Monday, October 6, 2014

What if: After size it's all about shape!

So once I established the boundaries the camper shell has to fit into, I needed to figure out its shape.

There's not much leeway with the lower portion of the shell, but once I'm above the  bed rails I have a little more 'freedom of expression' to play with.

Granted, staying within the practical and affordable does severely limit the options here, but there are options. Though I’ve already eliminated a curved transition between wall and roof on this project. I’ve built a few of those and, good looking as they are, they are a bi----, a hassle, to construct properly without expensive jigs and forms and even then are time consuming.

This is the structure of the curved roof of one of my previous rigs. That white roll sitting on top is the Filon skin ready to be installed, but it took a jig, a template and a lot of work to get the structure to this point. By the way, it seems impossible, but under the grey tarp in the background is a pallet with all the pieces of the 50'x30' steel building that houses my shop and our living quarters out in the country where we now reside.

Tarp off, ready for the move to the country. Notice the cribbing under the pallet. That's pretty much a solid block of steel sitting there so this thing is heavy!!

So anyway, basically I'm left with building the shell with straight sides all the way to the roof, or easing the transition between shell sides and roof by clipping the corners.

Straight sides result in the simplest construction but the greatest surface area for cross-winds to work on.  Clipping the corners off at 45 degrees, though more complicated to build than straight sides, would reduce the shell's direct exposure to crosswinds by slightly over 25%.

At least that was my initial thinking,
but then I went back and factored in the entire crosswind exposure, including the truck itself, and added back half the height of the 45 degree panels to account for the vectored force a crosswind would have on them. Now the overall improvement in crosswind exposure dropped to less than 10%. So clearly the crosswind advantage of the clipped corners isn’t quite as extensive as I first thought it would be.

I also thought clipped corners would have the effect of reducing the perceived bulk of the camper, but after drawing up and comparing the two versions something different than expected became apparent. When viewed from certain angles the straight sided version actually gives the impression of being shorter, squatter, maybe even tougher looking, (And what guy doesn't want tougher looking!) than the clipped corner version, especially when viewed from behind.

From that angle the shorter sidewalls of the clipped corner version actually give the impression of greater overall height for the entire shell compared to the taller sidewalls of the straight sided version.

I didn’t expect that.

I think it has something to do with the narrower roof of the clipped corner version making the door appear taller in combination with the increased visual bulk of the straight sided version giving the impression of a squatter overall look.

From the inside there would be little visual difference since the majority of the clipped corners are hidden inside the cabinetry.

Straight sides would result in more cubic feet of storage space in the upper cabinets, but maybe not as much as it appears since the top back corners of cupboards tend to be the least utilized space anyway.

Straight sides would result in four fewer shell panels and four fewer seams to deal with during construction. Clipped corners would mean slightly smaller and lighter individual shell panels to handle during construction.

It might look like clipped corners would result in a slightly lighter shell but by the time you add back in the structure for those four extra seams I don’t think that will be significant.

So basically it comes down to complication verses overall look, and I haven’t come down on either side yet, so I will continue to draw it up both ways. Though I have to admit that I'm a huge fan of the late boat designer Phil Bolger who often designed for function and simplicity, ignoring looks altogether; which sometimes resulted in boats that are so ugly they're adorable, not to mention beautiful gems of functionality, like the Martha Jane or his iconic Super Brick.

To clip

                                              or not to clip

I don't know yet.

(And I have got to get that Hamlet speech out of my head!!)


  1. Have you thought of going lighter and building a truck camper similar to what Campin Lite does? Or would the materials be too expensive? I think if I remember right from your first "what if" post, this camper would be an alternative based on reduced income. I am definitely not an engineer (accountant) but in my RV research rounded edges were better for aerodynamics. An example would the the rounded design of the Casita fiberglass trailers.

    I considered a truck camper last spring. At that time I had just bought a 2006 Chevy 2500HD 4x4 but made of the mistake of having a short bed. Campers were available but I kept thinking about the center of gravity along with the max weight it could carry.

    So you are really building this camper, it's just not a "what if" situation?

    1. I’ve looked at a number of composite, laminate and fiberglass construction alternatives over the years, in fact I’ve built with a fiberglass/foam composite before. It may be my bias towards wood speaking, but, analyzing these from a cost/benefit/practicality standpoint I have either stayed away or tried once, but have always come back to basic wood construction materials and methods for a one-off project. Taking a look at Camplite in particular, I don’t have the equipment to work and weld aluminum nor a vacuum table large enough to make the laminated composite panels they use. And their TC8.6 model, the one that comes closest in size to what I have come up with, has a dry weight of 2000 lbs. which means at least an F250. (Still don’t have an estimate on what my contraption will weigh since I haven’t finished building the spreadsheet, but I do have one wood frame camper with over-cab bed in my past that I managed to keep light enough to fit in an F150.)

      As for aerodynamics; my thinking goes like this: If there is a clear and significant improvement go ahead, as with the ‘fairing’ I’ve drawn on the front wall of the camper, but truth is, most RV’s spend a relatively small portion of their life actually going down the highway, and though we seem obsessed with fuel mileage, (along with saving a few cents at the pump.) the reality is, in the larger scheme of things, a little bit of aerodynamic improvement is just that, a little bit. If it were more than that, if there was a true cost/benefit, then the trucking industry, who’s equipment is on the road all day, day after day would have reverted their trailers back to the really cool rounded shapes of the 40’s and 50’s and put up with the increased construction costs and decreased load volume, but they haven’t.

      At this point this is still a 'what-if' project to address the situation where I have lost the van and the insurance payout isn’t enough to replace it like for like, so I would then have to come up with a less costly rig more in keeping with the payout so as to not dip into my travel budget to make up the difference. So no, I don't have any immediate plans to build it, but will have it in my back pocket just in case.