stelarKerbal

As I explained before, even if you set protections, thats not the problem on your kerbal. The problem is, if he is not part of the ship, its calculated as "something else", and thats the problem. the only solution I see is somehow make it part of the physics of the ship, and the only way i know for such is, to set it on a leather. or may be have several command seats so it can jump from one to another (but I am not sure that will work). I will test both theories later.

I think you are not havving actually "aerodinamic" forces, but the problem is just how anything "physical" works on the engine of the game. that saying, it does not happen fully correctly what happens in reality as, "you are inside a plane then the plane velocity is added to you". on thegame as soon as your kerbal "stops" being attached to the chair, its the same as being on the air. the only thing that stops it from falling are the "walls" of the plane, so basically the kerbal has a constant "acceleration" of your plane velocity. someting it "may" help is, besides having it with the chair. before doing what you want to do make it stand up and find a way to put a leder into it, I think that while in a leder is considered to still be part of the plane. solving your issue (as it also allows you for all experiments)