In support of an official event 

The Museum will be closed Sunday, May 25
In addition, the Presidential Gallery will be closed Saturday, May 24

Normal hours will resume on Monday, May 26
 

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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