McDonnell XH-20 Little Henry

The McDonnell XH‑20 “Little Henry” was an experimental light helicopter developed by McDonnell Aircraft Corporation in the early 1940s. Conceived in 1943 as a proof‑of‑concept platform, the XH‑20 used a simple coaxial rotor system driven by a 150‑horsepower Franklin engine, making it one of the first United States helicopters to employ an un‑powered tail rotor configuration. Only two prototypes were built, designated XH‑20 and XH‑20A, and they first flew in April 1944 at the company’s St. Louis facility. The aircraft’s compact airframe, open‑cage cockpit and minimalistic control system were intended to demonstrate the feasibility of inexpensive rotary‑wing machines for liaison and observation duties. Although the XH‑20 never entered production, the data gathered on rotor dynamics, vibration mitigation, and power‑to‑weight ratios directly informed McDonnell’s later successful designs, such as the MD‑500 series. The program also helped establish McDonnell’s reputation in rotorcraft engineering, contributing to the post‑war surge in helicopter development across the United States. Today the surviving XH‑20 prototype is preserved at the National Museum of the United States Air Force, serving as a tangible reminder of the early experimental era of American helicopter technology.

McDonnell Aircraft Corporation

McDonnell XH-20 Little Henry

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Design & Classification