PFR - Aerospace Engineering Sciences Senior Design Projects ...

Project Final Report – CUDBF April 30 th , 2009
ASEN 4028: Aerospace Senior Projects
13.2.2.5 Flight Test #6
After the pilot had five flights to practice flying the Buff-2 Bomber, and several initial design
problems had been fixed, the team felt comfortable installing the expensive Eagle Tree telemetry
system on the aircraft. The purpose of flight test #6 was to collect numeric flight data for the first
time on the empty aircraft. The goal was to gather data on takeoff speed, landing speed, top
speed, and average power draw and compare these to the predicted values.
Takeoff and landing speed were calculated using the standard value of 1.3*V stall . Without any
payload, the takeoff and landing speed was predicted to be 25 mph. The actual takeoff and
landing speeds were 27 mph and 23 mph respectively. The slight discrepancy in actual versus
predicted speed is due to the fact that RC aircraft takeoff and landing speeds are based upon pilot
judgment, and nearly impossible to fly at the exact chosen speeds.
After climbing to a safe altitude, the pilot attempted a brief (less than 10 second) full power
acceleration to see if the aircraft could reach the predicted top speed of 100 ft/s (68 mph). The
aircraft reached a top speed of 70 mph, exceeding the 100 ft/s top speed requirement set in the
PDD. The aircraft wasn’t flown at the top speed for an extended period of time because with RC
aircraft, there is a possible risk that the aircraft becomes unstable at such high speeds. A plot of
indicated airspeed versus time is shown in Figure 126. The airspeed is accurate to within 5 mph.
This discrepancy is due to imperfect mounting of the pitot tubes on the aircraft. The top speed
run occurred 130 seconds into the flight and lasted for only 10 seconds, allowing the aircraft to
accelerate from 35 mph to 70 mph (plus or minus 3mph).
70
Indicated Airspeed vs. Time
60
Indicated Airspeed (mph)
50
40
30
20
10
0
0 20 40 60 80 100 120 140 160 180 200
Time (seconds)
Figure 126: Indicated airspeed versus time on flight test #6
Finally, average current draw was predicted to be 20 amps. The average current draw throughout
the flight was 15.5 amps. A plot of the predicted versus actual current draw is shown in Figure
142