Investigations of the damping in roll of swept and tapered wings at supersonic speeds Page: 7 of 36
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6 NACA RM L53A13
plot. For the triangular wings the values of CZp at Iall three Mach
numbers are presented on one plot. The figure plotted in this manner
allows the theoretical values for isolated wings to be represented by
a single curve independent of Mach number. The theoretical predictions
of tCZ; were obtained from references 1, 2, and 4, according to the
geometric properties of the various wings.
For wings 1 to 28 (figs. 7 to 11), the damping in.roll agreed
quite closely with theoretical predictions for 3 cot A > 1.5. For
p cot A < 1.5, the agreement of the damping in roll with theory became
progressively less as 0 cot A decreased. For each value of PA, the
poorest agreement with theory was found at the lowest value of 13 cot A
obtained. The agreement was poorer for the wings having a taper ratio
of 0.25 than for the wings having a taper ratio of 0; evidence of this
is contained in the following table:
Approximate Minimum value Taper Mach Experimental CZp
value of PA of 13 cot A Wing ratio no. Theoretical PZCp
2.35 0.46 1 0 1.62 o. 804
6 .25 1.62 .563
3.00 .47 2 0 1.62 .642
10 .25 1.62 .382
4.00 .61 2 0 1.93 .555
10 .25 1.93 .439
5.00 .80 2 0 2.41 .519
10 .25 2.41 .403
6.80 1.02 4 0 2.41 .585
13 .25 2.41 .482
By referring to table I, it may be observed that the two wings compared
at each value of A had the same leading-edge-sweep angles and the
same aspect ratios. Thus, the principal difference. in the two was the
difference in the areas of the tip regions. The poorer agreement with
theory for the wings having a taper ratio of 0.25 was probably due to
separation of the flow at the tips and thickness effects. Separation
would cause a smaller pressure differential between the upper and lower
surfaces than that predicted by theory; this, acting on a larger tip
area, would cause a greater loss in lift at the tip of the wing having
a taper ratio of 0.25 than at the tip of the wing having a taper ratio
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McDearmon, Russell W. & Heinke, Harry S., Jr. Investigations of the damping in roll of swept and tapered wings at supersonic speeds, report, March 3, 1953; (https://digital.library.unt.edu/ark:/67531/metadc59536/m1/7/: accessed May 20, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.