It is an interesting idea about force feedback, but I can't easily read game settings from my dll.
Here is another "head shake" test version:
https://dl.dropboxusercontent.com/u/2918136/cfs/d3d8.20161221.zip
It is more correct now: previous version calculated forces at aircraft's center of gravity, but now they are properly calculated at cockpit location (including gunner stations).
I've also reduced vertical and forward movement, but increased the range of horizontal movement. I believe this is more correct for human body
This version also fixes the old "sky-colored triangles at edges of the screen" issue caused by head rotation when using TrackIR (though stock CFS3 doesn't seem to suffer from it as much as OFF). I'm not sure if there are any side-effects, will be interesting to know.
Finally, the effect is configurable now.
Add 3 lines into d3d8.ini:
OffsetSpring=12
OffsetResponse=6
RotationSpring=24
OffsetSpring and RotationSpring controls how fast the view returns to neutral position, i.e. how strong is the resistance to movement (offset) or rotation.
Minimum value for OffsetSpring is around 4, less than than might cause the view to drift even after a slight shake. Maximum is unlimited but there's probably no difference after 100 or so.
Setting RotationSpring to very low value produces an interesting effect -- the view tries to stay focused on the same point for some time regardless of aircraft rotation.
OffsetResponse basically controls the damping of head shake. Note that higher values means LESS damping, i.e. this parameter defines how quick the view responds to acceleration. It has no effect on rotation.