Aerodynamic Feature
The Aerodynamic Feature turns an authored surface into lift and drag forces. Add one feature for each wing, stabilizer, rudder, or other surface that should react independently to airflow.
The Aircraft Controller only commands Fans and Motors. This feature produces the actual aerodynamic force from the Part's velocity and surface orientation.
Add a surface
- Open a Part Model in the Part Model Editor.
- Add Aerodynamic in the Features panel.
- Place and rotate its Body Local Frame in the viewport.
- Enter the surface dimensions and coefficients, then resolve any validation errors.
- Add another Aerodynamic Feature for every independently positioned surface.
Surface frame
The Body Local Frame defines both the center of pressure and the surface axes:
- X — Chord: Forward-to-back direction of the surface.
- Y — Span: Direction from one side of the surface to the other.
- Z — Normal: Perpendicular to the surface.
Lift and drag are applied at the frame location. Moving it away from the center of mass therefore also produces a turning moment. Transform scale is ignored; use Span Meters and Chord Meters to set size.
Parameters
| Parameter | Description |
|---|---|
| Body Local Frame | Center of pressure and surface orientation relative to the Part Body. Location controls where force is applied. |
| Span Meters | Surface length along local Y. Increasing span increases area and aspect ratio and usually reduces induced drag. Must be greater than zero. |
| Chord Meters | Surface length along local X. Increasing chord increases area but reduces aspect ratio. Must be greater than zero. |
| Lift Slope Per Radian | Increase in lift coefficient per radian of effective angle of attack before stall. Higher values generate more lift at the same speed and angle. |
| Zero Lift Angle Degrees | Angle of attack that produces zero lift. A negative value produces positive lift when the geometric angle of attack is zero. |
| Stall Angle Degrees | Absolute effective angle where lift starts to fall. Valid range is greater than 0 and less than 89 degrees. |
| Base Drag Coefficient | Drag present even at a small angle of attack. Higher values reduce top speed and glide distance. |
| Span Efficiency | Wingtip efficiency from 0.01 to 1. Values closer to 1 reduce induced drag for the same lift. |
| Angle Drag Coefficient | Additional drag as angle of attack increases. It slows a surface that is strongly misaligned with airflow; it is not rotational damping. |
| Span Drag Coefficient | Drag against velocity along local Y. Increase it to suppress spanwise sideslip. |
| Enabled | Includes or excludes this surface from runtime aerodynamic calculation. |
Surface area is Span × Chord. Lift and drag grow with both area and the square of airspeed, so changing dimensions or speed can have a much larger effect than changing a Controller gain.
Tuning guide
- Confirm the frame axes before changing coefficients. A rotated or reversed frame produces forces in the wrong direction.
- Match Span and Chord to the physical surface.
- Tune Lift Slope and Zero Lift Angle until level flight is possible at the intended speed.
- Set Stall Angle for the desired high-angle behavior.
- Tune Base, Angle, and Span Drag after lift is stable.
- Tune the Aircraft Controller last.
If the aircraft pitches or yaws unexpectedly, inspect the force application location and center of mass before increasing damping. A correct force at an offset location naturally creates torque.