Sukhoi Su-47

The Sukhoi Su-47 Berkut also designated S-32 and S-37 during initial development, is an experimental supersonic jet fighter developed by Sukhoi Aviation Corporation. A distinguishing feature of the aircraft is its forward-swept wing.

The Su-47 was originally built as Russia's principal testbed for composite materials and sophisticated fly-by-wire control systems. The aircraft makes use of forward-swept wings allowing superb maneuverability and operation at angles of attack up to 45° or more.

TsAGI has long been aware of the advantages of forward-swept wings. Forward-swept wings offer lower wave drag, reduced bending moments, and delayed stall when compared to more traditional wing shapes. Unfortunately, forward sweep also induces twisting (divergence) strong enough to rip the wings off an aircraft built of conventional materials. Only recently have composite materials made the design of aircraft with forward-swept wings feasible.

The Su-47 is of similar dimensions to previous large Sukhoi fighters, such as the Su-35. To reduce development costs, the Su-47 borrowed the forward fuselage, vertical tails, and landing gear of the Su-27 family. Nonetheless, the aircraft includes reduced radar signature features (including radar absorbent materials), an internal weapons bay, and space set aside for an advanced radar.

To solve the problem of wing-twisting, the Su-47 makes use of composite materials carefully designed to resist twisting while still allowing the wing to bend for improved aerodynamic behavior. Due to its comparatively large wingspan, the Su-47 is to be equipped with folding wings, in order to fit inside hangars. Like its immediate predecessor, the Su-37, the Su-47 is of tandem-triplane layout, with canards ahead of wings and tailplanes. Interestingly, the Su-47 has two tailbooms of unequal length outboard of the exhaust nozzles. The shorter boom, on the left-hand side, houses rear-facing RADAR, while the longer boom houses a brake parachute.

The forward-swept midwing gives the unconventional appearance of the Su-47. A substantial part of the lift generated by the forward-swept wing occurs at the inner portion of the wingspan. The lift is not restricted by wingtip stall. The ailerons - the wing's control surfaces - remain effective at the highest angles of attack, and controllability of the aircraft is retained even in the event of airflow separating from the remainder of the wings' surface.

The wing panels are constructed of nearly 90% composites. The forward-swept midwing has a high aspect ratio, which contributes to long-range performance. The leading-edge root extensions blend smoothly to the wing panels, which are fitted with deflectable slats on the leading edge; flaps and ailerons on the trailing edge. The all-moving and small-area trapezoidal canards are connected to the leading-edge root extensions.

The disadvantage of such a wing design is that it produces strong rotational forces that try to twist the wings off, especially at high speeds. This twisting necessitates the use of a large amount of composites in order to increase the strength and durability of the wing. Despite this, the plane was initially limited to Mach 1.6. Recent engineering modifications have raised this limit.

The cockpit's design has focused on maintaining a high degree of comfort for the pilot and also on the pilot being able to control the aircraft in extremely high g-load manoeuvres. The aircraft is equipped with a new ejection seat and life support system. The variable geometry adaptive ejection seat is inclined at an angle of 60°, which reduces the impact of high g forces on the pilot. The seat allows dogfight maneuvers with significantly higher g loadings than can normally be tolerable. The Su-47 pilot uses a side-mounted, low-travel control stick and a tensiometric throttle control.

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