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Old Oct 22, 2012, 04:13 PM
jim2wright is offline
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prop direction for 4 engine ??

Hi,

Building my first 4 engine after successful build of a big twin model. Have been thinking about prop rotation directions. Am thinking props counter rotating next to each other. That way air between the adjacent nacelles is moving same direction (tangent to prop arc). Less likely to FOD the prop next to it if there's a problem? Does it matter much?

Thoughts?

Thanks in advance.
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Old Oct 22, 2012, 05:50 PM
Doug Bartley is offline
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JMHO, two outboard props turning CCW (normal) with two inboards CW. I assume this will be electric and reversed props available. Doug
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Old Oct 22, 2012, 05:56 PM
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Quote:
Originally Posted by jim2wright View Post
Does it matter much?

Thoughts?
Nope it does not make much difference at all. Just as in full scale they typically turn the same direction - all of them.

I think you will be hard pressed to tell any difference. And it is hard to find reverse props anyway.

Mike
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Old Oct 22, 2012, 06:31 PM
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Circular direction......
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Old Oct 23, 2012, 06:47 AM
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Quote:
Originally Posted by Zootster View Post
Circular direction......
Plus all sucking and blowing the same way

I have flown twins and fours, with counter rotating props and later changing them to all the same way. There was no noticeable difference in flight or trim, so it's more a case of how you fancy setting up your plane.

Just get the prop rpm within say 300 rpm of each other, even that is not all that important either as things can change some in the air as the props unload. Obviously you don't want them way off.
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Old Oct 23, 2012, 08:43 AM
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Just get the prop rpm within say 300 rpm of each other, even that is not all that important either as things can change some in the air as the props unload. Obviously you don't want them way off.
Funny you should mention that. When I started playing with differential thrust (for Yaw control) it was astonished at how far off you needed to be before one motor would provide sufficient yaw. On the OV-10 with twin large vertical stabs and rudders it was like 70% power from one motor!

It certainly differs model to model but now I start with about 30% differential and move up from there. Amazing.

Mike
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