In 1964, development of the H-16 was initiated in response to a U.S. Air Force requirement for a long range (1432 mi.) Rescue helicopter to pick up (1-1/2 way mission) bomber crews. The YH-16 became the largest helicopter in the world, having a rotor diameter of 82 feet and an overall length (rotors turning) of 134 feet. The fuselage was as large as that of a four-engine airliner and could accommodate three light trucks loaded through a rear ramp.
| YH-16 | |
| Mission | Transport and rescue |
| Crew | 3 |
| Passengers | 40 or 32 Litters |
| Engine | (2) P&W R 2180-11 |
| Horsepower | 1650 Each |
| Rotor Diameter | 82 ft |
| Fuselage Length | 78 ft |
| Weight Empty | 32,000 lb |
| Useful Load | 14,000 lb |
| Maximum Speed | 123 mph |
| Cruising Speed | 110 mph |
| Range | 230 Miles |
| Ceiling w/ Normal Load | 18,000 ft |
Initially powered with two P&W R-2180-11 radial engines (each in an engine room), the YH-16 was the first twin engine helicopter. Later, the YH-16 became the world’s first twin turbine helicopter.
The three blades in each rotor were all aluminum alloy step taper milled skins keeping a ± .002 inch tolerance through their 41 foot radius by a special process developed by Piasecki. The bonded blade was made in four pieces, with two outer skins, a honeycomb filler and a leading edge balance weight which was almost a mechanical fastener of the leading edges of the skins. The first flight of the YH-16 was 23 October 1953. The slow turning speed of the rotors (125 rpm) almost made the blades visible in their rotation and in-flight vibration was loping in character.
The size of the YH-16A fit the power output of the existing 1800 HP Allison T38 gas shaft turbine. However, the T-38 was not a free-wheeling turbine and thus not ideally suited for multi-turbine interconnection. A concept was developed to tune the two fixed shaft turbines to act in consonance. (This concept was later utilized in Air Geep II).
| YH-16A | |
| Mission | Transport and rescue |
| Crew | 3 |
| Passengers | 40 or 32 Litters |
| Engine | (2) Allison YT38-A-10 |
| Horsepower | 1650 Each |
| Rotor Diameter | 82 ft |
| Fuselage Length | 78 ft |
| Weight Empty | 32,000 lb |
| Useful Load | 14,000 lb |
| Maximum Speed | 123 mph |
| Cruising Speed | 110 mph |
| Range | 230 Miles |
| Ceiling w/ Normal Load | 18,000 ft |
The U.S. Army saw the H-16 as an answer to several of its military transport missions and joined in the project. The tall landing gear version was of particular interest since it allowed the rapid attachment of external loads or pods. The detachable pod could carry equipment and the troops could ride in main fuselage. In this way, both troops and their equipment could be landed simultaneously.
The fuselage was designed with a flat bottom to permit slugging a container or other external payload thus eliminating payload swing. Various pods were designed for special functions, including a field operating room, an electronics center, and a mobile repair center. The YH-16A became the world’s first twin turbine helicopter and established an unofficial speed record of 166 mph in 1956.
