Dependant on the aircraft, would you not still feel the buffeting over the tail as the wing starts to stall at the root? so you still have an indication...
The vane type you are talking about is indeed off battery power and if that is totally dead it will not work, BUT the amount of current it draws, the battery would have to be seriously flat to not operate it.
Last edited by NutLoose; 11th Jul 2007 at 11:43.