Checkboard, you clearly don't understand how an accelerometer works. The IN measures ground speed by integrating the output of three such devices. They consist of a ball and spring. The ball displaces due to the acceleration in exactly the same way as the fluid moves in your balance organs.
As you turn downwind, the fluid moves aft and the pilot percieves a pitch up. The increased groundspeed should induce the optical illusion of pitching down. Does the pilot unwittingly react by continuing the pitch up he is already sensing thereby reducing the airspeed? We know the True airspeed stays constant.
If as you claim everything in the aircraft maintains a constant velocity IN would never work would it ?
[This message has been edited by StrateandLevel (edited 10 February 2000).]