SM-50

This designation applied to the MiG-19 fitted with a booster rocket engine in a pod under­neath. Whereas previous mixed-power fight­ers had been primarily to test the rocket, the SM-50 was intended as a fast-climbing fighter, able very quickly to intercept high-flying bombers. The first SM-50 was a MJG-19S fitted with a removable ventral pack called a U-19 (from Uskoritel’, accelerator). Made at the MiG OKB, this was basically formed from two tubes arranged side-by-side with a nose fair­ing. It contained an RU-013 engine from L S Dushkin’s KB, fed by turbopumps with AK-20 kerosene and high-test hydrogen per­oxide. The pilot could select either of two thrusts, which at sea level were 1,300kg (2,866Ib) or 3,000kg (6,614Ib). To avoid the rocket flame the aircraft’s ventral fin was re­placed by two vertical strake-fins under the engines (which were RD-9BM turbojets with variable afterburning thrust but unchanged maximum rating). The first SM-50 began factory testing (incidentally after the Ye-50, and long after the first MiG-21 prototypes) in December 1957. Despite a take-off weight of 9,000kg (19,841 Ib) a height of 20,000m (65,617ft) was reached in under eight min­utes with the rocket fired near the top of the climb, boosting speed to l,800km/h (1,118mph, Mach 1.695). Dynamic zoom ceil­ing was estimated at 24,000m (78,740ft). Five pre-production SM-50s were built at Gor’kiy, but they were used only for research.

SM-12

Early in the production of the MiG-19 it was re­alised that the plain nose inlet was aerody­namically inefficient at supersonic speeds, and that a properly designed supersonic inlet would enable maximum speed to be signifi­cantly increased without any change to the engines. By the mid-1950s the OKB was well advanced with the prototypes that led to the MiG-21 and other types, all ofwhich had inlets designed for supersonic flight. In fact produc­tion of the MiG-19 in the Soviet Union was quite brief – it was left to other countries to discover what a superb fighter it was – and all had the original inlet. A total of four SM-12 (plus two derived) aircraft were built, with the nose extended to terminate in a sharp­lipped inlet. As in standard MiG-19s, across the inlet was a vertical splitter to divide the airflow on each side of the cockpit. This was used to support a conical centrebody whose function was to generate a conical shock­wave at supersonic speeds. For peak pres­sure recovery, to keep the shock cone focussed on the lip of the inlet the cone could be translated (moved in or out) by a hydraulic ram driven by a subsystem sensitive to Mach number. A similar system has been used on all subsequent MiG fighters, though the latest types have rectangular lateral inlets. SM-12/1 was powered by two RD-9BF-2 engines with a maximum rating of 3,300kg (7,275 Ib). SM – 12/2, /3 and /4 were powered by the R3-26, with a maximum rating of 3,800kg (8,377 Ib). All four SM-12 aircraft were fitted with im­proved flight control systems, wing guns only and new airbrakes moved to the tail end of the fuselage. A fifth aircraft, designated SM-12PM, was fitted withpylons fortwo K-5M guided missiles, which were coming into production as the RS-2U. This required a guid­ance beam provided by an RP-21 (TsD-30) in­terception radar. The scanner necessitated a greatly enlarged nosecone, which in turn demanded a redesigned forward fuselage with hardly any taper. Both guns were re­moved, and there were many other modifi­cations. The sixth and final version was the SM-12PMU, armed with two or four RS-2U missiles. This aircraft was intended to inter­cept high-altitude bombers faster than any other aircraft, so it combined two R3-26 en­gines with the U-19D rocket package. Numer­ous MiG-19 variants served as armament test-beds, mainly for guided missiles.