UNITED24 - Make a charitable donation in support of Ukraine!


Sukhoi S-54 / S-55 / S-56 Family

Currently there is no indicaiton this is an active program, the most priority in OKB Sukhoi being the Su-27BM.

The S-54 advanced trainer, based on Su-27 aerodynamics, the S-55 export fighter variant and S-56 carrier-based fighter have a strong resemblance to the Su-27, although with only one engine. Since 1990 the Sukhoi Design Bureau has been involved in the design of a system to replace Aero L-29 and L-39 jet trainers whose service life had expired and to give advance training to pilot cadets for the new generation of fighters. The work on developing a new fighter (a whole new family of fighters - S-54, S-55 and S-56) has been underway at the Sukhoi design bureau. The S-55 was described as an export version, with a raised cockpit indicating a primary attack specialisation. The S-56 would be an export carrier-based fighter.

Initially, the S-54 program, started in 1990, provided for the development of a supersonic combat trainer intended for Russian Air Force fighter pilot training as well as for export. The experience of making the Su-27 was supposed to be drawn on in designing the S-54. However, the successful upgrading of the Su-27 into the Su-33, Su-33KUB, Su-35, etc., as well as progress in aerodynamics, avionics, engines, electronics, allowed the S-54/-55/-56 developers to greatly bolster the potential capabilities of the prospective aircraft by turning this combat trainer into a real fighter with its performances matching or even exceeding those of the Su-27 and its cost and weight being twice as less.

The S-54/55/56 aerodynamic configuration resembles that of the Su-33 fighter. It incorporates all-moving foreplanes and empennage, rather high aspect ratio trapezoid wing joined smoothly with the airframe, twin tails. However, there are certain differences. In comparison with the latest version of the Flanker family - the Su-33KUB, the light fighter's aerodynamics features considerable improvements. The wing became adaptive, which led to enhancement of lift/drag ratio. To improve the fighter's manoeuvrability, the tails and ventral fins were made all-moving and positioned along the same axis.

The S-54/55/56 design does not make provision for the use of stealth coatings as great as the design of US 5th generation F-22 and JSF's one does. In particular, unlike the American aircraft, the Russian ones are going to have their weapons mounted only externally. However, their stealthiness was said to be enhanced by the factor of 10 through more thorough integration of weapons and the airframe, reducing the number of protruding parts, antennae, rigging, as well as through the use of radar-absorbent coatings and materials.

The S-54 is powered by a single AL-31 engine featuring three-dimensional TVC. With its regular takeoff, the fighter's thrust-to-weight ratio exceeds 1 by far. In the future, when the aircraft is fitted with a new-generation engine, it might produce non-afterburning supersonic cruising speed. The S-54's internal fuel cells hold 4,500 kg of fuel, while the F-15 (twice as heavier) can carry only 6,100 kg of avgas. This coupled with superior aerodynamic characteristics gives the S-54 the service range of 4,000 km (as compared, the F-15 has the service range of only 2,000 km when flown with no drop tanks).

The S-54 family fighters are going to be fitted with most sophisticated avionics. The radar nosecone diameter equals that of the Su-27 (about 1 m), which allows a powerful phased array radar (PAR) to be mounted on this light fighter to provide a detection range exceeding that of the F-16C or JSF. The S-54's radar will be augmented by a new electro-optical system comprising a low-level night system and capable of operating against both air and surface targets.

Like other prospective Russian fighters, the S-54 and its versions are expected to feature a powerful computer made of the Russian components and able to make dozens of billions calculations per second. The cockpit instrumentation layout is made with new principles in mind through the use of multifunction colour LCDs (14-15 inches in diagonal). The cockpit is planned to be fitted with an improved ejection seat derived from the K-36 ejection seat. A new g-suit and a new oxygen supply system would be provided to the pilots to enable the latter to be capable of maneuvering at 10-12 g. The crew would be provided with a new, lighter helmet integrated with a helmet-mounted display. Measures were taken to cut the ground crew strength.

S-55 Twin-seat Trainer

The S-55 twinseater the crew is seated shoulder-by-shoulder like at the Su-24, Su-27IB and Su-33KUB. This makes the pilot training much easier and simplifies the pilots' communication in flight. Despite the fighter's small size, the seat pitch is the same as in the cockpit of the Su-24.

The S-54/55 were formally offered to South Africa. They scored quite highly in the technical assessment but were eliminated on other grounds.

Join the GlobalSecurity.org mailing list

Page last modified: 16-10-2012 19:13:26 ZULU