xray328

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I'm going to use a 3 blade prop on an OS. 40 that currently uses a 10x6 two blade prop. What pitch/diameter do I need to get the same speed/thrust as the 2 blade? I'm just using the 3 blade to get an authentic look on a warbird type. What 3 blade would you use to equal a 2 blade 12x4?

Thanks!

Flak

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xray328,
I use Master Airscrew carbon fiber 3 bladed props all the time. I hve an OS40LA with a 9x7 (if I recall correctly) 3 bladed prop on my military Stinson Reliant...Looks and flies great with that propeller. Try it. Good luck.

jaka

Hi!
Sorry, but a small 3-blade prop would not look that good on a warbird as the diameter would not be large enough to be scale looking...and most importantly ...that prop wouldn't work as good as a two blade prop!
Instead go with a two blade 11x5 -11x6 or even 12x4 APC , RAM or Graupner "cam prop" (not the grey ones, they bad).

/JanK

Flak

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Jaka,
Sorry, but a three blade prop looks just fine and is quite efficient. I have a 3 bladed prop on by T/F Gold Edition P-40 with a ST 90 and it looks and flies great! I am currently finishing a 1/5th P-51B with a ST 3250 that will also have a 3 bladed propeller. What looks rediculous is a P-51D with a 2 bladed prop. Unfortunately, w/o a reduction drive a 4 bladed prop does not do very well. However, I have a T/F 1/7th Scale P-51D powered by an OS 1.08 that I intend to try a 4 bladed prop with soon. The worst that can happen is having to go back to a 2 bladed prop if the 4 blade doesn't work.

jaka

Hi!
I totally disagree ! A 3 or 4 blade prop doesn't look right on a warbird due to the necessary small diameter one has to use in order to have any performance at all.
To have a 1/7 scale Top Flite or the like, P-51 Mustang or Corsair use a 4-blade or 3 -blade prop you must use a 18-20" diameter prop and that isn't possible with a 10-15cc glow engine and besides there isn't any model props that resemble a hamilton standard prop...
Instead the best way to go is to use a big diameter 2-blade prop , preferably a APC. This will give you best flight performance.

Regards!
Jan K

aerowoof

the reason full size war birds use 3 and 4 blade props was ground clearance.with the horsepower the engines had the 2 blade prop diameter would have been too large,so to use all the horsepower the engines developed they used extra blades.remember these props were only turning 2000-3000 rpm and are more efficient at that rpm than a 9 or 10 inch 3 or 4 blade prop turning at 10,000 rpm.we have 2 blade props that will use all an engines hp without a clearance issue,if you want to use a 4 blade prop then use a static 4 blade and use a 2 blade for flying you will see a difference in performance,besides no one can see how many blades you have with the engine running in the air anyway.pattern fliers went to 3 blade props to quiet engine noise not for flight performance

TCrafty

For what it's worth. I've got a Thunder Tiger Lazy Tiger P-51 slow flyer with an OS 46LA on it. I wanted to put a three-blade prop on it so I got the Evolution 3-blader with the spinner cone. I put it on my 40LA first but it didn't fly the way I liked. It would fly, but not with authority. I went to a 46LA and it flies much better. I know that some will say that there's not that much difference but I can tell and I'm happier with it. Sure, it won't hover but it goes up pretty well. I like to throw the plane around a lot and don't typically fly too fast. It works for me and I'd suggest it to someone. I haven't used any other 3-bladed props on it but wondered if it would perform better with a different prop. Maybe someday I'll find out but for now I'm happy. Like I said, for what it's worth.

RICMOD5634

I fly a world star with a OS .46AX and a Master Airscrew 10X7 3 blade and it looks good and provides more than enough power. Mostly I'm flying at half throutle, at full you can't keep it from climbing.