ptuxbury

Hello all,

I'm trying to find a 3-blade prop to best fit with my Magnum XL 91RFS four stroke engine. I think the ideal 3-blade would be 13x6, 13x7, or 14x6, but I cannot seem to find anyone who makes these size plastic props.

I know Master Airscrew makes a 13x8, but I think that the extra inch in pitch might be too much. I also know Graupner makes a 12.5x7, which I'm considering, but it's going into a warbird though, so I was hoping for that extra 1/2 - 1 1/2" on the diameter for a more scale look.

Thanks,
ptuxbury

carrellh

There are very few 3 blade props available in the range that might possibly work on a 91 four stroke.

I found these, and punched the numbers into ThrustHP to get the "load" numbers. In theory, two props with the same load number will turn the same RPM on a given engine.

Master Airscrew
13x8 342732
14x7 403368
Graupner
12.5x7 256348
xoar, wood props
14x5 288120
14x6 345744

For comparison, here are some two blade load numbers
12x12 248832
13x9 257049
14x6 230496
14x7 268912
14x8 307328
15x6 303750
15x7 354375
16x6 393216

Our club is having a kit building contest and my brother and I will be entering a GP 40 size Corsair that is a tribute to the 3rd place Thompson Trophy Winner at the 1949 Cleveland National Air Race. The engine is a 70 four stroke. I'm buying a 16x8 three blade for the static judging and will switch to a 13x6 two blade for the flying competition.

Hobbsy

My Feedback: (102)

PT, Joe Zingali will put one of these together any way you want it and get it to you quicl]kly.

http://www.zingerpropeller.com/3_bladed_Propeller.htm