[Kazuaki Shimazaki II]

Originally Posted by SUBMAN1

Regardless, you have an IR signature that is equal or lower than the F-117, and no IRST device can find that so far, so we know that they aren't going to find the F-22 either.

I have every confidence that thanks to baffling, masking, and that nice stuff (for the record, seems to make sense but got a URL?) down the bottom, they've suppressed the IR from the back (at least if the burner is off). What I'm concerned about is that in the age of front-seeking missiles, they can also home off various heat sources from the front (though less efficiently), and the F-22, in supercruising, will greatly increase those blots.

Maybe that's a concern, maybe it isn't (at least not yet), but are tests actually being done to verify this, and if the tests come out less than well, what to do on the day when the suppression ceases to work. After all, sensors are moving ahead faster and a easier upgrade than trying to squeeze out any more heat suppression.

On Supercruise, we know we are out of the transonic region Approximately (Mach 1 to Mach 1.4 - many older fighters can't even power out of this region) at a very fuel efficient Mach 1.5. At Mach 2, yeah, 400 nmi may be a reality since again you are just burning gas when going faster than this, but not back at Mach 1.5. We know one pilot pushed the jet faster than Mach 1.7 without using afterburner.

Yes, the test pilot. I'm actually taking that into account. The problem is that 20000 pounds of fuel will not give a SUBSONIC fighter a 1000NM radius.

One thing that makes this jet hard to find data on is that even the engines are classified - They say 35,000 lbs as a public number, but if it can out accelerate an F-15 without usning AB, how much real thrust is it actually making???

Actually, I'll bet that it actually does make 35000 pounds static on the ground (or 36000, or 34000). As a rule, gross mis-statement of physical performance specs does not work - the Navy tried that "over 20 knots" crap 4 decades ago and as far as I can tell it fooled no one. For one thing, operators leak. For another thing, engineering principles are known worldwide and gross lies are quickly exposed by engineering analysis.

The answer IMO is probably simple - the F-22 uses a fixed ramp and the F-15 uses a variable ramp (one thing I will say Riccioni definitely took little account of as far as I can see when he pointed the number out as a paper stat). On the ground, the F-22's engine is actually cannot be at the optimal setting if it is to be at the optimal setting in its planned high-alt supersonic regime of flight (in fact, fixed ramps optimized for subsonic operation generally max out around Metz's reported supercruise speed even with the A/B pushing - see the plummet in the Su-24's top speed when they decided to go for fixed ramps, even though the only other change is that the plane got a little lighter from eliminating the variable ramps!). So the bench test (which became a catalog spec) compared an optimally tuned F100 to a suboptimally tuned F119. At the altitude where the F-22 actually supercruises, the F119's fixed ramp is in its element and we are comparing two optimally tuned engines - with the F119's military power coming in as close to or better than the F100's A/B. Add the fact that chase planes are likely to be carrying some "hangers" like cameras (IIRC, the F-15 flanks out at Mach 2.5 clean but Mach 1.78 when carrying Sparrows), add the part where the F-22's aerodynamics no doubt have a greater bias towards the supersonic, and the chase result is a done deal.

Which is one of the reasons I'm actually inclined to believe the 400NM test number (including 100NM of supercruise) as broadly accurate (apparently the radius is 600NM in full subsonic). In a world where engines have reached a fairly high level of development, it runs suboptimally at the subsonic cruise mode (yet that must still be significantly more efficient than the supersonic flight mode or it won't be subsonic), while in the supersonic mode it is at optimal performance but nevertheless must put out more thrust than it does in subsonic.