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Coflow Jet claims that their idea of sucking air from the trailing edge and blowing it out the leading edge improves efficiency.

But this looks like nothing but flow control done wrong to me. And by blowing at the leading edge, they give up on achieving laminar flow(!). They also claim that it increases transonic efficiency.

Does this work?

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    $\begingroup$ Interesting concept. I doubt their assertion that pumping air from back to front uses little energy. Also questionable is the selection of references in their PDF: In all papers the author of the PDF is a coauthor. I guess it works for them if enough gullible investors chip in. $\endgroup$ – Peter Kämpf Nov 3 '20 at 17:37
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    $\begingroup$ First red flag: a patent number in huge font on the first page, as if that proves anything (it doesn't). $\endgroup$ – Sanchises Nov 3 '20 at 20:47
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Amazing! British pioneer JW Dunne proposed this as a propulsion system around 1901 but Sir Hiram Maxim told him it would not work. (ref. unpublished documents in the Science Museum Archive's Dunne collection). Nine years later Henri Coanda built a ducted "jet" plane on broadly similar principles, which failed miserably (The Wikipedia article is not very good, but I know of none better online). But they all failed to understand the opportunities for suction lift, instead trying to exploit it to entrain a greater volume of air and create thrust.

More modern blown-wing systems have tried to improve on suction lift using similar methods, but have always foundered on the power requirements for the blower and structural weight penalties of all that wing ducting.

Here is a PDF from their web site. It appears to achieve high lift/STOL performance through high AoA and the Coanda effect, basically turning itself into a giant blown flap. Alternatively it provides modest forward thrust by stimulating circulation and thus maintaining lift at a slight negative AoA.

Well, it probably does work - see wind tunnel images - but I would also want to see those wing weights, blower power figures and cost-benefit analyses before believing it is any more practicable than yesterday's approach.

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    $\begingroup$ I still can't get the impression of "flow control done wrong" off me $\endgroup$ – Abdullah Nov 3 '20 at 16:24
  • $\begingroup$ "But they failed to understand the opportunities for suction lift, instead of trying to exploit it to entrain a greater volume of air". (Over a greater area of wing). Slots and slotted flaps seem to do the same thing. "Super suction" of migratory bird = lowering slats (lowering AOA too) on a fixed wing. Very well informed, but nothing terribly new here, with benefits only needed at high AOA. Very good + answer. $\endgroup$ – Robert DiGiovanni Nov 4 '20 at 13:46

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