1 August 1955: Test pilot Anthony W. LeVier made the first flight flight of the Lockheed U-2 high-altitude reconnaissance airplane at Groom Lake, Nevada. LeVier was conducting taxi tests in preparation for the planned first flight a few days away, when at 70 knots the U-2 unexpectedly became airborne.
LeVier later said, “I had no intentions whatsoever of flying. I immediately started back toward the ground, but had difficutly determining my height because the lakebed had no markings to judge distance or height. I made contact with the ground in a left bank of approximately 10 degrees.”
On touching down on the dry lake, the U-2’s tires blew out and the brakes caught fire. A landing gear oleostrut was leaking. Damage was minor and the airplane was soon ready to fly. Tony LeVier was again in the cockpit for the first actual test flight on 4 August.
The Lockheed U-2A is a single-place, single-engine aircraft powered by a turbojet engine, intended for very high altitude photographic reconnaissance. Thirty U-2A aircraft were designed and built for the Central Intelligence Agency by Lockheed Aircraft Corporation’s secret “Skunk Works” under the supervision of Clarence L. “Kelly” Johnson.
The company designation for the proposed aircraft was CL-282. Its fuselage was very similar to the XF-104 Starfighter and could be built using the same tooling. The reconnaissance airplane was produced under the code name Operation AQUATONE.
The U-2A was 46 feet, 6 inches (14.173 meters) long with a wingspan of 80 feet (24.384 meters). Its empty weight was 10,700 pounds (5,307 kilograms) and the gross weight was 16,000 pounds (7,257 kilograms). The engine was a Pratt and Whitney J57-P-37A which produced 10,200 pounds of thrust. This gave the U-2A a maximum speed of 528 miles per hour (850 kilometers per hour) and a ceiling of 85,000 feet (25,908 meters). It had a range of 2,200 miles (3,541 kilometers).
Because of the very high altitudes that the U-2 was flown, the pilot had to wear a David Clark Co. MC-3 partial-pressure suit with an International Latex Corporation MA-2 helmet and faceplate. The partial-pressure suit used a system of capstans and air bladders to apply pressure to the body as a substitute for a loss of atmospheric pressure. Each suit was custom-tailored for the individual pilot.
On 4 April 1957, Article 341 was flown by Lockheed test pilot Robert Sieker. At 72,000 feet (21,946 meters) the engine flamed out and the cockpit pressurization failed. Parts of the U-2 had been coated with a plastic material designed to absorb radar pulses to provide a “stealth” capability. However, this material acted as insulation, trapping heat from the engine inside the fuselage. This lead to a number of engine flameouts.
Sieker’s partial-pressure suit inflated, but the helmet’s faceplate did not properly seal. He lost conciousness and at 65,000 feet (19,812 meters) the U-2 stalled, then entered a flat spin. Sieker eventually regained consciousness at lower altitude and bailed out. He was struck by the airplane’s tail and was killed. The first U-2 crashed northwest of Pioche, Nevada, and caught fire. Robert Sieker’s body was found approximately 200 feet (61 meters) away.
Because of the slow rate of descent of the airplane while in a flat spin, the impact was not severe. Portions of Article 341 that were not damaged by fire were salvaged by Lockheed and used to produce another airframe.
19 April 1955¹: Lockheed test pilot Herman Richard (“Fish”) Salmon was flying the second prototype Lockheed XF-104 interceptor, 53-7787, conducting tests of the General Electric T171 Vulcan gun system.
At 47,000 feet (14,326 meters), Salmon fired two bursts from the T171. On the second burst, vibrations from the gun loosened the airplane’s ejection hatch, located beneath the cockpit, resulting in explosive decompression.
The Associated Press reported:
Test Pilot Leaps From New Jet
INYOKERN, Calif., April 20 (AP)—Herman R. (Fish) Salmon, former racing pilot and now a top test pilot, bailed safely from one of the Air Force’s hot new F104 jet fighters over the Mojave dessert [sic] Tuesday.
He was spotted on the desert after a two-hour search by military planes and brought to the Naval ordinance [sic] test station here for a physical examination. A preliminary checkup indicated he was not injured.
Salmon, 41, was on a routine test flight when he hit the silk. Authorities gave no hint what happened to the supersecret plane to make the bailout necessary. The craft’s height at the time it was abandoned was not given. The plane’s top speed has been unofficially estimated at 1,200 m. p. h.
