and empennage may not generate sufficient forces and moments to stabilize the aircraft. Inertia coupling tends to occur in aircraft with a long, slender , high-density fuselage . A simple, yet accurate mental model describing the aircraft's mass distribution is a rhombus of point masses : one large mass fore and aft, and

2952-620: The first glide test of the XS-1 in Jan 1946, when the British Ministry of Supply cancelled the Miles M.52 and ordered all research reports and other information be sent to Bell Aircraft. Bell Aircraft aerodynamicists working with NACA laboratories predicted significant longitudinal trim changes during transonic flight. John Stack and Robert Gilruth at NACA recommended that Bell mount the elevator on an adjustable horizontal stabilizer. Bell incorporated

Bell X-2 - Misplaced Pages Continue

3024-639: The first powered flight on 21 February. Both flights were piloted by Bell test pilot Jean "Skip" Ziegler . After NACA started its high-speed testing with the Douglas Skyrocket , culminating in Scott Crossfield achieving Mach 2.005 on 20 November 1953, the Air Force started a series of tests with the X-1A, which the test pilot of the series, Chuck Yeager , named "Operation NACA Weep". These culminated on 12 December 1953, when Yeager achieved an altitude of 74,700 feet (22,800 m) and

3096-399: The first two X-1 engines were pressurized with nitrogen , reducing flight time by about 1 + 1 ⁄ 2 minutes and increasing landing weight by 2,000 pounds (910 kg), but the rest used gas-driven turbopumps , increasing the chamber pressure and thrust while making the engine lighter. Bell Aircraft chief test pilot Jack Woolams became the first person to fly the XS-1. He made

3168-538: The flights, and John Stack for the contributions of the NACA. The story of Yeager's 14 October flight was leaked to a reporter from the magazine Aviation Week , and the Los Angeles Times featured the story as headline news in their 22 December issue. The magazine story was released on 20 December. The Air Force threatened legal action against the journalists who revealed the story, but none ever occurred. The news of

3240-918: The full case of a rolling aircraft, the connection between orientation and angular velocity is not entirely straightforward, because the aircraft is a rotating reference frame . The roll inherently exchanges yaw for pitch and vice-versa: θ y ˙ = ω y + ω r θ p θ p ˙ = ω p − ω r θ y {\displaystyle {\begin{aligned}{\dot {\theta _{\text{y}}}}&=\omega _{\text{y}}+\omega _{\text{r}}\theta _{\text{p}}\\{\dot {\theta _{\text{p}}}}&=\omega _{\text{p}}-\omega _{\text{r}}\theta _{\text{y}}\end{aligned}}} Assuming nonzero roll, time can always be rescaled so that ω r =1 . The full equations of

3312-511: The help of crewmembers on the RB-50, test pilot Joseph A. Walker successfully extricated himself from the plane, which was then jettisoned. Exploding on impact with the desert floor, the X-1A became the first of many early X-planes that would be lost to explosions. ( Bell Model 58B ) The X-1B (serial 48-1385) was equipped with aerodynamic heating instrumentation for thermal research (more than 300 thermal probes were installed on its surface). It

3384-515: The longitudinal trim system was fixed, and three more test flights. The Army Air Force was unhappy with the cautious pace of flight envelope expansion and Bell Aircraft's flight test contract for airplane #46-062 was terminated. The test program was acquired by the Army Air Force Flight Test Division on 24 June after months of negotiation. Goodlin had demanded a US$ 150,000 bonus (equivalent to $ 2.05 million in 2023) for exceeding

3456-578: The loss of aircraft and pilots before the design features to counter it (e.g. a big enough fin ) were understood. The term "inertia/inertial coupling" has been criticized as misleading, because the phenomenon is not solely an instability of inertial movement, like the Janibekov effect . Instead, the phenomenon arises because aerodynamic forces react too slowly to track an aircraft's orientation. At low speeds and thick air, aerodynamic forces match aircraft translational velocity to orientation, avoiding

3528-539: The only conventional (runway) launch of the X-1 program, attaining 23,000 ft (7,000 m) in 90 seconds. In 1997, the United States Postal Service issued a fiftieth anniversary commemorative stamp recognizing the Bell X1-6062 aircraft as the first aeronautical vehicle to fly at supersonic speed of approximately Mach 1.06 (1,299 km/h; 806.9 mph). The Bell X-1 is also the subject of

3600-464: The powered flight tests. Four more glide tests occurred at Muroc Army Air Field near Palmdale, California , which had been flooded during the Florida tests, before the first powered test on 9 December 1946. Two chambers were ignited, but the aircraft accelerated so quickly that one chamber was turned off until reignition at 35,000 feet (11,000 m), reaching Mach 0.795. After the chambers were turned off

