This guide was made in1993 by Paul K Guillows.IT shows a example.It says by modifiing your motor shaftto have a hook,you can use a loop' OF rubber to connect your motor to th propeller.This provides a shock absorbing mount and allows for simple thrust adjustment in the nose bearing. Thats it!I belive as I look at it more they saying hook a rubber between a electric motor and the porp reducing troque.The motor is mounted back in the fuse.Think this way you can use the prop giving to you in the kit they got many set ups they where using D and C size batterys
Found more on the other page.It says This system allows you to build conventional rubber power nose block with simple trust adjustments. allowing the battery and motor mounted closer to the C.G. the system can be converted from rubber to electric and back with in minutes.Cool!