Wreckage of the F104, one of two prototypes now being tested by Lockheed Aircraft Corp. for the Air Force, was found several miles south of the China Lake area.
A Lockheed spokesman said Salmon, of Van Nuys, Calif., was spotted by a search plane and apparently picked up by a Navy helicopter and flown here. Salmon took off on the test flight from Palmdale, about 70 miles south of here.
— Reno Evening Gazette, Volume LXXIX, Number 21, Wednesday, 20 April 1955, Page 24 at Columns 5–7.
Fish Salmon was wearing a David Clark Co. T-1 capstan-type partial-pressure suit and International Latex Corporation (I.L.C. Dover) K-1 helmet for protection in just such an emergency. The capstans are pneumatic tubes surrounded by fabric lacings, running along the arms, torso and legs. As the tubes inflated, the lacings pulled the fabric of the suit very tight and applied pressure to his body as a substitute for normal atmospheric pressure. The partial-pressure garment also enclosed his head, with a fiberglass helmet and a clear visor or face plate providing for vision.
The sudden loss of cabin pressure and drop to subfreezing temperatures caused Salmon’s face plate to fog over. Inflating air bladders pushed his helmet high on his head. The cockpit was filled with dust, fiberglass insulation and other debris. All this restricted his visibility, both inside and outside the airplane. The very tight pressure suit restricted his movements.
Fish Salmon cut the throttle, opened the speed brakes and began a descending turn to the left to reach a lower altitude. By the time he had reached 15,000 feet (4,572 meters) he had been unable to find a place on the desert floor to make an emergency landing. It was time to leave the crippled XF-104.
At 250 knots (288 miles per hour/463 kilometers per hour) the ejection seat fired Salmon out of the bottom of the cockpit. He had to open his parachute manually (the seat timer did not operate) and he made a safe landing.
The prototype XF-104 impacted the desert approximately 73 miles (117 kilometers) east-northeast of Edwards Air Force Base. It was completely destroyed. Fish Salmon landed about 2 miles (3.2 kilometers) away. He was found two hours later and rescued by an Air Force helicopter.
Occasionally, a satisfied user thanked the researchers at the Aero Medical Laboratory. One of these was Lockheed test pilot Herman R. “Fish” Salmon. On April 14, 1955,¹ Salmon was flying the second XF-104 (53-7787) at 47,500 feet while wearing a T-1 suit, K-1 helmet, and strap-fastened boots. As he triggered the General Electric M61 Vulcan 20 mm cannon for a test firing, severe vibrations loosened the floor-mounted ejection hatch and the cockpit explosively depressurized at the same time as the engine flamed out. The suit inflated immediately. Repeated attempts to restart the engine failed, and Salmon ejected at 15,000 feet. Fish reported, “I landed in a field of rocks ranging from one foot to five feet in diameter. My right arm was injured and my head struck a rock. The K-1 helmet hard shell was cracked, but there was no injury to my head. It took me 10 to 15 minutes to get out of the suit with my injured arm. Rescue was effected [sic] by helicopter approximately two hour after escape.” Salmon reported that the K-1 helmet was excellent for rugged parachute landings, and his only complaint was that the visor may impair vision at extreme altitudes.”
—Dressing for Altitude: U.S. Aviation Pressure Suits—Wiley Post to Space Shuttle, by Dennis R., Jenkins, National Aeronautics and Space Administration SP–2011–595, Washington, D.C., 2012, Chapter 4 at Page 141.
There were two Lockheed XF-104 prototypes. Initial flight testing was performed with 083-1001 (USAF serial number 53-7786). The second prototype, 083-1002 (53-7787) was the armament test aircraft. Both were single-seat, single-engine supersonic interceptors. The XF-104 was 49 feet, 2 inches (14.986 meters) long with a wingspan of 21 feet, 11 inches (6.680 meters) and overall height of 13 feet, 6 inches (4.115 meters). The prototypes had an empty weight of 11,500 pounds (5,216 kilograms) and maximum takeoff weight of 15,700 pounds (7,121 kilograms).
The production aircraft was planned for a General Electric J79 turbojet but that engine would not be ready soon enough, so both prototypes were designed to use a Buick-built J65-B-3, a licensed version of the British Armstrong Siddeley Sapphire turbojet engine. XF-104 53-7787 had been built with an afterburning Wright J65-W-7 turbojet, rated at 7,800 pounds of thrust, and 10,200 pounds of thrust with afterburner.
