Aircraft missile R-27 (K-27)

In accordance with the decision of the CPSU Central Committee and the USSR Council of Ministers dated 26th June 1974, development work on the fourth generation fighters - the future MiG-29 and Su-27 - was launched.

In the same year, Vympel Design Bureau prepared technical proposals for a new K-27 missile (product 470) designed to arm these promising aircraft. The development of the K-27 was entrusted to a team headed by A.L. Lyapin; the design was led by P.P. Dementiev and V.T. Korsakov.

The prospect of simultaneous development of two fighters of almost identical purpose as early as at the stage of the technical proposal in 1974 prompted a fundamental decision to create a system of unified missiles: K-27A for the light MiG-29 and K-27B for the heavy Su-27. It was assumed that the missile versions would differ in terms of propulsion systems and, accordingly, launch range. On the basis of established practice, it was considered appropriate to provide for each version of the missile with different propulsion systems, with a "radius" and "thermal" CNS. This was the definition of the concept of a "modular" missile with variable COS and propulsion systems.

It seemed very tempting to achieve interchangeability of propulsion systems by eliminating cable and gas connections of control equipment and gas generator in the central unit with the tail of the missile. However, the adopted scheme "duck" traditionally associated with the need to place in the tail of the steering machines drive aileron control. The fact that the front position of the rudders their deflection generates a bevel of air flow affecting the wings installed in the tail in such a way that a certain combination of angles of deflection of rudders, angles of attack and sliding, the phenomenon of reverse control on the roll - the moment from the aerodynamic forces on the wings acts in the direction opposite to the moment from the forces on the steering wheel, and exceeds it. Therefore, on almost all missiles made by the scheme of "duck", the rudders serve only to control the pitch and yaw, and on the channel of the roll are used either stabilizing ailerons or rollers, limiting the speed of rotation of the rocket on the roll.

Vimpel's designers managed to provide control of the rocket through all channels with differentiated deflection of the rudders, abandoning ailerons. For this purpose the K-27 used uniquely shaped butterfly wheels.  The adopted scheme was not unanimously approved. Thus, according to specialists of NII-2 (now GosNIIAS), the conditions of application of K-27 more corresponded to the "normal" scheme with the placement of the rudder to control the rocket in its tail part. In this case the resistance was reduced at small angles of attack and the aerodynamic quality was increased. However, the normal scheme required the control elements to be separated between the nose and tail sections of the missile, which violated the modular design principle. Unification of the missile's tail compartments with engines of different diameters was also called into question. That is why Vimpel's designers also worked out a "normal" scheme, but, relying on the support of TsAGI, kept the scheme chosen by them - something intermediate between the "duck" and "rotary wing".

Fundamentally new technical solutions were also used in the missile's onboard equipment. In the implementation of conventional semi-active CNS on promising Soviet missiles could not achieve superiority over the "Sperrow" AIM-7M, as domestic aircraft radars and CNS missiles were inferior to the U.S. counterparts on the backlighting potential and sensitivity of the receiver.  Therefore, in the course of development for missiles with radar GSN specialists NIIP based on the results of research adopted a combined scheme of operation with the ability to capture the target on the trajectory. It should be noted that the "Sperrow" used a more primitive technical solution: not even a simple inertial control without correction by radio, adopted on the R-24, and the starting, so-called "English" correction, similar to the scheme implemented in the R-23.

The final version was determined in 1976, when the sketch design was issued, reflecting the requirements of the decrees of January 19, 1975, which specified the requirements for MiG-29 and Su-27 respectively. The deadlines for submitting missiles for state testing were also set: 1978 for K-27 on the MiG-29 and 1979 for K-27E on the Su-27. The issue of equipping K-27 with MiG-23 aircraft was also studied. The next year, 1977, was marked by the first flights of the MiG-29 and Su-27 prototypes along with protection of the conceptual design, as well as by the start of full-scale testing of the missiles - two launches of ballistic "products 472" from a ground-based launcher.

The initial testing of the Rubin radar and missile homing heads was conducted at the LL-124 flying laboratory, created on the basis of the Tu-124. At the initial, autonomous flight testing stage, four ballistic and two program missiles were launched in early 1979 with the MiG-21 bis ¹ 116. A little later in the same year, and the first launches of six program and two telemetry K-27 with the modified MiG-23ML number 123. At the same time, two program and three telemetry launches of K-27E with Su-15T ¹02-06 (the so-called LL 10-10, more than MiG-23, adapted for the heavy version of the missile) were performed.

In accordance with the decision of the military-industrial complex of January 31, 1979, the issues of using radiocorrection on the inertial flight section of K-27 were considered. Design studies were also conducted to determine the possibility of a significant relief of the K-27 missile, but in those years they did not yield positive results for the "radium" version. TORs were developed for the lightweight thermal variant, but due to significant disaggregation with the rest of K-27 modifications, this direction was not developed.

The following year, the volume of flight tests increased many times. MiG-23ML was used to launch 22 program missiles, as well as six missiles with thermal GSN on parachute targets and La-17. Another 14 heat-seeking missiles were launched on similar targets with LL 10-10 (Su-15T), having completed rocket tests on this flying laboratory in 1980. State testing of the thermal version of the rocket began in May 1980. on the third pilot, not yet equipped with radar, MiG-29 number 902 (aka 912/3). This lack of equipment did not prevent the testing of the missile with a thermal CNS.

