Design help needed: Custom aero camper top

[huntersirg]

Hey Ecomoders,

Been reading here for awhile but never really started ecomodding besides a few rental car grill blocks for road trips.

I'm looking to design and build a high-top for my van tall enough to stand in the back. It will need to be at least 16" in the middle and was wondering if anyone had any ideas on front and rear design for best aero to squeeze the most MPG's out of this brink as I can.

I'd like to build it with plywood and fiberglass but still try to keep it as light as possible so open to other lowish cost materials so unfortunately no hightech carbon molded turtle top for me.

I would also eventually design a klamback in the form of rear cargo boxes that mount off the rear bumper and swing out of the way like a bike rack. If anyone has seen something done like this I would love to see pictures or ideas.

Working with a 2001 Ford E-250 4.2 v6 regular body.

Thanks for any help or suggestions out there!

Hunter

[aerohead]

Consider only a 16" raised center section down the length of the bed,covered with a recycled inverted canoe or kayak.
I've been looking at local billionaire's private jets at the airport.Many do not possess enough headroom to walk inside.They scrimp on this frontal area to save fuel while traveling seated,suffering for only a few moments for ingress/
egress.
If you actually integrated one of the boats into the roof as a detachable structure (with temporary closure when camping) you'd have a boat with you.

[aerohead]

For boat tail idea see the thread "Aero RV (custom boat tail for '95 Ford E-350 Class-C Motorhome)

[huntersirg]

Thanks Aerohead for the ideas, I actually have a boat that would almost work but would still require someone over 5"6 (I'm 5"8) to hunch over a bit. Also the thing is quite heavy and way to thick for to highest point on the van.

How about the corners on the sides would a sharp edge cut better or a smooth wide rounded side like most tops I see be more efficient?


Got a couple ways to make it that I'm pondering.

One would be to make the side templates out of 3/4 inch ply and add 2x3 cross beams then lay and curve 1/4 ply to shape fiberglassing over the out side and coating the inside with epoxy.

Or make the whole top out of 1/4 using a boat construction known as stitch and glue which would be less sturdy but much lighter. Coule be attached with sheet metal screws and the strongest body adhesive I can find. Then for extra security I can add some drip rail clamps that pull everything tight.

I will also need to have racks on top for paddleboards and gear but these could be removed for long distance trips.

Thanks again!

[huntersirg]

Revised the top a bit here to follow the aero template curve.

[freebeard]

klamback

I like it



Here is a useable boat topper. The problem is that to accommodate the crown in the roof the seats have to be set way low in the hull. This is from an old thread:

http://ecomodder.com/forum/showthrea...ver-28417.html

Platt Monfort was the designer of the Geodesic Aerolite boat:


Geodesic AiroLITE Boats - ultra lightweight SOF canoes and boats; plans, projects and tutorials

Note the diagonal bracing. I doubt there is a lighter construction method.

Stowing and deploying the paddleboard and gear would be a pain. Why not hang a hitch-mounted rack/box?

How about the corners on the sides would a sharp edge cut better or a smooth wide rounded side like most tops I see be more efficient?

An hard 'chine' wouldn't be a problem if the curve in plan and elevation are copacetic.

[grins2go_brett]

Before you get too extreme trying to follow "the template" for your top, let me give you this food for thought. I drive a 2007 Dodge (Mercedes) Sprinter high top cargo van. These vans are very fuel efficient for being a brick. I believe part of that has to do with what they do on the very back of the vans.

Here is a picture that somewhat shows what I'm referring to:

The part to look at is where the tail light housing is, and the body line that extends up the side from the front of that housing. From that body line back is only 6-7 inches. However, it is a smooth curve that ends at about 15 degrees inward from the side (from what I can measure with a straight edge and a protractor), and it is a "sharp" edge, providing a clean separation for the air. This same curve happens on the top as well, which you can see in the picture. I believe this setup, I'll call it a micro-boat tail, most likely tested in a wind tunnel extensively by Mercedes, must be just enough to suck that air inward and reduce the drag on the back of the van.

So I guess what I'm saying is, if you want to maximize your interior headroom from front to back, you might not have to sacrifice as much as you think. Obviously, the farther you go down in the back with the template will reduce your drag that much more. I just figured I'd present you with another option. Hope it makes sense and helps.

[freebeard]

[MobilOne]

Hi,
You also might get some ideas from tntt.com. In particular, look at the "foamies" section.

[Frank Lee]

Brett: while I'm sure the aerodynamicists worked on a clean aft cut-off, that huge arse end also has a huge trailing wake. The "micro boat tail" also gives micro results. It ain't slippery and the reason Sprinters have relatively good eco is the well-matched diesel drivetrain.