"Scott Ferrin" wrote in message
...

The F-119 engined F-22 has fixed inlets and is not especially fast.

What makes you think fixed inlets make a difference?

At high mach, the air bounces several successive shock waves off the
inlet, in the process of dropping the airspeed and increasing the air
pressure.

Airplanes such as the F4 Phantom, the Tomcat, F-15, Mig-25 and Mig-31
(among others) have variable inlets specifically so the inlet can be
tuned to the speed for most efficient operation. The SR-71 had a
spike arrangement in front of the engine that performed as a variable
inlet.

Airplanes such as the F-16 and F-22 use fixed inlets, and have lower
top speeds (according to Janes). Fixed inlets are used either to
reduce costs, or (in the case of the F-22) to improve stealth
caracteristics. Variable inlets aren't very stealthy.