20 November 1953: At Edwards Air Force Base, California, NACA’s High Speed Flight Station research test pilot Albert Scott Crossfield, Jr., rode behind the flight crew of the Boeing P2B-1S Superfortress as it carried the Douglas Aircraft Company D-558-II Skyrocket supersonic research rocketplane to its launch altitude. As the four-engine bomber climbed through 18,000 feet (5,486 meters), Crossfield headed back to the bomb bay to enter the Skyrocket’s cockpit and prepare for his flight.
The Douglas D-558-II was Phase II of a United States Navy/Douglas Aircraft Company/National Advisory Committee on Aeronautics joint research project exploring supersonic flight. It was a swept-wing airplane powered by a single Reaction Motors LR8-RM-6 four-chamber rocket engine. The Skyrocket was fueled with alcohol and liquid oxygen. The engine was rated at 6,000 pounds of thrust (26.69 kilonewtons) at Sea Level.
There were three Phase II aircraft. Originally, they were also equipped with a Westinghouse J34-W-40 turbojet engine which produced 3,000 pounds of thrust (13.35 kilonewtons). The Skyrockets took off from the surface of Rogers Dry Lake. Once the D-558-II reached altitude, the rocket engine was fired for the speed runs.
As higher speeds were required, the program shifted to an air launch from a B-29 (P2B-1S) drop ship. Without the need to climb to the test altitude, the Skyrocket’s fuel load was available for the high speed runs.
The D-558-II was 42.0 feet (12.80 meters) long, with a wingspan of 25.0 feet (7.62 meters). The leading edge of the wing was swept at a 35° angle and the tail surfaces were swept to 40°. The aircraft weighed 9,421 pounds (4,273 kilograms) empty and had a maximum takeoff weight of 15,787 pounds (7,161 kilograms). It carried 378 gallons (1,431 liters) of water/ethyl alcohol and 345 gallons (1,306 liters) of liquid oxygen.
The mothership, NACA 137, was a Boeing Wichita B-29-95-BW Superfortress, U.S. Air Force serial number 45-21787. It was transferred to the U.S. Navy, redesignated P2B-1S and assigned Bureau of Aeronautics number 84029. Douglas Aircraft modified the bomber for its drop ship role at the El Segundo plant.
Going above the planned launch altitude, the Superfortress was placed in a slight dive to build to its maximum speed. At the bomber’s critical Mach number (Mcr), the Skyrocket was just above its stall speed. At 32,000 feet (9,754 meters), Crossfield and the Skyrocket were released. The rocketplane fell for about 400 feet (122 meters) until the rocket engine ignited and then it began to accelerate.
Crossfield climbed at a steep angle until he reached 72,000 feet (21,946 meters), and then leveled off. Now in level flight, the D-558-II accelerated, quickly passing Mach 1, then Mach 1.5. Crossfield pushed the nose down and began a shallow dive. The Skyrocket, still under full power, built up speed. As it passed through 62,000 feet (18,998 meters) the Skyrocket reached its maximum speed, Mach 2.005, or 1,291 miles per hour (2,078 kilometers per hour).
Scott Crossfield was the first pilot to fly an aircraft beyond Mach 2, twice the speed of sound. During his career as a test pilot, he flew the Douglas D-558-II, the Bell X-1, Bell X-2 and North American X-15. He made 112 flights in rocket-powered aircraft, more than any other pilot.
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.
4 November 1941: Lockheed test pilot Ralph Burwell Virden was conducting high speed dive tests in the first Lockheed YP-38 Lightning, Air Corps serial number 39-689 (Lockheed’s serial number 122-2202).
As the airplane’s speed increased, it approached what is now known as its Critical Mach Number. Air flowing across the wings accelerated to transonic speeds and began to form shock waves. This interrupted lift and caused a portion of the wing to stall. Air no longer flowed smoothly along the airplane and the tail surfaces became ineffective. The YP-38 pitched down into a steeper dive and its speed increased even more.
Designed by famed aeronautical engineer Clarence L. “Kelly” Johnson, the YP-38 had servo tabs on the elevator that were intended to help the pilot maintain or regain control under these conditions. But they increased the elevator’s effectiveness too well.
The Los Angeles Times described the accident:
Witnesses said the twin-engined, double-fuselaged ship was booming westward at near maximum speed (unofficially reported to be between 400 and 500 miles an hour) when the duralumin tail assembly “simply floated away.”
A moment afterward the seven-ton craft seemed to put on a burst of speed, the the high whine of its engines rising.
It then went into a downward glide to about 1500 feet, then into a flat spin, flipped over on its back and shot earthward.
