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Ground contact

The basic setup is in step 6 of the conversion. This page is the extra detail.

Skids

  • A support's Skid Attach is the structural joint on the skid, not the bottom of the runner. The bottom of the runner comes from the contact area.
  • Supports and contact areas with the same Support Group move together. Keep mirrored groups matched up.
  • More Samples on a contact area covers the shape better without adding extra springs.
  • Leave the hard contact guard, native collider backup and catch settings on. They're what stop the skids sinking into rocks, buildings and edges.
  • Surface materials (grass, dirt, sand, snow, ice) and wet weather change grip and sinking on their own (category 17).

Wheels

  • Bind Compression M and Bind Radial Deflection M tell RFM how squished the strut and tire already are in the model's rest pose.
  • Steering: Steering Mode 0 is fixed, 1 follows the pedals, 2 is a free caster. Steered wheels behind the centre of gravity (a Chinook's aft gear) need Reverse Pedal Steer, so the nose still goes the way you push.
  • Steering Bone (on the strut, 07 Presentation) is a model bone RFM turns by the steering angle, for gear the aircraft's own animation doesn't steer (Mi-8: v_landing_gear_F_base). Steering Bone Axis picks yaw, pitch or roll in the bone's own frame, and Steering Bone Scale -1 flips it.
  • Wheel spin is published in degrees. Only use Rotation Signal Scale −1 if you need to reverse the direction.
  • To estimate a strut spring, take the static load on that strut ÷ how much you want it compressed at rest.
  • Don't know Bind Compression M? If the model sits on its wheels in its rest pose, use the static load on that strut ÷ its spring rate, otherwise use 0. Then check with Draw Ground that every tire is touching the ground when parked.
  • Brakes: the vanilla wheel/parking brake key (Space) brakes every tire with Braked ticked.

Shaking on the ground

If the aircraft shakes or yaws back and forth on the ground, find out why before you throw damping at it. Set one friction axis to 0 at a time (Mu Longitudinal, Mu Lateral). Setting one to 0 only turns off that axis, so you can narrow it down.

Ground Source (16)

0 = contact events with a terrain height fallback (the default, use this one), 1 = contact events only, 2 = terrain height only (the Huey's older setting).