Power unit for Foam Glider

I found these gliders on Amazon and was amazed at the performance. Of course eventually we try to improve on what is already a great product and I decided to add power.
These gliders are virtually indestructible and lend themselves to be easily modified and still retain strength.
The resulting flights are amazing, but be prepared to loose them as they are free flight and fly for a very long time, by putting the tail plane in stunt mode it produces what is best described as a drunken stunt pilot, but at least they stay closer to home.
Before making any alterations, balance the model on your fingertips under the wing to find the centre of gravity and mark with a sharpie, so that you can check the balance after the motor is fitted, you have to remove the dummy cockpit to remove the ball bearing that is fitted as a nose weight.
I have tried various iterations of the power plant but have settled on the one illustrated.
There may be other ways to produce the power plant but since I ha