Drag coefficient for antenna installation

[canaero]

For a simple loads calculation, I would like a good reference for drag coefficients of various shapes. Specifically, a cone placed vertically in the airstream as such _/\_ with flow from the side. I would prefer something online as time contraints and resources would preclude ordering textbooks etc.

Many Thanks,
JD

 

[gwolf]

If you can't find any references use the CD for a cylinder and integrate the forces over the length for the different diameters. As a first stab at it just assume a cylinder with mean diameter, then do your loads sums and see where you are. You are likely to be able to assume CD=1 for the whole structure with the base diameter and still get your stresses to work, if so - game over. Bag it, tag it, go home.

 

[RPstress]

Very few convex shapes and no "fair" ones seem to have a Cd much above 1.5 in aircraft-type environments (I may get corrected there). I sometimes use 1.5 as a way to get an initial upper bound.

 

[canaero]

Thanks for the useful info. The antenna described above was an old installation, instead of comparing properties between the old and new, a complete analysis was done for the new antenna to show negligable drag force (new antenna is a simple cylinder sticking up off the fuselage).

JD