Flutter tests of modified SB2U model in 16-foot tunnel Page: 2 of 49
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3 1176014036009 FAL ADVISORY COMMITTEE FOR AERONAUTICS
Bureau of Aeronautics, Navy Department
FLUTTER TflSTS OF MODIFIED SB2U MODrL
IN 16-FOOT TUNNEL
By Theodore Theodorsen, R. P. Coleman,
and N. H. Smith
These tests on the flutter characteristics of the
SB2U model were conducted after the model had been
modified so s to lower its flutter speed. This was
done in order to insure the occurrence of normal flutter
before anticipated skin failures. Such skin failure
appeared imminent near' top speed in the previous test
series already reported. For this' reason the wing
torsion frequency was lowered from 1575 cycles per
minute to 1330 cycles per minute. This latter value is.
closer to the originally intended model value and. so also
the flutter speed, predicted at about 125 miles per hour.
The model was tested to destruction. The value of
the measured fluter speed, however, exceeded the expected
value by more than 20 percent. It must be pointed out
that in the upper range above the predicted flutter speed,
or between 130 and 157 miles per hour, there appeared in all
the vibration records a high frequency response of a remark-
ably constant Crequency and amplitude, which response was
I~ II I
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Theodorsen, Theodore; Coleman, R. P. & Smith, N. H. Flutter tests of modified SB2U model in 16-foot tunnel, report, August 1943; (digital.library.unt.edu/ark:/67531/metadc60879/m1/2/: accessed December 14, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.