During flight test the clean E with PW-229s easily cruised above M 1.0 at
mil,
whether accelerating up to it or decelerating down to it. It is not
likely the
fully loaded E can do this.

By clean, do you mean w/o conformal tanks? By easily cruised, do you mean
accelerated through mach w/o resorting to A/B? Is this based on personal
experience?

I have little doubt the clean F-15E can sustain 1.2 give-or-take in mil ...
but the acceleration through transonic might be a problem. By the same
token, the F-14B/D's can also supercruise, but they need A/B to get there
first.

The difficulty is handling the transonic drag rise, largely a function of
the design drag characteristics of the jet. Low aspect ratio, area-ruled,
thin-winged aircraft tend to do best (think F-104, Mig-23). Drag rises
sharply starting around .92 or so and peaks around 1.1-1.2. Most aircraft
run into a wall here (particularly at military thrust) and the difference in
speeds attained is remarkably little (I found the F-8 to be a wee bit faster
in military than the F-4, but I never flew the older and cleaner Phantoms
.... the F-4H1 was reputedly good for 1.04 or so, similar to F-104). And
recent designs have generally abandoned minimum-drag configurations to
attain other, more useful, characteristics.

A/C top speeds are illusory ... sometimes I think they're based more on what
comes from marketing than engineering. The F-14 was attributed with 2.34
(it attained 2.41 ONCE in flight test and was artificially limited to 1.88
in the fleet ... though it got there easily enough). The F-18 has a 1.8
claim ... I know NO ONE who's seen close to that (so maybe once in flight
test?). The F-15 is always attributed with 2.5/1650mph ... again maybe once
in flight test? (The PsubS curves I've seen would suggest otherwise, and
perhaps nobody told them about what happens to plexiglas at those speeds.)
Of course when you hang some ordnance, drag goes up and speed goes down ...
sometimes dramatically.

If one restricts the argument to military thrust only, top speed ranges from
..92 or so (low thrust or high drag limited) to maybe 1.04. Not much of a
difference if you're trying to outrun an AIM-120.

R / John