Quote:
Originally Posted by KamperBob
Freebeard, thanks. Your pic in fine. You should've seen it sandwiched between two pix (#1-2 of 3) from Tesla's post #463. Those pix show for me (Win Vista, Firefox). Others? Especially Tesla: I'd prefer to understand your math.  |
It's been an evolutionary process, in summary:
I started looking for an equation to solve the template curve so I could calculate boattail dimensions at any point along the length rather than just the 10% increments.
Set up excel spreadsheet to plot template and compare different equations.
Stumbled onto the NASA symetrical airfoil equation and after a bit of jiggling found the 0039 profile was close enough to the template for my needs.
Then exploring how the template needed to be applied in plan view, then the penny dropped it needs to be applied in a radial fashion not just vertical or horizontal.
Re plotted points with the radial calculations, the distortion from corners is due to the diagonal being the largest radial dimension, hence setting the longest tail profile and gentler curve than the shorter dimensions of height or width.
Main point being when building a boattail, consideration needs to be given on how the height and width of vehicle compare to the radial measurement to the corners, most vehicles are slightly rounded over the top, so not too much of an issue, but for those that have a taller and more square profile there is greater risk of seperation at the corners if they are tapered too quickly.
The 0/0 point is ground level vertical centre to measure the radial distances to relevant vehicle points, the roof corners will usually be the longest dimension.
There are many other things to consider and I am still putting it all together.