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Old October 11th 03, 09:30 PM
John Carrier
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The lowered top speed wasn't primarily due to the blowout but due to
operational longevity. Most of today's US aircraft detuned engine wise
to save the taxpayer's money. When I last spoke to a RIO and on one
occasion he told me that he told his pilot to back off the throttle
as they we already over Mach 2.x. I guess they both weren't paying
attention to speed. This was sometime last year. The operational top
speed can be surpassed.


I flew the jet for a number of years. The airspeed limit (780 NATOPS, 850
manufacturer) was to preserve the airframe against possible flutter damage.
The mach limit was not. Until you exceed engine compressor temp limits
(sometimes an issue at 2+ mach) or heating limits on the airframe/canopy
(well above 2.0), IMN is generally not an issue ... sometimes it does
concern stability (ie: X-2 departure/crash following speed record run). So
unless your RIO friend was involved in the program with Grumman or had a
seat at Pax River, I wouldn't put much faith in his
statement. Most RIO's I knew, even the good ones, knew vary little about
the
aerodynamic capabilities of the jets they rode in.

BTW, the F15's has got a cap as well. IIRC, it's M1.81. Of course, the
aircraft can fly past this.


I wouldn't doubt it. Wonder what Streak Eagle did prior to its highest TTC
record.

In fact, in a past Red Flag a F15 has a hard time intercepting a RAAF
F111 in which the F15 ran out of gas.


Low altitude. The Vark is very very fast down low.

The overall acceleration numbers between the F15 and the F14B/D are
identical that's if the F14's wings are positioned at Auto. The F14A
was only a second behind. If the wings were set the manual and fully
aft, the F14B/D would be a great deal faster.


The wing program was based on best cruise. I don't think the auto program
would have a material overall impact on 1-G acceleration, but initially full
sweep was somewhat disadvantageous. Unloaded, it was beneficial to sweep
the wings manually.

Due the aerodynamics of
the F14, it's overall drag profile (CDp) (LE 45 deg for the F15 and 68
deg for the F14) is lower than the F15's thus a lower thrust
requirement to reach top speed. Which btw, during F14 testing, once
the aircraft hit the top speed requirement, they backed off the
throttles. Top speeds are only great for any aircraft when the
aircraft is clean with no pylons.


Very true. Ordnance invariably adds drag and the manuals indicate same.

I do recall a post from an USAF crew chief at Nellis that the F15 did
hit M2.5.


Quite possible when new and the engines were low time and had not been
downtrimmed for service life considerations.

If you were to compare the aircraft at the transonic regime and do a
drag race from M0.9 to Mach 1.8 or whatever speed, you'll see that the
F14 will get there quicker.


I wouldn't be surprised, the B/D acceleration to 1.6 is most impressive.

SEP for both the F14B/D and F15 are identical in the transonic regime.

Nevertheless, another RIO, Chunx, posted at a forum and said in the
90's that the F14B/D was known as the "world's fastest aircraft". I
guess that was due to the ability to unload and change the aero
profile and extend quickly from a fight thus dictating it. He doesn't
know if the latest F16 blocks with the newer engines out accelerate
the F14B/D when the wings are fully aft. So things may have changed.
Hoever, from what I read from F14 drivers, F18 drivers have a hard
time intercepting it.


Fastest in indicated airspeed, maybe close. The Grumman limit was 850KIAS
and I know people who have gotten it there. I've had the aircraft up to 750
with canoes. OTOH, the Thud was scary fast too (easy 800) and the Vark,
particularly the F (IIRC ... the high output engines) was supposedly good
for over 900. The Mig-29 was the quickest aircraft through transonic ...
left everything in the US inventory in the dust during drag races. OBTW,
the F-18 in all versions is notoriously slow. The aircraft is alleged to
make 1.8IMN, but I know NO ONE who's gotten particularly close (1.6 is about
it with a clean jet). In Q, 700KIAS is about it for the Bug ... less for
the E/F.

There is a difference between top end in Mach (at altitudes above the
tropopause) and KIAS. The SR-71 can cruise at 3.2, but at 82,000' that's
really not a very high IAS ... many aircraft could outrun it if you limit
the altitude to say 10,000' or less. In the most extreme example, the
Shuttle is a hypersonic vehicle, but has a relatively low Q-limit (600KIAS
or so).

R / John