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RPM diffrence after prop change


duncan_burdorf
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Can anyone clarify if the following change is a worry?

PAP F200 with:

standard (3 blade) carbon prop = 1400 RPM @ Idle

Wooden (2 blade) prop = 1800 RPM @ Idle

Is this something I should be worried about?

I'm worried that with the new wooden prop the motor will exceed 8000 RPM and that the motor will overheat!

Any suggestions? (Besides don't use full throttle!)

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Can anyone clarify if the following change is a worry?

PAP F200 with:

standard (3 blade) carbon prop = 1400 RPM @ Idle

Wooden (2 blade) prop = 1800 RPM @ Idle

Is this something I should be worried about?

I'm worried that with the new wooden prop the motor will exceed 8000 RPM and that the motor will overheat!

Any suggestions? (Besides don't use full throttle!)

you may have to change the reduction gearing

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Can anyone clarify if the following change is a worry?

PAP F200 with:

standard (3 blade) carbon prop = 1400 RPM @ Idle

Wooden (2 blade) prop = 1800 RPM @ Idle

Is this something I should be worried about?

I think you will have to measure the RPM at full throttle, with the wooden prop fitted .

Paul D

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Hi duncan

I replaced a 3 blader with a 2 (well I use both) without changing the reduction gear. The revs, at idle, picked up a bit with the 2 blade and up a bit at cruise and full throttle, but not over revving. Depends how steep the pitch is on your 2 blader as to wether you will need to change the gearing. If your reaching max recommended revs for your motor, that's how you'll get most thrust ,probably.

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ibbio: The reason is cost! 2 blade wooden cost £210 & 3 blade carbon around £450!

Thanks to Paul D and Flat Top Dave.

I will follow your advice! If it does rev over the recommended 8000 RPM is there anything else I can do as in an ideal world I would like to be able to switch props without having to change components!

Duncan

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Hi Duncan

I hope I'm wrong, but I guess you've had breakages ? I think you would have to change the redrive if your engine over revs. Or change your wooden 2 blade for one with a steeper pitch. The carbon ones have manufacturers numbers which reveal all the info on that set, so it's more likely you get exactly the right ones first time. Not sure if that's available on the cheaper wooden ones.

Do you know your redrive ratio that you're currently running. This question's come up alot on the PPG biglist. I bet if you feed in a search with your engine make and size, redrive ratio and prop diameter, the answer would come up. I might try that for you if I have a minute.

I might have to run for cover after this next comment, but, would you like to own a unit that doesn't smash propellers ?

Back in a bit if I can find the answers you need

Dave

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Hi Guys,

I checked against the standard carb. prop and its all kosher! I'm actually not sure if the prop is a PAP as it has PAP printed on the blades but has AEROBAT.es printed on the top of the prop!

Either way its all kosher!

I did rev my motor to max yesterday and only got as high as 7600 so well clear of the recommended 8000!

Duncan

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