SAWE Report - Cal Poly San Luis Obispo

5 Aerodynamics
The major aerodynamic aspects of the Vendetta are cruise lift-to-drag ratio and maximum
subsonic lift coefficients for landing performance. Wing design is critical to both of these
aerodynamic aspects as well as radar cross section. Area ruling was used to minimize the
supersonic wave drag on the aircraft and minimize the aircraft’s fuel consumption over the
mission.
5.1 Wing Sizing
The first aerodynamic aspects of the aircraft that were considered were the wing planform area
and aspect ratio. To select the optimum wing planform area and aspect ratio, the effect of these
two parameters on the specific excess power and fuel consumption over the design mission was
studied. The 1g military specific excess power at an altitude of 50,000 ft (15,240 m) and Mach
number of 1.6 was estimated using engine data and drag estimation based on component skin
friction drag and area ruling. The fuel consumption of the aircraft was estimated by numerically
integrating the engine fuel flow from over the design mission. The additional weight and
maximum cross sectional area of larger wing areas was considered in calculations, however the
mission profile was kept constant and the fuel weight at takeoff was kept constant at 59,250 lb
(26,875 kg). The results shown in Figure 5.1 indicate that a wing planform area of
approximately 1,500 ft 2 (139 m 2 ) and aspect ratio of 2 would maximize specific excess power
and minimize fuel consumption.
97
96
1,600 ft 2
Design Point
1,500 ft 2
Fuel Onboard
Specific Excess Power (ft/s)
95
94
93
92
1,700 ft 2
1,400 ft 2
1,300 ft 2
1,900 ft 2 1,200 ft 2
1,100 ft 2
Wing Area
91
1,800 ft 2 2,000 ft 2 Aspect Ratio 1.6
2.2
2.4
2
1.8
1,000 ft 2
90
57,000 58,000 59,000 60,000 61,000 62,000 63,000 64,000 65,000 66,000
Fuel Consumption over Mission (lb)
Figure 5.1 - Optimization of Wing Area and Aspect Ratio
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