The OS manual recommends a broad range of props for the engine:
I will be using fuel with 10% nitro.
I know people who run 14x7 on 91 four strokes, so that seems too big for my
The engine is going in a Goldberg Tiger 60 kit The kit specs list the weight as 7.5 pounds
The kit is described as a sport scale low wing trainer, so I do not expect to be boring holes in the sky. Any guidance on a starting point would be appreciated.
Thanks, SG
Higher pitch/smaller diameter props will give you more speed and less pull. Lower pitch/larger diameter props will give you the opposite. Unless it's a pylon racer, I've found most sport planes to be plenty fast enough with a "pull" prop.
The OS website
Dr.1 Driver "There's a Hun in the sun!"
Mine was happy with a 13 X 6 black MA......
A buddy and myself are flying the GP Venus with O.S. .70 Surpass II engines. We fly a two plane pattern formation thing with them. Anyway, we've been going through props trying different ones to see which we liked best. So far, we've tried the Master Airscrew 13x6, APC 13x6, APC
13x7, Bolly 13.5x6 and the APC 14x6. The prop we liked best is the APC 13x6. It offers enough thrust to hover a 6 Lb plane yet still lets the engine breath. The black Master Airscrew 13x6 is a joke. It just beats the air and hardly makes any thrust at all.The APC 14x6 and Bolly 13.5x6 are actually the same size (go figure) at
13.5x6. And while the Surpass .70 will swing these bigger props fairly well it takes it a long time to spool them up from low throttle and the overall aircraft speed is a little slower than we'd like.The APC 13x7 is just too fast for good aerobatics in my opinion, but you may like a faster plane than I do. If you really want fast I imagine an APC 12x8 would work well, but hovering ability will suffer and downline breaking will be nearly zero.
You have to choose the prop that suits you best.
I hope this helps.
Wiz
Yup, and between being inefficient and flexing, the true pitch is about 3/4 the ratred pitch. APC can't be beaten. Dr.1 Driver "There's a Hun in the sun!"
So could a piece of nylon rope!
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