XV-15 litho - NASA's History Office

As the leader of the V/STOL Project
Office, Woody Cook recognized that
the tilt rotor would have a niche for
military and civil applications between
the helicopter (with good hover efficiency,
low speed, and short range) and
higher disc loading concepts such as
the Harrier jet lift VTOL aircraft (with
poor hover performance, high speed
and longer range). With the critical
analytical tools for this concept being
honed and validated by the on-going
industry and Government work, he began to advocate the development of the
proof-of-concept aircraft to management at Ames and NASA Headquarters.
Woody’s colleague on the Army side was Paul F. Yaggy, the director of the Army
Air Mobility Research and Development Laboratory (AMRDL). Yaggy provided
a high level of support for the development of tilt rotor technology by co-funding
the research and by sharing in the staffing requirements. While Woody promoted
the TRRA project to NASA management, Paul advocated the activity to his command
organization, the U.S. Army Materiel Command.
Dr. Irving C. Statler was appointed as the director of the Ames Directorate, U.S.
Army AMRDL in September 1974 and became an enthusiastic and effective supporter
of the tilt rotor research aircraft project. In 1975 the tilt rotor project
acquired another important advocate when Dr. Richard (Dick) Carlson became
the Director of the Army AMRDL.
Project Advocacy
By late 1972, the Director of Ames Research Center, Dr. Hans Mark, recognized
that the technical “homework” had been done and done well, and that the tilt
rotor aircraft was a unique utility that could well serve the civil and military user.
Dr. Mark, therefore, strongly advocated continuing development of the tilt rotor
aircraft and carried this position to NASA Headquarters. During this time,
Langley Research Center, in a NASA/Army activity similar to the joint effort at
Ames, had been investigating the rotor systems research aircraft (RSRA). 21 This
aircraft was a compound helicopter with a changeable configuration that was
flown with and without wings and auxiliary turbofan jet engines. Figure 33
shows the RSRA in flight with the rotors, the wings, and the turbofan engines
installed. It was also flown as a fixed-wing turbofan aircraft with the rotor
removed. The use of the additional lift and propulsion devices would enable
flight research to be conducted on the rotor system and airframe over a broad
21 C. White, Jr., G. W. Condon, “Flight Research Capabilities of the NASA/Army Rotor Systems
Research Aircraft,” NASA TM-78522, September 1, 1978.
Figure 33.
Rotor Systems Research
Aircraft (RSRA).
(Ames Photograph
AC82-0089-17)
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