Sukhoi Su-15 (1949)

Sukhoi Su-15

Company type	Prototype jet interceptor aircraft
Industry	Aerospace
Founded	March 1947
Headquarters	Soviet Union
Products	Jet interceptor aircraft (prototype)

This article is about the subsonic Su-15. For the later supersonic interceptor, see Sukhoi Su-15.

The Sukhoi Su-15 (Aircraft P) was a Soviet prototype jet interceptor designed for all-weather operations, which ultimately did not proceed to mass production.

Development

The Su-15 represented one of the initial efforts to create a jet-powered interceptor capable of operating under all weather conditions. The Soviet authorities commissioned its development in March 1947, approving a preliminary midwing design by the Sukhoi Design Bureau that included features such as a pressurized cockpit, onboard radar, swept wings, and tandem-mounted engines. This concept bore resemblance to earlier projects like the Lavochkin La-200 and Mikoyan-Gurevich I-320. According to TsAGI, the wing sweep angle was set at 35 degrees. The first prototype was finalized on 25 October 1948, just four months after construction commenced.

The maiden flight took place on 11 January 1949, with test pilot G. M. Shiyanov at the controls. During flight evaluations, the Su-15 achieved speeds of 1032 km/h (557 knots, 641 mph; approximately Mach 0.888) at an altitude of 4,550 metres (14,930 ft) and 985 km/h (532 knots, 612 mph; Mach 0.926) at 10,950 metres (35,930 ft). However, vibrations exceeding acceptable levels were encountered when exceeding Mach 0.87.

On its 39th sortie on 3 June 1949, severe vibration forced test pilot S.N. Anokhin to eject from the aircraft. The precise cause of this incident remained undetermined. By that point, about 90% of the planned flight testing had been completed across 42 flights totaling 20 hours and 15 minutes of flight time.

Following this accident, the development program was discontinued and construction of the second prototype was halted.

The Su-15 featured an all-metal midwing monoplane configuration with wings swept at a 35° angle. Its design incorporated several distinctive elements: the twin Klimov RD-45 turbojet engines were arranged in tandem rather than side-by-side due to their large diameters. The forward engine was installed low in the fuselage with its exhaust directed beneath the center section, while the rear engine's nozzle extended out from the aft fuselage tip. To accommodate air intake ducts feeding the rear engine, the cockpit was offset slightly to the left.

The wing structure comprised two main spars and included two full-chord wing fences. Control surfaces consisted of hydraulically actuated ailerons and Fowler flaps. Air entered through a centrally divided nose intake featuring a central web. At the rear of the aircraft, two-start rockets were installed along with a pair of air brakes.

Operators

Template:USSR

• Soviet Air Force