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S-67 Blackhawk

The Sikorsky S-67 Blackhawk was a private-venture, prototype attack helicopter built in 1970 with Sikorsky Aircraft R&D funds. A tandem, two-seat aircraft designed around the dynamic drive and rotor systems of the Sikorsky S-61, it was designed to serve as an attack helicopter or to transport up to 8 troops into combat.

 

Design and development

S-67 development

When the Armed Aerial Fire Support System program was delayed, Sikorsky offered an armed SH-3 Sea King (Sikorsky S-61) version initially. After further AAFSS problems, the company developed an intermediate, high-speed, attack aircraft named the Sikorsky S-67 Blackhawk in 1970. Design work on the S-67 began in November 1969 with manufacturing following in February 1970. The Blackhawk first flew on 20 August 1970.

The S-67 featured a five-bladed main rotor and tail rotor. The main rotor was taken from the S-61, but was modified to have a hub fairing, swept main rotor blade tips and a special "alpha-1" linkage which was added to the main rotor controls to increase collective pitch sensitivity and so extend the collective pitch range. The 20° swept main rotor blade tips help to overcome a phenomenon called sub-multiple oscillating track (SMOT) that causes variations in tip track at high Mach numbers. These allowed the S-67 to achieve and maintain high cruise speeds. To reduce drag at high speed, the main wheels retracted fully into the stub wing sponsons. It had speed brakes on the wing trailing edges that could be used to decrease speed or increase maneuverability.

The S-67 was fitted with a moving map display, a hands-on-collective radio tune control, and night vision systems. Its armament included a Tactical Armament Turret (TAT-140) with a 30 millimetres (1.2 in) cannon, and could carry 16 TOW missiles, 2.75-inch (70 mm) rockets, or AIM-9 Sidewinder air-to-air missiles. The Blackhawk was powered by two General Electric T58-GE-5 1,500 shaft horsepower (1,100 kW) engines.

 

General characteristics

Crew: 2

Capacity: Up to 8 troops

Payload: 8,000 lb (3,600 kg)

Length: 74 ft 2 in (22.6 m)

Rotor diameter: 62 ft (18.9 m)

Height: 15 ft (4.57 m)

Airfoil: NACA 0012 Mod

Empty weight: 12,525 lb (5,681 kg)

Max. takeoff weight: 24,272 lb (11,010 kg)

Powerplant: 2 × T58-GE-5 turboshaft engine, 1,500 shp (1,100 kW) each

Rotor system: 5 blades on main rotor, 5 blades on tail rotor

Fuselage length: 64 ft 1 in (19.5 m)

Fuselage height: 16 ft 3 in (4.95 m)

Stub wing span: 27 ft 4 in (8.33 m)

Performance

Never exceed speed: 230 mph (370 km/h) in dive with ducted fan

Maximum speed: 193 mph (311 km/h)

Range: 220 mi (354 km)

Service ceiling: 20,000 ft (5,180 m)