BV: Flight Battery Analysis

For our SUAS team, I calculated the UAV's flight endurance using data gathered during flight testing. Before manufacturing, our team had developed performance estimates based on the planned components and expected aircraft characteristics. Once the UAV was built and flight-tested, we had real performance data that allowed us to develop a more accurate estimate of the actual flight endurance.

Using PX4 flight logs from a test flight, I extracted the battery telemetry (voltage, current) and velocity data in MATLAB. Using PX4 flight logs from a test flight, I extracted the battery telemetry (voltage, current) and velocity data in MATLAB. I then computed the instantaneous power draw (P = V x I) and total velocity from the velocity components, and identified distinct segments of the flight that correspond to either turns or straight-line segments based on the UAV's velocity.

For each segment type, I integrated current over time to find the battery capacity used, and integrated velocity to find distance covered. This gave me an average Ah per turn and Ah per meter on straights, which I then combined with the official competition course parameters (15-waypoint max, 3218.688 m lap distance) to estimate the battery capacity required per full lap, accounting separately for takeoff, cruise, turning, and landing power draw.

I estimate a lap time of approximately 4.8 minutes and a per-lap battery draw of ~1.23 Ah. Scaling this to a 7-lap mission, which was are target lap amount, my calculation showed the battery would fall short by approximately ~1.5 Ah, including the safety margin. This indicated that the team's pre-manufacturing endurance estimate had been too generous. This drove a new mission plan focused on minimizing UAV weight to recover the needed margins.