An F22 has a higher thrust to weight ratio. The F22 has around ~70,000lbf thrust from its F119 engines, where as the F15 has around ~48,000lbf thrust from its F100 engines.

But every metric I can find indicates that the top speed of the F15 is higher than the top speed of the F22 (though I have not found a concrete reliable source on either).

How is this the case?

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    $\begingroup$ With stealth, the goal is to shoot before the other plane realizes you are there. If you actually get into a dog fight, you've already made several mistakes. $\endgroup$ – zeta-band Sep 19 '19 at 20:22
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    $\begingroup$ I am aware of this fact and not sure how it at all relates to the question of speed. $\endgroup$ – ScottF Sep 19 '19 at 20:23

Aerodynamic heating will damage or destroy the composite wing of the F-22, especially around the leading edge where compression heating is highest. See here for the temperatures which supersonic flight causes.

Therefore, the F-22 has been restricted to Mach 1.8 for short duration and Mach 1.6 for prolonged flight. More speed will not be needed, anyway.

The internal weapons storage of the F-22 makes it bulkier than the F-15 which causes more wave drag. Also, the engine intakes were not designed to operate at speeds above Mach 2, so pressure recovery in them drops at higher speed. These two factors will affect the top speed of the F-22 negatively, so I would not be surprised if the F-15 is faster even without restrictions on the F-22 speed.

  • $\begingroup$ If I understand correctly, wave drag is the direct answer to the question. The first part (no need to go faster) explains why 70.000 lbf is sufficient $\endgroup$ – MSalters Sep 20 '19 at 11:56
  • $\begingroup$ @MSalters: I have no drag polars of both, but argue from first principles. I think that the intakes have even more to do with the lower speed. And temperature is still an issue. $\endgroup$ – Peter Kämpf Sep 20 '19 at 12:39
  • $\begingroup$ Is the plane hard limited to mach 1.8, or could a pilot override that in certain scenarios? $\endgroup$ – ScottF Sep 20 '19 at 15:11
  • $\begingroup$ @ScottF: Hard limiting the top speed of an aircraft is impossible. Even if the engines are automatically cut to idle, a simple dive lets it accelerate again. Therefore, an override is possible. $\endgroup$ – Peter Kämpf Sep 21 '19 at 22:51

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