9 May 1962: The Sikorsky S-64 Skycrane, N325Y, prototype of a heavy-lift helicopter, made its first flight at Stratford, Connecticut. The Skycrane was a turbine-powered evolution of the piston-engined S-60. The United States Army bought six S-64s for evaluation, and then ordered 54 production aircraft, designated CH-54A Tarhe, and 35 CH-54Bs. Sikorsky produced 12 S-64E and Fs for the commercial helicopter market.
The Sikorsky CH-54A Tarhe is a large single-main-rotor/tail rotor helicopter, specifically designed to carry large external loads. In U.S. Army service, it had a crew of five: pilot, co-pilot, third pilot and two mechanics. The third pilot was in a rear-facing cockpit position and flew the helicopter while it was hovering to pick up or position an external load.
The CH-54A is 88 feet, 5.9 inches (26.972 meters) long and 25 feet, 4.7 inches (7.739 meters) high. The main rotor has six blades and turns counter-clockwise, seen from above. (The advancing blade is on the helicopter’s right side.) The main rotor has a diameter of 72 feet (21.946 meters). The main rotor blades have a chord of 1.97 feet (0.601 meters) and incorporate a twist of -13°. The tail rotor has four blades and is placed on the left side of a vertical pylon in a pusher configuration. The tail rotor turns clockwise, as seen from the helicopter’s left side. (The advancing blade is below the axis of rotation.) The diameter of the tail rotor is 16 feet (4.877 meters). The chord of the tail rotor blade is 1.28 feet (0.390 meters).
The helicopter has an empty weight of 19,120 pounds (8,673 kilograms) a design gross weight of 38,000 pounds (17,237 kilograms) and overload gross weight of 42,000 pounds (19,051 kilograms).
The CH-54A is powered by two Pratt & Whitney JFTD12A-4A (T73-P-1) turboshaft engines, each rated at 4,000 shaft horsepower at 9,000 r.p.m. (N2) maximum continuous power at Sea Level, and 4,500 shaft horsepower at 9,500 r.p.m. (N2) for takeoff, 5-minute limit, or 30 minutes, with one engine inoperative (OEI). The maximum gas generator speed (N1) is 16,700 r.p.m. The T73-P-1 is an axial-flow free-turbine turboshaft engine with a 9-stage compressor section, 8 combustion chambers and a 4-stage turbine section (2-stage gas generator and 2-stage free turbine). It is 107.0 inches (2.718 meters) long, 30.0 inches (0.762 meters) in diameter, and weighs 966 pounds (438 kilograms). The helicopter’s main transmission is limited to a maximum 6,600 horsepower.
It has a useful load of 22,880 pounds (10,342 kilograms) and can carry a payload of 20,000 pounds (9,072 kilograms) from a single point cargo hoist.
The CH-54A has a maximum cruise speed of 115 knots (132 miles per hour, 213 kilometers per hour). It’s range is 217 nautical miles (250 miles, 402 kilometers). The CH-54A has a hover ceiling in ground effect (HIGE) of 10,600 feet (3,231 meters) and its service ceiling is 13,000 feet (3,962 meters).
The United States Army has a tradition of using Native American names for its aircraft. Tarhe (pronounced tar-HAY) was a famous chief, or sachem, of the Wyandot People of North America, who lived from 1742–1818. He was very tall and the French settlers called him “The Crane.”
N325Y, the prototype Sikorsky S-64, was damaged beyond repair in an accident near Arboles, California, 19 August 1968. The FAA registration was cancelled.
© 2017, Bryan R. Swopesby