Several persons said that they thought they had heard an explosion during the dive, but qualified observers doubted it. . .
. . . Fellow pilots at Lockheed said, “Ralph was the best we had, especially in power dives.”
Robert E. Gross, president of Lockheed, said, “Ralph Virden was a great pilot but an even greater man. If anyone ever had national defense at heart it was he, who every day was carrying the science of aviation into new and higher fields.”
Various witnesses said the ill-fated ship’s tail assembly could be followed easily as its bright surfaces glinted in the sun during its drop to earth. It landed several blocks from the scene of the crash.
Mrs. Jack Davenport of 1334 Elm Ave., left her ironing board when she heard the unfamiliar roar of the plunging plane’s engines.
“I ran out and saw it passing over us, very low. It disappeared among the trees and then zoomed back into sight just before crashing in the next block,” she said. “It looked just like a toy airplane. I knew the pilot didn’t have a chance, as the ship was too low and going too fast.”
—Los Angeles Times, Vol. LX, Wednesday, 5 November 1941, Page 1, Column 6, and Page 2, Column 5.
The YP-38 crashed into the kitchen of Jack Jensen’s home at 1147 Elm Street, Glendale, California. Fire erupted. Ralph Virden was killed. The airplane’s tail section was located several blocks away.
39-689 was the first of thirteen YP-38 service test aircraft that had been ordered by the U.S. Army Air Corps shortly after the XP-38 prototype, 37-457, had crashed on a transcontinental speed record attempt, 11 February 1939. 39-689 made its first flight 16 September 1940 with test pilot Marshall Headle at the controls. With hundreds of production P-38s being built, Lockheed continued to use the YP-38 for testing.
The YP-38s were service test prototypes of a single-place, twin engine long range fighter with a unique configuration. There was not a fuselage in the normal sense. The cockpit, nose landing gear, and armament were contained in a central nacelle mounted to the wing. Two engines and their turbochargers, cooling systems and main landing gear were in two parallel booms. The booms end with vertical fins and rudders, with the horizontal stabilizer and elevator between them. The P-38 was 37 feet, 9–15/16 inches (11.530 meters) long, with a wingspan of 52 feet, 0 inches (15.850 meters) and height of 12 feet, 10 inches (3.952 meters).
The P-38’s wings had a total area of 327.50 square feet (30.43 square meters). Their angle of incidence was 2° and there was 5° 40′ dihedral. The leading edges were swept aft 5° 10′.
The YP-38 had an empty weight 11,171 pounds (5,067 kilograms). The gross weight was 13,500 pounds (6,123 kilograms) and the maximum takeoff weight 14,348 pounds (6,508 kilograms).
The YP-38 was powered by two counter-rotating, liquid-cooled, turbosupercharged 1,710.597-cubic-inch displacement (28.032 liter) Allison V-1710-27 right-hand tractor and V-1710-29 left-hand tractor, single overhead cam (SOHC) 60° V-12 engines (Allison Engineering Co. Models F2R and F2L) with a Normal Power rating of 1,000 horsepower at 2,600 r.p.m., and 1,150 horsepower at 3,000 r.p.m. for takeoff. They drove three-bladed Curtiss Electric constant-speed propellers with a diameter of 11 feet, 6 inches (3.505 meters) through a 2.00:1 gear reduction. In a change from the XP-38, the propellers rotated outboard at the top of their arc. The V-1710-27/-29 engines were 7 feet, 1-5/8 inches (2.175 meters) long, 2 feet, 5-9/32 inches (0.744 meters) wide and 3 feet, 0-17/32 inches (0.928 meters) high. The V-1710-27/-29 weighed 1,305 pounds (592 kilograms)
The YP-38 had a maximum speed of 405 miles per hour (651.8 kilometers per hour) at 10,000 feet (3,048 meters) and it could climb from the surface to 20,000 feet (6,096 meters) in six minutes. Normal range 650 miles (1,046 kilometers).
Lockheed built one XP-38, thirteen YP-38s, and more than 10,000 production fighter and reconnaissance airplanes. At the end of World War II, orders for nearly 2,000 more P-38 Lightnings were cancelled.
Ralph Burwell Virden was born 11 June 1898, at Audobon Township, Illinois. He was the second child of Hiram R. Virden, a farmer, and Nancy Carrie Ivy Virden.
Virden attended Bradley Polytechnic Institute at Peoria, Illinois. At the age of 17, 15 October 1918, Ralph Virden enlisted in the U.S. Army. With the end of World War I less than one month later, he was quickly discharged, 7 December 1918.
