"The Big Fitz" Drive Unit Trills

The #1 system was a 750 Graupner motor, 1.5 – 1.0 gear reduction, 12v power supply and scratch built gearing motor mount and shaft on a 2 inch prop. She was way over powered and the shaft I scratch built was built wrong. I had problems with the gears trying to drill out the holes to accommodate the 4mm shaft on the 750 motor, and was just plain noisy. 

The #2 system was a 600 Gruapner drive unit with a 2 – 1 gear reduction, scratch built shaft done right this time and the same 2 inch prop. This combination proved to work much better. I’m sure I could get 16 knots out of her, enough power but not to much. Again though it is way to noisy with those big teeth gears.

The #3 system was the same  600 Graupner motor and motor mount, but I used a MFG aircraft belt drive system modified to work with the current mount and shaft. After a few problems worked out, she is running great, and has very little noise.