FAA Part 107 Remote Pilot (UAG)Loading and PerformanceHard
A pilot operates a multirotor sUAS at a high-elevation site (10,000 feet MSL) compared to sea level. Which combination of effects should the pilot expect?
- AAir density has no effect on rotor lift production
- BThinner air requires higher rotor RPM to generate lift, increasing current draw and reducing battery endurance
- CThinner air reduces required RPM, extending battery endurance
- DBattery chemistry produces more capacity at high altitude, offsetting reduced air density
Show answer & explanationAnswer & explanation
Correct answer: B. Thinner air requires higher rotor RPM to generate lift, increasing current draw and reducing battery endurance
At high altitude, lower air density means each rotor revolution produces less lift, so the flight controller commands higher RPM to compensate. Higher RPM draws more current from the battery, reducing overall endurance.
Why the other options are wrong
- A. Rotor lift is directly dependent on air density; this option is false.
- C. Thinner air requires more, not less, RPM to maintain lift.
- D. Battery capacity is unaffected by altitude and does not compensate for reduced air density.
High Altitude Effects on Electric sUAS
Reduced air density at high altitude requires rotors to spin faster to maintain lift, increasing current draw and reducing battery endurance.
- Less lift per rotor revolution at altitude
- Higher RPM needed, drawing more current
- Battery endurance decreases at high elevation
Memory trick: Thin air makes rotors spin harder, draining the battery faster.