Alternate mounting of motors on a hexacopter

[SamaraMedia]

I saw a photo the other day of a hexacopter that had three motors facing up and three motors facing down alternately around the craft. I've never seen that configuration before and wondered of the pros and cons of the setup. On one hand you could probably get away with running larger props since the tips would not hit as they would in a traditional setup but wondered if it would matter if the larger props would cause an undue amount of prop wash or would I be better served running a Y6 config to be able to use a larger motor prop combo. Right now I'm a little under 800mm so I'm limited to a 14" prop without hitting tips.

Thanks,

John

 

[Scott Drysdale]

It could have something to do with the ability to fold it up tighter to fit into a smaller case in a way that prevents the props from touching.
The FC won't know the difference since you simply configure the 3 wires to each motor as required to achieve the rotation direction required.
I happened to see one brought in by an RCMP officer to a local Hobby shop.
Some of the fold in parts are large klunky and heavy rubber clamps that I have seen somewhere before as just for tent trailers or roof racks....
Here is a web site c/w photo. http://www.chaoschoppers.com/Industrial_UAV.php

 

[SleepyC]

I spoke to Robert Vess (A aerodynamic engineer , works with F1 and Nascar and many airplane manufacturers) about having the prop tips over lap by about 1” and he said there should be no noticeable issues.
That a regular coaxial rig would suffer much worse problems and efficiency loss than just having your prop tips cross a little.

So on a 800mm Hex, the largest size prop you can fly is a 15” by alternating the motors up and down, you could go 16” - 18"

 

[Bartman]

if you hang some yarn or ribbon under the props as they're spinning you'll see there's very little prop wash under the tips and it doesn't really pick up until you're an inch or two under the spinning arc of the props. this would be for about a 14 inch prop so the effect will vary depending on the diameter and design of the propellor blades.
bart

 

[SamaraMedia]

I spoke to Robert Vess (A aerodynamic engineer , works with F1 and Nascar and many airplane manufacturers) about having the prop tips over lap by about 1” and he said there should be no noticeable issues.
That a regular coaxial rig would suffer much worse problems and efficiency loss than just having your prop tips cross a little.

So on a 800mm Hex, the largest size prop you can fly is a 15” by alternating the motors up and down, you could go 16” - 18"

Yeah, that's what I was thinking since right now I'm restricted to 14 max since my build is just shy of 800mm. Would like to get some heavy lift motors and 15" props on 6s if possible.

Thanks

 

[SamaraMedia]

It could have something to do with the ability to fold it up tighter to fit into a smaller case in a way that prevents the props from touching.
The FC won't know the difference since you simply configure the 3 wires to each motor as required to achieve the rotation direction required.
I happened to see one brought in by an RCMP officer to a local Hobby shop.
Some of the fold in parts are large klunky and heavy rubber clamps that I have seen somewhere before as just for tent trailers or roof racks....
Here is a web site c/w photo. http://www.chaoschoppers.com/Industrial_UAV.php

That's the article I was thinking about. Foldability makes sense with the alternate mounting.

Thanks

 

[SamaraMedia]

if you hang some yarn or ribbon under the props as they're spinning you'll see there's very little prop wash under the tips and it doesn't really pick up until you're an inch or two under the spinning arc of the props. this would be for about a 14 inch prop so the effect will vary depending on the diameter and design of the propellor blades.
bart

Thanks Bart, I might have to look a little closer on those MN4008's you're selling...