Failure to meet predicted performance and poor reliability under test had led to some disenchantment with the large Lyulka TR-3 turbojet specified for the 1950 supersonic fighter programme. In consequence, the MiG 0KB elected to initiate development of a derivative of its contending TR-3-powered I-¬350 as a back-up programme, this, the 1-360 (SM-2), having close-paired Mikulin AM-5 small-diameter turbojets but being otherwise similar.

The SM-2 single-seat fighter proposal embodying an essentially similar wing to that of the I-350 with 55° sweepback at quarter chord (60° at leading edge). Powered by two AM-5F turbojets each with an afterburning rating of 2700kg and having an armament of two 37mm N-37D cannon in the wing roots, the first SM-2 – by now assigned the official designation of I-360 – was flown on 24 May 1952.

This was unique in having a T-type horizontal tail, and, on 25 June, it attained Mach=1.04 in level flight. Subsequent testing revealed that the wing tended to blanket the tailplane at high angles of attack, and, to rectify this deficiency, the tailplane was lowered to a mid point on the fin. Flight test (as the SM-2A) revealed little improvement and the surface was then further lowered to the base of the fin (as the SM-2B), this being accompanied by some increase in the vertical tail surface area, and satisfactory handling characteristics resulting.

The trials conducted (comprising 132 flights) ended in the loss of the aircraft in 1953 as a result of tail flutter at high speed, together with those of a further prototype, the SM-9 which had joined the test programme on 27 May 1952, were considered sufficiently successful to warrant immediate preparations for manufacture of a pre-series under the designation M1G-19.

Max take-off weight: 6820 kg / 15036 lb
Wingspan: 9.04 m / 29 ft 8 in
Length: 13.90 m / 45 ft 7 in
Height: 3.95 m / 13 ft 0 in

In the early 1950s, the MiG OKB was engaged in the simultaneous development of MiG-17 de¬rivatives and potential successors to the M1G-17. A derivative was the SM-1, or 1-340, which mated the forward fuselage, wings and tail surfaces of the MiG-17 with a new centre and rear fuselage accommodating paired 4,850 lb st (2 200 kgp) Mikulin AM-S single-shaft turbojets. Trials with the SM-1, which apparently commenced at the beginning of 1952, were largely concerned with the engine installation as similarly paired AM-5s had meanwhile been selected to power a more advanced fighter, the 1-360. In consequence, the SM-1 did not progress beyond prototype status. Earlier, in 1951, another MiG-17 airframe had been fitted with a Lyulka TR-3 axial-flow turbojet of 10,140 lb st (4600 kgp) as the S1-16, this serving as a test-bed for the I-350, and in 1953, yet a further MiG-17 airframe, the SR-2, was to be fitted with a Kliinov VK-5F centrifugal-flow turbojet of 6,834 lb st (3100 kgp), this being the ultimate Soviet development of the Rolls-Royce Nene. No performance data or weights are available for the SM-1, and overall dimensions were similar to those of the MiG-17F apart from a length of 36 ft 11 in (11,25 m) and a height of 12 ft 7.9 in (3,86 m).

Max speed: 1193kph at 1000m / 1154kph at 5000m
Time to 5000m: 0.94 min

Designed to meet the demands of a twin-engined all-weather fighter programme initiated in January 1948, the MiG OKB offered the Izdeliye R, a side-by-side two-seat swept-wing fighter with the engines in tandem. The nose intake fed a plenum chamber around the forward engine compressor, this engine exhausting below the fuselage and a duct leading back to the aft engine which exhausted via an orifice in the extreme tail. Armament comprised three 37mm N-37 cannon.

Competing with proposals from the Lavochkin and Yakovlev bureaux – all three contenders being awarded three-prototype contracts – the MiG fighter was assigned the official designation I-320.

The first prototype, the R-1 powered by two 5,005 lb st (2270 kgp) RD-45F engines, was flown on 16 April 1949.

The R-2 and R-3 were each powered by paired of 5,952 lb st / 2700kg VK-1 engines and embodied various modifications, the R-3 featuring a strength¬ened wing. The VK-1-powered prototypes could take-off and cruise on the power of either engine, and the I-320 was initially tested with Torii-A (Thorium-A) radar mounted in a cone above the air intake. This single-antenna radar which demanded manual tracking was succeeded by the basically similar but improved Korshun (Kite) radar with which the I-320 was tested during July-August 1951. Development of the I-320 was discontinued when the requirement to which it had been designed was overtaken by a more advanced one. Develop¬ment was discontinued in favour of the Yak-25 which was capable of accommodating a larger radar.

1-320 (R-1)
Engines: 2 x RD-45F, 5,005 lb st (2 270 kgp)
Max speed, 658 mph (1 060 km/h) at 14,765 ft (4 500 m)
Ceiling, 49,540 ft (15 100 m)
Endurance, 3.0 hrs
Empty weight, 16,241 lb (7 367 kg)
Loaded weight, 22,630 lb (10 265 kg)
Span, 46 ft 7 in (14,20 m)
Length, 51 ft 8 7/8 in (15,77 m)
Wing area, 443.47 sq ft (41,20sq.m)

I-320 R-2
Max take-off weight: 12095 kg / 26665 lb
Wingspan: 14.20 m / 46 ft 7 in
Length: 15.77 m / 51 ft 9 in
Wing area: 41.20 sq.m / 443.47 sq ft
Max. speed: 1090 km/h / 677 mph
Range: 1205 km / 749 miles