Hi Kimmo.
The Tri has a slight lead at the moment…
I ended up using a 35mm two blade.
My opinion is: The most efficient would be a REALLY big single blade prop with a counter balance, which of course would be totally impractical. I think the most sensible option would be a two or three blade, as big a diameter as the model would allow, with lots of pitch. As Ashley rightly points out, rubber motors are high torque engines, and the prop will need lots of bite to stop the motor unwinding too fast. The other option is to gear the prop up if a smaller prop is required.
Here's a notion, what about a geared up prop, and some sort of clock type escapment to control rate of rubber unwinding, perhaps with some sort or servo operated over ride for a throttle… (way too complicated, I know, Just a thought)
I am Intrigued by you paddle idea, I'd like to know more please.
Now that is an interesting model Ashley. Rubber full length of the hull, v drive and tractor prop, unless I'm horribly mistaken? Do tell more…..
Thanks for the encouragement Andy, always welcome!
Aj
Edited By Amy jane September on 28/02/2015 21:35:59