What is the formula for rudder command?

• A. DM R (Direction + Magnitude + Rudder)
• B. Heading command
• C. Rate of turn
• D. Rudder angle only

Answer: (A)

The essential idea is that steering input is a complete command that translates the maneuver goal into a concrete control action. The rudder command is expressed as DM R, which stands for Direction + Magnitude + Rudder. This means you specify which way to turn (left or right), how strongly to turn (the size of the turn or yaw rate you want), and the actual rudder position to achieve that turn. Having all three components lets the steering system or autopilot generate the correct actuator input to produce the desired maneuver.

If you only gave a heading target, you’d be specifying the end state rather than the input to reach it. If you only specified a rate of turn, you’d have the result in mind but not the direction and intensity of the input needed to achieve it. If you provided just the rudder angle, you’d have an actuator setting without the intent or required turn magnitude, which can lead to incorrect or suboptimal maneuvers. The DM R formulation combines intent (direction and magnitude) with the actual control input (rudder angle) for a complete command.