Quote:
Originally Posted by JulianEdgar
Why pick that one? Why not pick one of the five differently shaped ones shown in the video? No doubt we could find lots of cars that match those five too. So what does all that mean? Absolutely nothing. Using a template - any template - is just absurd. If only it were as simple as following a template....
The angled extension reduces the wake size, as evidence by the dust. Typically, a reduced wake size = reduced drag. As you say that is not definitive, but it's a guide that is right most of the time. But by all means do some pressure testing x area and let us know the results - I don't have a monopoly on testing.
I am not sure what you mean? None of my modifications in the book were done following a template (any template) and no template is mentioned (let alone lauded) in my description of any modifications in the book. That reflects the professional literature, where 'pure shapes' are given typically only a few pages in a full book - they're simply not that important in the real world. Reading only professional literature and doing my own testing, I'd never even heard of a template when I wrote the book. Had I done so, I would have spent some pages debunking the approach.
Basically, people here have been sucked-in over a long period of time by a completely fallacious approach, vehemently argued by someone who hasn't even read a professional aero textbook more recent than 1987.
As I said in the video, you need do only the most rudimentary testing on a variety of cars to see that much of what is said here about the template is just rubbish. It's no coincidence that those people here who have actually done that testing are also those that most question the validity of the template approach.
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I would pick "that one" because it is the one most people on here use. Also based on your comments on what you believe it is supposed to represent it would be the more accurate one to use. (Not that I believe the claims asserted of what "the template" means.) I realize the main basis of your video is that "the template" doesn't fit the cars you posted, thus it would be counterproductive should the template start fitting several of them closely.
I have built and tested several "angled extensions" on several vehicles, the results are already documented on this site. Results logged over many thousands of miles. Does this qualify as the most rudimentary testing?
I have several "basic shapes" saved that I use in my planning. Tools in a toolbox for design. I do not have the time or computing/testing resources to develop original aero designs from scratch. I am not hung up on proving any of them right or wrong. I have repeatedly used the AST-II and/or the AST top view and the resulting projects hit my projections for drag change reasonably closely and made the handling changes I desired. Thus I will continue using them.
Since you apparently don't know, FYI there are photographs of "template based" projects in your book. You may want to edit them out in the second edition.