Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Effects of Large VS Small circumference curves at upper corners

4536 · 06-16-2010, 03:26 PM

For Aerohead, and anyone else interested.

Most vehicles have fairly short circumference curves in their transition from their sides to their top. So I suspect that little thought needs to be devoted to their taper characteristics from front to rear. However what about a vehicle with a large circumference curve?

Of course one of the advantages of the large circumference curves is its lower suseptibility to direct crosswinds which is always a concern with a trailer or high profile vehicle. Also it will presumably be more aerodynamic with any off center winds that are encountered.

Based on the Streamlined template, the following is the case for the trailer I am constructing. (see 6-14-10 "AeroTrailer from Scrap Materials" thread):
1. Each of the 24" vertical sides of my areodynamic trailer has a faster taper than the top because the D for the sides is 74" and the D for the top is 136". (53" high from floor to top at its highest point plus 15" from top of floor to pavement X 2 = 136").
2. There is a 29" radius curve that transitions upward and inward between the upper vertical sides and the top. The right and left curves account for 58" of the 74" width of upper part of the trailer at its widest point. Therefore only 16" in the center at the very top is flat (horizaontal). The trailer will be Kamm backed at about 79" rear of the widest, tallest point.
Therefore, what should the lateral (hoizontal) taper of the mid point in the circumfrance of the curve be, as it transitions to the rear?
What should the verticle taper be for that midpoint in the curve?

I ask this as that midpoint occurs at a shorter width than the sides and a lower height than the top.

Is it as simple as transitioning that mid point vertically with the roof and laterally with the sides?

Or is there some more complex equation that involves a chord perpendicular to the mid point of that curve and runs downward to the ground and is then doubled to determine D. Wouldn't this most likely provide a corner that bulged outward as it transitioned rearward due to a slower taper than the sides and top?

06-16-2010, 03:26 PM	#1 (permalink)
4536 EcoModding Lurker Join Date: Jul 2009 Location: los angeles Posts: 18 Thanks: 2 Thanked 4 Times in 1 Post	Effects of Large VS Small circumference curves at upper corners For Aerohead, and anyone else interested. Most vehicles have fairly short circumference curves in their transition from their sides to their top. So I suspect that little thought needs to be devoted to their taper characteristics from front to rear. However what about a vehicle with a large circumference curve? Of course one of the advantages of the large circumference curves is its lower suseptibility to direct crosswinds which is always a concern with a trailer or high profile vehicle. Also it will presumably be more aerodynamic with any off center winds that are encountered. Based on the Streamlined template, the following is the case for the trailer I am constructing. (see 6-14-10 "AeroTrailer from Scrap Materials" thread): 1. Each of the 24" vertical sides of my areodynamic trailer has a faster taper than the top because the D for the sides is 74" and the D for the top is 136". (53" high from floor to top at its highest point plus 15" from top of floor to pavement X 2 = 136"). 2. There is a 29" radius curve that transitions upward and inward between the upper vertical sides and the top. The right and left curves account for 58" of the 74" width of upper part of the trailer at its widest point. Therefore only 16" in the center at the very top is flat (horizaontal). The trailer will be Kamm backed at about 79" rear of the widest, tallest point. Therefore, what should the lateral (hoizontal) taper of the mid point in the circumfrance of the curve be, as it transitions to the rear? What should the verticle taper be for that midpoint in the curve? I ask this as that midpoint occurs at a shorter width than the sides and a lower height than the top. Is it as simple as transitioning that mid point vertically with the roof and laterally with the sides? Or is there some more complex equation that involves a chord perpendicular to the mid point of that curve and runs downward to the ground and is then doubled to determine D. Wouldn't this most likely provide a corner that bulged outward as it transitioned rearward due to a slower taper than the sides and top?