Overview

The DSPOILER parameter group configures Differential Spoilers, also known as Split Ailerons, Decelerons, or Drag Rudders.

This control surface configuration is common on flying wings (like the B-2 Spirit) where there is no vertical stabilizer. Yaw control is achieved by splitting the aileron on one wing (opening it like a clam shell) to create drag on that side.

Key Concepts

1. Drag for Yaw

• Yaw Left: Open Left Spoiler (Left Upper Surface Up, Left Lower Surface Down).
• Yaw Right: Open Right Spoiler.

2. Crow Braking

Both spoilers can be opened simultaneously to act as airbrakes, increasing drag for steep descents without increasing airspeed.

• DSPOILER_CROW_W1 / W2: Weighting for how much inner/outer surfaces move during braking.

3. Aileron Match (DSPOILER_AILMTCH)

Ensures that the roll authority is maintained even when spoilers are deployed.

Parameter Breakdown

• DSPOILER_OPTS: Options bitmask.
• DSPOILER_CROW_W1: Weighting for inner control surface.
• DSPOILER_CROW_W2: Weighting for outer control surface.

Integration Guide

1. Outputs: Map 4 servo outputs: Left Outer, Left Inner, Right Inner, Right Outer.
2. Functions: Use 24 (Left Elevon) and 77 (Right Elevon) or specific spoiler functions depending on the mix.
3. Tune: Adjust rudder mixing to get sufficient yaw authority without inducing adverse roll.

Developer Notes

• Library: ArduPlane/servos.cpp
• Complexity: Requires careful mixing to handle Roll (Aileron), Pitch (Elevator), and Yaw (Drag) simultaneously on the same surfaces.