Prop Size
 

I need to downsize the prop on my ASP 40. Currently it is using a 11 x 5, I need to drop down to a 9" if possible. What should I use a 9 x 7 or can I do this???

The reason for the downsize is that it need to be further up from the floats, according to the rules. I would prefer not to make the aircraft stand any taller on the floats.

Thanks

Seems like a reasonable choice under the circumstances. It should be about the right load for the engine however a larger propeller disk with less pitch, like you had with the 11 x 5, would be more desireable on a high drag float plane. Can you do a 10 x 6? No harm in trying the 9 x 7 to see how it works. It may be fine.

Re: Prop
 

Thanks John.. I will pickup a 10 x6 and 9 x7 and try them. Thanks for responding.

I have to agree with John.
A 10X6 would be ideal, if it will fit.
You will lose some pull with a 9X7, but it is fine for the engine.

Ronm

Guys,

What about going to a 3 blade prop to try and gain some of the blade area back by having to drop the diameter? Something like a 9 x 6 3 blade.

Just a thought.

You would need to use a something more like a 9X8 3-blade.
I think you would lose too much going to a 3-blade in this marginal-power situation.
Might be worth a try though!

Ronm

Maybe see if your buddies have a few props in that category to try. Then hook a fish scale on the tail and see what your thrust is. Use your original that was working for you and try to keep near the same. Then you could try it. Might save from buying props you won't use.
John