The XF-104 had a maximum speed of 1,324 miles per hour (2,131 kilometers per hour), a range of 800 miles (1,287 kilometers) and a service ceiling of 50,500 feet (15,392 meters).
The General Electric T171 Vulcan was a prototype 6-barrelled 20 mm “Gatling Gun” automatic cannon. The barrels were rotated at high speed by a hydraulic drive. The gun is capable of firing 6,000 rounds per minute. The initial production version was designated M61. The cannon system was installed in a weapons bay on the left side of the F-104, between the cockpit and engine intakes.
The first prototype Lockheed XF-104, 53-7786, was also destroyed, 11 July 1957, when the vertical fin was ripped off by uncontrollable flutter. The pilot, William C. Park, safely ejected.
¹ Reliable sources give the date of this incident as both 14 April and 19 April. Contemporary news reports, published Wednesday, 20 April 1955, say that the accident took place “yesterday” and “Tuesday,” suggesting that the correct date is 19 April.
20 December 1968: After 199 flights, the National Aeronautics and Space Administration cancelled the X-15 Hypersonic Research Program. A 200th X-15 flight had been scheduled, but after several delays, the decision was made to end the program. (The last actual flight attempt was 12 December 1968, but snow at several of the dry lakes used as emergency landing areas resulted in the flight being cancelled.)
The X-15A rocketplane was designed and built for the U.S. Air Force and the National Advisory Committee for Aeronautics (NACA, the predecessor of NASA) by North American Aviation, Inc., to investigate the effects of hypersonic flight (Mach 5+). Design work started in 1955 and a mock-up had been completed after just 12 months. The three X-15s were built at North American’s Los Angeles Division, at the southeast corner of Los Angeles International Airport (LAX), on the shoreline of southern California.
The first flight took place 8 June 1959 with former NACA test pilot Albert Scott Crossfield in the cockpit of the Number 1 ship, 56-6670.
While earlier rocketplanes, the Bell X-1 series, the the Douglas D-558-II, and the Bell X-2, were airplanes powered by rocket engines, the X-15 was a quantum leap in technology. It was a spacecraft.
Like the other rocketplanes, the X-15 was designed to be carried aloft by a “mothership,” rather than to takeoff and climb to the test altitude under its own power. The carrier aircraft was originally to be a Convair B-36 intercontinental bomber but this was soon changed to a Boeing B-52 Stratofortress. Two B-52s were modified to carry the X-15: NB-52A 52-003, The High and Mighty One, and NB-52B 52-008, Balls 8.
From 8 June 1959 to 24 October 1968, the three X-15s were flown by twelve test pilots, three of whom would qualify as astronauts in the X-15. Two would go on to the Apollo Program, and one, Neil Alden Armstrong, would be the first human to set foot on the surface of the Moon, 20 July 1969. Joe Engle would fly the space shuttle. Four of the test pilots, Petersen, White, Rushworth, and Knight, flew in combat during the Vietnam War, with Bob White being awarded the Air Force Cross. Petersen, Rushworth and White reached flag rank.
One pilot, John B. (“Jack”) McKay, was seriously injured during an emergency landing at Mud Lake, Nevada, 9 November 1962. Another, Michael James Adams, was killed when the Number 3 ship, 56-6672, went into a hypersonic spin and broke up on the program’s 191st flight, 15 November 1967.
Flown by a single pilot/astronaut, the X-15 is a mid-wing monoplane with dorsal and ventral fin/rudders and stabilators. The wing had no dihdral, while the stabilators had a pronounced -15° anhedral. The short wings have an area of 200 square feet (18.58 square meters) and a maximum thickness of just 5%. The leading edges are swept to 25.64°. There are two small flaps but no ailerons. The entire vertical fin/rudder pivots for yaw control.
Above 100,000 feet (30,840 meters) altitude, conventional aircraft flight control surfaces are ineffective. The X-15 is equipped with a system of reaction control jets for pitch, roll and yaw control. Hydrogen peroxide was passed through a catalyst to produce steam, which supplied the control thrusters.
The forward landing gear consists of a retractable oleo strut with steerable dual wheels and there are two strut/skids at the rear of the fuselage. The gear is retracted after the X-15 is mounted on the NB-52 and is extended for landing by its own weight.