3672-681: The program before the National Advisory Committee for Aeronautics could commence detailed flight research with the aircraft. The search for answers to many of the riddles of high-Mach flight had to be postponed until the arrival three years later of the most advanced of all the experimental rocket aircraft, the North American X-15 . Two aircraft completed a total of 20 flights (27 June 1952 – 27 September 1956). Data from Concept Aircraft: Prototypes, X-Planes and Experimental Aircraft General characteristics Performance Aircraft of comparable role, configuration, and era Related lists Bell X-1 The Bell X-1 ( Bell Model 44 )

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3744-613: The project was years behind schedule, but he had established a new speed record of Mach 2.87 (1,900 mph, 3,050 km/h). About this time, the YF-104A was demonstrating speeds of Mach 2.2 or 2.3 in a fighter configuration. The X-2 was living up to its promise, but not without difficulties. At high speeds, Everest reported its flight controls were only marginally effective. High speed center of pressure shifts along with fin aeroelasticity were major factors. Moreover, simulation and wind tunnel studies, combined with data from his flights, suggested

3816-685: The speed of sound. Flight tests of the X-1-2 (serial 46-063) would be conducted by NACA to provide design data for later production high-performance aircraft. The first manned supersonic flight occurred on 14 October 1947, over the Mojave Desert in California , less than a month after the U.S. Air Force had been created as a separate service. Captain Charles "Chuck" Yeager piloted USAF aircraft #46-062, nicknamed Glamorous Glennis for his wife. The airplane

3888-425: The stabilizer with rapid adjustment in pitch to accommodate large changes of trim. A contractor test flight by Tex Johnston showed an unacceptable lost motion between the pilot's input to the horizontal stabilizer and the stabilizer actuator which was corrected before the XS-1 was handed over for the high speed research program. The whole tailplane could be moved or just the elevator at fixed stabilizer settings. It

3960-489: The summer of 1946, the M52 was cancelled. In place of the manned full-scale M.52 it was decided to test 3/10 scale models of the aircraft, rocket propelled, dropped from an aircraft, and controlled by an autopilot. On the 10th of October 1948 a model achieved Mach 1.38 in level flight. The Bell XS-1 would have a conventional horizontal tail-plane but with trimming available on the stabilizer. It would be required for pitch control when

4032-399: The test team by surprise until they realized that extra control was available by moving the horizontal stabilizer. The tailplane trim setting had to be accurately set on the ground to ensure a controlled drop at the beginning of a flight. Scott Crossfield relates an inadvertent one-degree error flipping the X-1 on its back after being dropped from the mother plane. The tailplane configuration

4104-684: Was drop launched from the bomb bay of a B-29 and reached Mach 1.06 (700 miles per hour (1,100 km/h; 610 kn)). Following burnout of the engine, the plane glided to a landing on the dry lake bed. This was XS-1 flight number 50. The three main participants in the X-1 program won the National Aeronautics Association Collier Trophy in 1948 for their efforts. Honored at the White House by President Truman were Larry Bell for Bell Aircraft, Captain Yeager for piloting

4176-526: Was a four-chamber design built by Reaction Motors Inc ., one of the first companies to build liquid-propellant rocket engines in the U.S. After considering hydrogen peroxide monopropellant , aniline / nitric acid bipropellant , and nitromethane monopropellant as fuels, the rocket burned ethyl alcohol diluted with water with a liquid oxygen oxidizer . Its four chambers could be individually turned on and off, so thrust could be changed in 1,500 lbf (6,700 N) increments. The fuel and oxygen tanks for

4248-485: Was carried over to the X-1A series. All subsequent supersonic aircraft would either have an all-moving tailplane or be "tailless" delta winged types. Swept wings were not used because too little was known about them. As the design might lead to a fighter, the XS-1 was intended to take off from the ground, but the end of the war made the B-29 Superfortress available to carry it into the air. The rocket engine

4320-485: Was destroyed upon impact after it was jettisoned from its EB-50A mothership. ( Bell Model 44 ) The X-1E was the result of a reconstruction of the X-1-2 (serial 46-063), in order to pursue the goals originally set for the X-1D and X-1-3 (serial 46-064), both lost by explosions during 1951. The cause of the mysterious explosions was finally traced to the use of Ulmer leather gaskets impregnated with tricresyl phosphate (TCP),

