Graupner 50mm 4-Blade for 4mm Threaded Shaft


Graupner 50mm 4-Blade prop for 4mm threaded shaft. Looks good in the pack. PropGr50mm01.jpg (38157 bytes)
Take a saw of your choice and slice a slot for the drive dog on the front of the prop to match the stock nylon prop's slot.  PropGr50mm03.jpg (38140 bytes)
Saw off the rear tip of the prop and the end cap of the threaded brass insert. Saw carefully and sand square. Don't let the brass heat up enough to melt the plastic prop. I left the 4mm threads alone. They just slipped over the 6-32 shaft threads and centered the prop nicely.  PropGr50mm05.jpg (38673 bytes)
The prop looks pretty good mounted. 50mm is the maximum size prop I would try. It just fit by less than 1/16" from the skeg and the hull. PropGr50mm06.jpg (30112 bytes)
This side view shows you why this prop did not perform as well as the cheap, stock prop. It doesn't have much pitch to start with and looses much of that near the tips of the blades. Since it didn't do as well as the stock prop, no further tests were performed. This may be a great prop with other motors however. 


PropGr50mm07.jpg (33043 bytes)