Replacing Class c motorhome body for touring act

[trooper Tdiesel]

hears some info from some one that has done aro mods to a RV before.

http://ecomodder.com/forum/showthrea...d-e-18151.html

[freebeard]

It looks like you have the idea of the Template, but you can define the top curve however you want. Slide the template back ~4' until the top of their windshields coincide. You'll need to shrink the template maybe 5%.

Then lastly, will the long angled descent across the roof help that much on aerodynamics (like in the template)? Why doesnt it show up on production bigger vehicles?

Two words: Dodge Magnum

OK, longer answer: 1930's Beer Trucks

[freebeard]

...also Canadian furniture moving vans in the 40's.

The rooftop blister I told you about in the Introduction thread is in the thread trooper Tdiesel pointed to:
http://ecomodder.com/forum/showthrea...tml#post250241

erm, #post250241; the forum software obscures that.

[capturedbyrobots]

Freebeard! You rule!
I've never seen those trucks before. I covet!
The last pic you showed is about as big as I could go.
With a design like the last pic ( Okeefes) I wouldn't even need the boat tail.

So I need the height in the camper. I might eventually even redo the nose if this all works out. Moving the template back would give me more high roof area right?
I'll try to move it today and see how it looks.

I've been really trying to decide on framing. I've looked into lots of different materials. If I wanted it to come together easy, I could do the teardrop trailer type of construction, bent plywood on rounded wood or metal ribs then skin it in galvanized. I could just do the standard flat sides up to a decent radius to the roof with plywood and 2x2 framing. I bet metal studs and galvanized would be the lightest way to go, and the most easily repairable, but the 1/2 or even 1/4in plywood (for easier curves) would give it more durability if it was sandwiched in-between.

I wonder, is there any metal construction stud material that is similar to the way cargo vans are framed? It's like a U channel with a flat flange folded into some thick sheet metal. That would be ideal stud material for this job.

[capturedbyrobots]

Like this, but thinner if I can find it.
U-Flange Posts

[freebeard]

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

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}

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:

Moving the template back would give me more high roof area right?

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.

[freebeard]

It was in Shelter, p. 126: the Superellipse.
Superellipse - Wikipedia, the free encyclopedia
Rotate this 45° and use the top half:



I almost forgot Drop City :
Drop City - Wikipedia, the free encyclopedia
They used triangles cut out of car tops, with no internal framing (requires compound curves).

[Sven7]

When you taper the rear the wheels may stick out a bit. Consider these...


1935 Auto Union Rekordwagen Typ Lucca. Hans Stuck by kitchener.lord, on Flickr


1921 Rumpler Tropfenwagen chassis by kitchener.lord, on Flickr

[freebeard]

Lord Kitchener is cool.

Here is a little preview from my upcoming 'Project, the Third' post:


And here is the Bowlus Papoose, from the bottom of the Bowlus Trailers Models page:

Possibly more in line with a commercial vehicle.

[ron22]

Suprised this has not been posted yet

3d model of the dymaxion car
For light weight cover it in fabric like older airplanes are
Here is a youtube of it

http://www.youtube.com/watch?v=5u2qP...hannel&list=UL