FAA Part 107 Remote Pilot (UAG)OperationsHard
A remote pilot is preparing for a sUAS flight in an area known for high winds. To ensure stable flight and prevent potential loss of control, what aerodynamic principle should the pilot be most aware of regarding the sUAS's performance in these conditions?
- AInduced drag.
- BStall speed.
- CGround effect.
- DParasite drag.
Show answer & explanationAnswer & explanation
Correct answer: D. Parasite drag.
In high winds, a sUAS needs to exert more power to maintain position or progress against the wind. This increased power demand is primarily to overcome parasite drag, which increases with the square of the airspeed. While induced drag is also present, parasite drag becomes the dominant factor at higher airspeeds, making the sUAS less efficient and potentially less stable in strong head/crosswinds.
Why the other options are wrong
- A. Induced drag is related to lift production and decreases with airspeed, so it's less of a primary concern than parasite drag in high wind conditions.
- B. Stall speed is primarily relevant for fixed-wing aircraft and refers to the minimum speed for lift; sUAS (multirotors) typically don't 'stall' in the same manner, though they can lose lift.
- C. Ground effect occurs when flying very close to the ground, not directly related to high wind performance at altitude.
Parasite Drag
Drag that does not contribute to lift, increasing with airspeed. It includes form drag, skin friction drag, and interference drag.
- Increases with the square of the airspeed.
- Dominant form of drag at higher airspeeds.
- Significant factor for sUAS performance in high winds.
Memory trick: Fast Winds Fuel Parasite Drag