R-33 (missile)

The Vympel R-33 (Вымпел Р-33, NATO reporting name: AA-9 Amos) is a long-range air-to-air missile developed by the Soviet Union. It is the primary armament of the MiG-31 interceptor, intended to attack large high-speed targets such as the SR-71 Blackbird, the B-1 Lancer bomber, and the B-52 Stratofortress.

Generally similar to the U.S. Navy's retired AIM-54 Phoenix, it uses a combination of semi-active radar homing for initial acquisition and mid-course updates, and inertial navigation to reach the target at extreme range. The Zaslon phased array radar of MiG-31 allows four missiles to be guided simultaneously at separate targets.

The R-33 AAM remains in service with the CIS and Russian forces (See MiG-31 operators).

Development
The history of the R-33 missile is tightly bound to the story of its launcher, the MiG-31. The development of the modernized MiG-25, E-155MP, was authorized by a governmental decision of 24 May 1968. There was a competition for future missiles for the E-155MP. Izdeliye 410 by "Vympel" of A.L.Lyapin won, while the K-50 by PKPK of M.R.Bisnovat lost. The missile was assigned the development name K-33, continuing the series of K-13 and K-23 missiles. The development was headed by vice-chief designer V.V.Zhuravlev and leading designer Y.K.Zakharov.

The R-33/MiG-31 missile/interceptor combination is similar to the earlier Bisnovat R-40/MiG-25 combination, although it is much more versatile and modern in that the MiG-25 was very heavily specialized for the interception of large supersonic targets such as the North American Aviation XB-70 bomber, and as such lacks maneuverability and is not really suitable for air combat maneuvering. The MiG-31 is a much more versatile and capable aircraft and is still able to employ the older R-40.

Two prototypes were built in 1968 with "duck" scheme to fit an underwing carriage, similar to the Bisnovat R-40.

The draft project was completed in 1970 and conversion of flying labs was initiated. One of these labs was converted from an early MiG-25 (aircraft P-10) and was used in 1972 for autonomous test launches of the first K-33 from the upgraded APU-40 carriage. A MiG-21 (№76211524) was converted into the LL-21 flying lab to test the missile seekers, and Tu-104 №42324 was converted at into LL-104-518 (also known as LL-2) NTK "Vzlet" to test the "Zaslon" radar along with the homing heads mounted in missile mockups GVM-410.

The K-33 was evaluated with the RGS-33 SARH seeker and the TGS-33 IR seeker. Other candidates included an active radar homing and a dual IR/radar homing seeker. The final decision was made in favor of semi-active radar homing with inertial initial stage. The homing device, designated MFBU-410 was developed by B.I.Ermakov under the supervision of Akopyan.

The missile design was changed to allow use of a bigger seeker and to fit the missiles to the new under-fuselage carriage. The new design was started in the new draft project of 1972 (top wings folding, reduced wingspan (from 1100 mm to 900 mm), catapult launch only, enlarged warhead). One dummy, 5 programmed, and 8 trial missiles were built in 1972 for the new design.

Three of those 14 missiles were launched from the MiG-25P-10 in 1973. Different warhead types (high explosive fragmentation and continuous-rod warhead) were evaluated, and tests of the radar and seeker systems were conducted on the LL-2.

1974 saw 11 more launches from MiG-25P-10, 40 more trial missiles. The first AKU-33 launchers and B-410 warheads were built. MFBU-410/"Zaslon" tests were continued at Akhtubinsk using LL-2.

The first flight of the future MiG-31 (aircraft №831) was on 16 September 1975 (w/ 12 more flights by the end of the year). 20 more launches were performed from the MiG-25-P-10 before the aircraft was sent to the factory to upgrade its launchers.

The first telemetric missile launches from the LL-2 (Tu-104, which is the root of the legend of the "Tu-104 missile carrier" and the "Soviet armed civil aircraft") were performed that year.

Development continued in 1976, including launches at PRM-2 parachute targets in April of that year. The factory tests were completed in 1977 with 32 launches from the aircraft №832,  with the first launch against a MiG-17 drone on 26 March 1977). The guidance systems were improved during 1978, and the radar/missile combination performed a simultaneous launch at 4 targets in August of that year.

State trials started in March 1979 using MiG-31 №83210. They were successfully completed in 1980. A governmental decision from 6 May 1981 recommended R-33 into service.

R-37
A governmental decision of 8 April 1983 authorized the development of K-37 (izdeliye 610, upgraded version of R-33) for the MiG-31M. The first flight of MiG-31M №0151 was on 21 December 1985. The first launches of K-37 were performed from MiG-31M in 1988. The tests were continued up to 1997.

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