Originally Posted by
noneofyourbusiness
Commando Cody
Tiltrotor wins on speed and range, which is what the Army wanted. So why did Sikorsky bid what was likely to be a losing design? People rightfully questioned whether the X2 could be scaled up to a larger size. Defiant proved the answer is yes.
You are right regarding engines, the Honeywell engine on Defiant was going to be scaled up to provide 7500 hp each compared to the demonstrator 5000 hp, giving a total of 15000 hp, which would provide more lift. Given larger engines and more time, hitting 260 knots, matching the X2, seems plausible. Though fuel burn rate might be very high.
Raider is intriguing regarding its low max speed, it had plenty of engine. Maybe Boeing or Sikorsky figured out how to solve the problem for Defiant? But I don't see how they would have been able to significantly improve aerodynamics. So maybe improving vibration control was the solution?
To my mind Sikorsky was hoping the problems that had plagued X2 so far could be worked out and at a lower cost than a Tilt-Rotor. They may also have felt that if performance of the two competitors was close, Army's familiarity with them plus their political influence would pull them through. Keep in mind X2 was all they had and they had spent some significant money on it over the years. I don't think it can be said that Defiant proved X2 technology could be scaled up to this size. At best it would have to be a profound, "Maybe".
You know, one of Sikorsky's complaints in filing the protest was their claim that Army had always wanted a Tilt-Rotor and this was reflected in their original requirements which they said were later changed, to allow others to compete. I take this to be referring to the original anticipated speed requirement of 250 knots which in the final specs was lowered to 235 knots. Given that Sikorsky said that on Defiant they had lots more power they hadn't yet used, I don't believe more power would have gotten them any more speed or they would have claimed that. . The X2 demonstrator briefly hit 260 knots, but was grounded after that. I think that like Bell, it was the hot and high HOGE requirement that drove ultimate power required.
Vibration control undoubtedly would have been a big factor in higher speeds, but with what we've seen so far is it fair to say that the problem was solved? They came up short in a number of other areas as well.