Quote:
Originally Posted by RobertSmalls
Have a look at the streamlining template.
Thinking big is good, and you may want to think bigger. The distance from where the curved roofline begins to where it meets the ground (roughly the length of the boattail), is 1.78*D, where D is twice the height of the vehicle. In your case, that's 6.34m! That's obviously not going to happen.
But if you line up the template with the widest part of the TOP view of your minivan, you find that D is the width of your vehicle, 1.90m, and 1.78*D is 3.39m. That's still a little long, but 70% of that length (i.e. 2.37m) gives you almost as good of a result. See this thread for drag reduction estimates for shorter boat tails. Even a 50% chop, 1.69m, looks to be good for a very large reduction in Cd.
I like the way it looks, and you'd probably have the least thirsty seven-passenger vehicle on this site. Very cool, and I hope you do it. |
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When I apply the template to my beetle the length I get for a 70% length kammback is a 2996mm long or 2.996 meters (9 '6") long
The 70% length is 2.0972 meters or 6'10" in length from about the drivers seat to the end of the kamm / boattail
My Beetle has close to 1 ft. of its width in its fender flares, If I measure the width of the cars sides , the hatch backs width is 1.397 meters or 4ft 7" from 1 side of the car across the hatch to the other side.
Using the width of the car as 1.75d:
the length I get is :
1.397 x 2 = 2.794 meters , minus 30% = 1.9558 meter or 6ft and 5 inches for the 70% length compromise.
I have just Measured my Car from the rear bumper to the location of roof camber and it comes out to a very close 6ft 8 inches , 3 inches off of the 70% compromise.
I could go even shorter , to the 50% compromise and have a easy time with it.. 1.397 meters or 4ft 7" long from roof camber point
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My 98 Beetle Dimension
Length: 4,129 mm (162.6 in)
Width: 1,721 mm (67.8 in)
Height: 1,498 mm (59.0 in)
Wheelbase: 2,515 mm (99.0 in)
Curb weight: 1,230 kg (2,712 lb)
I have been thinking more on the rear hatch and a secondary rear hatch for access is seeming like the better / best way to go. It would allow me to have the Kammback securely mounted in the hatches current position and join more seamlessly with the roof filler insert.
I am now thinking having it hinged will be unnecessarily difficult , and may be problematic.