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

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

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

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!

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

See here

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