PhOTOS: (Clockwise from far left) A test flight of the XH-20, flown by Charles R. Wood Jr., chief helicopter test pilot for McDonnell Aircraft; the XH-20 hovers over McDonnell Aircraft’s XHJD-1 Whirlaway, the first twin-engine helicopter; the prototype XH-20, now on display at the National Museum of the U.S. Air Force near Dayton, Ohio. BOEING ARChIVES The first untethered flight of the XH-20 came on Aug. 29, it a “flying jeep” or “aerial motorcycle.” But McDonnell engineers 1947. Initially the XH-20 used propane for fuel, but engineers and the company’s public relations people referred to the XH-20 soon determined that automobile gasoline was sufficient, as Little Henry, from Eleanor Graham’s 1945 children’s book titled and several octane ratings were tested. Through testing and Henry the Helicopter. That name stuck with the Air Force, too. flight evaluation, McDonnell Aircraft and the U.S. Air Force The concept demonstration contract between McDonnell and determined there were several advantages for using ramjet- the Air Force was successfully closed in July 1953. McDonnell powered helicopters, including weight savings and an had accomplished its task of developing and proving the concept increase in load capacity. of ramjet technology for helicopter propulsion. The XH-20 could lift about 500 pounds (225 kilograms). Based on the XH-20 prototypes, McDonnell Aircraft also devel- And it had “excellent controllability,” according to Charles oped the Model 79 “Big Henry” utility helicopter, a larger and more Wood Jr., chief helicopter test pilot for McDonnell. He reported powerful ramjet-powered helicopter for agricultural use. But high that the XH-20 “turns on a spot in either direction; cartwheels fuel consumption and engine noise diminished its attractiveness as and lazy eights are easy for the pilot.” a commercial product, and the project was abandoned. Two XH-20 flying test stands were developed, Little Henry Today, the first XH-20 prototype is part of the collection at the and Little Henry No. 2, a two-seat prototype that flew for the U.S. Air Force Museum at Wright-Patterson AFB, Ohio. n first time on Jan. 4, 1949. henry.t.brownlee-jr@boeing.com With its open frame and steel tube structure, the XH-20 more closely resembled a go-kart than a flying test stand used to dem- Learn more about Little Henry and see a video at onstrate ramjet technology for military helicopters. Some called www.boeing.com/history/mdc/littlehenry.htm BOEING FRONTIERS / OCTOBER 2012 11
Frontiers October 2012 Issue
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