Having seen the Air Cadet Grob 109s (Vigilants) in action, I question the suitability of the Rotax 912 for the task.
Day after day, hour after hour, the Vigilants take off, fly a circuit and land. As a result, for a large part of the flight, the engine will be at the low RPMs which give the propeller gear reduction a pounding, due to the resulting torque reversal (the same thing which destroys dual mass flywheels and alternator belts in diesel cars).
The Jabiru 2200 has been proven in the 109; surely a direct drive engine such as this would be a simpler and less trouble-prone powerplant?
Last edited by Mechta; 2nd Nov 2015 at 11:32.