FAA Aerodynamics of sUAS 2

Question 1

What is 'pitch' as it relates to sUAS propeller blades?

Accepted Answer

The theoretical distance a propeller would advance through the air in one complete revolution

Answer

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.

Question 2

Why do most multirotor sUAS use counter-rotating propellers on opposite arms?

Accepted Answer

They cancel out the reactive torque effect, preventing the aircraft body from spinning

Answer

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.

Question 3

What aerodynamic principle allows a multirotor sUAS to accelerate into forward flight from a hover?

Accepted Answer

Tilting the aircraft forward converts a portion of rotor thrust from vertical lift into horizontal propulsion

Answer

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.

Question 4

How does increased payload weight primarily affect the hover efficiency of a multirotor sUAS?

Accepted Answer

It reduces hover efficiency by requiring higher RPMs, increasing power consumption and reducing flight time

Answer

Heavier weight requires more thrust, demanding higher motor RPMs that consume more battery power, directly reducing hover endurance and overall flight time.

Question 5

What is 'translational lift' and when does it occur in sUAS operations?

Accepted Answer

Improved rotor efficiency that occurs as the sUAS transitions from hover into forward flight, entering undisturbed air

Answer

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.

FAA - Part 107 Test Practice Test

FAA - Part 107 Test Practice Test

FAA Aerodynamics of sUAS 2