# How to adjust helicopter parameters, helicopter model version 1

## 0 General information

Please read this file for a description of helicopter parameters.

## 1 Suggested steps

It is assumed that values for mass and inertia already are correct.

1. Copy and modify the values of an existing model.
2. Set all of the following values to zero: `aero.yaw.dist`, `aero.pitch.dist`, `aero.roll.dist`, `aero.yaw.moment_mul`, `aero.yaw.off`, `aero.yaw.cp_to_yaw`, `aero.roll.ForwardToRoll`, `aero.yaw.vane`, `aero.pitch.vane`
3. Start CRRCSim, set wind speed and thermals to zero. Load the model you want to adjust. Save settings. Easiest way to try settings is to just quit CRRCSim (hit 'q'), edit and save parameter file, start CRRCSim again.
4. If `power.fixed_pitch` is set, adjust `aero.pitch.off` and `power.automagic.F` to set maximum climb rate and climb rate at neutral stick.
   For a collective pitch heli, adjust `aero.pitch.off`, `aero.pitch.ctrl` and `power.automagic.F`.
5. Adjust `aero.yaw.ctrl`, `aero.pitch.ctrl`, and `aero.roll.ctrl` for full stick rotation rates in rad/second.
6. Does the heli rotate around the correct point? Adjust its center of gravity.
7. Adjust lift in ground effect with `GroundEffect.climb.mul` and `GroundEffect.climb.exp`.
8. Fly around and adjust `aero.yaw.vane`, `aero.pitch.vane`, and `aero.speed.damp`.
9. Remove `aero.pitch.damp` and `aero.pitch.dist`. They are taken from `aero.roll.damp` and `aero.roll.dist` if they don't exist.
10. Adjust `aero.roll.damp` and `aero.roll.dist`. You may want to tweak `Disturbance.tau_filter` and `Disturbance.time`, too.
11. Do you think `aero.pitch.damp` and `aero.pitch.dist` should differ from `aero.roll.damp` and `aero.roll.dist`? If this is the case: define them.
12. Adjust `aero.yaw.damp`, `aero.yaw.damp_min_rel`, and `aero.yaw.dist`.
13. If the model has a heading lock gyro, set `aero.yaw.HeadingHold` to something greater than zero and `aero.yaw.moment_mul` to one.
    Otherwise, you should ideally increase `aero.yaw.moment_mul` to one and adjust `aero.yaw.off` and `aero.yaw.cp_to_yaw`. Setting `aero.yaw.moment_mul` to something smaller than one makes this easier -- but maybe less realistic.
14. Adjust increase of disturbances in ground effect: `GroundEffect.dist.mul` and `GroundEffect.dist.exp`.
15. Finally, you may want to tweak `aero.roll.ForwardToRoll`.