Exploring Ducted Props with 3D Printing

[ZFreakyFlier]

A sleep deprived idea came into my head when thinking about an active cooling system for a friend's Mikado, the result was scary, and I may have stumbled into the gateway for EDFs. These 1806 motors used to have an overheat problem when using 6045 bullnoses, but the 5040 3 bladed props kept it perfectly cool, however, when I made this shroud, the amount of thrust it produced increased immensely for the amount of throttle commanded, sounded a lot meaner and louder too. Motor got hot and the ESC got hot too, very interesting results to someone with no experience in EDFs, planning a build that uses smaller props, and a smaller cowl. Now may the whole community make me repent for my sacrilege.

 

[earthsciteach]

Nothing to repent! Ducting props increases efficiency as it decreases the loss of lift at the prop tips, just like winglets do for wings. The smaller the gap between the prop and shroud, the greater the increase. What if the prop was affixed to the shroud so the entire assembly spun? I doubt a 3D printed shroud would hold together, but that would be the greatest increase in efficiency the shroud could offer. At least, I think it would be. The motor would have to spin additional mass, so maybe not.

 

[Konrad]

Spinning the shroud would negate the benefits of the stators to remove the helical slip steam. Then there are the real world concerns with mass and the centripetal loads.

If looking for thrust and at the same time minimizing airframe drag look into the Q-tip prop. Note; the tip does add load to the blade root. Also the added load (work) will require a drop in diameter to stay within the same motor rotor load.
http://www.ridgeaire.com/images/pictures/2207.jpg