NASA 

National Aeronautics and 

Facts

Space Administration 

Dryden Flight Research Center 

P.O. Box 273

Edwards, California 93523 

AC 661-276-3449 

FAX 661-276-3566 

pao@dfrc.nasa.gov FS-2002-09-065 DFRC 

X-36 Tailless Fighter Agility Research Aircraft 

Project Summary 

The NASA/Boeing X-36 Tailless Fighter Agility Research Aircraft successfully completed a 31-flight research program at 

NASA Dryden Flight Research Center, Edwards, Calif., in November 1997. The X-36 project team developed and 

demonstrated the tailless fighter design using advanced technologies to improve the maneuverability and survivability of 

possible future fighter aircraft. The X-36 program met or exceeded all project goals. 

In a follow-on effort, the Air Force Research Lab (AFRL) contracted Boeing to fly AFRL’s Reconfigurable Control for Tailless 

Fighter Aircraft (RESTORE) software as a demonstration of the adaptability of the neural-net algorithm to compensate for inflight damage or malfunction of effectors, i.e., flaps, ailerons and rudders. Two RESTORE research flights were flown in 

December 1998, proving the viability of the software approach. 

Accomplishments 

The first flight of the X-36 occurred on May 17, 1997, with the final flight closing the original program on Nov. 12, 1997. A 

total of 31 safe and successful research flights were flown during that 25-week period, accumulating a total of 15 hours and 

38 minutes of flight time and using four different versions of flight control software. The aircraft reached an altitude of 20,200 

feet and a maximum angle of attack of 40 degrees. 

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with their

The X-36 project team examined the aircraft’s agility at low 

speed/high angles of attack and at high speed/low angles of 

attack. The X-36’s speed envelope reached up to 206 knots 

(234 miles per hour); the aircraft was very stable and maneuverable and handled very well at both ends of the speed 

envelope. 

For the follow-on RESTORE program, two flights were 

flown with the adaptive neural-net software running in conjunction with the original proven control laws. Several inflight simulated failures of control surfaces were introduced 

as a problem for the reconfigurable control algorithm. Each 

time, the software correctly compensated for the failure and 

allowed the aircraft to be safely flown in spite of the degraded 

condition. 

Technical Specifications 

The X-36 is a 28-percent scale representation of a theoretical 

advanced fighter aircraft configuration. The Boeing Phantom 

Works (formerly McDonnell-Douglas) in St. Louis, Mo., 

built the X-36, in a cooperative agreement with NASA Ames 

Research Center, Moffett Field, Calif. It was designed to fly 

without the traditional tail surfaces common on most aircraft. 

Instead, a canard forward of the wing is utilized, in addition 

to split ailerons and an advanced thrust-vectoring nozzle for 

directional control. The X-36 is unstable in both the pitch and 

yaw axes; therefore, an advanced, single-channel digital flyby-wire control system, developed with some commercially 

available components, stabilizes the aircraft. 

Fully fueled, the X-36 prototype weighs about 1,250 pounds. 

It is 19 feet long and three feet high with a wingspan of just 

over 10 feet. A Williams International F112 turbofan engine 

provides about 700 pounds of thrust. A typical research flight 

lasts approximately 35 to 45 minutes from takeoff to touchdown. 

Using a video camera mounted in the nose of 

the vehicle (and an on-board microphone), 

the X-36 is remotely-controlled by a pilot in 

a ground station virtual cockpit. A standard 

fighter-type head-up display 

(HUD), in addition to a moving-map representation of the 

vehicle’s position within the 

range, provides excellent situational awareness for the pilot. This pilot-in-the-loop 

approach eliminates the need for expensive 

and complex autonomous flight control systems and the risks associated 

inability to deal with unknown or unforeseen 

phenomena once in flight. 

Teamwork 

The X-36 project team, consisting of employees from Boeing, 

and NASA’s Ames and Dryden Research Centers. The project 

was an unparalleled accomplishment for a remotely-piloted 

aircraft program. 

Ames and the Phantom Works developed the technologies 

required for tailless agile flight beginning in 1989. Based on 

positive results of extensive wind tunnel testing and computational fluid dynamics (CFD) analysis, McDonnell-Douglas 

in 1993 proposed building the remotely-piloted scale aircraft 

technology demonstrator to validate the advanced technologies in a real flight environment. 

In 1994, the Phantom Works began fabrication of the two X36 vehicles using rapid prototyping techniques in its St. Louis 

facility. NASA and Boeing were full partners in the project, 

which was jointly funded under a roughly 50/50 cost-sharing 

arrangement. The combined program cost for the development, fabrication, and flight testing of the two prototype 

aircraft was approximately $21 million. Ames led the X-36 

program providing government oversight. In the flight test 

phase, Dryden provided the flight test experience, infrastructure and range support. 

Funding 

The X-36 Program received its funding from NASA’s Office 

of Aero-Space Technology (OAT) in Washington, D.C., and 

from the Boeing Co. 

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