If you want to fly your 1/4 scale sailplane by yourself with no towplane avaialable ,this is what you need.This is a bolt on electric power pod.
Just fit you 40size( equivilant) elec motor and ESC ,add batteries inside the fuse and go fly.
The ESC fits inside the pod verticle leg and the motor bolts directly to the unit to make a strong integral item.
It is easily removed with 2 nuts and the wiring connectors and then you go back to aerotowing.
Also can be sold complete with motor ,prop and ESC.