Quote:
Originally Posted by kach22i
Thank you Aerohead for putting this all in one spot.
I assume all of these radius's are modeled on a 90 degree return angle on a flat plane and not some complex curve tapered teardrop form with a NACA foil number.
Let's say one takes a symmetrical cord foil and cuts the fish head off at the thickest point, then puts a 2 inch radius at corners.
How much would that alter the drag coefficient?
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1) Correct, like on a can of SPAM.
2) Kamm and Fachsenfeld did almost exactly what you're describing, but they analyzed the fish head ( It's been called a 'cod's head' ) without the tail, then started adding increments of the tail back on. I'll have to grab those for next time.
3) Fredrick Lanchester analyzed a streamline body with a blunt nose, but I don't remember if Cds were presented. The schematic drawings focused more on turbulence.
4) The performance of the softened, 2" radius would depend on the thickness of the wing section where the cod's head was removed. It would also depend on 2-D closed test section ( attached to, and spanning both walls ), or 3-D testing, unbounded, out in 'free' air, like a solar racer.
It would also depend on if it's a laminar wing or not. If so, anything but the ogival nosepiece would render completely different Cd. It would destroy the Reynolds number.
I'll try and remember to grab things for two weeks from now. I have out of town company for a week, starting Sunday.