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Old May 04, 2012, 05:34 AM
Martin - AKA mr.sneezy
PLMS's Avatar
Adelaide, Australia
Joined May 2004
1,677 Posts
Discussion
Scratch building quad frames, and prop clearance..

I've read hundreds of posts and many many threads on this forum so far, but I've not stumbled across posts discussing the way to size a frame for a quad yet. (yes I used 'search this forum'

Two initial questions - Is there a thread here discussing how to build a quad frame that's 'just big enough' for a certain spec motor and props ?

Then if not, can anybody tell us how much clearance you should have between the blade tips as they arc past the pod carrying the flight control board ?

I'd guess that you'd want enough so that down droughts from the blades does not blast across the pod/board and induce vibration or buffeting. I'd guess that would be bad for a baro sensor as well.
Soooo.... How much clearance seems to be enough ?

A third question while I think of it - Are all X style quad frames 'square', or do any use frame angles that make it longer front to back than the width ?

(My equipment is going to run 10x4.5" or 11x4.7" SF props BTW)

Thanks for any answers.
Martin
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Old May 04, 2012, 01:14 PM
Emress
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United States, SD, Rapid City
Joined Nov 2011
1,935 Posts
the frame should be symmetrical as possible. foam on the FC and balanced blades also help a lot on vibrations. keeping the airflow away from the FC would be good! that would be especially for baro as it measures air pressure. most people put some foam over it to help more.

when i made my cheap CF frame, it was about 6in between each prop and about 5in from the end of the prop to the FC. But you can move them closer if you want. i think it was at least 3in between props(for smaller sport quads)? and then a props length between props for super stable. i dunno, but its so that the air being pushed by the props doesn't interfere with other props. the further the props are apart, the more stable, but slower yaw and flips.

here's mine: http://3.bp.blogspot.com/-7zxSBUVOvg...1600/Done!.jpg
and log: dduino.blogspot.com
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Old May 05, 2012, 12:11 AM
Martin - AKA mr.sneezy
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Adelaide, Australia
Joined May 2004
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Quote:
Originally Posted by sirbow2 View Post
here's mine: http://3.bp.blogspot.com/-7zxSBUVOvg...1600/Done!.jpg
and log: dduino.blogspot.com
Ah, very functional looking, my kind of style.
I noted that you have extra length on the arms past the motor clamps. Is that to 'tune' the arm length to find the stability sweet spot, or to protect the motors a bit from being hit ?
Thank for the info on the prop clearance. Sounds like 3" is a good minimum then so far.
Martin
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Old May 05, 2012, 01:37 AM
Emress
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United States, SD, Rapid City
Joined Nov 2011
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more of a prop protector. i was going to go all the way past the end of the props, but the CF wasn't long enough/ motors not close enough, oh well.
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