The rocketplane’s cockpit featured both a conventional control stick as well as side-controllers. It was pressurized with nitrogen gas to prevent fires. The pilot wore an MC-2 full-pressure suit manufactured by the David Clark Company of Worcester, Massachusetts, with an MA-3 helmet. The suit was pressurized below the neck seal with nitrogen, while the helmet was supplied with 100% oxygen. This pressure suit was later changed to the Air Force-standardized A/P22S.
The X-15 is 50.75 feet (15.469 meters) long with a wing span of 22.36 feet (6.815 meters). The height—the distance between the tips of the dorsal and ventral fins—is 13.5 feet (4.115 meters). The stabilator span is 18.08 feet (5.511 meters). The fuselage is 4.67 feet (1.423 meters) deep and has a maximum width of 7.33 feet (2.234 meters).
Since the X-15 was built of steel rather than light-weight aluminum, as are most aircraft, it is a heavy machine, weighing approximately 14,600 pounds (6,623 kilograms) empty and 34,000 pounds (15,422 kilograms) when loaded with a pilot and propellants. The X-15s carried as much as 1,300 pounds (590 kilograms) of research instrumentation, and the equipment varied from flight to flight. The minimum flight weight (for high-speed missions): 31,292 pounds (14,194 kilograms) The maximum weight was 52,117 pounds (23,640 kilograms) at drop (modified X-15A-2 with external propellant tanks).
Initial flights were flown with a 5 foot, 11 inch (1.803 meters)-long air data boom at the nose, but this would later be replaced by the “ball nose” air sensor system. The data boom contained a standard pitot-static system along with angle-of-attack and sideslip vanes. The boom and ball nose were interchangeable.
The X-15s were built primarily of a nickel/chromium/iron alloy named Inconel X, along with corrosion-resistant steel, titanium and aluminum. Inconel X is both very hard and also able to maintain its strength at the very high temperatures the X-15s were subjected to by aerodynamic heating. It was extremely difficult to machine and special fabrication techniques had to be developed.
Delays in the production of the planned Reaction Motors XLR99 rocket engine forced engineers to adapt two vertically-stacked Reaction Motors XLR11-RM-13 four-chamber rocket engines to the X-15 for early flights. This was a well-known engine which was used on the previous rocketplanes. The XLR11 burned a mixture of ethyl alcohol and water with liquid oxygen. Each of the engines’ chambers could be ignited individually. Each engine was rated at 11,800 pounds of thrust (58.49 kilonewtons) at Sea Level.
The Reaction Motors XLR99-RM-1 rocket engine was throttleable by the pilot from 28,500 to 60,000 pounds of thrust (126.77–266.89 kilonewtons). The engine was rated at 50,000 pounds of thrust (222.41 kilonewtons) at Sea Level; 57,000 pounds (253.55 kilonewtons) at 45,000 feet (13,716 meters), the typical drop altitude; and 57,850 pounds (257.33 kilonewtons) of thrust at 100,000 feet (30,480 meters). Individual engines varied slightly. A few produced as much as 61,000 pounds of thrust (271.34 kilonewtons).
The XLR99 burned anhydrous ammonia and liquid oxygen. The flame temperature was approximately 5,000 °F. (2,760 °C.) The engine was cooled with circulating liquid oxygen. To protect the exhaust nozzle, it was flame-sprayed with ceramic coating of zirconium dioxide. The engine is 6 feet, 10 inches (2.083 meters) long and 3 feet, 3.3 inches (0.998 meters) in diameter. It weighs 910 pounds (413 kilograms). The Time Between Overhauls (TBO) is 1 hour of operation, or 100 starts.
The XLR99 proved to be very reliable. 169 X-15 flights were made using the XLR99. 165 of these had successful engine operation. It started on the first attempt 159 times.
The highest speed achieved during the program was with the modified number two ship, X-15A-2 56-6671, flown by Pete Knight to Mach 6.70 (6,620 feet per second/4,520 miles per hour/7,264 kilometers per hour) at 102,700 feet (31,303 meters). On this flight, the rocketplane exceeded its maximum design speed of 6,600 feet per second (2,012 meters per second).
The maximum altitude was reached by Joe Walker, 22 August 1963, when he flew 56-6672 to 354,200 feet (107,960 meters).
The longest flight was flown by Neil Armstrong, 20 April 1962, with a duration of 12 minutes, 28.7 seconds.