In 1919, Ralph Virden married Miss Florence I. McCullers. They would have two children, Kathryn and Ralph, Jr. Kathryn died in 1930 at the age of ten years.
During the mid-1920s, Virden flew as a contract mail pilot. He held Airline Transport Pilot Certificate No. 628, and was employed by Gilmore Aviation and Pacific Air Transport. For thirteen years, Virden was a pilot for United Air Lines. He joined Lockheed Aircraft Company as a test pilot in 1939. He had flown more than 15,000 hours.
Virden lived at 4511 Ben Ave., North Hollywood, California, with his family. Ralph, Jr., now 19 years of age, was also employed at Lockheed. (Following his father’s death, the younger Virden enlisted in the United States Navy.)
After the accident, Lockheed, the Air Corps and the National Advisory Committee on Aeronautics (NACA) undertook an extensive test program of the P-38.
October 27, 1954: between August 1954 and May 1956, Joseph A. Walker, the National Advisory Committee for Aeronautics’ chief project test pilot for the Douglas X-3 supersonic research aircraft, made twenty research flights in the “Stiletto.”
On the tenth flight, 27 October, Walker took the X-3 to an altitude of 30,000 feet (9,144 meters). With the rudder centered, he put the X-3 into abrupt left aileron rolls, first at 0.92 Mach and then at Mach 1.05. Both times, the aircraft violently yawed to the right and then pitched down. Walker was able to recover before the X-3 was completely out of control.
This was a new and little understood condition called inertial roll coupling. It was a result of the aircraft’s mass being concentrated within its fuselage, the gyroscopic effect of the turbojet engines and the inability of the wings and control surfaces to stabilize the airplane and overcome its rolling tendency. (Just two weeks earlier, North American Aviation’s Chief Test Pilot George S. Welch had been killed when the F-100A Super Sabre that he was testing also encountered inertial roll coupling and disintegrated.)
A post-flight inspection found that the X-3 had reached its maximum design load. The airplane was grounded for the next 11 months.
The Douglas X-3, serial number 49-2892, was built for the Air Force and NACA to explore flight in the Mach 1 to Mach 2 range. It was radically shaped, with a needle-sharp nose, very long thin fuselage and small straight wings. Two X-3 aircraft had been ordered from Douglas, but only one completed.
The X-3 was 66 feet, 9 inches (20.345 meters) long, with a wing span of just 22 feet, 8.25 inches (6.915 meters). The overall height was 12 feet, 6.3 inches (3.818 meters). The X-3 had an empty weight of 16,120 pounds (7,312 kilograms) and maximum takeoff weight of 23,840 pounds (10,814 kilograms).
It was to have been powered by two Westinghouse J46 engines, but when those were unsatisfactory, two Westinghouse XJ34-WE-17 engines were substituted. This was an axial flow turbojet with an 11-stage compressor and 2-stage turbine. It was rated at 3,370 pounds (14.99 kilonewtons) of thrust, and 4,900 pounds (21.80 kilonewtons) with afterburner. The XJ34-WE-17 was 14 feet, 9.0 inches (4.496 meters) long, 2 feet, 1.0 inch (0.635 meters) in diameter and weighed 1,698 pounds (770 kilograms).
The X-3 had a maximum speed of 706 miles per hour (1,136 kilometers per hour) and a service ceiling of 38,000 feet (11,582 meters).
The X-3 was very underpowered with the J37 engines, and could just reach Mach 1 in a shallow dive. The X-3′s highest speed, Mach 1.208, required a 30° dive. It was therefore never able to be used in flight testing the supersonic speed range for which it was designed. Because of its design characteristics, though, it was very useful in exploring stability and control in the transonic range.
At one point, replacing the X-3’s turbojet engines with two Reaction Motors XLR-11 rocket engines was considered. Predictions were that a rocket-powered X-3 could reach Mach 4.2. However, with Mach 2 Lockheed F-104 becoming operational and North American Aviation’s X-15 hypersonic research rocketplane under construction, the idea was dropped. Technology had passed the X-3 by.
In addition to Douglas Aircraft test pilot Bill Bridgeman, the Douglas X-3 was flown by Air Force test pilots Lieutenant Colonel Frank Everest and Major Chuck Yeager and NACA pilot Joe Walker.
Joe Walker resumed flight testing the X-3 in 1955. Its final flight was 23 May 1956. After the flight test program came to an end, the X-3 was turned over to the National Museum of the United States Air Force, Wright-Patterson Air Force Base, Ohio.
