[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [New Search]
On 29 Aug 2005 at 21:32, Dave Hall wrote: > I would expect the Fastback to have better aerodynamics than the Square simply > from the shape, but then the Squareback is the only wagon I know that doesn't > kick up dirt onto its back window, so i wouldn't be surprised to find it has > unusual aerodynamics. Aerodynamics is a strange mistress. Things don't always turn out the way we expect them to and the best aerodynamic shape is often not the most visually "obvious" one. Wind tunnel tests often bring out unusual results, like the fact that falling raindrops aren't actually the teardrop shape that we all expect. Rather they are kind of rounded in the front and mostly flat on the back. Pretty much like a short lead bullet. This flat-backed bullet shape actually turns out to be a more aerodynamic shape than the teardrop shape we all expect. I'm guessing here, but I suspect that the squareback benefits from this same phenomenum. What I've heard is that a long taper at the rear (the fastback) leads to a long region of turbulence where the air slipping by is trying to tear away from the auto body. The result is a large amount of vortex shedding, which carries away energy. While it seems totally counterintuitive, sometimes it's better to let the air stream break away from the body "cold turkey" rather than tapering off slowly. As to reality, I really don't know, but I don't see fastys going any faster than squares with the same engine. -- ******************************* Jim Adney, jadney@vwtype3.org Madison, Wisconsin, USA ******************************* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~