Subject: NASA X-31
Date: 3 Nov 94 04:19:51 GMT


              X-31 ENHANCED FIGHTER MANEUVERABILITY DEMONSTRATOR
                                       
   
   The NASA Dryden Flight Research Center is using two X-31 Enhanced
   Fighter Maneuverability (EFM) demonstrators to obtain data that may
   apply to highly-maneuverable next generation fighters.
   
   The X-31 program is showing the value of thrust vectoring (directing
   engine exhaust flow) coupled with advanced flight control systems for
   close-in air combat at very high angles of attack.
   
Background

   "Angle-of-attack" (alpha) is an engineering term to describe the angle
   of an aircrafts body and wings relative to its actual flightpath.
   During maneuvers, pilots often fly at extreme angles of attack -- with
   the nose pitched up while the aircraft continues in its original
   direction. With older aircraft designs this would lead to loss of
   control which can result in the loss of the aircraft, pilot, or both.
   
   Thrust vectoring paddles on the X-31's exhaust nozzle direct the
   exhaust flow to provide control in pitch (up and down) and yaw (right
   and left) to improve control. In addition the X-31s are configured
   with movable forward canards and fixed aft strakes. The canards are
   small wing-like structures set on the wing line between the nose and
   the leading edge of the wing. The strakes are set on the same line
   between the trailing edge of the wing and the engine exhaust. Both
   supply additional control in tight maneuvering situations.
   
   The X-31 research program is producing technical data at high angles
   of attack. These data will give engineers and aircraft designers a
   better understanding of aerodynamics, effectiveness of flight controls
   and thrust vectoring, and airflow phenomena at high angles of attack.
   This is expected to lead to design methods providing better
   maneuverability in future high-performance aircraft and make them
   safer to fly.
   
Phase One

   Phase I was the conceptual design phase. During this phase the payoff
   expected from the application of EFM concepts in future air battles
   was outlined and the technical requirements for a demonstrator
   aircraft were defined.
   
Phase Two

   Phase II carried out the preliminary design of the demonstrator and
   defined the manufacturing approach to be taken. Three governmental
   design reviews were held during this phase to thoroughly examine the
   proposed design. Technical experts from the U.S. Navy, Federal
   Ministry of Defense, and NASA contributed to the careful examination
   of all aspects of the design.
   
Phase Three

   Phase III initiated and completed the detailed design and fabrication
   of two aircraft. This phase required that both aircraft fly a limited
   test flight program. The first aircraft rolled out on Mar. 1, 1990,
   followed by a first flight on Oct. 11, 1990. The X-31 took off from
   Palmdale, CA, runway 07, piloted by Rockwell chief test pilot Ken
   Dyson. It reached a speed of 340 mph and an altitude of 10,000 ft
   during its initial 38 min. flight. The second aircraft made its first
   flight on Jan. 19, 1991, with Deutsche Aerospace chief test pilot
   Dietrich Seeck at the controls.
   
Flight Summary

   During the program's initial phase of operations at Rockwell
   International's Palmdale, CA, facility the aircraft were flown on 108
   test missions before starting operations they were moved to Dryden.
   
   At Dryden an international team of pilots and engineers is expanding
   the aircraft's flight envelope, including military utility evaluations
   that will pit the X-31 against similarly equipped aircraft to evaluate
   the maneuverability of the X-31 in simulated combat.
   
   The X-31 achieved controlled flight at 70 degrees angle of attack at
   Dryden on Sept. 18, 1992.
   
   On Apr. 29, 1993, the No. 2 X-31 successfully executed a minimum
   radius, 180-degree turn using a post-stall maneuver, flying well
   beyond the aerodynamic limits of any conventional aircraft. The
   revolutionary maneuver has been dubbed the "Herbst Maneuver," after
   Wolfgang Herbst, a German proponent of using post-stall flight in
   air-to-air combat.
   
   Evaluation of the X-31 as a fighter maneuverability demonstrator by
   the ITO is scheduled to conclude by Dec. 1993.
   
Program Management

   An international test organization, managed by the Defense Advanced
   Research Projects Agency (DARPA), is conducting the flight tests. In
   addition to DARPA and NASA, the International Test Organization (ITO)
   includes the U.S. Navy, the U.S. Air Force, Rockwell International,
   the Federal Republic of Germany, and Deutsche Aerospace (formerly
   Messerschmitt-Bolkow-Blohm). About 110 people from the ITO agencies
   are assigned to the program. NASA is responsible for flight test
   operations, aircraft maintenance, and research engineering.
   