4392-410: Was especially true for propeller aircraft, but equally true for early jet fighters as well. The effect became obvious only when aircraft began to sacrifice aerodynamic surface area to reduce drag, and use longer fineness ratios to reduce supersonic drag. Such aircraft were generally much more fuselage-heavy, allowing gyroscopic effects to overwhelm the small control surfaces. The roll coupling study of

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4464-466: Was intended to investigate aerodynamic phenomena at speeds greater than Mach 2 (681 m/s, 2,451 km/h) and altitudes greater than 90,000 ft (27 km), specifically emphasizing dynamic stability and air loads. Longer and heavier than the original X-1, with a stepped canopy for better vision, the X-1A was powered by the same Reaction Motors XLR-11 rocket engine. The aircraft first flew, unpowered, on 14 February 1953 at Edwards AFB, with

4536-544: Was intended to test armaments and munitions in the high transonic and supersonic flight regimes. It was canceled while still in the mockup stage, as the development of transonic and supersonic-capable aircraft like the North American F-86 Sabre and the North American F-100 Super Sabre eliminated the need for a dedicated experimental test vehicle. ( Bell Model 58D ) The X-1D (serial 48-1386)

4608-517: Was launched from the B-50 for his first flight in a rocket airplane. He had been instructed to follow the "optimum maximum energy flight path". With nozzle extenders and a longer than normal motor run, Apt flew an extraordinarily precise profile; he became the first man to exceed Mach 3, reaching Mach 3.2 (2,094 mph, 3,370 km/h) at 65,500 ft (19,960 m). The flight had been flawless to this point, but shortly after attaining top speed, Apt attempted

4680-502: Was modified with a larger vertical tail to increase its directional stability. The F-102 was modified to increase wing and tail areas and was fitted with an augmented control system. To enable pilot control during dynamic motion maneuvers the tail area of the F-102A was increased 40%. In the case of the F-101 Voodoo (first flown in 1954), a stability augmentation system was retrofitted to

4752-480: Was modified." Another NACA research pilot, Scott Crossfield , described it more bluntly as a "way to commit suicide to keep from getting killed." While the X-2 had delivered valuable research data on high-speed aerodynamic heat build-up and extreme high-altitude flight conditions (although it is unclear how much, as the unmanned Lockheed X-7 and IM-99 were among the winged vehicles operating at comparable or higher velocities in this era), this tragic event terminated

4824-623: Was placed as high as possible above the wing wake with a thinner section than for the wing to separate the high drag rise from the wing from compressibility effects on the tail. Initially, as increases in speed were made in small steps towards possibly unknown control difficulties the horizontal stabilizer was left at its pre-launch angle set on the ground as there was concern that adjusting it at high speed would cause severe control problems. Nevertheless, in October 1947, when test pilot Yeager ran out of elevator authority (no pitch control) at Mach 0.94 it took

4896-401: Was probably disabled by the severe release forces. As the capsule fell for several minutes to the desert floor, he did not exit so that he could use his personal parachute before ground impact, and was killed. The aircraft continued to fly in a series of glides and stalls before landing and breaking into three pieces (separate from the capsule). A proposal to salvage the aircraft and modify it for

4968-407: Was shaped like a bullet, it had thin wings and a slab tailplane for controlled flight at the speed of sound and beyond. Miles' chief aerodynamicist, Dennis Bancroft, was interviewed many years later in 1997 on his reason for needing an all-moving tailplane in his 1944 design. In 1944 Miles was told to go ahead with the construction of three prototypes. In February 1946, with a first flight expected in

5040-415: Was similar to the X-1A except for having a slightly different wing. The X-1B was used for high-speed research by the U.S. Air Force starting from October 1954, prior to being transferred to the NACA during January 1955. NACA continued to fly the aircraft until January 1958, when cracks in the fuel tanks forced its grounding. The X-1B completed a total of 27 flights. A notable achievement was the installation of

5112-438: Was the first of the second generation of supersonic rocket planes. Flown from an EB-50A (s/n #46-006), it was to be used for heat transfer research. The X-1D was equipped with a new low-pressure fuel system and a slightly increased fuel capacity. There were also some minor changes of the avionics suite. On 24 July 1951, with Bell test pilot Jean "Skip" Ziegler at the controls, the X-1D was launched over Rogers Dry Lake , on what

5184-420: Was to become the only successful flight of its career. The unpowered glide was completed after a nine-minute descent, but upon landing, the nose landing gear failed and the aircraft slid ungracefully to a stop. Repairs took several weeks to complete and a second flight was scheduled for mid-August. On 22 August 1951, the X-1D was lost in a fuel explosion during preparations for the first powered flight. The aircraft

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