What is the best airfoil shape for flight in ground effect over water?

  • $\begingroup$ Why closed? The principle of GE vehicle is well known. Which airfoil, which angle of attack to use are valid questions. An hydrofoil is similar to an airfoil. Related: Wing in Ground (WIG) Effect Vehicles. $\endgroup$ – mins May 16 '16 at 0:58
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    $\begingroup$ In my opinion it's unclear because it has several questions, each of which has minor problems. Overall the question fits the "What's your favorite?" or “I use ______ for ______, what do you use?” types that are listed as questions to avoid. My suggestion would be to break up or simplify the question so it's clear what you really want to know. Another way to improve it might be to focus on how you choose the airfoil, not what you should choose, or instead provide specific acceptance criteria so we know what exactly you mean by "best airfoil". $\endgroup$ – Cody P May 16 '16 at 7:34
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    $\begingroup$ I would second @CodyP 's suggestion. This needs to be broken up into a few questions so that all issues can be addressed separately (possibly with links between them.) $\endgroup$ – Jay Carr May 17 '16 at 21:22
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    $\begingroup$ This question has been the subject of a lot of research over the years. You may find this paper in particular to be helpful in answering your question. $\endgroup$ – Juan Jimenez Oct 8 '17 at 20:23
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    $\begingroup$ Optimal airfoil shape has nothing to do with the fact whether the aircraft is ground effect or not. What matters is getting the minimum drag for the operating CL $\endgroup$ – ABCD Jun 15 '18 at 8:09

There are three considerations for this design:

  1. Airfoil shape
  2. Aspect ratio
  3. Dihedral/Anhedral

Airfoil shape: high lift undercambered thick and very forgiving - good idea near the ground Gottingen 436, NACA 4412

Low aspect ratio: lower stall speed, better compression lift from ground effect, more stable in pitch

Anhedralled wings: this actually provides more roll stability in ground effect as the LOWER wing has more lift. Anhdralling also helps "trap" more air underneath the wings for greater lift.

Ground effect designs would be similar for travel over flat land or water. Good info in links provided by @mins and @Juan Jimenez.

  • $\begingroup$ The Achilles Heel of WIG is the instability in pitch as the plane comes out of ground effect and the center of pressure moves forward. Planform shape is a real target of opportunity for making WIG more usable. $\endgroup$ – MikeY Apr 10 '19 at 0:15
  • $\begingroup$ Spruce Goose seemed to do OK. Not sure about that reverse Delta, or constantly flying low. $\endgroup$ – Robert DiGiovanni Apr 10 '19 at 2:18
  • $\begingroup$ I think it left performance gains on the table, though. Anyway, WIGs are cool. $\endgroup$ – MikeY Apr 10 '19 at 11:00

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