The Sikorsky XH-39 (manufacturer designation S-59), developed by

Sikorsky Aircraft Sikorsky Aircraft is an American aircraft manufacturer based in Stratford, Connecticut. It was established by aviation pioneer Igor Sikorsky in 1923 and was among the first companies to manufacture helicopters for civilian and military use. Pre ...

in 1954, was the U.S. Army's first turbine-powered helicopter. It was fast and innovative, but ultimately rejected by the

United States Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...

in favor of the

Bell UH-1 Iroquois The Bell UH-1 Iroquois (nicknamed "Huey") is a utility military helicopter designed and produced by the American aerospace company Bell Helicopter. It is the first member of the prolific Huey family, as well as the first turbine-powered helic ...

Design and development

The four-seat XH-39 was powered by one Continental CAE XT51-T-3 400 shp (298 kW)

turboshaft A turboshaft engine is a form of gas turbine that is optimized to produce shaftpower rather than jet thrust. In concept, turboshaft engines are very similar to turbojets, with additional turbine expansion to extract heat energy from the exhaust ...

engine, a license-built development of the

Turbomeca Artouste The Turbomeca Artouste is an early French turboshaft engine, first run in 1947. Originally conceived as an auxiliary power unit (APU), it was soon adapted to aircraft propulsion, and found a niche as a powerplant for turboshaft-driven helicopter ...

. It was developed from a previous Sikorsky model, the H-18 (company model S-52), and had the same layout. It differed in using retractable landing gear, modified tail rotor, and four-blade main rotor. In the end, the U.S. Army selected the Bell XH-40, prototype of the UH-1 Huey. Two YH-18As were modified into XH-39s; one for flight testing and the other for static test. On 26 August 1954, the XH-39 set a world helicopter speed record of 156.005 mph (251 km/h) over a three kilometer closed course at Bradley Field (now

Bradley International Airport Bradley International Airport is a public international airport in Windsor Locks, Connecticut, United States. Owned and operated by the Connecticut Airport Authority, it is the second-largest airport in New England. The airport is about halfw ...

) in Windsor Locks, Connecticut. The same year, on October 17, 1954, it set an unofficial world helicopter altitude record of 24,500 ft (7,474 m) at Bridgeport, Connecticut. In addition to the two XH-39s, one S-59, serial number 52004, registration number N74150, was produced for use for company demonstration flights. It has been restored and is now on display at the New England Air Museum, Windsor Locks, Connecticut.

Variants

;XH-39 :Former YH-18A modified for static testing, not flown and later modified back to YH-18A standard. ;XH-39A :Former YH-18A modified for flight testing.

Specifications (XH-39)

References

Notes

Bibliography

* Harding, Stephen. ''U.S. Army Aircraft Since 1947''. Shrewsbury, England: Airlife, 1990. . * Polmar, Norman and Floyd D. Kennedy, Jr. ''Military Helicopters of the World: Military Rotary-wing Aircraft Since 1917.''. Annapolis, Maryland: Naval Institute Press, 1981. .

External links

"Sikorsky Model XH-39 (S-59)." at Global Security
(accessed 12 May 2008) {{USAF helicopters United States military helicopters 1950s United States military utility aircraft H-039 1950s United States helicopters Single-turbine helicopters Aircraft first flown in 1954