China Civil UAV Theory Questions — Questions 356–365

This question tests discharge rate and battery capacity unit conversion. Option A: 2Ah × 30C = 60A. Option B: 30000mAh × 5C = 30Ah × 5C = 150A. Option C: 20000mAh × 5C = 20Ah × 5C = 100A. Option B has the largest current.

Study note: Ni-Cd has strong memory effect, is cheap, and must not be discharged; otherwise choose lithium batteries. Ni-Cd batteries have severe memory effect and must be fully discharged with high current before charging.

When setting up an ESC, the motor must be connected so it can output signals normally.

The larger the stator coil diameter, the larger the propeller it suits. The greater the stator height, the higher the speed it suits. The 2820 has a 28mm diameter and 20mm height; the 3508 has a 35mm diameter and 8mm height. Clearly the 2820 is taller and the 3508 is thicker.

At high altitude the air is thin, lift is low, the engine takes in less air, and power drops, so power loss increases and flight time decreases.

At high altitude the air is thin and multirotor lift is insufficient, making liftoff difficult. Reducing the aircraft's weight increases the lift available for liftoff and helps it take off successfully. Other options: changing to larger props raises propeller-motor matching issues, and a larger-capacity battery cannot increase power — it adds weight instead.

After the pilot operates the ailerons, the aircraft rolls about its longitudinal axis, changing its roll rate, bank angle, and other flight states. Lateral control moment equals lateral damping moment. In lateral control, every left-right position of the control stick corresponds to a roll rate. For pitch control, stick position corresponds to angle of attack. For directional control, rudder position corresponds to sideslip angle.

The ESC's full name is electronic speed controller (Electronic Speed Control), abbreviated ESC. Depending on the drive motor, ESCs are brushed or brushless. The ESC regulates motor speed according to the control signal. The flight controller sends control signals to the ESC, controlling motor speed indirectly; the device that controls speed directly is the ESC.

A multi-axis aircraft changes heading by changing rotor torque. Heading change is achieved by a rotational moment about the vertical axis, usually called the yaw axis. To produce this moment, a quadcopter adjusts the speeds of two opposite propellers.

Axes of motion: the X, Y, Z axes of the motion coordinate system. Degrees of freedom: forward/back, left/right, up/down movement, roll, pitch, yaw.