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Project Final Report – CUDBF April 30 th , 2009 ASEN 4028: Aerospace Senior Projects Figure 134: Buff-2B airborne during flight test #12 13.2.2.10 Flight Test #13, 14, 15, and 16 The purpose of flight test #13 was to assess the aerodynamic handling qualities of the Buff-2B with the empty water bottle payload (1.0 lbs of payload). Another goal was to trim the aircraft out for future flights with the water bottle payload. After the successful flight test #13, the competition course was marked out in order to begin simulating competition mission #1. Competition mission #1 consisted of two laps flown as fast as possible with the empty water bottle payload. The goal of flight test #14, 15, and 16 was to fly the competition course as fast as possible, compare lap time to the predicted value of 1:00 per lap, and verify the predicted power draw with the empty water bottle payload. The following times represent the time it took to fly two laps from takeoff until crossing the finish line of the second lap while airborne. Flight test #14 = 2:02 Flight test #15 = 2:00 Flight test #16 = 1:58 These flight times closely matched the predicted value of 1:00 per lap, with the pilot improving after each flight attempt. The average power draw was recorded on flight test #15 and was 198 W for the entire flight. This was very close to the predicted value of 200 W. Figures of current draw and battery voltage over time are shown in Figure 135. Battery power usage throughout the flight is shown in Figure 136. 148
Project Final Report – CUDBF April 30 th , 2009 ASEN 4028: Aerospace Senior Projects 35 Amp Draw 25 Battery Pack Voltage 30 24 Amp Draw (amps) 25 20 15 10 5 0 0 20 40 60 80 100 120 140 160 180 200 Time (seconds) Voltage (V) 23 22 21 20 19 18 17 16 15 0 20 40 60 80 100 120 140 160 180 200 Time (seconds) Figure 135: Battery amp draw and voltage versus time on flight test #15 500 Power Usage 450 400 Power Usage (W) 350 300 250 200 150 100 50 0 0 20 40 60 80 100 120 140 160 180 200 Time (seconds) Figure 136: Battery power draw versus time on flight test #15 The largest observed discrepancy is the takeoff current draw was much lower than predicted. The reason for this was the pilot decided it was unnecessary to use full power on takeoff with a very light aircraft, since takeoff distance is a function of weight squared. This is better for the battery pack life as it reduces the heat generated on takeoff. The maximum current draw on takeoff was only 30 amps, compared to 60 amps that can be drawn when needed. Aside from this discrepency in flying style, all other predictions were very close to the predicted value. Some photographs from flight test #13-16 are shown in Figure 137. 149
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PFR - Aerospace Engineering Sciences Senior Design Projects ...

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