Hi Steve; Hank i believe uses AXI 5320 motors with 19 " three blabe props and 4 5000 Mh batteries he has plenty of power but the cost is way too much for me at a $1000.00 per set and they may be good for opnly 100 flights with the need for 4 chargers at the field and having to run the trucks while charging as the car batteries drop to low volts unless running would make it way too expensive and way too much hassel for me but he proves that large electric is possible. I have been looking at 4 stroke for my second Twin Otter plane would like the 220 gasser it would require cutting into the firewall about 1 inch but would still leave enough room for fuel. I have not checked the length of the OS pumper but may be a better choice the cheapest is the Evolution 35cc I am using on my 1st Twin Otter John