Sukhoi Su-27 - Design

Design

The Su-27's basic design is aerodynamically similar to the MiG-29, but it is substantially larger. It is a very large aircraft, and to minimise its weight its structure has a high percentage of titanium (about 30%, more than any of its contemporaries). No composite materials were used. The swept wing blends into the fuselage at the leading edge extensions and is essentially a cropped delta (the delta wing with tips cropped for missile rails or ECM pods). The Su-27 is also an example of a tailed delta wing configuration, retaining conventional horizontal tailplanes, though it is not a true delta. It has two vertical tailfins outboard of the engines, supplemented by two ventral fins that fold down for additional lateral stability.

The Su-27’s Lyulka AL-31F turbofan engines are widely spaced, both for safety reasons and to ensure uninterrupted airflow through the intakes. The space between the engines also provides additional lift, reducing wing loading. Movable guide vanes in the intakes allow Mach 2+ speeds, and help to maintain engine airflow at high alpha. A mesh screen over each intake prevents debris from being drawn into the engines during take-off.

The Su-27 had the Soviet Union’s first operational fly-by-wire control system, developed based on Sukhoi OKB’s experience in the Sukhoi T-4 bomber project. Combined with relatively low wing loading and powerful basic flight controls, it makes for an exceptionally agile aircraft, controllable even at very low speeds and high angles of attack. In airshows the aircraft has demonstrated its manoeuvrability with a Cobra (Pugachev’s Cobra) or dynamic deceleration – briefly sustained level flight at a 120° angle of attack. Thrust vectoring has also been tested (and is incorporated on later Su-30MK and Su-37 models), allowing the fighter to perform hard turns with almost no radius, incorporate vertical somersaults into level motion and limited nose-up hovering.

The naval version of the 'Flanker', the Su-27K (or Su-33), incorporates canards for additional lift, reducing take-off distances (important because the aircraft carrier Admiral Kuznetsov has no catapults). These canards have also been incorporated in some Su-30s, the Su-35, and the Su-37.

In addition to its considerable agility, the Su-27 uses its substantial internal volume for a large internal fuel capacity. In an overload configuration for maximum range, it can carry 9,400 kg (20,700 lb) of internal fuel, although its manoeuvrability with that load is limited, and normal load is 5,270 kg (11,620 lb).

The Su-27 is armed with a single 30 mm Gryazev-Shipunov GSh-30-1 cannon in the starboard wingroot, and has up to 10 hardpoints for missiles and other weapons. Its standard missile armament for air-to-air combat is a mixture of Vympel R-73 (AA-11 Archer), Vympel R-27 (AA-10 'Alamo') weapons, the latter including extended range and IR guided models. More advanced Flanker variants (such as Su-30, −35, −37) may also carry Vympel R-77 (AA-12 Adder) missiles.

The Su-27 has a high-contrast tuneable HUD and a Helmet mounted display capability.