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XH-26 Jet Jeep
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Photo:
Robert Deering 10/18/2012 National Museum of the USAF Wright-Patterson AFB (FFO) Dayton, Ohio |
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At the
request of the U.S. Army in 1951, the U.S. Air Force
initiated the development of a one-man, pulsejet-driven
helicopter for observation, liaison and reconnaissance
purposes. This unarmed helicopter had to be collapsible,
capable of aerial delivery to troops in rugged terrain,
and assembled quickly with simple tools. The American
Helicopter Division of the Fairchild Engine and Airplane
Corp. won the design competition and produced the rugged
and uncomplicated Model XA-8. Under the military
designation XH-26, the aircraft first flew in January
1952. Constructed of aluminum, except for the aft fuselage which was laminated fiberglass, the XH-26 did not use any gears. Rather than having an internal engine like other helicopters, the Jet Jeep was powered by two 6.75-inch pulsejets on the end of each rotor blade tip. Designed by American Helicopter, each of these pulsejets weighed 16 pounds and produced 35 pounds of thrust. Started with an internal compressed air system, the engines did not have to be warmed up, and the XH-26 could take off in just 30 seconds. Furthermore, since the pulsejets produced no torque like engines on other helicopters, the tiny, belt-driven tail rotor was not used for anti-torque but to improve directional control. American Helicopter chose the name "Jet Jeep" because the XH-26 would be used like a Jeep in the air, and it could use the same fuel as the Jeep. When collapsed, its 5-foot-by-5-foot-by-14-foot container fit on a trailer towed by the one-quarter ton Jeep. If stripped for air drop, the Jet Jeep weighed less than 300 pounds, and it could be assembled by two men in just 20 minutes. The Army and USAF evaluated five prototype Jet Jeeps, and they proved to be a rugged aircraft with a top speed of 80 mph and a ceiling of 7,000 feet. However, the pulsejets produced so much noise that the Army found the aircraft unsuitable, and cost considerations forced the cancellation of the program. TECHNICAL NOTES: Engines: Two American Helicopter AJ-7.5-1 pulsejets Fuel capacity: 50 gallons Range: 135 miles Endurance: Approx. 2 hours Source: National Museum of the United States Air Force |
