China Civil UAV Theory Questions — Questions 406–415

Camera displacement compensation controls aircraft motion so the camera stays stable despite its existing displacement. This avoids image shake and blur caused by aircraft motion and improves shooting clarity and stability. Unstable aircraft attitude is compensated by the gimbal; motion during flight produces displacement, which requires camera displacement compensation — hence option A.

Study note: when hinge is an option, choose it. A multi-axis aircraft has fixed-pitch rotors and no hinge moment.

A gain antenna is designed to increase radiated signal strength in one specific direction. If the signal is sent in that direction, the receiver may indeed receive a stronger signal, increasing remote control range. But range is also affected by environmental factors, equipment factors, and frequency band selection, so it does not necessarily increase range.

Dihedral changes airflow direction, making the aircraft more stable under crosswinds or disturbances. Dihedral improves stability but does not directly increase maneuverability, which depends more on the power and control systems. Dihedral does not reduce power loss, which depends mainly on the power system, load, and flight mode; and because dihedral makes rotor-plane lift produce extra mutually canceling horizontal components, it may increase power loss.

Yaw motion is achieved by changing each rotor's reaction torque; pitch motion is achieved by changing the speeds of the front and rear rotors on the X axis.

A multi-axis aircraft's mechanical structure is relatively simple, and its propellers generally spin at high speed, controlling flight direction by changing rotor tilt angles. This design consumes more energy to overcome air resistance during flight, reducing aerodynamic efficiency.

A multi-axis aircraft must have more than three rotor axes. Three-rotor UAVs are uncommon; balancing reaction torque requires an additional servo.

According to the relevant diagram, the American (Mode 2) stick layout uses the left stick's up-down movement to control throttle or altitude.

According to the relevant diagram, the Japanese (Mode 1) stick layout uses the right stick's up-down movement to control throttle or altitude.

Revised June 17, 2025. ≤100Wh (commonly within 20000mAh): may be carried on board without declaration. 100–160Wh (e.g., professional equipment batteries): advance airline approval required, maximum 2 per person. >160Wh (e.g., large outdoor power stations): prohibited.