Sukhoi Su-47

infobox Aircraft
name = Su-47 "Berkut"



caption =
type = Technology Demonstrator
manufacturer =Sukhoi
designer =Sukhoi Design Bureau of Moscow
first flight = 25 September 1997
introduced =January 2000
retired =
status = Experimental
primary user = Russian Air Force
more users =
produced =
number built = 1
unit cost =1.67 billion rubles(Russia) $70 million(U.S.)
developed from =
variants with their own articles =

The Sukhoi Su-47 "Berkut" (Russian: Су-47 Беркут - Golden Eagle), 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, similar to that of the Tsybin's LL-3. [http://aeroweb.lucia.it/~agretch/RAFAQ/six5th_5.html Russian Aviation Page: Sukhoi S-37 Berkut (S-32) ] ] Its NATO reporting name is "Firkin". The sole aircraft produced is an advanced technology demonstrator prototype and manufacture of a planned second flying prototype was canceled.

This aircraft is often erroneously referred to as the Su-37, which is in fact a completely different aircraft.

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.

Like its US counterpart, the Grumman X-29, the Su-47 is primarily a technology demonstrator, one intended to lay the foundation for the next Russian fighter. Such a fighter must not only be as advanced as the US F-22 Raptor, but must also compete for funding with the more conventional MiG 1.44. 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.Fact|date=December 2007

Design

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),Fact|date=June 2008 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 2.34 at high altitudes and a greater than 9g capability. [http://www.airforce-technology.com/projects/s37/]

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. The main problem with this, however, is that the Su-47 is at a high risk to spin out of control with little chance of recovery.

The swept-forward wing, compared to a swept-back wing of the same area, provides a number of advantages:

*higher lift-to-drag ratio
*higher capacity in dogfight maneuvers
*higher range at subsonic speed
*improved stall resistance and anti-spin characteristics
*improved stability at high angles of attack
*a lower minimum flight speed
*a shorter take-off and landing distance

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, 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. [http://www.aerospaceweb.org/aircraft/fighter/s37/] 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. [http://www.aerospaceweb.org/aircraft/fighter/s37/] Therefore, it is likely that any derivative production aircraft based on Su-47 research will utilize a conventional wing layout.

Thrust vectoring

Although not revolutionary, 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 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 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. Many experts, however, claim that the cockpit gives the pilot very low visability due to poor design. This reclined seating arrangement was first used in the F-16 Fighting Falcon but was determined to be of little value. However, it was replicated in the F-22A Raptor.

Operators

;RUS
*Russian Air Force

pecifications (Su-47)

aircraft specifications

plane or copter?=plane
jet or prop?=jet

ref=World Aircraft & Systems Directory
crew=1
length main=22.6 m
length alt=74 ft 2 in
height main=6.3 m
height alt=20 ft 8 in
span main=15.16 m to 16.7 m
span alt=49 ft 9 in to 54 ft 9 in
area main= 61.87 m²
area alt= 666 ft²
empty weight main= 16,375 kg
empty weight alt= 36,100 lbs
loaded weight main= 25,000 kg
loaded weight alt= 55,115 lb
max takeoff weight main= 35,000 kg
max takeoff weight alt= 77,162 lbs
engine (jet)=Lyulka AL-37FU(planned) flying prototypes used 2 Aviadvigatel D-30F6
type of jet=afterburning, thrust-vectoring (in PFU modification) turbofans with digital control
number of jets=2
thrust main=83.4 kN
thrust alt=18,700 lbf
afterburning thrust main=142.2 kN
afterburning thrust alt=32,000 lbf
more general=

Thrust vectoring: ±20° at 30° per second in pitch and yaw

max speed main= Mach 2.34 [http://aeroweb.lucia.it/~agretch/RAFAQ/six5th_5.html]
max speed alt= 2,500 kmh, 1,552 mph)
* At sea level: Mach 1.31 (1,400 km/h, 870 mph
cruise speed main=
cruise speed alt=
range main=3,300 km
range alt=2,050 mi
ceiling main=18,000 m
ceiling alt=59,050 ft
climb rate main=233 m/s
climb rate alt=46,200 ft/min
loading main= 360 kg/m²
loading alt= 79.4 lb/ft²
thrust/weight=
armament=Number of hardpoints: 14: 2 wingtip, 6-8 under wing, 6-4 conformal under fuselage
* Guns: 1× 30 mm GSh-30-1 cannon with 150 rounds
* Missiles: 14 hardpoints (2 wingtip, 6-8 underwing, 4-6 conformal under the fuselage)
** Air-to-air: R-77, R-77PD, R-73, K-74
** Air-to-surface: X-29T, X-29L, X-59M, X-31P, X-31A, KAB-500, KAB-1500

ee also

aircontent
related=
similar aircraft=
* F-22
* Grumman X-29
* Mikoyan Project 1.44
* Sukhoi PAK FA
lists=
see also=
* Medium Combat Aircraft
* Mitsubishi ATD-X

References

*

External links

* [http://www.fighter-planes.com/info/s37.htm S-37 Berkut at Fighter-Planes.com]
* [http://aeroweb.lucia.it/~agretch/RAFAQ/six5th_5.html S-37 at Russian Aviation Page]
* [http://www.warfare.ru/?catid=255&linkid=1609 S-37 at Russian Military Analysis]
* [http://www.airforce-technology.com/projects/s37/ S-37 at airforce-technology.com]