My Turboprop as an AAS

During a visit to Wieser Modellbau, I saw a 2.2-meter Pilatus B4; its somewhat stocky fuselage is perfect for my project. My initial thoughts were that, because of the small propeller—which would have to fit inside the fuselage nose—I would be forced to increase the RPM. The main shaft and spinner had to be hollow, with enough space for a rod that extends and retracts the fuselage nose using a servo.

Next, I milled an aluminum bearing block to house the motor, the gearbox, and the ball bearing for the main shaft. The entire unit is bolted to the rear plywood spar. The second ball bearing

bearing for the main shaft, and in front of it is the self-turned spinner with the mount for the two propeller blades.

Initial tests confirmed that the design works: As the RPM increases, the propeller blades move outward and are pulled back together by two O-rings as soon as I shut off the motor.

The maiden flight went off without a hitch—it climbed at an angle of about 20–30 degrees, since I wanted a model for flying off a slope. With my AAS (Anti-Stall System), I no longer have to worry about forced landings. I’m very pleased with the result.

Hanspeter Stöckli