N231YE
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Why Did The Sikorsky S-72 "X-Wing" Fail?

Wed Jul 04, 2007 1:14 am

Hello,

I was wondering why the Sikorsky S-72 "X-wing" failed. From the description of this aircraft, it seemed as if it had a promising future with the Army and NASA, then possibly on to civilian versions. It was a hybrid helicopter/aircraft, that could take off vertically, but could shut down its rotors in flight, and had the speed of a jet aircraft. However, the aircraft never made it, and was Withdrawn from use in the early 90s:



 
dl021
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RE: Why Did The Sikorsky S-72 "X-Wing" Fail?

Wed Jul 04, 2007 1:51 am

Money, feasibility with current technology and lack of interest from high enough up.

The thing was a little ahead of it's time, but they got some good info from the program. It'll come again sometime.
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Lemurs
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RE: Why Did The Sikorsky S-72 "X-Wing" Fail?

Wed Jul 04, 2007 3:26 am

Probably a fair amount of lobbying from the Osprey crowd of the "Special Interest" machine that is the defense industry, too. Too similar, too cheap, too threatening to the cash-rich money pit that the V-22 promised it could be...
There are 10 kinds of people in the world; those who understand binary, and those that don't.
 
bhmbaglock
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RE: Why Did The Sikorsky S-72 "X-Wing" Fail?

Wed Jul 04, 2007 7:13 am

Quoting N231YE (Thread starter):
Probably a fair amount of lobbying from the Osprey crowd of the "Special Interest" machine that is the defense industry, too. Too similar, too cheap, too threatening to the cash-rich money pit that the V-22 promised it could be...

Probably no connection whatsoever. The X wing was a basic research aircraft that was cancelled right about the time the V-22 hit FSD; maybe even a year or two earlier. Notably, it did not ever attempt a conversion between flight modes. I'm not even sure that it ever flew with power to the rotors for that matter.

Also, since the X wing money was coming from NASA vs primarily USMC for V-22 it's even more doubtful. PX Kelly and his predecessor were powerful and influential but I don't think their reach extended to NASA by any means. It certainly wasn't because Dick Cheney was a big fan of the V-22 either.

Beyond this, the X wing technology had not even been demonstrated, much less matured at this time; even now two decades later the aerodynamics required have not been demonstrated in practice. In contrast, the tilt-rotor concept had been studied extensively and successfully over the better part of two decades with the XV-3 and XV-15. Boeing had also demonstrated use of a composite rotorcraft airframe with the Model 360 and was at the time at least 5-10 years ahead of Sikorsky in rotor blade technology.

Another important factor to consider is the CH-53. Remember, the V-22 began just a few years after the Desert One debacle and at the time promised to eliminate some very big problems in Marine aviation exemplified by what happened during the failed hostage rescue attempt. Sikorsky could have proposed a larger X wing but this would have magnified the technical risk even more; it would also have been an implicit admission that the CH-53 wasn't up to this type of mission. The reality is that they reasonably did not attempt this and instead pursued(unsuccessfully) the X wing as a funded research project and improved versions of the CH-53(very successfully).

Unfortunately a combination of over ambitious requirements, poor program management, schizoid funding, and serious problems from unexpected areas like hydraulics put it about a decade and a half behind where it was originally expected and obviously much over the original budget.

One good thing you can say for the X wing was that it looked really cool on the cover of Popular Science as a painting.
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aeroweanie
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RE: Why Did The Sikorsky S-72 "X-Wing" Fail?

Wed Jul 04, 2007 7:26 am

I worked on X-wing. From the very beginning, it was apparent to me that they were pouring tons of money into a concept only supported by wishful thinking. After seeing this, I avoided the project like the plague.

The original funding came from DARPA and it was pushed by Bob Williams, who later pushed another wishful thinking project - NASP.

The conversion of the RSRA to carry X-wing never flew and was a waste of a perfectly good airframe.
 
CTR
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RE: Why Did The Sikorsky S-72 "X-Wing" Fail?

Wed Jul 04, 2007 8:07 am

Quoting BHMBAGLOCK (Reply 3):
Probably no connection whatsoever. The X wing was a basic research aircraft that was cancelled right about the time the V-22 hit FSD;



Quoting Aeroweanie (Reply 4):
worked on X-wing. From the very beginning, it was apparent to me that they were pouring tons of money into a concept only supported by wishful thinking.

Thank you BHMBAGLOCK and Aeroweanie for concise technical replies. Some days it seems that there are more conspiracy theories revolving around the V-22 Osprey than the JFK assassination.

Wait! The V-22 is built in Texas and JFK was shot in Texas! Just a coincidence? I think not.

Have fun,

CTR
Aircraft design is just one big compromise,,,
 
N231YE
Topic Author
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RE: Why Did The Sikorsky S-72 "X-Wing" Fail?

Wed Jul 04, 2007 9:25 am

Interesting...I forgot about the fact that the V-22 was in the works at the same time, thus, common sense would say that the better of the conflicting programs wins.

Anyways, thanks for the responses.

N231YE
 
aeroweanie
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RE: Why Did The Sikorsky S-72 "X-Wing" Fail?

Wed Jul 04, 2007 9:55 am

Gee, I saw "X-wing" and the flash of bad memories led me to miss the other comments.

The JVX program, that led to the V-22, came to life in 1982. Lockheed actually started X-wing in the mid-1970s, but bailed and DARPA convinced Sikorsky to pick it up in the late 1970s. X-wing died in the late 1980s. X-wing's demise was unrelated to JVX and the V-22. During the Reagan/Bush I years, military development money flowed very freely, so the two programs didn't compete for funds.

Sikorsky contemplated bidding on JVX and for one short period (a day or two) had an agreement to partner with Rockwell Columbus. This all fell apart and only Bell-Boeing bid on the program.
 

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