Quote:
Originally Posted by betasniper
See Tesla's post:
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My point exactly,
there is no longitudinal section template for going from square to round, and there is no plan template for going from square to round. Therefore using the Part-C template for these purposes is completely misguided and in error.
Post #463
http://ecomodder.com/forum/showthrea...c-9287-47.html
Quote:
Originally Posted by Tesla
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I first did a rough hemisphere to test the calculations, my co ordinates are not perfect, (hence the rough inner plots), but it does show regular increasing reduction as one would expect of half a teardrop form, chart below:
Then I punched in a set of coordinates for a square, to represent a basic vehicle profile, y crosses x at 0 (ground level), chart below:
What it does show is that the corners, being a diagonal profile are further from the focal point, hence their rate of taper is reduced, but the sides at ground level have the shortest length and the most aggressive change.
I am begining to doubt the narrowest dimension rule, this diagonal effect, for me seems to give some explanation why the whole square vehicle is so bad aerodynamically, because it is very difficult to get those corners together without seperation occuring............................
I'm sure there are many other things that come into play and no vehicle is completely square, but it does highlight the potential issues with corners being too aggressive in taper, and if looking for a vehicle to aero customize, it's worth paying more attention to the curvature of the frontal cross section, if it is really square, that will work against you more than if it is more circular. |
The study of going from square to round and the drag creating vortexes which may result are far more relevant to boattailing than the hemispherical sectioned template Part-C .....in my humble opinion.
The template as first introduced as I understand it was meant to be used as a template for creating boattails on existing automobiles (I've already quoted aerohead recently on this).
However as shown in the cross section study I did, adaption from square to round is not even a consideration. This could be an extreme oversight, or not a big deal (see Tesla's comments), the more I think about it, the more I see need for a remedy.
My contention is that square does not fit round, it should not be a "hard-sell", it should sell it's self.
Proposal: Two new templates need to be developed in 3D (eighty or ninety percent length?)
Industrial Design - Transportation Photos by kach22i | Photobucket
Tesla's post #400 is very interesting, describes the conditions but no plan template. The sides will come in quicker than the roof.
Is that anything like re-scaling the template for different lengths and conditions?
Link:
http://ecomodder.com/forum/showthrea...c-9287-40.html
http://s184.photobucket.com/user/kac...?sort=3&page=1
Conclusion: We need at least a new plan template showing the more aggressive truncation.
Then we need several 3D models to fit typical situations.
Then we need at CFD models/videos/stills and testing to examine the airflow and possible vortexes to take it to the next level. That being full scale models/projects and wind-tunnel testing to verify.