January 25, 1991: X-29 Agility Testing Begins

  • Published
  • Air Force Flight Test Center

A series of X-29 high Angle of Attack agility test sorties began.  The forward-swept wing experimental jet exhibited better flying qualities in the high angle of attack range than many current operational fighters, and without the weight and complexity of special flaps, slats, or thrust vectoring systems.

An extensive high angle-of-attack (AOA) flight testing program has been performed with the X-29-2 (AF 82-0049) forward swept wing research aircraft. The high AOA envelope expansion phase cleared the aircraft to fly in a broad flight regime and produced important data on the high AOA clearance process and data analysis. Lessons learned during the military utility phase on the tactical advantages and disadvantages associated with high AOA maneuvering are impacting programs such as the X-31, HARV, and F-22. Insight on the critical forebody flow-field of the X-29 at high AOA was gained using on-surface pressure measurements and off-surface flow visualization during the aerocharacterization phase. The Vortex Flow Control (VFC) experiment conducted on the X-29 successfully proved the viability of a pneumatic blowing device manipulating forebody vortices to act as an aircraft controller, an historical first. Finally, throughout the aircraft #2 flight test program, important data concerning the aircraft's air data system, digital flight control system, vertical tail, engine, and subsystems operating in the high AOA environment were gathered. This paper is intended as a broad overview of the high AOA testing of the X-29, with the purpose of directing the reader towards the numerous excellent references which describe the flight test program in more detail.

Two X-29As were built by Grumman after the proposal had been chosen over a competing one involving a General Dynamics F-16 Fighting Falcon. The X-29 design made use of the forward fuselage and nose landing gear from two existing F-5A Freedom Fighter airframes (63-8372 became 82-0003 and 65-10573 became 82-0049).  The control surface actuators and main landing gear were from the F-16. The technological advancement that made the X-29 a plausible design was the use of carbon-fiber composites. The wings of the X-29, made partially of graphite epoxy, were swept forward at more than 33 degrees; forward-swept wings were first trialed 40 years earlier on the experimental Junkers Ju 287 and OKB-1 EF 131. The Grumman internal designation for the X-29 was "Grumman Model 712" or "G-712".

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