With a model so big, the tow plane is not always available. So the idea of a self launch system was present from the very beginning. The original has a jet sustainer, mounted behind the main wing spar in fuselage. Because of some bad experiences with another model, we knew that we need a simplicity of a nose mounted drive. And furthermore, it should allow the start without further aids like dollies or similar. With the Fema retractable main gear (wheel diameter 150 mm) we get a comfortable clearance using a 20 x 13 folding prop. For the engine selection I was again consulting a renown specialist Andreas Reisenauer and the following power train was used:
Accumulator 12s 9.000 mAh LiPo
Motor controller Roxxy BL Control 9120-12 120/150 A Opto
Motor Scorpion - HK 5020 - 710 KV
Gear Super Chief 4:1 planet gear polygon 6 x 7
Folding prop Freudenthaler RF 20 x 13 CFK
And it works! With an average consumption of 75 A the prop is turning 7.400 rpm and the model is climbing from 5 to 6 ms-1. The start behaviour is completely harmless, ther is no tendency to nose dive. After less than twenty metres the model is airborne and climbing. The climb angle should be controlled either by manual height control or by flight phase specific trimmer.