RE: How to choose propeller?
 

Having much more than a 6 pitch is pretty useless at small fields on typical .15 to .60 size sport planes that have a lot of drag. The engine's power can be put to greater use with your 3-4-5-6 pitch varieties.
If you want a general philosophy to go by, always use the least amount of prop pitch that will get your job done.

RE: How to choose propeller?
 

Excellent summary[sm=thumbs_up.gif][sm=thumbs_up.gif]

RE: How to choose propeller?
 

Thankyou.......it took me several years of lugging around the so called "correct" prop when I first got into the hobby to discover by accident what changing pitch would do in real terms.
The LHS was out of 10x6 and 10x5 props, all they had was 10x4s. I nervously bought a 10x4, put it on my Fox .40 powered Aerosport20 and the 10x4 prop really made that combo come alive!

It gave the plane unlimited vertical
It improved throttle response
It made the carb adjustments less critical [most of all idle speed]
The engine ran cooler
The plane was quicker to recover from "ackward" situations
The length of our 240 foot long runway seemed to double because of the lower landing speeds
Throttle management had a much finer feel

I wish I had tried this sooner, but the 10x6 was the prop that all the experts told me to use.....

RE: How to choose propeller?
 

Hi!
Well... try a RAM 10x6!

RE: How to choose propeller?
 

I have a stinking box of props of all sorts and sizes. Even a couple of broken props in there.. you know, typical parts box for a typical modeler. Over the years, I've collected quite a selection of props.. but it seems that when I really need one of a specific size, there ain't one in that darned box!!! Jeech.. [:@]

RE: How to choose propeller?
 

Guys, I have a query to send and would like to hear your feedback.  I have a World Model P51 Mustang size 46.  Engine is OS 55AX.
I installed a Tru-turn spinner 3" and a 3-blade 13x8 propeller. 

Is this alright or am I killing my engine?

Anybody try 11x8 3-blade on P51 size 46 ?

Thanks in advance.

RE: How to choose propeller?
 

I've run 3-blades on OS46AX and OS55AX engines. The only one I could find to try that came close to working on the 55AX was a Master Airscrew 11.5x6(3), which is a 12x6(3) trimmed in diameter. I used one of the 12x6(3)s that had been flying on one of my OS61FX engines. The 12x6(3)s are a very good choice for that 61 on 3 of my models: AeroWorks Yak 54, AW Extra260, and GreatPlanes Skybolt. However, the prop was too much load for the OS55AX. Trimming 1/8" from each blade wasn't enough, but another 1/8" did the trick. The resulting prop worked well on a TigerII for the short while before I got rid of the plane.

I had wanted to try a MA11x7(3) but never found one. I didn't want to try it enough to make an effort to find the prop because I'm a big fan of prop-swept-area, or more simply of prop diameter.

RE: How to choose propeller?
 

all of this is good information. taste and flight style are important considerations. however, make sure you dont get to far away from factory recomendations. doing so could burn up a motor very fast from overheat or overspeed. as a basic rule, find the average range/load recommended, then if you increase pitch, decrease diameter. if you decrease pitch, increase diameter. try to stay in the recommended rpm range for the motor. to low rpm's is likely to much prop. two strokes have ranges of rpm's where they excel. there is play room, but watch for it and you will find it. the motor should not sound heavily labored at max rpm,s. consider also the plane you are flying. not many are going to try to knife edge and prop hang a trainer; or a high dollar warbird that wasnt designed for that type of flying. can the do it? some, yes. but not all. the more you do the more you learn. but no one is born with the knowledge. your gonna fold em'; crash em; and stall em. but your out there doing it and learning. hope this helps, good luck.