Blackbird v. Mig-25

Vello Kala wrote:

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


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?


I don't think that comparing MiG-25 to SR-71 is entirely inappropriate,
considering that the Blackbird was one of MiG-25's primary targets and
both aircraft were designed for high-speed, high-altitude recon roles.
MiG-25 was designed as an interceptor and in this role it has
outstanding performance. MiG-25 can be compared to SR-71 in terms of
performance needed to intercept the Blackbird. MiG-25 certainly had the
right performance for that. MiG-25 was also designed as a recon plane
and in this role it can also be directly compared to the SR-71.

And some comments about the comments in this thread. MiG-25 is not made
of stainless steel but of nickel steel alloy similar in composition to
the nickel alloy used for X-15. The Valkyrie, on the other hand, was
made of predominantly stainless steel.

Operational requirements for MiG-25 differed drastically from those of
SR-71. MiG-25 was designed to operate as any other Soviet fighter
aircraft without any specialized facilities. This was also a factor in
the choice of airframe design and construction materials. Nickel steel
alloy used in MiG-25 construction does not carry a strength penalty when
compared to titanium. MiG-25 was build to have an exceptionally strong
airframe. One must not forget that MiG-25 had to meet a substantially
higher level of airframe stress requirements than SR-71.

MiG-25 was a mass-produced combat aircraft (a total of 1,186 were
manufactured), while the total production run of the entire
A-12/YF-12/SR-71 line was only 49 aircraft or so.

Design of the MiG-25 started in 1959 as the Ye-155P
(http://www.aeronautics.ru/mikoyan/mig25_31/page_10.htm) multi role
interceptor. The Ye-155P was not being developed specifically to counter
the A-11/A-12, although the Soviets knew about this project and about
its performance requirements. Intercepting low-flying cruise missiles,
for example, was one of the roles for the Ye-155P from the very
beginning. At the time the Soviets were concerned with the US and
British advances in cruise missile development - Regulus, Rascal, Blue
Steel, all of which had Mach 2++ capability.

The late 1950s and the early 1960s was a time of particular Soviet
obsession with heavy interceptors. During this period USSR produced
several aircraft of this type, including La-250, I-75, Ye-150/152,
Tu-128. Various Russian publications indicate that the Soviets learned
about the A-11 project sometime in the summer of 1960. The Ye-155
project got its official Central Committee go-ahead in 1961, so it seems
like there is a clear link between the two aircraft but there isn't one.

Soviets learned about the A-11 in 1960, while the work on the Ye-155
concept begun in 1959. In any case, even in 1960 Soviets had only a
rough idea of the expected performance of A-11/12, which, at best, was
one of the reasons for the Ye-155's expeditious approval by the Central
Committee in 1961 but not for the aircraft's concept. The B-58 became
operational, the XB-70 was in development, the A-5 flew in 1958 and it
is believed that Mikoyan was particularly impressed by this aircraft. In
other words, there were plenty of real threats justifying the
development of the Ye-155 other than the A-12, which in 1959 existed
only in the form of a diverse collection of wind tunnel models.

I read Belyakov's book, where he mentions Soviet knowledge of the A-11
program. However, the immediate question in my mind was: why would it
appear so critical of a threat to the Soviets to prompt a massive
development effort of an advanced interceptor as Ye-155? The Soviets
became aware of the Suntan project prior to the A-11. They were aware of
the Valkyrie. The Ye-155 itself seems closer in design to the A-5 than
to A-11. At that time the PVO wanted an interceptor, while the VVS
desired a new recon plane. The very fact that a decision was made to
combine these two requirements in a single aircraft clearly shows that
the Ye-155 could not have been created to counter specifically the A-11.


--
Regards,

Venik

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