Sukhoi Su - 47 Berkut The Su - 47 Berkut ( Russian for Golden Eagle ) or S - 37 Berkut is a supersonic fighter developed by sukhoi aviation . Development . Originally known as the S - 37 , Sukhoi redesignated its advanced test aircraft as the Su - 47 in 2002 . Officially nicknamed Berkut ( Golden Eagle ) , 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 , with research including the development of the Tsibin LL and study of the captured Junkers Ju 287 in the 1940s . Forward - swept wings yield a higher maximum lift coefficient , reduced bending moments , and delayed stall when compared to more traditional wing shapes . At high angles of attack , the wing tips remain unstalled allowing the aircraft to retain aileron control . 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 project was launched in 1983 on order from the Soviet Air Force . But when the USSR dissolved , funding was frozen and development continued only through funding by Sukhoi . Like its US counterpart , the Grumman X - 29 , the Su - 47 is primarily a technology demonstrator for future Russian fighters . However , Sukhoi is now attempting to market the Su - 47 to the Russian military and foreign customers as a production fighter in its own right . Design . Outline of the Sukhoi Su - 47 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 . Though similar in overall concept to the American X - 29 research aircraft of the 1980s , the Su - 47 is about twice the size and far closer to an actual combat aircraft than the US design . To solve the problem of wing - twisting , the Su - 47 makes use of composite materials carefully tailored 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 Russian 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 . Maneuverability . The Su - 47 has extremely high agility at subsonic speeds , enabling the aircraft to alter its angle of attack and its flight path very quickly while retaining maneuverability in supersonic flight . The Su - 47 has a maximum speed of Mach 1 . 6 at high altitudes and a 9g capability . Maximum turn rates , and the upper and lower limits on airspeed for weapon launch , are important criteria in terms of combat superiority . The Su - 47 aircraft has very high levels of maneuverability with maintained stability and controllability at extreme angles of attack . Maximum turn rates are important in close combat and also at medium and long range , when the mission may involve engaging consecutive targets in different sectors of the airspace . A high turn rate of the Su - 47 allows the pilot to turn the fighter aircraft quickly towards the next target to initiate the weapon launch . Like most other fighters with fly by wire controls , the Su - 47 achieves some of its high maneuverability through relaxed stability . The swept - forward wing , compared to a swept - back wing of the same area , provides a number of advantages in comparison to most of the other aircraft : Fuselage . The Su - 47s fuselage is oval in cross section and the airframe is constructed mainly of aluminium and titanium alloys and 13 % ( by weight ) of composite materials . The nose radome is slightly flattened at the fore section , and has a horizontal edge to optimise the aircraft ' s anti - spin characteristics . Wings . The forward - swept midwing gives the unconventional ( and characteristic ) appearance of the Su - 47 , earning it the nickname of ' devil ' and ' slingshot ' . 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 downside 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 strengthening , the plane was initially limited to Mach 1 . 6 . Recent engineering modifications have raised this limit , but the new limit has not been specified . Nevertheless , it is rumored that the Su - 47 prototype recently suffered some manner of wing failure during testing . As a result , Western analysts speculate that Sukhoi engineers have restored the prototype to a conventional swept - wing layout . Apparently , the engineers reached the same conclusions with regard to the viability of a forward - swept layout as their counterparts at Grumman did twenty years ago with the X - 29 . Therefore , it is likely that any derivative production aircraft based on Su - 47 research will utilize a conventional wing layout . Thrust vectoring . The thrust vectoring ( with PFU engine modification ) of ±20° at 30° / second in pitch and yaw will greatly support the agility gained by the forward - swept - wings . Cockpit . 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 maneuvers . 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 and missile avoidance 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 . Pilots , however , claim that the cockpit gives them low visibility due to poor design . This reclined seating arrangement was first used in the American F - 16 , but was determined to be of little value .