Quote:
Originally Posted by Xist
I was actually trying to make good use of my time--sleeping!  However, I jumped out of bed at this idea.
For a given body moving through air, does the air itself care the size of the body?
Let's say that we could purchase plastic or fiberglass boat hulls that fit the template perfectly for a Prius. They might be too narrow or wide, but couldn't you cut it down the middle and trim or add spacers?
Now, if that is the ideal taper, what about objects of other sizes? What if you had a big and rounded old bus. I doubt that the corners would fit, but let's say that they do. The shell is too wide, so you cut it down the middle, cut a piece of fiberglass of the correct curve, and attach it. Would you continue at 22°?
If I boat-tailed a go-kart (I bet that you won't dare me to!), would I have the full 0°-22° taper (could I still use part of the theoretical boat tail?) or, since it would be so much shorter (vertically), might I only get to 8°? |
As far as size,the air doesn't know the difference (My Fortran IV professor would kill me for saying that).The air velocity must match such that 'dynamic similarity',or,'verisimilitude' exists for the body as far as Reynolds number is concerned.
If you found a boat hull which at the height of the Prius,happened to match the contour of the 'Template' you could use it for an 'ideal' body.And narrowing would be a must.
I've tried this with the full-boat-tailed trailer project.You'd want to find a better 'candidate' boat than the one I used.
The only parameter that's critical is the overall height above the ground where the body will be the tallest.Everything is scaled from there.
So with the go-kart,you'd probably use the top of the rollbar as your 'peak' and go from there.But bear in mind that you've got to have 'clean' air coming at the tail,so the kart would have to be completely enclosed for it to function.
I have a 21-foot sailboat hull which will become a 5th-wheel RV trailer.
If I live long enough to do it.