Got a GMS 32 that I plan to use for a speed plane. They call for a 8-6 wood prop for break in and sport flying. The specs say that the practical rpm range for this engine is 2000 to 20000 rpm with peak hp at 18000 rpm. Yes- yes I know that hp doesn't mean anything. They say I should use a wood prop because glass filled ones flex and cause vibrations. Has anyone had any experience with this. If I want speed can I use a 8-7 wood prop? And if so where do I get one? Should I go with a smaller diameter? And what pitch would I use for a 7 in prop? I am new to this so any suggestions are helpfull.

I would not be concerned when using a glass filled prop as long as it is balanced. According to Thrusthp calculator an 8x6 and a 7x10 would have close to the same load. The seven inch would be faster IF the airframe is small/clean enough. You could also take an 8x7 or 8x8 and cut it down to about 7.5". I would use a prop that would unload to atleast 18,000 in the air or around 17,000 rpm on the ground.

If you go to APCs' website, you can order direct from them. They have a great selection of props in that size range. Give us some feedback about what you come up with and how the GMS performs!

Great Thanks for the info. Looked up APC and it looks like I can just about any prop I want. If I take a 8-8 and cut it down, do I cut it at an angle or just straight? I have a good prop balancer so that will be ok. The airframe is strong and sleek. Shouldn't be a problem for this engine. Would love to talk some more but I need to order some props. Will keep in touch. Hope to send pics when I learn how to add them.

I always tried to leave the tip shape like it was manufactured. Cut it and then sand to shape and balance. Post some pics and keep us informed.