Free-flight tests of 45 degree swept wings of aspect ratio 3.15 and taper ratio 0.54 to measure wing damping of the first bending mode and to investigate the possibility of flutter at transonic speeds Page: 2 of 26
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NACA RM L54C22 3 1176 01437 1430
NATIONAL ADVISORY COMMTITEE FOR AERONAUTICS
FREE-FLIGHT TESTS OF 45 SWEPT WINGS OF ASPECT
RATIO 3.15 AND TAPER RATIO 0.54 TO MEASURE WING DAMPING
OF THE FIRST BENDING MODE AND TO INVESTIGATE TEE
POSSIBILITY OF FLTTER AT TRANSONIC SPEEDS
By Burke R. O'Kelly, Reginald R. Lundstrom,
and William T. Lauten, Jr.
Free-flight tests have been made on two pairs of wings of aspect
ratio 3.15, taper ratio 0.54, and 45 sweepback in the transonic speed
range to measure wing damping and to investigate the possibility of flutter.
The first bending and torsional frequencies for the first model were 37
and 148 cycles per second and the corresponding values for the second
model were 51 and 122 cycles per second. The mass ratio of the wings was
similar to that of current fighter-type wings at about 30,000 feet.
Flutter did not occur during either flight. The maximum Mach number of
the first model was 1.50 and for the second model the maximum Mach num-
ber was 1.39. One pair of wings was equipped with small devices to excite
the bending mode of the wings and the total damping was measured from the
The wing-exciting technique as utilized is useful in flutter work
especially in that information can be obtained on flutter susceptibility
even though flutter does not occur.
Free-flight tests at zero lift at transonic speeds have been con-
ducted by the Langley Laboratory to determine the wing-damping character-
istics and to investigate the possibility of flutter of these wings.
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O'Kelly, Burke R.; Lundstrom, Reginald R. & Lauten, William T., Jr. Free-flight tests of 45 degree swept wings of aspect ratio 3.15 and taper ratio 0.54 to measure wing damping of the first bending mode and to investigate the possibility of flutter at transonic speeds, report, October 12, 1954; (digital.library.unt.edu/ark:/67531/metadc60398/m1/2/: accessed January 22, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.