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1948 - All-Weather Barrage Interceptor

The requirement for an all-weather interceptor was posed in 1948, when the commander of the Air Defense of the USSR Marshal L.A.Govorov suggested the development of a barrage interceptor. The idea of this airplane is not new, but if in the past two-engine fighter planes were designed primarily to accompany bombers, then in the second half of the 1940s, their task was to fight strategic aircraft of a probable enemy, as US aircraft launched bomber flights along the borders of the Soviet Union. But if in the south-west direction they were opposed by numerous regiments of fighter aviation, then the eastern and northern directions remained almost unguarded. In these conditions, three aircraft design bureaus, headed by P.O.Sukhoi, A.I. Mikoyan and S.M. Lavochkin, the design of interceptors with a large range and duration of flight began.

As is well known, the basis for the development of aircraft was, as a rule, a joint decision of the CPSU Central Committee and the Council of Ministers. But these documents only set the task without explaining the reasons for its appearance and the ways to solve it. And the basic requirements for airplanes were born not in the depths of the Politburo, but were developed, first of all, by the specialists of the Design Bureau, based on the capabilities of the industry. The main trendsetter in military aviation in those years was the Scientific and Testing Institute, but in practice it turned out that the requirements developed in the Moscow suburb of Chkalovskaya appeared after the government decree was already signed.

Lavochkin, Mikoyan, and Sukhoi had produced such aircraft by 1950, but they were unsatisfactory. In the 19481950 competition for a long-range, radar-equipped interceptor, none of the aircraft were selected for production. The requirement was evidently cancelled due to technological considerations. Thus, it appears that both the requirement and competition are rather flexible concepts as they apply to APVO decisions.

The contest for the interceptor was not announced and all three projects (Su-15, I-320 and La-200) were not united by a single plan. The first to design a similar interceptor with a radar "Thorium" began in the EDO, led by P.O.Sukhoi, who chose, as it seemed, the most profitable configuration of the aircraft with a tandem placement of engines.

The 1948 requirement for an all-weather interceptor resulted in development of three different two-engine, radar-equipped prototypes the Su-15, the La 200A, and the MiG-310. Among Sukhois ill-fated activities was a 1948 attempt at an all-weather interceptor, the SU-15. It featured a curious staggered fuselage arrangement of the production version of the Nene engine, the RD-45. The SU-15 would have been a heavy machine with a radome to house an Air Intercept scanner mounted over a common opening which served both engines. The aircraft would have featured a good 750-mile radius and transonic speed, but unfortunately it disintegrated in one of its first flights.

Lavochkin in 1948 also attempted to create an all-weather fighter. As with the Sukhoi aircraft, it featured two engines, probably RD-45s, mounted in the fuselage. A radome would have been housed inside a large circular intake which served both engines. Likewise, Mikoyan and Gurevich participated in the all-weather interceptor design activity. The MiG prototype, the I-320, had similar features and performance as the other two aircraft. Of three aircraft the MiG was the first to successfully fly. The SU-15 crashed in 1949, the MiG performed successfully in the winter and the Lavochkin flew in February.

But the Mikoyan designers also resorted to another approach. It is likely that none of the three models were passed after it was found that the rather primitive Izumrud radar could be fitted to the MiG-15. The fuselage mounting of two large centrifugal engines in the fuselage was an ungainly, inefficient and expensive arrangement without compensating advantages in range. Further, the short acquisition range of the Izumrud may have made greater demands on maneuverability than either aircraft seemed to offer, especially when compared with the MiG-15. Nevertheless, the SU-15, the La-200, and the I-320 do indicate the order of Soviet priorities. Attention was first focused on the achievement of a world standard day interceptor.

The main obstacle in the way of aircraft manufacturers was the choice of the engine. However, there was nothing to choose from. At Arkhip Ljulki things were not going well and the aircraft builders did not have much hope for the appearance of a turbojet with an axial compressor of the right thrust. The development of the TRD-7 in the prison design bureau of the Ministry of Internal Affairs, stationed on the territory of the Rybinsk motor plant, was stopped in connection with the purchase of the English "Nene". So there was only one hope for RD-45F. But this engine, proceeding from a large diameter, did not allow designers to explore several layouts of the machine, leaving only one way - to place them one after another, removing the gas jet of the front turbojet engine under the fuselage (the so-called redo scheme).

During the factory flight tests of the single-seat Su-15, a range of 1208 km was obtained. At normal take-off weight, its maximum speed reached 1045 km / h, and the limiting number M in flight with a decrease reached 0.967. For a fighter weighing 10 437 kg in 1949 this was not bad data. But the aircraft was in danger. In one of the flights, such strong vibrations came upon her, that S.N. Anokhin was forced to eject. The work on the Su-15 was stopped.

These were awkward designs which attempted to incorporate two centrifugal flow engines and a radar in the same fuselage. They were dropped in favor of a radar modification of the MiG-15a short-range interim expedient. Then, and only then, did the focus shift to an all-weather capability. The requirement appears to have been dropped when it was found to be technologically inconvenient; a simpler expedient was adopted instead. The failures of the SU-15 with the post war purges did cast a long shadow through Soviet aviation history. Sukhois post war record, to those who did not appreciate a number of his technical innovations, appeared to be a series of disasters. Judged by a more objective standard, he was the only major designer who had failed to create a jet prototype suitable for series production.

It was not until 1951, with the development of the Mikhulin AM-5 small, efficient, axial-flow engine that a long-range, all-weather interceptor became technically convenient. Such an engine made practical an alternate aircraft configuration which would accommodate the large radome associated with Soviet air intercept radars of that era.

The leaders in the creation of a long-range interceptor were OKB-155 and OKB-301. Having made a bet in both OKB on the redesigned engine layout, it remained to choose a radar sight. In this direction the teams of V.V. Tikhomirov and Slepushkin. Earlier all the ball was ready for the radar "Thorium", it was in version "A" and was placed aboard the interceptor. Another feature of the I-320 was the two-seater cabin crew, with the pilot and the operator in a row. The aircraft's armament consisted of three H-37 cannons with a total ammunition capacity of 150 cartridges.

But all the efforts of OKB-155 were in vain. The characteristics of the finalized P-2 aircraft (meets the designation P-3) turned out to be worse than that of its main rival La 200 from the Korshun radar, which, despite similar deficiencies with the I-320, was recommended for serial construction. But the government decided otherwise, leaving the question of supplying the Air Force with aircraft of a similar purpose.

There is sufficient evidence to believe that the aircraft which would eventually accommodate the requirement for an all-weather area interceptor, the YAK-25, arose outside of the normal process of Soviet research and development decision-making. Stalins acceptance of modifications and his preference for continuing to improve the MiG series stymied the development of a true all-weather area defense interceptor until Yakovlev wrote directly to Stalin suggesting a new design.

In meetings with Stalin, Yakovlev found that Beria tried to undercut his design and to put Yakovlev and Aviation Minister Khrunichev in personal jeopardy. Prodded by Beria, Stalins temper flared, and it was only with great difficulty that he was persuaded to hear Yakovlevs full story. The result of the meeting was approval for Yakovlev to proceed with development of the YAK-25 all-weather interceptor. The YAK-25 appears to have been the result of an initiative of the designer taken up directly with Stalin. Thus, the aircraft that was wanted concurrently with the formation of PVO in 1948 was not available until 1954.




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