Aerodynamics of sUAS Flashcards
7 cards from real FAA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Aerodynamics of sUAS flashcards as text
In straight-and-level, unaccelerated flight, which statement about the four aerodynamic forces is correct?
Answer: Lift equals weight and thrust equals drag
In unaccelerated level flight, opposing forces must be equal — lift balances weight and thrust balances drag.
What effect does high density altitude have on sUAS rotor performance?
Answer: Rotor efficiency decreases because less dense air generates less lift per revolution
Thinner air at high density altitude means each rotor revolution moves less air mass, reducing lift and requiring higher RPMs to maintain hover.
Which combination of environmental conditions results in the highest density altitude?
Answer: High elevation, hot temperature, high humidity
High elevation reduces pressure, hot temperatures reduce air density, and high humidity displaces denser oxygen molecules — all three factors combine to create maximum density altitude.
What is 'ground effect' as it applies to multirotor sUAS operations?
Answer: Increased rotor efficiency caused by reduced induced drag when flying close to the ground
Ground effect occurs when rotor downwash is interrupted by the ground surface, reducing induced drag and increasing lift efficiency within approximately one rotor diameter of the surface.
As an sUAS enters a steeper banked turn, what happens to the load factor and power requirement?
Answer: Load factor increases and power requirement increases
In a banked turn, the vertical component of lift must still support the aircraft's full weight, so total rotor thrust must increase — raising both load factor and power draw.
What is 'vortex ring state' in the context of multirotor sUAS operations?
Answer: A dangerous condition where the aircraft descends into its own rotor downwash, causing loss of lift
Vortex ring state occurs during a steep, slow powered descent when rotor downwash recirculates back into the rotor disc, causing the rotor to lose lift in a potentially unrecoverable condition.
How does increasing altitude above sea level affect the relationship between true airspeed and indicated airspeed?
Answer: True airspeed is greater than indicated airspeed at higher altitudes
At higher altitudes with less dense air, the aircraft must move faster (true airspeed) to achieve the same dynamic pressure reading (indicated airspeed) as at sea level.