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TVC was not part of the ATF specification. The F-22 didn't HAVE to have it, LockMart put it in anyway to make it better. NorthGrum went for extra-stealthy and didn't.


Keep in mind that from what I've read BOTH planes satisfied the "plane" part of the ATF competition. The F-22 wasn't a "better" plane than the F-23 to any significant degree. Instead, LM won on the other parts of the competition.

In short, the USAF believed LM was more likely to deliver the F-22 as advertised, with the least troubles, and cost growth and so on. They had less confidence in NG's ability to execute the F-23 program to the same degree.


Actually, I think it safe to say that had NG been the one making the F-22 and LM the F-23 that in that case the F-23 would have won!


This is true as far as the TVC but the Air Force did weigh that into the evaluation formula in stating it would be a bonus. HOWEVER the winning engine from Pratt was designed from square one to have TVC. It was designed with the universal mounting sytem to allow it to be back fitted to F-15's in case the ATF was completely killed off. If one digs into the history of the F-15 it was designed to have TVC but the materials technology for the petals was not adequte to handle the flight loads at that time (1973). I was heavily involed with the ATF engine program at Pratt during the early 90's. Pratt by the way was able to deliver ahead of time the flight engines while Ge was late by several months delaying the whole fly off the airforce waited for them even though the F-22 and 23 Protypes with the Pratt engine were ready to go. The 23 flew first with PWA's and the F-22 First flew with the GE's the Airframe to fly first was chosen on a coin toss. And by allowing GE to fly the second airframe first was a bone thrown thier way. Their "Dual cycle" engine had real problems from square one. As far as IR signature went a lot of it was due to the PWA's exhaust temp being much lower then the GE's which had a lower bypass ratio due to the "Dual cycle" design which was intended to act as a turbo fan at takeoff and midsonic ranges and then switch to a turbojet cycle at high speeds were they are more efficent in theory then a turbofan.

Another thing that hurt the XF-23 was wingtip contrails. During fairly moderate G loads during a turn the inner wingtip would forma huge wingtip vortex contrail that magniifed the RCS. Plus was a big visual hint soemthing was there. As well the weapons bay was non functional as far as being able to mount and launch a weapon during the flight test program while not required the YF-22 had a fully functional weapons sytem on board and did launch both a sparrow and Sidewinder during the eval program. The YF-22 also had a fully functional aerial refueling system when flown and did tankoff from a KC-135 while the F-23 could only simulate this. Later the second PWA powered 23 's refuel sytem was succesfully tested during late eval flights.

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