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XH-39 (S-59)
Sikorsky XH-39.jpg
Sikorsky XH-39
Role Helicopter
Manufacturer Sikorsky Aircraft
Introduction not produced
Primary user United States Army
Number built 1[1]
Developed from Sikorsky S-52

The Sikorsky XH-39 (manufacturer designation S-59), developed by Sikorsky Aircraft 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 in favor of the Bell UH-1 Iroquois.

Design and developmentEdit

The four-seat XH-39 was powered by one Continental CAE XT51-T-3 400 shp (298 kW) turboshaft engine, a license-built development of the Turbomeca Artouste. 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.[1] 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) in Windsor Locks, CT.[2] The same year, on October 17, 1954, it set an unofficial world helicopter altitude record of 24,500 ft (7,474 m) at Bridgeport, CT.[3]

In addition to the two XH-39's, one S-59, serial number 52004, registration number N74150, was produced for use for company demonstration flights.[2] It has been restored and is now on display at the New England Air Museum, Windsor Locks, CT [4]

VariantsEdit

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)Edit

Sikorsky S-59

S-59 during runup

Data from U.S. Army Aircraft Since 1947[5]

General characteristics
  • Crew: Four
  • Length: 41 ft 0 in (12.50 m)
  • Rotor diameter: 35 ft 0 in (10.67 m)
  • Height: 9 ft 7 in (2.92 m)
  • Disc area: 962 ft² (89.4 m²)
  • Empty weight: 2,105 lb (957 kg)
  • Loaded weight: 3,361 lb (1,528 kg)
  • Powerplant: 1 × Continental CAE XT51-T-3 turboshaft, 400 shp (298 kW)

Performance

  • Maximum speed: 136 knots (156 mph, 251 km/h)
  • Cruise speed: 120 knots (138 mph, 222 km/h)
  • Range: 243 NM (280 mi, 451 km)
  • Service ceiling: 17,900 ft (5,460 m)
  • Disc loading: 3.49 lb/ft² (17.1 kg/m²)
  • Power/mass: 0.12 hp/lb (0.20 kW/kg)

See alsoEdit

ReferencesEdit

Notes
  1. 1.0 1.1 Polmar and Kennedy 1981, p. 288.
  2. 2.0 2.1 http://www.sikorskyarchives.com/S-59.php
  3. "Sets Helicopter Record." Popular Mechanics, February 1955, p. 113, bottom of page.
  4. http://neam.org/index.php?option=com_content&view=article&id=882
  5. Harding 1990, p. 233.
Bibliography
  • Harding, Stephen. U.S. Army Aircraft Since 1947. Shrewsbury, England: Airlife, 1990. ISBN 1-85310-102-8.
  • Polmar, Norman and Floyd D. Kennedy, Jr. Military Helicopters of the World: Military Rotary-wing Aircraft Since 1917.. Annapolis, Maryland: Naval Institute Press, 1981. ISBN 0-87021-383-0.
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External linksEdit

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