[1] 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.

[1] As a functional helicopter it was a simple open-frame steel-tube construction.

[1] Allotted the military designation XH-20 the first of two first flew on the 29 August 1947.

[1] 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.

Aircraft of comparable role, configuration, and era