   The X-31 is the first international experimental aircraft development
   program administered by a U.S government agency. It is a key effort of
   the NATO Cooperative Research and Development Program.
   
   Gary Trippensee is the ITO director and NASAUs project manager at
   Dryden.
   
   Pilots of the X-31 EFM aircraft include: NASA pilot Rogers Smith; U.S.
   Navy pilot Cmdr. Al Groves; German pilots Karl Lang and Dietrich
   Seeck; Rockwell International pilot Fred Knox; and Air Force Flight
   Test Center pilot Lt. Col. Jim Wisneski.
   
Aircraft Specifications

   Designed and constructed as a demonstrator aircraft by Rockwell
   International Corporation's North American Aircraft and Deutsche
   Aerospace.
   
   The aircraft has a wing span of 23.83 ft (7.3 m). The fuselage length
   is 43.33 ft (12.8 m).
   
   The X-31 is powered by a single General Electric F404-GE-400 turbofan
   engine, producing 16,000 lb (71,168 N) of thrust in afterburner.
   
   Typical takeoff weight of the X-31 is 16,100 lb (7,303 kg).
   
   The X-31 design speed is Mach 0.9 with an altitude capability of
   40,000 ft (12,192 m).
   
   
     _________________________________________________________________
   
   Gary Trippensee, Dryden Project Manager
   (805) 258-3163
   
   
   Image: Dryden EAO Logo Icon
   Don Nolan
   NASA Dryden Flight Research Center
   Edwards, Calif. 93523
   (805) 258-3447
   Don_Nolan@qmgate.dfrf.nasa.gov
   
   
   Modified: Feburary 2, 1994


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From: dadams@netcom.com (Dean Adams)
Subject: Re: NASA X-31
Organization: Aurora Information Systems


In article <39m9j8$fko@coyote.rain.org> k3omalle@sisko.sbcc.cc.ca.us () writes:
>|>              X-31 ENHANCED FIGHTER MANEUVERABILITY DEMONSTRATOR
>|>   The NASA Dryden Flight Research Center is using two X-31 Enhanced
>|>   Fighter Maneuverability (EFM) demonstrators to obtain data that may
>|>   apply to highly-maneuverable next generation fighters.

 >***Here's a good example of a good, solid, money - eating disinformation
 >campaign. 

No, that is a good example of someone flaunting their ignorance. 

 > The thrust vectoring concept has been working to perfection in 
 > the Harrier for 25 years now.

The Harrier's vectored thrust is derived from its unique Pegasus
turbofan engine and the four movable nozzles.  That concept and
implimentation is TOTALLY different from that being used in both
the X-31 EFM and F-18 HARV programs.  The Harrier can vector its
thrust in a *single* axis over about a 98 degree range, from all
back for forward flight to straight down/slightly forward for
vertical landing.  That has no similarity to the three-dimensional
thrust vectoring used on the X-31. 

 >  And now what does NASA want to do?  STUDY thrust vectoring. 

Not just NASA.  The program began in the 1980s and was originally
sposored by DoD, DARPA, and the German Ministry of Defense.

 > Of course, the relative ineffectiveness of vectoring thrust at
 > the aft end versus the center of gravity will be studied some 
 >time in the future.

Wrong.  Vectored thrust at the aft (which BTW where the engine exhaust
is located), can be quite effective.  It can also reduce the size of
the tail and rudder authority required.  Most importantly it can
increase the maneuvering ability of a fighter aircraft.  

 >  And, of course, 5 years from now they will decide to 
 >study Augmented/afterburner thrust vectoring, too.

Phew... where have you been.  The X-31 has an afterburner, and the
YF-22 and YF-23 have already tested engines using (2-dimensional) 
thrust vectoring nozzles (with AB, of course).  There is also a new
F-16 program with an axisymetric thrust vectoring nozzle.  Both of
these have built on data from the X-31 and HARV programs.

 > But we can't have too many supersonic, VTOL, Stops-on-a-dime,

More ignorance.  The X-31 program has nothing at all to do with VTOL.
If you want to talk about spending new money on VTOL, then talk about
the ASTOVL program.

 > right-angle-turning fighters  around, can we?

A fighter that can out-turn the other guy can KILL the other guy.
I'd say we can't have too many of those around...

 > Then people will suspect that we've had them all along.  So NASA will
 > continue to STUDY the program until it becomes technically obvious what
 > they should do.  They might even burn up 35 years of lag time as well.
 >  Oh, well, it's only our money.

What causes you to drone on so long in ingorance.  In this case you
hear "thrust vectoring" and you can think of nothing but "Harrier".


