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This is a theoretical question, the belt sander is an analogy to help visualize. How would a rectangular wing that is able to make its outer skin circulate around the airfoil perimeter perform?

Feasibility issues aside, would this contraption help delaying airflow separation at high AoA ?

enter image description here

user721108
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    One prototype of the yov-10a bronco had a rotating-cylinder-flap concept. It enabled a flap deflection to up to 80°, thereby postponning stall. The problem was, that a real wing is bending and therefore the rotating part of this flap has to be designed according to the experienced bending, which was a challenge. Found a report about the concept here: https://blackpony.org/v4-yov10a881nasarep.pdf – Artur Mar 21 '22 at 10:40
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    Related? https://www.youtube.com/watch?v=hBq-gNkBZWw Also-- ultra-simple demonstration of rotating cylinder creating lift-- hold sytrafoam drink cup horizontally, open palm of one hand on top, open palm of other hand on bottom, give it a hard spin as you throw it, if spin direction is such that top surface is moving away from direction of travel (the more natural way to throw it), cup "flies" a long way, if spin direction is such that top surface is moving toward direction of travel, flight path curves sharply earthward and cup quickly hits ground-- – quiet flyer Mar 21 '22 at 12:58
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    I find the belt sander hilarious in an aviation.se post. Look at it chillin'! – George Menoutis Mar 22 '22 at 07:50
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    "now with included de-icing system" – EarlGrey Mar 22 '22 at 14:12
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    Related : Flettner Rotor - related to the Magnus Effect – J... Mar 22 '22 at 17:03
  • You'd want to increase lift by circulating the belt in the opposite direction. As it is, air speed is reduced on the upside and increased on the downside - increasing pressure above and decreasing pressure below the "wing". This works in the opposite direction of desired lift. – Zac67 Mar 22 '22 at 19:34
  • @Zac67 No, you've got it backwards, and for the wrong reasons. Read the Magnus Effect link above. – J... Mar 23 '22 at 12:36
  • @J... The Magnus effect doesn't really apply: it requires the leading and the trailing edges to be exposed to actually redirect the air stream. With flaps like in the diagram, the Bernouilli effect outweighs Magnus and that demands a reversal of the rotation. – Zac67 Mar 23 '22 at 12:59
  • @Zac67 I don't see how that makes sense. I think you need to post an answer with some mathematics. – J... Mar 23 '22 at 13:07

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RE "Feasibility issues aside, would this contraption help delaying airflow separation at high AoA?":

According to a team that tested it, yes:

The major advantages of a Magnus effect device are high-lift forces or rather high wing-loading and stall resistance [...]

Their design housed the treadmill in such a way that only the upper moving surface is exposed. According to their tables, they tested only up to 5° AOA. They acknowledge the complexity and added weight—and I'll add to that, reduced thrust and fuel capacity to power and house the system, respectively.

enter image description here

Side note: if the goal is not a novel STOL RC plane, one popular and tested method for high AOA is leading-edge root extensions (LERX).

  • This is a great find, even if I don't get why they only test a small portion on the upperwing in the first place. Maybe it's the result of previous testings. – user721108 Mar 22 '22 at 08:34