Half the motors upside down and big props. Will it work?

Questions & Answers
1

I want to run 18.5" props on a 1000mm Octocopter frame. As this diagram from eCalc shows they will smack into each other.

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But - if I mount the arms of my octo alternatively motor up, motor down as on my MikroKopter hex:

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Then there is no physical interference. But will I lose efficiency through the disturbed air of one prop interfering with the airflow of the two adjacent [props? Has anyone tried it with overlappng props before.

If I go co-ax then I am in a different mess of problems. Ideally you need different size props and/or different kv motors top and bottom or so I’ve been told. And it’s trial and (expensive?) error to get the best performance.

I looked at eCalc and put in frame dimensions and equipment weights for a set of motors and props being auctioned at the moment. With 12S batteries the maximum take off weight could be over 30kg!

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2

Should be fine. You could keep them all the right way up, and just use a 5mm spacer too.

See here

3

Interesting wee aircraft. Slightly smaller than the one I’m thinking of building. I probably need at least 50mm spacers.