In 1981, autonomous launches from the flying laboratory of the MiG-23ML began the factory phase of testing the "radium" rocket. Later tests were carried out on the MiG-29 ¹ 918 - the first complete radar, from which the first shot down an air target. However, the radar overflights brought an unpleasant surprise. It turned out that with the installation on the MiG-29 its detection range turned out to be almost a third less than the specified one.

The design and development of the "radium" missile with a catapult version of the launcher AKU-470, as well as field development of AKU-470 in ground conditions. Thermal version of the missile continued to be tested: nearly four dozen launches of software and telemetry missiles, including La-17, were conducted. The first thermal launches of La-17 missiles were also made from the Su-27 prototype, the T-10-4 aircraft.

The following year, 24 more missiles of various configurations were launched, including three combat missiles, completing the first stage of state trials on the MiG-29. In 1983, it was mainly possible to carry out the second stage programme on both MiG-29 (launches were made from aircraft No 902, 919 and 920) and the Su-27. In 1983, another 39 launches of K-27 and 66 of K-27E were made. In addition, a special programme on the MiG-29 No 921 examined the engine stability during rocket launches. The state tests were completed in 1984. Both versions of the K-27 rocket were adopted for service in 1987 under the designation of R-27R and R-27T.

The large volume of tests of the K-27 family of missiles, in addition to the novelty of the problems solved, was determined by the fact that the MiG-29 and Su-27 carried different radio electronic systems with different mathematical support. The correctness of the algorithms had to be verified by actual use of the missiles, which increased the testing volume by dozens of launches.

It is well known that already after the start of testing the T-10 (the Su-27 prototype), it was decided to make major changes to the design, actually corresponding to the development of the aircraft almost all over again. In particular, the main decisions on the onboard radar were radically revised as well. The new versions of the K-27 were developed by MiG-29 (No 920) from June to September 1984.

Testing of the K-27E rocket was somewhat delayed and accompanied by the introduction of modifications to the CNS, inertial system, radio command line equipment. Only in 1990 the missile was adopted for service in the versions of R-27ER and R-27ET. Production was launched at the Artem Plant in Kiev.

In general, the developed missile armament had an advantage over the Sperrow AIM-7F in terms of launch range, achieved through the implementation of inertial guidance area. The modular principle of building a family of missiles allowed to create modifications of missiles with enhanced energy capabilities, in the reach of approaching modern long-range missiles and have high efficiency in combat at medium and short distances due to the high average speed of flight. The creators of the missiles were awarded the State Prize in 1991.

Export versions of R-27R-1 and R-27T-1 missiles were produced in connection with deliveries abroad of MiG-29A from 1988 and MiG-29B from 1986, while R-27ER-1 and R-27ET-1 were produced in connection with deliveries abroad of Su-27 in the 1990s.

It is envisaged that R-27 family rockets will also be used on earlier models of second and third generation fighters after their comprehensive upgrade, in particular, on the MiG-21-93 project.

In addition to the four main versions of R-27ER missiles, a K-27P missile with a passive homing head was also created. The work began under the decision of the MIC of August 18, 1982. Even earlier in the Omsk Central Design Bureau (former Design Bureau-373), the team led by G. Bronstein designed the GSN, and in 1981 there was a draft design. Preliminary tests were conducted in 1984-1985 mainly on MiG-29 ¹970 and 971. The tests were completed with a positive result in 1986, with recommendations for the adoption and serial production. Tests of the K-27EP as part of the Su-27 weaponry were conducted from 1986 on aircraft No 10-21, 10-22, 10-23, 10-31, 10-32 and were completed in 1989. The missile was not offered to the foreign market for a long time, but in 2004 it was demonstrated at the Fidae-2004 exhibition.

A number of aircraft showrooms presented materials on the variant of the R-27EA missile with a combined guidance system. This variant uses CSS ARGS-27 - inertial, with radiocorrection and active radar self-direction at the end site, which ensures the principle of "shot and forgotten". Deployment of full-scale development works on this option began by the decision of the MIC of July 19, 1982. The draft design of the active CLO was released back in 1981. The most difficult task for its designers - employees of A.M. Sukhov's laboratory at the Agat Research Institute - was the creation of a small-size transmitting device with a power of 30-60 W with a multi-beam klystron as a vacuum output device.

The conceptual design for the R-27EA missile as a whole was completed in 1983. In 1984, for the application of K-27A were prepared MiG-29 ¹919, the next year - ¹ 925, but later these machines were used for more priority work - testing a promising missile RVV-AE. In fact, flight tests of K-27A were conducted on MiG-29 ¹ 970 and 971. In 1985 they performed three launches, the next year - five.

In the ARGS-27 it was planned to use Alice onboard digital computer on 588 series chips, but its development was so difficult that the use of other types of calculators began to be considered. Time was wasted, and in 1988-1989, due to reduced funding, research on the ARGS-27 was practically suspended in order to continue the work on CLO for the RVV-AE rocket. Nevertheless, the work in this area was continued by the Agat Research Institute on a proactive basis. As a result, it was possible to reduce the weight of this modification of the COS one and a half times - from 21.5 to 14.5 kg, as well as to increase the range of capture.

On the whole, the development of the K-27 family of missiles made it possible to implement to the fullest extent the principle of unification both for the armament of the "heavy" and "light" class fighters and for the creation of the most important elements of the missile, unified for the variants with different range and targeting principles. V.G. Karaskov, A.L. Reidel, P.P. Vasiliev, A.B. Prigornikir made a great contribution to the development of the rocket on Vimpel.

Abroad, this missile was named AA-10 Alamo.