I am running an OS .46 FX, I just broke my 11 X 5 Prop for it. I have a couple of other props kicking around, please let me know if I should not use the prop on the plane:

11 X 9 APC
11 X 4 APC
10 X 7.5 Master Airscrew (3 blade)
10 X 5 Master Airscrew
10 X 6 Master Airscrew (3 Blade)

Will I be way overproping the engine with the 11 X 9, or under proping with the 11 X4? Really looking for the best short term option, I will not be able to get to the LHS until Friday and want to fly tomorrow.

Thanks for your help.

11 x 4 will be the best short term option

manks,

I'd run the 10 X 7.5 threeblade and see how it does. The 10 X 6 or the 10 X 5 is going to turn up alot more. The 11 X 9 IMO is just to much prop and the 11 X 4 ????? Whatever your choice is remember you control the throttle. So a flatter pitch is OK the speed of the airplane will be slower, but the takeoff and climb enhanced. Just don't run at full throttle all the time with a lower pitched prop if you don't need the power. Power management is a great tool once learned.

Thanks, I slipped the 11 X 7.5 on the plane for now, I will bring a couple of other props with me, I agree on the 11 X 9, I could go to the 10 X 6 if need be as well.

Cheers!

manks

Normally your instruction manual will give a benchmark prop, and options. If all else fails read the instructions. Sorry, don't mean to be smart. But, seriously check the book, or go online to the engine manufacturers web site. They will give you all options.

10x6 three blader is the closest to your 11.5. That is the one I would use.

Just be aware of the effects on changing props out like that. As a rule of thumb, same diameter, lower pitch means higher RPM and more power, but less speed. The opposite is true for going higher in pitch. Changing the diameter with the same pitch will give you lower RPM and lower power, same speed.. eventually.

For your engine, try to experiment with the various props you DO have. Then you can judge by the results of your flying as to what prop you like the best. Once you get a replacement, see if that prop is what you want to use and stick with it. Those small props are relatively inexpensive.. two or three bucks each should not break the bank.. so get two or three of them once you decide that's the size you really want to stick with.

And, always remember.. more noise does not equate to higher power, just more noise and more wear and tear on the engine. Set an RPM limit at full throttle based on a little research, remembering that the manufacturer numbers are usually a bit boastful and usually not attainable. Then stick to a prop that keeps your performance there while maintaining approximately that RPM range ( +/- about 500 RPM is a good starting point but not necessarily the objective. Any good working RPM is good. To low, though, you lose power).

CGr.