McDonnell XH-20 Little Henry

McDonnell XH-20 Little Henry in the Research & Development Gallery at the National Museum of the U.S. Air Force on December 28, 2015. (U.S. Air Force photo)

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Bensen X-25A Gyrocopter

Bensen X-25A Gyrocopter(front) and McDonnell XH-20 Little Henry(rear) in the Research & Development Gallery at the National Museum of the U.S. Air Force on December 28, 2015. (U.S. Air Force photo)

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McDonnell XH-20 Little Henry

Unlike most helicopters, the Little Henry did not need a transmission or tail rotor. (U.S. Air Force photo)

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McDonnell XH-20 Little Henry

DAYTON, Ohio -- McDonnell XH-20 Little Henry tail section undergoing restoration during Spring, 2016 (photo 1 of 4). This aircraft is on display in the R &D Gallery at the National Museum of the U.S. Air Force. (U.S. Air Force photo)

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McDonnell XH-20 Little Henry

DAYTON, Ohio -- McDonnell XH-20 Little Henry tail section undergoing restoration during Spring, 2016 (photo 2 of 4). This aircraft is on display in the R &D Gallery at the National Museum of the U.S. Air Force. (U.S. Air Force photo)

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McDonnell XH-20 Little Henry

DAYTON, Ohio -- McDonnell XH-20 Little Henry tail section undergoing restoration during Spring, 2016 (photo 3 of 4). This aircraft is on display in the R &D Gallery at the National Museum of the U.S. Air Force. (U.S. Air Force photo)

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McDonnell XH-20 Little Henry

DAYTON, Ohio -- McDonnell XH-20 Little Henry tail section undergoing restoration during Spring, 2016 (photo 4 of 4). This aircraft is on display in the R &D Gallery at the National Museum of the U.S. Air Force. (U.S. Air Force photo)

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McDonnell XH-20 Little Henry

The XH-20 was essentially a test stand built to research ramjet-propelled helicopter rotor blades. The XH-20 first flew in May 1947, but its fuel was delivered through a flexible line from tanks on the ground. In May 1948, it made its first flight with self-contained fuel tanks. Being a test stand, Little Henry was never intended to fly at any appreciable altitudes or distances.

While the XH-20 proved that a helicopter could use ramjet-propelled rotor blades, it was very loud and consumed fuel at a high rate. The XH-20 on display, the only one built and flown, was obtained by the museum in 1953.

TECHNICAL NOTES:
Engines: Two McDonnell-developed ramjets mounted at the rotor tips
Maximum forward speed: About 50 mph
Rotor tip speed: 410 mph
Rotor diameter: 20 feet
Weight: 290 lbs. empty

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McDonnell XH-20 Little Henry

Bensen X-25A Gyrocopter

McDonnell XH-20 Little Henry

McDonnell XH-20 Little Henry

McDonnell XH-20 Little Henry

McDonnell XH-20 Little Henry

McDonnell XH-20 Little Henry