drag coefficients for ellipse

Try searching here.

Do you mean a strut or a body of rotation?



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

Greg

I think I mean a strut - its a cross beam of an offshore structure designed to support marine current turbines, and has a major axis dimension of 5m and a minor axis of 1m, and a total length of 30m.

Best not to use Cd, in that case. Assuming you can get enough fineness to prevent separation the usual approach is to use a surface area*skin friction coefficent.

Um, at which point I have to admit I don't know where to find /that/.

Well, here's a formula

R (lbf)=.0089*S (sq ft)*(V(knots))^1.825

Where S is the total surface area. .0089 is for a good surface, increase by 1/3 for a typical marine surface, and it could be anything up to .044

I hope you can find later figures than those, they were taken by Mr Froude!

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

Hoerner - Fluid Dynamic Drag has the answer. Reynolds number must be considered. See my FAQ in the Aircraft Eng. Forum for details on getting the book. It takes a few weeks. If you need to know now, tell me Rn, c, and t of the section, and I can give you an estimate.


Steven Fahey, CET
"Simplicate, and add more lightness" - Bill Stout