Page 3 - Combined_141_OCR
P. 3
2
crease the test Reynolds number in comparison to that of
the very large present day airplanes. For the nonengineers,
Reynolds number of automobiles is a scaling relationship
of vehicle speed and wheelbase. In addition, a test facility
with a very large test section and with very low controlled
speed was necessary to test the upcoming vertical and short
take-off and landing airplanes. These models would have
Fig. 2 - United States Airforce C-5A high energy air (that is, with ejectors) directed toward the
tunnel walls, and that constraint had to be reduced. The
result of these requirements is a tandem test section wind
tunnel shown from the air in Fig. 5. This particular facility
is also a very good size for testing automobiles aerodynam-
ically, and it is the only nongovernment wind tunnel where
aerodynamic testing of automobiles can be accomplished
with low blockage effects. The blockage of a full scale
car in the forward test section is about 3%, and the top speed
is about 115 mph. Speeds obtainable in the downstream test
section reach 200 mph, but the blockage is up to only
6-1/2%. In the aircraft industry, this is truly a low speed
wind tunnel, but it has capabilities of reaching just about
Fig. 3 - Lockheed L-1011 the top of the speed range of even the Formula I type racing
vehicles.
Fig. 4 - Lockheed L-500
Fig. 5 - Low speed wind tunnel
