Quote:
Originally Posted by aerohead
I printed a copy of your side elevation photo and enlarged it to fit the AST to analyze it both as a normal saloon body,and a Jaray combination form.
*The roofline descends as steep as 36-degrees,which might work if it was a very narrow single-seat,or tandem layout (think P-38 Lightning cockpit).
*With a shoulder-to-shoulder side by side cabin you'd be looking at Paul Jaray's narrowest 'Kombination' car of Cd 0.245 potential (about half the drag of the original Beetle).
*With a standard width cabin,you'd have separation right as your contour hit 22-23-degrees down-slope,with horrific attached vortices and higher drag.
*Your lower body,minus the greenhouse is fine.Although I'd recommend dropping the leading edge of the nose down even with the belly of the chassis.You don't want any high pressure ram-air striking under the nose or you'll have the same front lift of the Beetle.
*How you do the greenhouse is going to determine your outcome.
*If you can find a photo of the upcoming 2016 VW Golf,you'll see that it's roofline is right on the 'Template',with Cd 0.24,same as today's Tesla S.This more gradual contour is a sure thing for flow attachment on a standard width cabin.
|
How does the Pillbug do so well, as it is considerably "under the Template"? My theory is that the air coming around the sides of the greenhouse add to the air coming over the roof and is able to more easily follow the sharper angle, same with the EV-1. Here is my unfinished X-Car, "unscientifically" compared to the Pillbug, but it's a close representation. The Elevation lines, also done spur of the moment, show a similar pattern to the Pillbug. I will do that better in the future!