SUKHOI aircraft-carrier ramp, and it later made hookequipped simulated carrier landings. T10-4, first flown by Ilyushin on 31st October 1979, tested the new engines and avionics. So great was the need to test avionics that the Komsomolsk factory was contracted to build five further prototypes. These were designated T10-5, -6, -9, -10 and -11 (T10-7 and -8 were significantly modified). These additional prototypes were generally similar to T10-3, apart from the fact that the fins were canted outwards. The T10-5 flew in June 1980, and the remainder were all on flight test by autumn 1982. Pavel Sukhoi died on 15th September 1975, and was succeeded as General Constructor by Mikhail P Simonov. Soon after he took over, the first detailed information on the McDonnell Douglas F-15 became available. Computer simulations found that the T-10 did not meet the requirement that it should be demonstrably superior to the USAF aircraft. Simonov ordered what amounted to a fresh start, telling the author 'We kept the wheels and ejection-seat'. Designated T-10S, from Seriynii, production, the new fighter can only be described as brilliant. Ever since the first pre-series example, the T10-17, was flown by Ilyushin on 20th April 1981 it has been the yardstick against which other fighters are judged. An enormous effort was made by Nil using T10-17 and T10-22 to clear the redesigned aircraft for production. The first true series aircraft, designated Su-27, was flown at Komsomolsk in November 1982. The T-10 wing had 0째 dihedral, and a symmetric profile with a ruling thickness/chord ratio of 3.5 per cent, rising to 5 per cent at the root. The leading edge was fixed. It left the fuselage with a sharp radius and with a sweep angle of 79째, curving round to 41째 over the outer panels and then curving back to Kiichemann tips. The main torsion box had three spars and one-piece machined skins. Most of the interior was pressurized and formed an integral tank, while high-strength ribs carried armament suspension points. The oval-section fuselage forward section was designed to accommodate the intended large radar, followed by the cockpit with a sliding canopy. Behind this came an equipment bay, followed by a humpbacked 'forecastle tank' and then a broad wing centre-section tank which could be considered as part of both the wing and fuselage. A further tank was placed in the keel beam between the engines. The latter were of the Lyul'ka AL-21F-3 type, each with an afterburning rating of 11,200kg (24,691 Ib). Each was placed in a large nacelle or gondola under the wing, tilted outward because of the inboard wing's sharp taper in thickness. Each engine air duct was fed by a wedge inlet behind the leading edge, standing well away under the wing's underskin to avoid swallow-
ing boundary-layer air. Each inlet contained a variable upper ramp, with auxiliary side inlets for use on take-off, and a curved lower portion. The large engine gondolas provided strong bulkheads on which were mounted the two vertical fins and the tailplanes. The AL-21 had its accessories mounted on top, and the massive structure and fins immediately above made access difficult. From the third aircraft the engine was the Lyul'ka AL-31F, which had been specially designed for this aircraft. It had an afterburning rating of 12,500kg (27,557 Ib), and offered several other advantages, one being that it was half a tonne (1,100 Ib) lighter than the AL-21F. It had its accessories partly underneath and partly far forward on top, and the vertical tails were moved outboard away from the engine compartments. The main landing gears had large (1,030 x 350mm) tyres on single legs and retracted forwards, rotating the wheel through 90째 to lie flat in the root of the wing in a bay closed by side doors and large front doors which served as airbrakes. The tall nose gear had a single unbraked wheel with a 680 x 260mm tyre. It retracted backwards, and was fitted with an all-round mudguard to protect the engine inlets. The main-wheel wells required a thick inboard section of the wing adjacent to the engine gondolas, and this was carried to the rear to provide strong beams to which the tailplanes (and in the redesigned aircraft the fins) were pivoted. The T-10 flight controls comprised conventional ailerons, two rudders and the independently controlled tailplanes. All these surfaces were driven by power units each served by both the completely separated 210kg/cm2 (2,987 lb/in2) hydraulic systems. These systems also drove the plain flaps, landing gears (with independent airbrake actuation), nosewheel steering,
T-10
engine inlets and mainwheel brakes. The flyby-wire system governed pitch control by the tailplanes used in unison, and provided threeaxis stabilization. The mechanical controls worked directly by the pilot's linkages to the surface power units governed the ailerons and rudder. The five internal fuel tanks were automatically controlled to supply fuel without disturbing the aircraft centre of gravity. A special oxygen system was provided to ensure engine restart and afterburner light-up at high altitude. T10-1 was built with no provision for armament, but in its modified state it had seven hardpoints on which external stores could be suspended. Despite the fact that the basic aircraft had to be completely redesigned, the T-10 family of prototypes were stepping stones to the greatest fighter of the modern era.
Dimensions (T10-1 as built) Span 14.7m Length 19.65m Wing area 59.0 nf
48 ft 2V, in 64 ft 5K in 635 ft2
Weights Weight empty Loaded
18,200kg 25,740kg
40,1 23 Ib 56,746 Ib
Performance Max speed at sea level, at high altitude; Service ceiling Range
l,400km/h 2,230 km/h 17,500m 3,100km
870 mph (Mach 1.145) 1,386 mph (Mach 2.1) 57,415ft 1,926 miles
T10-1 after modernization.
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