Sikorsky S-67
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| S-67 Blackhawk | |
|---|---|
 S-67 Blackhawk in 1972, flown by Sikorsky Test Pilots Kurt Cannon (rear seat) and Byron Graham (front seat). |
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| Type | Attack/assault helicopter |
| Manufacturer | Sikorsky |
| Introduced | 1970 |
| Status | Destroyed (1974 crash) |
| Number built | 1 |
| Developed from | S-61 |
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.
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[edit] Development
Following the cancellation of the Armed Aerial Fire Support System program and prior to the Advanced Attack Helicopter program, Sikorsky offered an intermediate high-speed attack aircraft based on dynamic components of the S-61 (which evolved into the Sea King helicopter).[1]
The result was the Sikorsky S-67 Blackhawk, which featured a five-bladed main rotor and tail rotor. The main rotor was taken from the Sikorsky 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 that cause variations in tip track at high Mach numbers.[2][3] These allowed the S-67 to achieve and maintain very high cruise speeds. To reduce drag at high speed, the main wheels were made fully retractable. It had speed brakes on the wing trailing edges that deployed as commanded by the pilot, or automatically at a set airspeed to improve dive speed control and reduce pilot targeting workload during firing runs.
The S-67 was fitted with a moving map display, a hands-on-collective radio tune control, night vision systems, a Tactical Armament Turret (TAT-140) with a 20 mm cannon, 16 130 mm TOWs, and 2.75 inch rockets or Sidewinder air-to-air missiles. The Blackhawk was powered by two General Electric T58-GE-5 1500 shp engines.
[edit] Operational history
The S-67 Blackhawk, along with a specially modified Bell 309 "King Cobra", was put through a series of flight test evaluations in 1972 by the Army. Neither aircraft was selected to replace the AH-56 Cheyenne. Instead, the Army chose to create a new program to select an attack helicopter, which would become the AH-64 Apache several years later.
The S-67 performed a series of aerobatic maneuvers during its various marketing tours, including rolls, split-s, and loops. The S-67 was reputed to be very smooth and responsive, in spite of its size and speed.
Piloted by Sikorsky Test Pilots Kurt Cannon and Byron Graham, the S-67 established two E-1 class world speed records on December 14, 1970 by flying at 216.84 mph (188.4 knots) over a 1.86 mile (3 km) course,[4] and 220.85 mph (191.9 knots) on a 15/25 kilometer course on 19 December 1970.[5] These records stood for 8 years. As part of internal Sikorsky R&D efforts, in 1974 the S-67 Blackhawk had a 3.5 foot diameter fan-in-fin fitted instead of its original conventional tail rotor. In this configuration it reached a speed of 230 mph (199.9 knots) in a test dive. The original tail rotor and vertical tail fin were re-installed in August 1974.
[edit] Fatal crash
The lone S-67 prototype crashed while conducting a low-level aerobatic demonstration at the Farnborough Air Show in September 1974, killing Sikorsky test pilots Kurt Cannon and Stu Craig.[6]
Development on the S-67 ceased after this accident.[7]
[edit] Legacy
The aft fuselage and vertical tail design of the S-67 was used as a basis for the Sikorsky S-72 Rotor Systems Research Aircraft (RSRA), which later became the test bed for the X-Wing Stopped Rotor Program.[citation needed]
In 1976, Sikorsky Aircraft lifted the trademark on the name "Blackhawk" and allowed the US Army to assign that name to the UH-60 Black Hawk Utility Tactical Transport System (UTTAS).[citation needed]
[edit] Specifications (S-67 Blackhawk)
This aircraft article is missing some (or all) of its specifications. If you have a source, you can help Wikipedia by adding them.General characteristics
- Crew: 2
- Capacity: 8 troops
- Payload: 8,000 lb ()
- Length: 74.15 ft (22.6 m)
- Rotor diameter: 62 ft (18.9 m)
- Height: 5.0 m ()
- Empty weight: 12,524 lb (5681 kg)
- Max takeoff weight: 24,272 lb (11,010 kg)
- Powerplant: 2× T58-GE-5 turboshaft engine, 1500 shp () each
Performance
- Service ceiling 17,000 ft ()
[edit] See also
Related development
Comparable aircraft
Related lists
[edit] References
- ^ Apostolo, G. (1984). The illustrated encyclopedia of helicopters. New York: Bonanza Books.
- ^ Leoni, Ray (2007) "Black Hawk: The Story of a World Class Helicopter", AIAA, p. 70.
- ^ US Patent: Blade for High Speed Helicopter
- ^ Speed over a straight 3 km course at restricted altitude : 348.97 km/h. Fédération Aéronautique Internationale. Retrieved on 2007-08-05.
- ^ Speed over a straight 15/25 km course : 355.48 km/h. Fédération Aéronautique Internationale. Retrieved on 2007-08-05.
- ^ "1/1976 Sikorsky S-67 Blackhawk, N671SA, Report on the accident at Farnborough, Hampshire", UK Air Accidents Investigation Branch, September 1974.
- ^ Donald, David (1998). The Complete Encyclopedia of World Aircraft. New York: Barnes & Noble Books.
- Derived from text at Historic U.S. Army Helicopters - Modern era helicopters
[edit] External links
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