North American Aviation X-15A-1 56-6670 is on display at the Smithsonian Institution National Air and Space Museum. X-15A-2 56-6671 is at the National Museum of the United States Air Force.
Always Another Dawn: The Story of a Rocket Test Pilot, by A. Scott Crossfield and Clay Blair, Jr., The World Publishing Company, Cleveland and New York, 1960
At The Edge Of Space, by Milton O. Thompson, Smithsonian Institution Press, 1992
X-15 Diary: The Story of America’s First Spaceship, by Richard Tregaskis, E.F. Dutton & Company, New York, 1961; University of Nebraska Press, 2004
X-15: Exploring the Frontiers of Flight, by David R. Jenkins, National Aeronautics and Space Administration http://www.nasa.gov/pdf/470842main_X_15_Frontier_of_Flight.pdf
The X-15 Rocket Plane: Flying the First Wings into Space, by Michelle Evans, University of Nebraska Press, Lincoln and London, 2013
6 November 1958: NASA Research Test Pilot John B. (Jack) McKay made the final flight of the X-1 rocketplane program, which had begun twelve years earlier.
Bell X-1E 46-063 made its 26th and final flight after being dropped from a Boeing B-29 Superfortress over Edwards Air Force Base on a flight to test a new rocket fuel.
When the aircraft was inspected after the flight, a crack was found in a structural bulkhead. A decision was made to retire the X-1E and the flight test program was ended.
The X-1E had been modified from the third XS-1, 46-063. It used a thinner wing and had an improved fuel system. The most obvious visible difference is the cockpit, which was changed to provide for an ejection seat. Hundreds of sensors were built into the aircraft’s surfaces to measure air pressure and temperature.
The Bell X-1E was 31 feet (9.449 meters) long, with a wingspan of 22 feet, 10 inches (6.960 meters). The rocketplane’s empty weight was 6,850 pounds (3,107 kilograms) and fully loaded, it weighed 14,750 pounds (6,690 kilograms). The rocketplane was powered by a Reaction Motors XLR11-RM-5 rocket engine which produced 6,000 pounds of thrust (26.689 kilonewtons). The engine burned ethyl alcohol and liquid oxygen. The X-1E carried enough propellants for 4 minutes, 45 seconds burn.
The early aircraft, the XS-1 (later redesignated X-1), which U.S. Air Force test pilot Charles E. (“Chuck”) Yeager flew faster than sound on 14 October 1947, were intended to explore flight in the high subsonic and low supersonic range. There were three X-1 rocketplanes. Yeager’s Glamorous Glennis was 46-062. The X-1D (which was destroyed in an accidental explosion after a single glide flight) and the X-1E were built to investigate the effects of frictional aerodynamic heating in the higher supersonic ranges from Mach 1 to Mach 2.
The X-1E reached its fastest speed with NASA test pilot Joseph Albert Walker, at Mach 2.24 (1,450 miles per hour/2,334 kilometers per hour), 8 October 1957. Walker also flew it to its peak altitude, 70,046 feet (21,350 meters) on 14 May 1958.
There were a total of 236 flights made by the X-1, X-1A, X-1B, X-1D and X-1E. The X-1 program was sponsored by the National Advisory Committee on Aeronautics, NACA, which became the National Aeronautics and Space Administration, NASA, on 29 June 1958.
14 October 2012: At 12:08 p.m. MDT (1808 UTC) Felix Baumgartner jumped from the gondola of a helium-filled balloon at 127,852.4 feet (38,969.4 meters) over eastern New Mexico.
The free fall distance was 119,431.1 feet (36,402.6 meters). He fell for 4 minutes, 19 seconds before deploying his parachute and touched down after nine minutes, 3 seconds. During the free fall, he reached 843.6 miles per hour (1,357.6 kilometers per hour), Mach 1.25.
The Fédération Aéronautique Internationale (FAI) recognizes three Sub-Class G-2 World Records set by Baumgartner with this jump:
16669: Vertical Speed Without Drogue: 1,357.6 kilometers per hour (843.6 miles per hour miles per hour)
Felix Baumgartner wore a custom-made full-pressure suit designed and manufactured by the David Clark Co., Worcester, Massachusetts, based on their S1034 Improved Common Suit.
The helium balloon, with a volume 29,470,000 cubic feet, was manufactured by Raven Aerostar, Sioux Falls, South Dakota. Baumgartner’s pressure capsule was designed and built by Sage Cheshire Aerospace, Lancaster, California.