Skip Top nav bar link group topnav end piece go to business section go to education section go to history section go to gallery section go to news section go to organizations section go to research section go to search engine go to site index topnav end piece
NASA Meatball NASA Dryden X-31 Enhanced Fighter Maneuverability Demonstrator banner
X-31 Unloading Returning from Paris Air Show X-31 Unloading Returning from Paris Air Show

Photo Number: EC95-43153-1
Photo Date: 1995

Formats: 539x480 JPEG Image (94 KBytes)
1150x1024 JPEG Image (460 KBytes)
3000x2670 JPEG Image (4,852 KBytes)

Photo
Description:
After being flown in the Paris Air Show in June 1995, the X-31 Enhanced Fighter Maneuverability Technology Demonstrator Aircraft, based at the NASA Dryden Flight Research Center, Edwards Air Force Base, California, is off-loaded from an Air Force Reserve C-5 transport after the ferry flight back to Edwards. At the air show, the X-31 demonstrated the value of using thrust vectoring (directing engine exhaust flow) coupled with advanced flight control systems to provide controlled flight at very high angles of attack.

Project
Description:
The X-31 Enhanced Fighter Maneuverability (EFM) demonstrator flew at the Ames- Dryden Flight Research Facility, Edwards, California (redesignated the Dryden Flight Research Center in 1994) from February 1992 until 1995 and before that at the Air Force’s Plant 42 in Palmdale, California. The goal of the project was to provide design information for the next generation of highly maneuverable fighter aircraft.

This program demonstrated the value of using thrust vectoring (directing engine exhaust flow) coupled with an advanced flight control system to provide controlled flight to very high angles of attack. The result was a significant advantage over most conventional fighters in close-in combat situations. The X-31 flight program focused on agile flight within the post-stall regime, producing technical data to give aircraft designers a better understanding of aerodynamics, effectiveness of flight controls and thrust vectoring, and airflow phenomena at high angles of attack.

Stall is a condition of an airplane or an airfoil in which lift decreases and drag increases due to the separation of airflow. Thrust vectoring compensates for the loss of control through normal aerodynamic surfaces that occurs during a stall. Post-stall refers to flying beyond the normal stall angle of attack, which in the X-31 was at a 30-degree angle of attack.

During Dryden flight testing, the X-31 aircraft established several milestones. On November 6, 1992, the X-31 achieved controlled flight at a 70-degree angle of attack. On April 29, 1993, the second X-31 successfully executed a rapid minimum-radius, 180-degree turn using a post-stall maneuver, flying well beyond the aerodynamic limits of any conventional aircraft. This revolutionary maneuver has been called the "Herbst Maneuver" after Wolfgang Herbst, a German proponent of using post-stall flight in air-to-air combat. It is also called a "J Turn" when flown to an arbitrary heading change.

The aircraft was flown in tactical maneuvers against an F/A-18 and other tactical aircraft as part of the test flight program. During November and December 1993, the X-31 reached a supersonic speed of Mach 1.28. In 1994, the X-31 program installed software to demonstrate quasi-tailless operation.

The X-31 flight test program was conducted by an international test organization (ITO) managed by the Advanced Research Projects Office (ARPA), known as the Defense Advanced Research Projects Office (DARPA) before March 1993. The ITO included the U.S. Navy and U.S. Air Force, Rockwell Aerospace, the Federal Republic of Germany, Daimler-Benz (formerly Messerschmitt-Bolkow-Blohm and Deutsche Aerospace), and NASA. Gary Trippensee was the ITO director and NASA Project Manager. Pilots came from participating organizations.

The X-31 was 43.33 feet long with a wingspan of 23.83 feet. It was powered by a single General Electric P404-GE-400 turbofan engine that produced 16,000 pounds of thrust in afterburner.


NASA Photo by: NASA

Keywords: Ames-Dryden Flight Research Facility ; Dryden Flight Research Center; Herbst Maneuver; Wolfgang Herbst; J Turn; Advanced Research Projects Agency; Defense Advanced Research Projects Agency; U.S. Navy; U.S. Air Force; Rockwell Aerospace; the Federal Republic of Germany; Daimler-Benz; Deutsche Aerospace; Messerschmitt-Bolkow-Blohm; Gary Trippensee; General Electric; X-31; Paris Air Show; Enhanced Fighter Maneuverability Aircraft; thrust vectoring; C-5


Last Modified: February 6, 2002
Responsible NASA Official: Marty Curry
Curator: PAO Webmasters

NASA Website Privacy Statement