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.70 Surpass Prop and RPM

Old 06-01-2007, 03:04 AM
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Default .70 Surpass Prop and RPM

I am a new the 4 stoke engine and I am wondering what I RPM I should see for a given prop? Is there a chart I can use as a guide? I plan on trying a 12x8, 13x8, and a 14x7.

Any help would be appreciated.

Tom
Old 06-01-2007, 07:49 AM
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Default RE: .70 Surpass Prop and RPM

13 x 6 high 8 or low 9k range depending on nitro
Old 06-01-2007, 10:23 AM
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Default RE: .70 Surpass Prop and RPM

We don't have a prop/RPM chart available for your engine. We normally prop the engine to turn around 10,000 RPM at full throttle when leaned to just rich of peak RPM. An APC 12 x 8 propeller will usually work well. What you want to do is select a propeller that will give you that RPM on the ground and still fly your airplane the way you want. Go for the RPM first. Larger propellers will turn lower RPM and won't allow the engine to develop its power as well.
Old 07-31-2007, 08:04 PM
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Default RE: .70 Surpass Prop and RPM

The sweet spot I have found with the .70 is an APC 13x7 for most sport planes. this size is a next generation design and looks a little differnt that most of the other APC's in that size range. I had this combo on a sig kadet arf w/floats, around 8 lbs and it got of the water fast. and cruised reall well even with the extra drag of the flots in the air.

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