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
What is 'pitch' as it relates to sUAS propeller blades?
Answer: The theoretical distance a propeller would advance through the air in one complete revolution
Pitch is the theoretical forward distance a propeller travels per revolution based on blade angle — a higher pitch moves more air per revolution but demands more torque from the motor.
Why do most multirotor sUAS use counter-rotating propellers on opposite arms?
Answer: They cancel out the reactive torque effect, preventing the aircraft body from spinning
Each spinning rotor creates reactive torque that would rotate the aircraft body opposite to the rotor's direction; counter-rotating pairs cancel these torques to maintain yaw stability.
What aerodynamic principle allows a multirotor sUAS to accelerate into forward flight from a hover?
Answer: Tilting the aircraft forward converts a portion of rotor thrust from vertical lift into horizontal propulsion
By pitching nose-down, the total thrust vector tilts forward — dividing into a vertical component (lift) and a horizontal component (forward thrust) to produce acceleration.
How does increased payload weight primarily affect the hover efficiency of a multirotor sUAS?
Answer: It reduces hover efficiency by requiring higher RPMs, increasing power consumption and reducing flight time
Heavier weight requires more thrust, demanding higher motor RPMs that consume more battery power, directly reducing hover endurance and overall flight time.
What is 'translational lift' and when does it occur in sUAS operations?
Answer: Improved rotor efficiency that occurs as the sUAS transitions from hover into forward flight, entering undisturbed air
As the aircraft moves forward, rotors continuously encounter undisturbed air rather than recirculating their own downwash, making each revolution more efficient and producing more lift for the same power.
What is the aerodynamic effect of propeller blade damage such as chips, cracks, or nicks on sUAS flight?
Answer: Blade damage causes vibration, reduces thrust efficiency, and can lead to catastrophic failure mid-flight
Even minor blade damage creates aerodynamic imbalance that produces vibrations stressing motor bearings, reducing sensor accuracy, and risking catastrophic structural failure during flight.
What role does the flight controller's IMU (Inertial Measurement Unit) play in maintaining aerodynamic stability?
Answer: It measures acceleration and angular rates, enabling the flight controller to adjust individual rotor speeds to correct attitude deviations
The IMU detects tiny changes in pitch, roll, and yaw many times per second, enabling the flight controller to make rapid rotor speed adjustments that keep the aircraft aerodynamically stable.