XV-15 litho - NASA's History Office

this and an additional contract, Boeing conducted analytical design studies
and performance predictions for a range of tilt rotor hover and cruise operating
conditions. A series of 5-foot diameter proprotors was tested in the Army
7- by 10-foot wind tunnel at Ames (figure 28). Also, to investigate the effect
of model scale on measured performance, 13-foot diameter proprotors of the
same blade configurations were fabricated. Between 1969 and 1973, these
proprotors (as well as others having additional twist configurations) were
tested in the ONERA (Office National d’Etudes et de Recherches
Aerospatiales) 8-meter (26 feet) diameter S-1 wind tunnel in Modane-
Avrieux, France (figure 29), the Ames 40- by 80-foot wind tunnel (figure 30),
and at the Air Force Aero Propulsion Laboratory, Ohio. Test operations covered
a range of axial-flow flight conditions including hover-mode and airplane-mode
flight from slow speeds up to a high-speed flight Mach number
of 0.85. These experimental investigations also examined the changes in
blade twist due to the aerodynamic and rotational loads and the effect of this
“live twist” on cruise performance. The resulting data 19 enabled the validation
of analytical proprotor performance codes by Government and industry engineers.
19 A summary of the results of these tests is provided in “A Summary of Wind Tunnel Research
on Tilt Rotors from Hover to Cruise Flight” by W. L. Cook and P. Poisson-Quinton, presented at
the AGARD- Fluid Dynamics Panel Specialists’ Meeting on the Aerodynamics of Rotary Wings,
Marseille, France, September 13-15, 1972.
Left:
Figure 29.
13-ft. diameter proprotor in
the ONERA S-1 wind tunnel,
France. (Ames Photograph
A98-0905-5)
Right:
Figure 30.
13-ft. diameter proprotor in
the Ames Research Center
40- by 80-ft. wind tunnel.
(Ames Photograph
ACD-98-0209-11)
25