F-18 High Alpha Research Vehicle (HARV) | |
---|---|
F-18 HARV in high alpha maneuver | |
Role | Test aircraft |
Manufacturer | McDonnell Douglas |
Status | Prototype from military service |
Primary user | NASA |
Number built | 1 |
Developed from | McDonnell Douglas F/A-18 Hornet |
The High Alpha Research Vehicle was a modified American McDonnell Douglas F/A-18 Hornet used by NASA in a three-phase program investigating controlled flight at high alpha (angle of attack) using thrust vectoring, modifications to the flight controls, and with actuated forebody strakes. The program lasted from April 1987 to September 1996. [1] [2]
NASA reported that in one phase of the project, Armstrong Flight Research Center "research pilots William H. "Bill" Dana and Ed Schneider completed the envelope expansion flights in February 1992. Demonstrated capabilities included stable flight at approximately 70 degrees angle of attack (previous maximum was 55 degrees) and rolling at high rates at 65 degrees angle of attack. Controlled rolling would have been nearly impossible above 35 degrees without vectoring." [3] Performance figures were not listed for other phases.
The aircraft is now on display at the Virginia Air and Space Center in Hampton, Virginia. [4]
The McDonnell Douglas F/A-18 Hornet is an all-weather supersonic, twin-engine, carrier-capable, multirole combat aircraft, designed as both a fighter and attack aircraft. Designed by McDonnell Douglas and Northrop, the F/A-18 was derived from the latter's YF-17 in the 1970s for use by the United States Navy and Marine Corps. The Hornet is also used by the air forces of several other nations, and formerly by the U.S. Navy's Flight Demonstration Squadron, the Blue Angels.
For fixed-wing aircraft, ground effect is the reduced aerodynamic drag that an aircraft's wings generate when they are close to a fixed surface. During takeoff, ground effect can cause the aircraft to "float" while below the recommended climb speed. The pilot can then fly just above the runway while the aircraft accelerates in ground effect until a safe climb speed is reached.
In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases. This occurs when the critical angle of attack of the foil is exceeded. The critical angle of attack is typically about 15°, but it may vary significantly depending on the fluid, foil, and Reynolds number.
In fluid dynamics, angle of attack is the angle between a reference line on a body and the vector representing the relative motion between the body and the fluid through which it is moving. Angle of attack is the angle between the body's reference line and the oncoming flow. This article focuses on the most common application, the angle of attack of a wing or airfoil moving through air.
A leading-edge extension (LEX) is a small extension to an aircraft wing surface, forward of the leading edge. The primary reason for adding an extension is to improve the airflow at high angles of attack and low airspeeds, to improve handling and delay the stall. A dog tooth can also improve airflow and reduce drag at higher speeds.
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The Grumman X-29 was an American experimental aircraft that tested a forward-swept wing, canard control surfaces, and other novel aircraft technologies. Funded by NASA, the United States Air Force and DARPA, the X-29 was developed by Grumman, and the two built were flown by NASA and the United States Air Force. The aerodynamic instability of the X-29's airframe required the use of computerized fly-by-wire control. Composite materials were used to control the aeroelastic divergent twisting experienced by forward-swept wings, and to reduce weight. The aircraft first flew in 1984, and two X-29s were flight tested through 1991.
The Rockwell-Messerschmitt-Bölkow-Blohm X-31 is an experimental jet aircraft designed to test fighter thrust vectoring technology. It was designed and built by Rockwell and Messerschmitt-Bölkow-Blohm (MBB), as part of a joint US and German Enhanced Fighter Maneuverability program to provide additional control authority in pitch and yaw, for significantly more maneuverability than most conventional fighters. An advanced flight control system provided controlled flight at high angles of attack where conventional aircraft would stall or lose control. Two aircraft were built, of which only one has survived.
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William Harvey Dana was an American aeronautical engineer, U.S. Air Force pilot, NASA test pilot, and astronaut. He was one of twelve pilots who flew the North American X-15, an experimental spaceplane jointly operated by the Air Force and NASA. He was also selected for participation in the X-20 Dyna-Soar program.
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