The McDonnell Aircraft Corporation Tip-Jet, Convertiplane Programs

McDonnell Aircraft Corporation began pursuing rotorcraft technologies shortly after its beginnings in 1939. The course of these developments from the late 40’s was strongly influenced by two engineers from WWII Germany, Dr. Kurt Hohenemser and Friedrich von Doblhoff. In 1949 McDonnell analytically and experimentally explored the benefits of a compound, tip-jet rotorcraft concept operated at unusually high advance ratios under the sponsorship of the Office of Naval Research (ONR). In 1951 McDonnell received three separate contracts; one to develop a Navy assault type helicopter, another for a high speed convertiplane for the Army and Air Force, and a third for a cargo unloader type helicopter for the Navy. The Army and Air Force sponsored XV-1 convertiplane was completed through flight test and became the first rotorcraft to achieve a speed of 200 mph in 1955, reaching an advance ratio of 0.95 in flight. Despite company efforts to sell the technology, no production orders materialized. Attempts were made to utilize the unique technologies for internally sponsored programs, but these ventures yielded little outside interest. By the early 1960’s McDonnell’s management made a decision to direct resources toward fixed wing aircraft withdrawing from their rotorcraft efforts. The XV-1 and other McDonnell designs stand as a unique rotorcraft technology path that was never fully exploited.