Micro Motor Community

Design principles for ducts?


#1

Hi all,

I’m just designing another whoop style micro build and was wondering about the shape and relative dimensions of the duct. I have a basic understanding of the principles behind ducted props, the coander effect and reduction of tip vortices but was wondering if there are specific formulae for dimensioning such as the lip radius and height of the main shaft etc.

Another question I have is whether whether the curved lip at the top of the duct is even desirable on a multirotor as it seems this works against horizontal flight and I notice recent ducted designs like the king kong tiny7 use straight tubes.

Anyone?


#2

Just to close this, the best information on duct design appears to be here


#3

There’s a fair bit out there, I’d meant to reply to this thread but got distracted and forgot, sorry about that!
The main thing I found us that proper ducts are heavy. But not so heavy that they’re automatically not worth it on larger quads.
Of course, larger quads also already have a ton of power.

If you do something/anything with ducts, please let us know though!


#4

My interest is in creating a tiny whoop style quad (3D printed and using 0703 motors and the new 16x16 1S stack from BG) but experimenting with the duct shape to try to incorporate the lift generating feature in addition to reducing tip vortices. Judging from the data in the linked article, the duct shape on most TW quads is neither optimal for increasing prop efficiency (the gap between the duct and the prop tip is a lot bigger than the 1% figure quoted from the research) nor do they have the proper shape to produce lift from the air moving over the duct lip.

I realize the lift generation only really works when the duct is roughly level but for an indoor quad this is probably the case enough of the time that it might extend flight times a worthwhile amount.

It’ll be fun to try anyway :slight_smile:


#5

I’m looking for the same frame, but I need a low profile mount for camera.

See my thread on thingiverse: http://www.thingiverse.com/thing:1676674/#comment-1298692

I think that e010 ducts are right for lift effect compared to weight. Also the curved bevel help to keep durability.


#6

This is interesting, his conclusion is that ducts don’t work (but strut angle is important)? http://www.shendrones.com/goldberg/