They will also caution you as to Max Weight of non-lifting components. There is a battery to be added, as well as the motor. Positioned to hopefully keep the CG the same as it was before. But, when I was asking at the convention about the installation (as it would go very nicely in an HP-11. Lots of prop clearance, too!), about all I got from them was "You must be very careful about the maximum weight of non-lifting parts." This may well keep several designs from having the FES retrofitted.

Steve