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Blackhawk

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Not to be confused with the UH-60 Black Hawk

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The Sikorsky S-67 Blackhawk was a private-venture, prototype attack helicopter built in 1970 with Sikorsky Aircraft R&D funds as a NATO rival to the Soviet Mil-24 Hind. A tandem, two-seat aircraft designed around the dynamic drive and rotor systems of the S-61 Sea King, it was designed to serve as an attack helicopter or to transport up to 8 troops into combat.

The S-67 Blackhawk, along with the Bell 309 "King Cobra", was put through a series of flight test evaluations in 1972 by the U.S. Army. Neither aircraft was selected to replace the AH-56 Cheyenne. Instead, the Army chose to create the new Advanced Attack Helicopter program, which would lead to 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 14 December 1970 by flying at 348.97 km/h (217 mph) over a 3 km (1.9 mi) course, and 355.48 km/h (221 mph) on 15 to 25 km (9.3 to 16 mi) course on 19 December 1970. These records stood for 8 years.

As part of internal Sikorsky R&D efforts, in 1974 the S-67 had a 3.5-foot (1.1 m) diameter ducted fan fitted instead of its original conventional tail rotor. The S-67 with fan was tested over 29 flight hours to compare to the conventional tail. In this configuration it reached a speed of 230 mph (370 km/h) in a test dive. The original tail rotor and vertical tail fin were re-installed in August 1974.

The lone S-67 prototype crashed while conducting a low-level aerobatic demonstration at the Farnborough Airshow in September 1974. During a low-level roll maneuver, the nose dropped below the horizon resulting in a momentary descent which eliminated the altitude safety margin for a safe completion of the maneuver. The aircraft struck the ground in a level attitude and immediately burst into flame. Sikorsky test pilot Stu Craig died on impact, and test pilot Kurt Cannon died nine days later from his injuries. Development work on the S-67 ceased after this accident.

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