Tuesday, March 06, 2012

XFV-12 Mach V/STOL Epic Aircraft Flops

from http://www.aero-web.org/specs/rockwell/xfv-12a.htm
my comments

Interesting concept promised a pocket Phantom with M2 and sparrow missle capability plus V/STOL. Too bad a plane with more thrust than weight (30,000 lb with afterburner) could not lift itself off the ground. It did not even demonstrate a conventional takeoff / landing, although wind tunnel tests indicated it should have flown just fine, though the tiny outrigger "main" wheels look much too frail to withstand rolling takeoffs or landings. No wonder it make "worst airplanes ever" book list. Crazy venetian blind wings were even proposed for C-130 which would probably have worked even worse. F-35 may be first operational supersonic v/stol if they can work out technical kinks and costs.

Showing Tail thrust cap and deployed wing section
Tethered Flight Never Got off the Ground


The F401 engine is another example of a military program failure. The idea was to navalize the advanced F100 used on the F-15 Eagle to by increasing thrust to 28,000 lb to upgrade the F-14 Tomcat. But it was dropped for cost reasons in favor of keeping the troubled TF-30 used on the F-111. It was also chosen for the ill-fated XFV-12. It had an additional stage added to the F100. The latest F100 engines have 29,000 lb of thrust.

Some background on the technology of the engine which worked fine for the USAF F-15 and F-16:

F100/F401 Augmented Turbofan Engines - High Thrust-to-Weight Propulsion Systems

The mission requirements laid down in 1968 for advanced Air Force and Navy air superiority fighters dictated a quantum step forward in performance of their propulsion systems, particularly in terms of thrust-to-weight ratio and inlet-engine compatibility. Design features incorporated in the F100/F401 engines to meet the weight requirement include high aerodynamic stage loadings, a high temperature turbine with advanced cooling techniques, and a balanced beam exhaust nozzle concept which significantly reduces the weight of this component. Weight has also had a strong influence on selection and development of materials, metallurgical processes, and fabrication techniques. Inlet compatibility/stability considerations are addressed by fundamental aerodynamics, together with stability augmentation devices, such as variable camber inlet guide vanes, variable compressor geometry, and a fully modulated augmentor with smooth transition throughout the augmentation range.

Info on the engine  from 1974 Flight Magazine

F401 Augmented two-shaft turbofan. The F401 is under development, with only partial support by the USN, to power the Grumman F-14B 2x28,100lb A/B F401-PW-400 first flight of which took place in September last year. It seems unlikely that a production option on the engine will be exercised by the Navy Development of the F401 and F100 are the responsibilities of the USAF/  USN Joint Engine Project Oflice. The F401 has also been selected. for the Rockwell International XFV-12A shipboard. augmentor-wing V/Stol fighter 1x21,000lb F401-PW-400)  two demonstrator prototypes of which are being built under Navy contract. Initial flight of the XFV-12A is planned for the third quarter of this year. 

PW_F401_engine_for_XFV-12_fighter.JPG‎ (547 × 301 pixels, file size: 125 KB, MIME type: image/jpeg)

The configuration of the F401 is similar to that of the F100 except for an additional “booster” stage behind the fan.

Resin Model kit:


In the early 1970s there was a requirement put forth for the next generation VTOL fighter to replace the AV-8A Harrier that was then being developed for the RAF and USMC. The big difference was that this one was to be capable of supersonic speeds and operate from small ships. This meant a rather compact aircraft and new flying/lifting surfaces. A proof of technology aircraft was offered by Rockwell (formerly North American) that incorporated a 'thrust-augmented' wing.
This concept had the interest of the Navy and Rockwell was fully funded to provide one prototype, designated XFV-12. The aircraft was a mixture of bits and pieces from other planes as well as new sections. The nose was developed from an A-4, and the main fuselage from an F-4 Phantom, though it was a single engine aircraft. The use of a 30,000 lb thrust Pratt & Whitney F401 turbofan provided the needed power. Ducted air was run from the engine compressor stages to the tilting 'ejector flap' in the canard and main wings. This flap could rotate for vertical take off and then move to close the wing for normal flight. In 1978, the first hover rig test was undertaken without any success. Despite other attempts at redesigning the vertical lifting mechanisms, nothing seemed to work and in 1981 the Navy got tired of tossing money at it and cancelled the program without the aircraft ever achieving flight.

Other comments on site: 
 Elkhart, IN
My dad was on the design team that designed the XFV-12A aircraft for the Navy. He also helped to design the A-5A/RA-5C Vigilante and the OV-10 Bronco. I am just now beginning to see why he was so secretive at that time in his life. After the Columbus plant was closed, he moved down to Texas and helped on the design of both the XV-15 and the V-22 Osprey. On the V-22, he was able to bring back some plans for the engine nacelles. We lived about a mile or so from the Bell plant and always went out to look to see what V-22 was all about. He also made some trips out to the NAR California plant to help on some other aircraft of the time although I have not found out what, yet. I am thinking it was the XB-70 by a sample of the honeycomb he brought back. He also helped with some Boeing missiles but again, I do not know what. He passed away back in '06. I just added a couple new XFV-12A pictures.
06/26/2010 @ 17:02 [ref: 26731]
 Indianapolis, IN
A word about this aircraft, if u don't mind. Then you guys can go back to your psyco-babbling re-fighting of your versions of world history, ok? The father of a friend was a Navy aircraft tech first working with Douglas & then eventually Rockwell in what he called "a hands-on advisory capacity" at Muroc, among other places. He observed this plane as "never leaving the ground more than a few yards, spending most of it's time doing what appeared to be high-speed taxi tests and bouncing along down the tarmac the last few weeks I was assigned there." (his exact words, not mine). Hope all this helps some. a personal observation: As far as useless, I wouldn't say so- it probably was at least a catalyst for us forcing GB to let us steal the technology, so we could build it under license cheaper (like GE did in 1944 to Whipple).
03/02/2010 @ 20:32 [ref: 25808]
 Virgil H. Soule
 Frederick, MD
Does anyone know what happened to the prototype?
05/20/2008 @ 07:34 [ref: 20959]
 Tulsa, OK
The U.S. Navy cheated us taxpayers when it clampted down on the bad results of the XFV-12A. Other VTOL designers could have benefitted from the details of the XFV-12A failure. Instead, the U.S. Navy apparently put a black-out on the failure of the XFV-12A project. I could never find any technical papers about the XFV-12A.

This all happened in the 1970's. This was not the only project on which the Navy flim-flammed us taxpayers. That was all in the 1970's and 1980's. I trust that the Navy is more honest nowadays.

From a designer of carrier-based airplanes.
01/25/2008 @ 10:04 [ref: 19425]

No comments: