The McDonnell XH-20 Little Henry was a 1940s American

experimental An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs when a ...

lightweight

helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...

designed and built by

McDonnell Aircraft The McDonnell Aircraft Corporation was an American aerospace manufacturer based in St. Louis, Missouri. The company was founded on July 6, 1939, by James Smith McDonnell, and was best known for its military fighters, including the F-4 Phantom I ...

Development

The McDonnell Model 38 was a lightweight experimental helicopter sponsored by the United States Army Air Force to test the concept of using small

ramjet A ramjet, or athodyd (aero thermodynamic duct), is a form of airbreathing jet engine that uses the forward motion of the engine to produce thrust. Since it produces no thrust when stationary (no ram air) ramjet-powered vehicles require an as ...

s at the tips of the rotor blades. As a functional helicopter it was a simple open-frame steel-tube construction. Allotted the military designation XH-20 the first of two first flew on the 29 August 1947. Although the XH-20 flew successfully the ramjets were noisy and burnt a large amount of fuel and plans to build a larger two-seat XH-29 were abandoned.

Variants

''Data from:'' U.S.Military Aircraft Designations and Serials since 1909 ;XH-29 ;XH-20 ;McDonnell Model 38:experimental lightweight helicopter, two built. ;McDonnell Model 79:a proposed two-seat development, cancelled.

Operator

; *

United States Air Force The United States Air Force (USAF) is the Aerial warfare, air military branch, service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part ...

Aircraft on display

*''46-689'' the first XH-20 is on display at the

National Museum of the United States Air Force The National Museum of the United States Air Force (formerly the United States Air Force Museum) is the official museum of the United States Air Force located at Wright-Patterson Air Force Base, northeast of Dayton, Ohio. The NMUSAF is the ...

Specifications

References