The McDonnell XH-20 Little Henry is a 1940s American experimental lightweight helicopter designed and built by McDonnell Aircraft.
The McDonnell Model 38 was a lightweight experimental helicopter sponsored by the United States Army Air Force to test the concept of using small ramjets 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.
Data from: U.S.Military Aircraft Designations and Serials since 1909