14 October 1938: At Buffalo, New York, test pilot Everett Edward Elliot made the first flight in the new Curtiss-Wright Corporation’s Model 75P, a prototype for a single-engine pursuit plane which had been designated XP-40 by the U.S. Army Air Corps.
Curtiss-Wright’s Chief Engineer, Donovan Reese Berlin, had taken the tenth production P-36A Hawk, Air Corps serial number 38-10, and had its air-cooled radial engine replaced with the Harold Caminez-designed, liquid-cooled, supercharged, 1,710.597-cubic-inch-displacement (28.032 liter) Allison Engineering Co. V-1710-C13 (V-1710-19).
The V-1710-19 was a single overhead cam (SOHC) 60° V-12 engine with four valves per cylinder and a compression ration of 6.65:1. It had a Normal Power rating of 910 horsepower at 2,600 r.p.m. at Sea Level, and 1,060 horsepower at 2,950 r.p.m. for Takeoff. At 10,000 feet (3,048 meters), the V-1710-19 had Maximum Continuous Power rating of 1,000 horsepower at 2,600 r.p.m., and Military Power rating of 1,150 horsepower at 2,950 r.p.m. The engine required 100/130-octane aviation gasoline. It drove a three-bladed Curtiss Electric constant-speed propeller through a 2:1 gear reduction. The V-1710-19 was 8 feet, 1.75 inches (2.483 meters) long, 3 feet, 4.75 inches (1.035 meters) high and 2 feet, 4.94 inches (0.735 meters) wide. It weighed 1,320 pounds (599 kilograms).
At 1,829.39-cubic-inches (29.978 liters), the original Pratt & Whitney Twin Wasp S1C1-G (R-1830-17) 14-cylinder radial engine had greater displacement and produced 80 horsepower more for takeoff than the Allison V-12. The long, narrow V-12, though, allowed for a much more streamlined engine cowling for higher speed and greater efficiency.
In the early testing, the XP-40 was much slower than expected, reaching only 315 miles per hour (507 kilometers per hour). (The P-36A Hawk had a maximum speed of 313 miles per hour). Engineers experimented with different placement for the coolant radiator, oil coolers and the engine air intake. The Air Corps project officer, Lieutenant Benjamin Scovill Kelsey, had the prototype sent to the National Advisory Committee for Aeronautics (NACA) Research Center at Langley Field, Virginia, where the full-size airplane was placed inside a wind tunnel.
Over a two-month period, NACA engineers made a number of improvements. The radiator was moved forward under the engine and the oil coolers utilized the same air scoop. The exhaust manifolds were improved as were the landing gear doors.
When they had finished, Lieutenant Kelsey flew the modified XP-40 back to Curtiss. Its speed had been increased to 354 miles per hour (570 kilometers per hour), a 12% improvement.
By December 1939 the airplane had been further improved and was capable of 366 miles per hour (589 kilometers per hour).
The Curtiss Hawk 75P, XP-40 38-10, was 31 feet, 1 inch (9.574 meters) long with a wingspan of 37 feet, 4 inches (11.354 meters) and overall height of 12 feet, 4 inches (3.734 meters). It had an empty weight of 5,417 pounds (2,457.1 kilograms) and maximum gross weight of 6,870 pounds (3,116.2 kilograms).
The prototype had a maximum speed of 342 miles per hour (550 kilometers per hour) at 12,200 feet (3,719 meters) with a gross weight of 6,260 pounds (2,839.5 kilograms). Its range was 460 miles (740 kilometers) flying at 299 miles per hour (481 kilometers per hour) with 100 gallons (378.5 liters) of fuel. With 159 gallons (601.9 liters) and with speed reduced to 200 miles per hour (322 kilometers per hour), the XP-40 had a maximum range of 1,180 miles (1,899 kilometers).
The prototype was armed with two air-cooled Browning AN-M2 .50-caliber machine guns mounted above the engine and synchronized to fire forward through the propeller arc.
The Air Corps placed an initial order for 524 P-40s. This was the largest single order for airplanes by the U.S. military up to that time. The first production model was the P-40 Warhawk, armed with two .50-caliber machine guns. There was only one P-40A variant which was a P-40 modified as a camera aircraft. The definitive pursuit model was the P-40B Warhawk, which retained the two .50-caliber guns of the P-40 and added two Browning M2 .30-caliber machine guns to each of the wings.
The P-40B was best known as the airplane flown by the American Volunteer Group fighting for China against the Japanese. They were called the “Flying Tigers”. Between 1939 and 1945, Curtiss built 13,738 P-40s in many configurations. They flew in combat in every theater of operations during World War II.