CH-54 Tarhe carrying an M551 Sheridan tank on a sling mount in Vietnam.

Initial work on the Sikorsky heavy-lift 'sky-crane' helicopter began in 1958, with the S-60. The S-60 was a piston-engined prototype that was equipped with an autopilot for stable hover, and featured a skeletal fuselage with a crew cockpit; the copilot could swivel his seat to face both fore and aft, and control it from either position. The skeletal nature of the helicopter allowed it to carry customizable, underslung 'modules' - nearly 100 troops, a medical outpost, a radar structure, etc.

The first flight of the turboshaft-powered S-64 "Skycrane" was May 9, 1962, with the U.S. Army eventually purchasing 105. Used in Vietnam for transport and downed-aircraft retrieval, it was highly successful, but the 'adaptable' nature of the module system was in fact a limitation: it could be a transport or a skycrane, but not both at the same time. The Boeing CH-47 Chinook gradually supplemented it in combat, although Skycranes remained in U.S. National Guard service until the early 1990s.

The Sikorsky S-65 (CH-53 series) Stallions were designed with multimission capabilities in mind, having learned from the CH-54's lessons, and were much more successful.

Today, Erickson Air-Crane, Central Point, Oregon, USA, operates the largest fleet of S-64 helicopters in the world. After obtaining the type certificate and manufacturing rights in 1992, Erickson remains the manufacturer and world’s largest operator of S-64s. It is traditional to give each S-64 an individual name, such as Andy's Pride in the adjoining picture.

General characteristics

• Rotor Diameter: 21.95 m (72 ft)
• Length: 26.97 m (88 ft 6 in) rotors turning
• Height: 7.75 m (25 ft 5 in)
• Weight: maximum take-off 21,319 kg (47,000 lb)
• Powerplant: two 3579 kW (4,800 shp) Pratt & Whitney T73-P-1 turboshaft engines
• Max Speed: 169 km/h (105 mph)
• Max Range: 370 km (230 miles)
• Climb rate: 1,330 ft/min (405 m/min)
• Ceiling: 18,330 ft (5,600 m)