Quote:
Originally Posted by orange4boy
More darned questions....
Some people have reported a loss of mpg after installing belly pans. What are some possible causes for increasing drag with belly pan? For instance: If one inadvertantly created a venturi under a car would that increase drag? Or is that venturi unavoidable? If a van was nose down due to rear seat removal would that increase drag? Is parallel best?
I was trying to get the tail shorter but I guess you can't fool physics.  (Or aerohead or bicycle bob) Darn.
By the way here is the link to my newly finished roof and sides extensions, soon to be kamm back. I'd be thrilled if you would give it a look. It was mentioned to me to concentrate on the rear end. It's a start.
http://ecomodder.com/forum/showthrea...evia-9437.html
Thanks guys!  |
I have no published reports which suggest that a problem such as this is possible.And not to dis-respect those claiming the degraded performance,I'd have to be there to investigate it myself and do some mutual head-scratching.----------------- I do have a paper from FIAT which experimented with a bagful of vehicle configurations and they did observe that by altering undercar flow,the uppercar flow can definitely be affected.Obviously,if you have the proper tools,you can quickly isolate an area and remedy it.---------------------------- With respect to a venturi,this is something you'd really have to work at creating.If the pan is parallel with the ground until it can begin a continuous upsweep angle for the diffuser everyone should be okay.------------------------- As far as your stainless roof extension,I've been watching it.If you're anywhere near Sanger,Texas,you can drop by and teach me Metal fabrication technique,She's a beauty!------------------ As far as the drag reduction goes,you can't cheat on the curvature,and your drag reduction will be an arithmetic function of the new,smaller wake area the extension creates as compared to the vehicles original wake.--------EXAMPLE: your extension allows for a 10% wake area reduction,that translates to a 10% drag reduction.Simple huh?-------------- A 10% drag drop would net you 5% AND 6% MPG improvement at 55 and 70 mph respectively.-------- So using,say the template,you can engineer your extension on paper and know the results before you ever begin buying materials.--------------- And yes,the rear is where the action is.Since 1922 the rear of the car has been known to be the chief source of drag for ground vehicles,and the only way to reduce it,after attached flow is in the bag for the forebody,is the gently tapering tail as depicted in the template.