Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

2-blade vs 3-blade

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Old 09-09-2015, 04:27 PM
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rcpollo
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Default 2-blade vs 3-blade

Flying an OS-46 on a 3-blade 10X7.5. Will the plane fly faster on a 2-blade 10X7? The 2-bladed prop weighs 7 grams less, so perhaps I'll get more RPM, but I lose a little bit of the pitch. I can't go to a longer prop because of clearance. is there another prop you might recommend to pick up air speed?

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Old 09-09-2015, 06:09 PM
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MJD
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How do you figure prop weight is going to affect rpm..?

The 10x7 2 blade is going to be less load than a 3 blade 10x7.5, so I expect it to turn more rpm and is likely to bring the engine up the horsepower curve a bit but depends on which model .46. I would expect a bit more speed on a clean airframe - the 10-7 APC - .46 combo is known to pull Quickie 500's along pretty smartly. If you want a similar load then 10-8 is closer but I doubt faster.
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Old 09-10-2015, 03:15 AM
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Thanks. I will try the 10X7 and compare.
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Old 09-10-2015, 11:53 AM
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3-blade prop has more tip loss and requires more power to turn it at = RPM
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Old 09-10-2015, 04:56 PM
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If you choose a 3 blade prop that takes good advantage of your engine's power and gives the airframe adequate thrust, they work just fine. I rarely have a reason to use one, other than curiosity.
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