Convair XF-92A Dart
The Consolidated Vultee Aircraft Corporation (Convair) XF-92A Dart was America’s first delta wing aircraft. It was built as a test bed for a proposed interceptor that never materialized. The XF-92A was then used to test the delta-wing concept. The delta wing's large area (425 square feet), thin airfoil cross section, low weight, and structural strength made a great combination for a supersonic aircraft. The aircraft was powered by an Allison J33-A-29 turbojet engine with an afterburner.
Convair XF-92A Dart
The single-place XF-92A airplane had a delta wing swept at 60 degrees. It was 48.2 feet long, had a 31.3-foot wingspan, and was 17.5 feet high at the tip of the vertical stabilizer. It was controlled by a conventional rudder and full-span elevons that functioned as elevators and ailerons. [1]

Convair and the U.S. Air Force flew the XF-92A from 1948 to 1953. The Consolidated-Vultee Model 7002 aircraft was built as a flying mock-up to investigate delta wing behavior at low and high subsonic speeds for the proposed XF-92 delta wing interceptor. Powered by a ramjet with small rockets inside the combustion chamber, it would have been a manned surface to air missile, with a short range, Mach 1.65 top speed, and a flight time at high altitude of 5.4 minutes. The XF-92's engine was soon determined to be impractical, and the project was canceled in 1948.

Although the XF-92 program had ended, the Model 7002 was being prepared to fly. Its role remained that of a test vehicle for the delta wing configuration. The aircraft was delivered to Muroc Air Force Base, Calif., on April 1, 1948. Its first flight, an inadvertent hop during a high-speed taxi test was made on June 9, 1948, by Consolidated-Vultee test pilot Sam Shannon. The official first flight was made on Sept. 18, and the Phase I testing began. This demonstrated that the aircraft was airworthy, and continued through August 1949. The Phase I flights were conducted by both Shannon and fellow company test pilot William Martin.

With the final flight on Aug. 26, 1949, the aircraft was turned over to the Air Force for Phase II testing by Maj. Charles E. "Chuck" Yeager. The aircraft was given the Air Force designation XF-92A, and carried the serial number 46-692. Although the aircraft carried the designation of a prototype fighter, its role was now that of research aircraft. The Phase II flights were tests by Air Force pilots to see if the aircraft met the contract specifications. The first Phase II flight was made by Yeager on Oct. 13, 1949. (A day short of two years after his Mach 1 flight.) The tests were completed with a final flight on Dec. 28, 1949, by Maj. Frank Everest [3].

After the Air Force's plans for an interceptor failed to materialize, the NACA High-Speed Flight Research Station, which had supplied engineering, instrumentation, and operational assistance to the Air Force during its flights, took over the flight test program in 1953.

A. Scott Crossfield was the NACA pilot selected for the XF-92A research flights. His introduction to the aircraft, during a taxi across the lakebed, was memorable. He recalled years later, "Nobody wanted to fly the XF-92. There was no lineup of pilots for that airplane. It was a miserable flying beast." Before the taxi, Everest briefed Crossfield, who recalled, "He told me, 'Keep the nose up so it will slow down. Because it will roll a long ways.' Well, I let the nose come down and on the nose wheel. I couldn't get it back up. It didn't have enough tail power to do it. So that airplane was rolling like mad towards the edge of the lakebed.... I saw a county road off to the left. And I managed to get that thing turned and head up that country road. Burned out the brakes. Just melted them right there. Rolled up that county road about 100 yards. And fortunately no damage to the airplane. Came out pretty well, except the brakes were all burned out." The road was later named "Crossfield Pike."

Crossfield flew a total of 25 flights in the XF-92A between April 9, 1953 and Oct. 14, 1953. The initial 13 flights were for data on static longitudinal stability; dynamic stability; directional control; longitudinal and lateral stability and control, and low speed stability and control. These were followed by 10 flights to test different wing fence configurations. The wing fences were designed to control the tendency of swept wing aircraft to pitch up at low speeds and in turns. The initial six flights were made at speeds under Mach 1. The last four were for data on low-speed lateral and directional control with the wing fences. On one flight, the modified wing fences buckled during the test. The XF-92A undertook two low-speed lateral and directional control flights without the wing fences. These were both made on Oct. 14, 1953. When the XF-92A landed on the lakebed after the second flight, its nose gear collapsed. Crossfield was unharmed, but the XF-92A never flew again. The Air Force subsequently donated the XF-92A to the University of the South in Sewanee, Tenn. The aircraft was transferred to the Air Force Museum in 1969, where it is now on display [3].

 Besides validating the thin delta wing principle, the XF-92A played a major role in supporting the development of the Convair F-102A interceptor, the Air Force’s first attempt at an all-weather, supersonic interceptor. In 1953, the XF-92A experienced a landing gear failure on rollout after landing at the NACA High-Speed Research Station and the aircraft was retired [1,2].

Convair XF-92A Dart
January 1953. This NACA photograph of the XF-92A was taken at the South Base of Edwards Air Force Base.  [Larger Image] The photograph shows the pitot-static probe, used to measure airspeed, Mach number, and altitude, mounted on a noseboom protruding from the aircraft's nose engine inlet. Also attached to the pitot-static-probe portion of the noseboom are flow direction vanes for sensing the aircraft's angles of attack and sideslip. The Convair XF-92A aircraft was powered by a Allison J33-A turbojet engine with an afterburner, and was unique in having America's first delta wing. The delta wing's large area, thin airfoil cross section, low weight, and structural strength made this design a promising combination for a supersonic airplane.

Convair XF-92A Dart in flight
This 1953 NACA High-Speed Flight Research Station photo, taken near Edwards Air Force Base, shows an aft view of the XF-92A in flight above a layer of clouds [2].

XF-92A 3-View line art
References
  1. NASA Dryden Flight Research Center, XF-92A on Ramp
  2. NASA Dryden Flight Research Center, XF-92A In Flight
  3. NASA Dryden Flight Research Center, XF-92A Fact Sheet

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