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Rockwell/MBB X-31 design evolution

hesham

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My dears,

do you know Rockwell SNAKE project?

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overscan

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It was an early configuration of what evolved into the Rockwell/MBB X-31 project
 

hesham

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Thank you dear overscan.
 

flateric

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Later Rockwell artist's concept of SNAKE - almost X-31 configuration already
 

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overscan

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The initial SNAKE configuration bore a superficial resemblance to the earlier HiMAT design (canard and wing-mounted twin vertical tails); however, the new configuration was designed analytically with computers and a minimum amount of wind-tunnel tests. Unfortunately, Croom’s aerodynamic tests of the initial SNAKE configuration in the Langley 30- by 60-Foot (Full-Scale) Tunnel indicated unacceptable stability and control characteristics. The configuration was unstable in pitch, roll, and yaw for all angles of attack.

Based on their extensive experience with stability and control characteristics of advanced fighters, Croom and Johnson provided the Rockwell team with several recommendations to cure the problems exhibited by the SNAKE configuration. The configuration modifications resulted in satisfactory characteristics, and the aerodynamic deficiencies of the initial SNAKE design had been eliminated. Rockwell was grateful for the guidance and innovation contributed by Langley in the evolution of the SNAKE configuration.
http://oea.larc.nasa.gov/PAIS/Partners/X_31.html

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overscan

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Here we see how the Rockwell SNAKE studies and MBB J-90/P-30 studies merged into the X-31.

Source:

Hannes Ross, EADS-Military Aircraft & Mike Robinson, The Boeing Company, X-31: 20 Years of Successful International Cooperation
AIAA 2003-2572
 

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flateric

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Oh, it was real mutato potato then...
 

richard

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It seems that VFW was involved too ,and that the X-31 and TFK were closely related .
- Two VFW studies for the TFK shown at the Hannover Salon in 1980 (Air et Cosmos 1980)
- VFW-FSW (1982) shown by Overscan in the TFK topic
- X-31 4 views as tried at Langley (Luftfahrtfoschung in Deutschland ; Hirschel,Prem,Madelung; Bernard&Graefe Verlag 2001)
 

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overscan

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In 1981, VFW was taken over by MBB, having been merged with Fokker to form VFW-Fokker in 1969, but then de-merged to form an independent company again in 1980.
This should help. From 1981 VFW was part of MBB.
 
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overscan

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overscan

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Thanks to Dan Raymer's autobiography "Living in the Future" we can understand the design progression now.

The original SNAKE design was developed by Rockwell Columbus division as the LA division were too busy with B-1 work. Later on, the project was returned to LA division, but it was too different to the MBB (TKF-90) configurations to use any of the MBB work. The Germans were putting in money and wanted it to look like the Eurofighter they were developing while the US fighter effort at that time was all stealthy and hence classified. Rockwell's LA division essentially started the design again with something that looked more like the Eurofighter. Result - happy Germans :)

There's a lot more about it and other projects in the book, so buy it for the full story :)
 

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Steve Pace

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Didn't the X-31 fly a few times without its vertical tail? -SP
 

Stargazer2006

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Machdiamond said:
No it never flew without its vertical tail but the flight control system laws were modified to simulate tailless handling qualities for a study that was illustrated by a photo montage.
Here is photographic evidence of this: the same picture published with and without the tail fin. Please note that the caption says "Photo concept".
 

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overscan

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Here's some interesting stuff on the SNAKE / early X-31.

As richard suggested earlier in the topic, it turns out the initial SNAKE configuration was developed at VFW (later, MBB) in 1980 as an alternate TKF study. It was sent to Rockwell to work on and give to NASA to test, as both companies were interested in post-stall manouvering.

This wasn't the only configuration tested - there was also this scaled-down single engine MBB TKF-90 design.

Source: Stephen Ransom Configuration Development of a Research Aircraft with Post-Stall Maneuverability in AIAA Journal of Aircraft, 1983

http://crgis.ndc.nasa.gov/historic/20-Foot_Spin_Tunnel_(645)_Models_and_Tests_N-Z#X-31_and_Rockwell-MBB_Snake
 

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hesham

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Rafael

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Are these last related to Rockwell's SNAKE?
 

flateric

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Mark Nankivil

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Very interesting video - thanks Flateric! Mark
 

hesham

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A good report about Rockwell/MBB X-31;

http://www.fzt.haw-hamburg.de/pers/Scholz/ewade/2007/EWADE2007_Ross.pdf
 

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Motocar

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Cutaway drawing Rockwell/MBB X-31, author Mike Badrocke and published in the magazine Combat Aircarft
 

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ScrutorAudax

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Hesham, are the nodes on each side of the aircraft depicted in Fig. 17 (MBB-VFW 3.png) for translational thrust in post-stall maneuvers?
 

hesham

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ScrutorAudax said:
Hesham, are the nodes on each side of the aircraft depicted in Fig. 17 (MBB-VFW 3.png) for translational thrust in post-stall maneuvers?
Hi Scrutor,

to be honest,I don't know,maybe someone can help.
 

hesham

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Later Rockwell artist's concept of SNAKE - almost X-31 configuration already
From L+K 3/1988,it's first time for me to know it was called EFM,Enhaced Fighter Maneuverability.

.
 

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Apophenia

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From L+K 3/1988,it's first time for me to know it was called EFM,Enhaced Fighter Maneuverability.
The joint US-German research project was called the Enhanced Fighter Maneuverability program so the X-31 prototypes became the 'EFM demonstrators'.
 
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