Sukhoi Su-47

https://en.wikipedia.org/wiki/Sukhoi_Su-47

The Sukhoi Su-47 Berkut (Russian: ????? ??-47 ??????, lit. 'Golden Eagle') (NATO
reporting name Firkin), also designated S-32 and S-37 (not to be confused with
the twin-engined delta canard design offered by Sukhoi in the early 1990s under
the designation Su-37) during initial development, was an experimental
supersonic jet fighter developed by Sukhoi Aviation Corporation. A
distinguishing feature of the aircraft was its forward-swept wing that gave the
aircraft excellent agility and maneuverability. While serial production of the
type never materialized, the sole aircraft produced served as a technology
demonstrator prototype for a number of advanced technologies later used in the
4.5 generation fighter Su-35BM and current fifth-generation jet fighter Sukhoi
Su-57.

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.

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. At high angles of attack, the wing tips remain
unstalled allowing the aircraft to retain aileron control. Conversely to more
conventional rear-swept wings, forward sweep geometrically creates increased
angle of incidence of the outer wing sections when the wing bends under load.
The wings experience higher bending moments, leading to a tendency for the wings
to fail structurally at lower speeds than for a straight or aft-swept wing.

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 was
primarily a technology demonstrator for future Russian fighters.


Role
Experimental aircraft/Technology demonstrator

Manufacturer
Sukhoi

First flight
25 September 1997

Status
Cancelled

Primary user
Russian Air Force

Number built
1

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.

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

* higher lift-to-drag ratio
* better agility in dogfight situations
* 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

The forward-swept midwing gives the Su-47 its unconventional appearance. A
substantial part of the lift generated by the forward-swept wing occurs at the
inner portion of the wingspan. This inboard lift is not restricted by wingtip
stall and the lift-induced wingtip vortex generation is thus reduced. 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.

A downside of such a forward-swept wing design is that it geometrically produces
wing twisting as it bends under load, resulting in greater stress on the wing
than for a similar straight or aft-swept wing. This requires the wing be
designed to twist as it bends—opposite to the geometric twisting. This is done
by the use of composites wing skins laid-up to twist. The plane was initially
limited to Mach 1.6.

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 other aspects of the
design.

Specifications (Su-47)

General characteristics
Crew: 1
Length: 22.6 m (74 ft 2 in)
Wingspan: 15.16 m to 16.7 m (49 ft 9 in to 54 ft 9 in)
Height: 6.3 m (20 ft 8 in)
Wing area: 61.87 m² (666 sq ft)
Empty weight: 16,375 kg (36,100 lbs)
Loaded weight: 25,000 kg (55,115 lb)
Max. takeoff weight: 35,000 kg (77,162 lb)
Thrust vectoring: ±20° at 30° per second in pitch and yaw
Powerplant: 2 × Aviadvigatel D-30F11 afterburning, thrust vectoring (in PFU
modification) turbofans Dry thrust: 83.4 kN (18,700 lbf) each
Thrust with afterburner: 142.2 kN (32,000 lbf) each


Performance
Maximum speed: Mach 1.65 (Achieved in test flights) (1,717 km/h, 1,066 mph) At
sea level: Mach 1.16 (1,400 km/h, 870 mph)

Range: 3,300 km (2,050 mi)
Service ceiling: 18,000 m (59,050 ft)
Rate of climb: 233 m/s (46,200 ft/min)
Wing loading: 360 kg/m² (79.4 lb/(sq ft))
Thrust/weight: 1.16 (loaded) / 1.77 (empty)




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