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12-26-2011, 06:35 PM | #1 |
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I am: Stephane L
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large prop/low rpm vs small prop/high rpm
Hello everyone and Merry Christmas. I am trying to wrap my head around the different effects of prop pitch and speed and hoping someone here can help me.
Let's say I have a Park 480 - 910kv spec'd to turn a 10X7 prop. the motor's rated output is 250 watts. Now compare this to a Turnigy 2627 -3800kv spec'd to turn a 4.1 x4.1 prop. this motor's rated output is 260 watts. I realize there would be other things to address - ESC, room for the larger prop, etc - but all things remaining equal - would either one work just as well as the the other on a given plane? Or are there other factors that lend themselves better to high speed props vs low speed? Thanks for any insight provided. |
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12-26-2011, 09:09 PM | #2 |
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I am: Philip A
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Re: large prop/low rpm vs small prop/high rpm
Your forgetting one important parameter: pitch speed (pitch x rpm's)
The larger prop will have a lower speed and more thrust. This is best suited to an scale, aerobatic , or 3D plane. The smaller and faster spinning prop will produce less thrust and more top speed. This setup is best suited to fast pusher jet type plane. |
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12-27-2011, 11:42 AM | #3 |
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I am: Stephane L
Join Date: Dec 2010
Location: Williams Lake, BC
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Feedback: 15 / 100%
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Re: large prop/low rpm vs small prop/high rpm
I think it is starting to kick in-
The low rpm, larger (higher pitch) prop will muscle the plane forward - slow and steady. the high rpm, smaller (lower pitch) prop will only move the plane forward a small amount with each rev, but makes up for it by making lots more revs. The 10X7 will move fwd 7" for every revolution , whereas the 4.1 x4.1 will only move fwd 4.1" for every revolution. But the 4.1 is at 3800kv which is more than 4 X the 910 of the 10 X7. That explains how the smaller, low pitch prop at higher KV makes the plane move faster. Is my logic correct? |
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12-28-2011, 07:08 AM | #4 | |
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I am: Philip A
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Re: large prop/low rpm vs small prop/high rpm
Quote:
Each has their uses, just keep that in mind. I typically use larger props (>7") as they tend to be more efficient and work well with the parkflyer planes I normally fly. |
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12-28-2011, 12:31 PM | #5 |
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I am: Tyler P
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Re: large prop/low rpm vs small prop/high rpm
Don't know if you were just using the 480 as an example or not, but it will handle a 12x6 APC just fine if you have the clearance for one. If you plan to use it in a 40+ inch 3D machine you could even drop the pitch down to a 5 or so. I found the 6 just a bit too torque. My torque rolls would end up spinning way too fast, lol!
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