SAWE Report - Cal Poly San Luis Obispo

5.3 Wing Thickness
The effect of wing thickness on the performance of the aircraft was studied so that the optimum
thickness could be chosen. Initially a wing thickness of 3% of the chord was chosen based on
existing supercruising aircraft. Increasing the root thickness of the wing was considered to
reduce the weight of the wing. The effects of wing root thickness on wing weight, cross sectional
area, and fuel consumption were studied. The weight of the wing was estimated using the
method presented in Raymer, and the additional cross sectional area was calculated numerically.
The resulting wing weights and cross sectional areas for wing root thicknesses from 3% to 6%
are shown in Figure 5.4. The effect of the resulting weights and cross sectional areas on the fuel
consumption during the mission were estimated using the same method used for the wing sizing.
The results in Figure 5.5 show that the larger cross section of a thicker wing root adds more
wave drag than the induced drag savings from the reduced wing weight. Based on this result, a
constant wing thickness of 3% was chosen.
8,500
8,000
t root = 3%
Weight of Wing (lb)
7,500
7,000
t root = 4%
t root = 5%
6,500
t root = 6%
6,000
14 15 16 17 18 19 20 21 22
Maximum Frontal Cross Sectional Area of Wing (ft 2 )
Figure 5.4 - Effect of Root Chord Thickness on Wing Weight and Cross Sectional Area
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