RobRiley, "the feature of double ellipticals is that they excite spanwise flow up to the tip. The idea is to balance the work the wing is doing from root to tip. Ordinarily the tips lose efficiency, so sucking air from the body of the wing increases the speed of flow over that section to the tip rebalances effort.
Hence while the shape of the wing has more area at the bottom than the top (technically lowering CE) the efficiency or work done across the span is meant to be equal."
Here is my problem conceptually, I am a little confused so bear with me : ) Here are some conflicts as I try to think this out.
On a plane, the highest airflow is at the root, from the prop. And it is the dirtiest there too, lots of P factor. On a boat the highest airflow is at the top and it is cleanest there too. Planes design twist in the wing so that it stalls at the root first, they don't want to drop a wing.
Lift mostly comes from the curvature, not just the surface area. So more camber means more lift. So I need to reduce camber towards the tip.
Less camber though, narrows the AOA before stalling, which is exactly the opposite of what I want at the tip. I want a very wide AOA there +/- 15˚ would be great and I can get that with a thick camber.... A thin camber might be +/- 8˚ and if the tip stalls that is huge drag, that is the worst of all possible outcomes.
The tip will have the highest wind, and largest AOA variations so I am almost forced to make it a thick camber, otherwise it is always going to stall....
Theoretically I need an upside down spitfire wing : )
So I think Atlantis got it right, a very thick wing all the way up and design and plan for a higher CoE, maybe just make the wing a little shorter and really optimize the heck out of it. Try and get a CL of 1.2 and .02 drag, it should be doable.
Sailing is backwards in so many ways.
Talador
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Posted by: taladorwood@yahoo.com.au
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