China Civil UAV Theory Questions — Questions 952–961

The control station's operating system does not affect the use of the software, so it need not be checked. Further reading, pre-takeoff ground-station checks: (1) control-station power, antenna, and other connection checks; (2) control-station power check; (3) control-station software check; (4) satellite positioning system check; (5) preplanned route and waypoint check.

The link equipment model does not affect flight safety, so it need not be checked. Further reading, pre-takeoff communications-link checks: (1) link range or field-strength check; (2) flight-stick control-surface and throttle feedback check; (3) external control-box control-surface and throttle feedback check.

When a propeller rotates, besides producing thrust that drives the aircraft forward, it also produces a torque opposite to the direction of rotation. For most UAVs, the propeller rotates counterclockwise (viewed from the nose toward the tail), so it produces a moment that yaws the nose to the left. In a climb, the throttle is larger, the propeller's left-yawing moment is larger, and with other moments unchanged the aircraft tends to yaw left. To balance this leftward tendency, the pilot must use the rudder to produce a rightward moment. In this situation, the rudder should be deflected to the right (hold right rudder) to maintain the flight direction.

Takeoff-and-landing operations are unrelated to cruise. The takeoff-and-landing operator takes part in the takeoff and landing phases of control, and does not take part in the cruise phase.

When a propeller rotates, besides producing thrust that drives the aircraft forward, it also produces a torque opposite to the direction of rotation. For most UAVs, the propeller rotates counterclockwise (viewed from the nose toward the tail), so it produces a moment that yaws the nose to the left. In a descent, the throttle is reduced, the propeller's left-yawing moment decreases, and with other moments unchanged the aircraft tends to yaw right. To balance this rightward tendency, the pilot must use the rudder to produce a leftward moment. In this situation, the rudder should be deflected to the left (hold left rudder) to maintain the flight direction.

When the aircraft is pulled back (the stick is pulled aft), the elevator deflects upward. This produces an additional downward lift on the horizontal tail, raising the nose. As the nose pitches up, the aircraft's angle of attack (the angle between the wing chord line and the direction of airflow) increases. Increasing the pull and decreasing the glide angle helps slow the UAV's descent speed.

The third-turn position is an important point in the UAV landing process; it marks the start of the final stage of landing. The choice of third-turn position directly affects the subsequent flight path. A wrong position can leave less room for adjustment before landing, increase the difficulty of the descent, and cause the aircraft to miss the intended landing point. The fourth-turn position is the last turn point in the UAV landing process and affects landing accuracy and safety. A wrong position can cause an improper landing speed or direction, or cause the aircraft to miss the intended landing point.

A manned aircraft has the person in the aircraft, a first-person view; a UAV has the person outside the aircraft, a third-person view. The UAV takeoff-and-landing operator controls the aircraft's takeoff and landing with an external control box, has no instruments in view, and needs ground personnel to report the values. The two major differences between UAV visual observation and manned visual observation are: (1) a manned aircraft observes the landing field from the aircraft, while a UAV is observed from the landing field; (2) the UAV takeoff-and-landing operator learns instrument reference values from ground personnel reports, while the manned pilot can read the instrument reference values directly.

Go-around procedure: (1) After deciding to go around, promptly and gently apply full throttle, hold direction, and gently pull the stick so the aircraft gradually enters a climb, maintaining the climb state. (2) For a low-altitude go-around, while adding throttle, watch the ground ahead (below 2 m in altitude, if the aircraft is sinking, continue the landing action); after full throttle is applied and the aircraft enters the climb, shift attention to the distance. (3) After the go-around, with 40° flaps and the landing gear down, keep the throttle at 100%. (4) When the flaps need to be retracted, the lift coefficient falls and the aircraft will sink, so pull the stick appropriately to avoid losing too much altitude.

Go-around procedure: (1) After deciding to go around, promptly and gently apply full throttle, hold direction, and gently pull the stick so the aircraft gradually enters a climb, maintaining the climb state. (2) For a low-altitude go-around, while adding throttle, watch the ground ahead (below 2 m in altitude, if the aircraft is sinking, continue the landing action); after full throttle is applied and the aircraft enters the climb, shift attention to the distance. (3) After the go-around, with 40° flaps and the landing gear down, keep the throttle at 100%. (4) When the flaps need to be retracted, the lift coefficient falls and the aircraft will sink, so pull the stick appropriately to avoid losing too much altitude.