McDonnell Douglas and the National Aeronautics and Space Administration
(NASA) embarked on a joint project in 1994 to
develop a prototype fighter aircraft designed for stealth and agility.
The result -- after only 28 months -- was a subscale tailless
aircraft called the X-36. The 28 percent scale, remotely piloted X-36
has no vertical or horizontal tails, yet it is expected to be
more maneuverable and agile than today's fighters. In addition, the
tailless design reduces the weight, drag and radar cross
section typically associated with traditional fighter aircraft.
In a series of flight tests, the low-cost X-36 research vehicle demonstrated
the feasibility of using new flight control technologies
in place of vertical and horizontal tails to improve the maneuverability
and survivability of future fighter aircraft. During flight, the
X-36 used new split ailerons and a thrust-vectoring nozzle for directional
control. The Ailerons not only split to provide yaw
(right-left) control, but also raise and lower asymmetrically to provide
roll control. The X-36 vehicle also incorporated an
advanced, single-channel digital fly-by-wire control system developed
with commercially available components.
Fully fueled, the X-36 prototype weighed 1,300 pounds. It is 19 feet
long and measures 11 feet at its widest point. It is 3 feet
high and is powered by a Williams Research F112 engine that provides
about 700 pounds of thrust. Using a video camera in
the nose of the vehicle, a pilot controls the flight of the X-36 from
a virtual cockpit -- complete with head-up display (HUD) --
in a ground-based station. This pilot-in-the-loop approach eliminates
the need for expensive and complex autonomous flight
control systems.
McDonnell Douglas has been working under contract to NASA Ames Research
Center, Moffett Field, Calif., since 1989 to
develop the technical breakthroughs required to achieve tailless agile
flight. Based on the positive results of extensive wind
tunnel tests, McDonnell Douglas in 1993 proposed building a subscale
tailless research aircraft. In 1994 McDonnell Douglas
and NASA began joint funding of the development of this aircraft, now
designated the X-36. Under the roughly 50/50
cost-share arrangement, NASA Ames is responsible for continued development
of the critical technologies, and McDonnell
Douglas for fabricating the aircraft.
McDonnell Douglas built the X-36 with a combination of advanced, lowcost
design and manufacturing techniques pioneered by
the company's Phantom Works research-and-development operation.
Among these techniques are:
advanced software development tools for rapid
avionics prototyping;
low-cost tooling molds;
composite skins cured at low termperatures
without the use of autoclaves, and;
high speed machining of unitized assemblies.
Two identical subscale research vehicles were produced by the team for
use in the flight test program. Including design and
production of the two aircraft and flight testing, the total cost of
the X-36 program was only $17 million. A total of 25 flights,
conducted by McDonnell Douglas, took place during a six-month flight
test program designed to prove the aircraft's superior
agility. Initial tests focused on the low-speed, high angle-of-attack
performance of the X-36.