That U-Flange stock is 1.5—2 lbs per lineal foot. Do the math. Galvanized sheet metal is "inexpensive" but heavy. Consider the FRP panels they use to line the walls in gas station rest rooms.
The Bowlus trailers (pre-dates Airstream) used aluminum over welded electrical conduit. They made a 30' motor home that weighed 3500 lbs.
Bowlus Trailers - Models
This morning Google images led me back to Ecomodder and this post by trebuchet3:
http://ecomodder.com/forum/showthrea...html#post77352
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All of that aside. I've been collecting a set of "Aero Rules" - here's a few that apply... I haven't really edited these - so pardon any goofy language Names in the curly brackets are the source/author
Front Corners shall not have a radius to vehicle width ratio (r/W) no less than .045 {PAWLOWSKI}
Winshield angle from vertical shall be biased towards 90 degrees to reduce cD {G.W. CARR} but, the reduction is not as much as assumed. After beyond 60 degrees, there is almost no further reduction and may result in optical refraction and cabin heat issues {R. BUCHHEM, et. al.}
Lower Stagnation Point is better {R. BUCHHEM, et. al.}
Optimal roof camber ratio (a_r/l_r): .065 Where a_r is height above "flat" roofline and l_r is the length of "flat" roofline. Assumes FA remains constant. delta cD = -0.02 {R. BUCHHEM, et. al.}
Optimal taper angle is highly dependent on the "history" of flow. {HUCHO}
With increasing length, positive effect of tapering become weaker. "Bob-tailing" or truncating thet taper results in little loss in drag reduction {D.J. MAULL, W. KAMM}
Rear diffusers: For a given area ratio (outlet area/inlet area), long diffusers are better. The same drag reduction can be had with a smaller angle rather than a shorter diffuser). Small angle = 2 degrees {J. POTTHOFF}
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I interpret 'roof camber ratio' as longitudinal rather than lateral and I see that in the post just above this one, Big Dave name-checks Bowlus.
You wrote:
Quote:
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Moving the template back would give me more high roof area right?
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It probably won't change much. Keep in mind that The Template assumes a half-circle in cross-section. There exists a mathematical figure that is halfway between a circle and a square. I can't remember the name, and my books are in boxes instead of bookshelves.
Google isn't helping; maybe I'll remember the name (anything is possible). I think it would make a good cross-section.