Quote:
Originally Posted by JulianEdgar
Huh? I am using the template nominated in the tools section of the site, the one I have seen used numerous times when purporting to do each of the following (absurd) uses:
- Show where there is separated and attached flow on existing cars
- Guide the shape of rear extensions
- Show how rear spoilers on sedans should be positioned and shaped
- Allow the assessment of the ‘aerodynamic purity’ of cars)
If you want to pick a different template - fine, but it's an equally absurd approach.
I don't know how often it has to be stated, but 'low drag shapes' (let alone any sort of template) are given basically zero coverage in any current textbook on car aero. And it's not because they've forgotten to include it.
So you can either decide that this site has come up with an extraordinary breakthrough in car aerodynamics.... or this site is on the wrong track. I am afraid in any car engineering debates, I always back the professionals over amateurs - and professionals certainly don't use any type of aerodynamic template.
|
1) The 1st-gen Honda Insight and 2nd-gen Prius on are both considered 'Kamm' cars.
2) 'Kamm' was actually Baron Reinhard von Koenig-Fachsenfeld, owner of the German patent for 'K'-form vehicles. While Kamm had lectured on this form of vehicle, Fachsenfeld had already won races with , and sold the technology within the German automotive industry.
3) A great deal of research at the FKFS had to deal with dimensional analysis between Walter E. Lay's ' pseudo-Jaray', multi-element, built-up scale models, and Fachsenfeld's 'tweaking' into bread sliced, vertical truncations.
4) The models could predict where separation would occur. The models could predict the drag coefficient for any given body length, from zero-to-100% body length ( creating a streamlined half-body of revolution).
5) For small Verjungungsverhaltnis, the K-form was always lower in drag than the Jaray form, until a certain, critical ratio of Vejungungsverhaltnis was reached, after which, neither J or K form had any advantage with respect to drag.
6) For the 'short' vehicles, the K-form always offered more usable interior cabin space. Making it a favorite.
7) Lay reported as low as Cd 0.12 for his long-tail ( lang-heck ) model.
8) If my German translation worked out, then Fachsenfeld and Kamm were able to reproduce the same value with their model, which softened the upper tail surface into an arc, rather than a simple straight-sided cone.
9) BamZipPow's 1-wheel trailer roughly follows Lay's original tail architecture.
Pulling the trailer, Bam realizes mpgs unheard of with the 'naked' T-100, even in light of the obvious weight penalty.
10) Hucho wrote that half-bodies could eliminate separation. And produce Cds approaching that of the half-body without wheels, if attention was paid to wheel integration. Something Goro Tamai knows a lot about.
11) This isn't some abstract, theoretical exercise we're talking about. It's simply off-the-shelf-technology, empirically quantified, for 98-years now.
