Quote:
Originally Posted by Tesla
I went back and had a look around for some ellipsoid drag data, mainly found info on airships, the one thing was that all these shapes seem to centre on the 2.5 - 4:1 Fineness ratio.
So what's going on there?
If you can take the template or reverse it or use an ellipsoid with the same Fineness ratio and basically get the same drag.
We have a sphere, which I think I read had a Cd of 1, if we put a cone on the front or rear it comes close to the template drag or if we split it and insert a cylinder between the two halves, we again get a drag figure approaching the template.
This has to be related to the boundary layer and it's developement over a distance, the front and rear angles don't change but drag does.
So this suggests to me that in some cases the frontal design may have a significant bearing on the overall drag.
I know that being in the impact/pressure zone there is almost guaranteed attachment with almost any frontal design, but seems to me there is something a bit more subtle there than just plain attachment.
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I spent over 20-minutes addressing all your questions and was rewarded by losing it all when I hit Submit Reply.I've worked on it since yesterday when I saw this post.I'm not going to do it again.
Here's the deal.Forget all about the front of the vehicle.
Buy Hucho's book.It will answer all your questions.