In article ,
"Vello Kala" writes:
Aircraft Speed Altitude Mach Number
SR-71 Blackbird 2,275 mph
(3,660 km/h) 80,000 ft
(24,385 m) Mach 3.35
MiG-25 2,110 mph
(3,390 km/h) 42,650 ft
(13,000 m) Mach 3.2

Standard Admonition - beware of the data. Context is everything, and
there's not enough there.



This data is from Aerospaceweb. Question: SR-71 looks like alien plane, have
very special design (incl tanks what start to keep fuel on flight only)etc
etc. Mig-25 looks as pretty usual plane. But difference in speeds is
relative minor, expecially if to look at what altitude it is reached. How it
is possible? Do anybody have more data? Say, about SR-71 performance at 40
000 feet?

SR-71's don;t fool around at a mere 40,000'. The purpose of the SR-71
is to carry a set of reconnaisance sensors at Mach 3+ at 80,000+ ft
(Mostly plus) for several hours. (Acturally, take off, top up from a
tanker, cruise out a Mach 3+/80K+ for a couple hours, hit another
tanker, Mach 3+ for another couple hours, all the way to wherever and
back. (Oh, yeah, all while having a radar signature equivalent to a
glider) Prepping an SR-71 for flight takes hours. It has a lot of
exotic materials and systems, and is more akin to a spaceship than a
normal airplane. I requires special fuels special lubricants and
hydraulic fluids, and weird stuff like TriEthyl Borane to keep the
fires lit. It flies in a delicate balance of shockwaves, all expertly
positioned to provide balanced flight and peak performance.

A MiG-25 is a bomber interceptor (Although it did find secondary roles
as a recon airplane and a bomber). It's intended to sit at the end of
a runway, make a scramble takeoff, and roar straight at an incoming
B-58, guided by a data link from its GCI (Ground Control Intercept)
site, and shooting the bomber in the face with large Air-to-Air
missiles, and return directly to its base.

(Many accounts claim that the MiG-25 was intended to intercept B-70s,
the Mach 3 Bomber that North American built in the late 1950s adn
early 1960s, and which never went into service. I, quite frankly,
doubt it, Even with the B-70's huge radar signature, its closing
speeds would be so fast that a minor course change by the bomber
wouldn't be able to be countered by the MiG, (Or if the B-70 wasn't
kind enough to fly straight at the MiG's base) and the MiG didn't
have any speed advantage in the almost inevitable tail chase that
would result. It does, however, have the perfect performance envelope
for taking on a Mach 2, 60,000' airplane like a B-58.)
The MiG was intended to be flown by normal service pilots, use normal
fuels and systems, and be maintained by 20 year old conscripts in
Siberia. Making an airplane that can do all those things wasn't a
trivial acheivement.

Another way to look at it is that the MiG-25 has pretty much the
ultimate perforance that can be acheived with a normal shape, and
fairly normal materials. (Stainless Steel, for the most part)
If you're going to go faster and higher, you need to start making
exotic airplanes like the SR-71.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster