Yet another aerocap idea
 

My mind has been chewing for a while now on ways to make a practical aero cap for a truck. By "practical" I mean something that accomplished the aerodynamic advantage of a "traditional" aero cap, but also allows the driver to utilize the full bed when needed. Basically, that mean it needs to be easily removeable by one person.

Here's my latest idea. Why not use hoops and canvas? Think like the construction of an old covered wagon or an army cargo truck like this one:
http://www.secoaugusta.com/images/2.5_1.jpg
http://www.hansenwheel.com/products/...Wagonsmall.JPG
But rather than all the hoops being the same, make the hoops shorter and shorter as you go further back. Because of the taper, you'd have to sew some pleats into the canvas to get it to fit correctly. You could use snaps or ties to hold the canvas down. The hoops could either be made of bent metal (maybe conduit) or maybe wood.

Removing it would be fairly easy. The canvas could be folded and stored in the cab and it could be mad so you could move all the hoops to the front of the bed out of the way.

I would think it would also be (relatively) lightweight, depending on what type of hoops & canvas you used.

What does everybody else think?

you could, its the same concept as a vinyl/leather toneau cover

Works great as long as you have stringers so the sheathing has flutes that run longitudinally.

Or, make the hoops longitudinal. Use Dacron instead of canvas, comes in lots of colors, heat-shrinkable with an iron or heat gun, to custom fit. A gagillion ultralight airplanes can't be wrong.

Lightweight app. for this can be shamelessly borrowed from kayak designs, such as George Dyson's baidarkas. Google for that. Geodesic canoes and kayaks, too.

Also, foam sculpts easily, add fiberglass for sandwich structure that is also good and light.

I kinda like the idea of the longitudinal ribs. I could make plywood ends (front and back) and then the make ribs that fit in slots in the ends.

I was just considering doing the something similar to my pickup. Check out this site for some ideas. Kudzu Craft

I always thought this would be a good idea for driveaway operators.

They get to their destination and rarely ever get backhauls, so they put up an aerocap as described and drive back economically.

The trick is it has to go up quick & easy - in a driving rainstorm.

another
 

It doesn't matter how you get the shape.So if you can( and you should be able to)get the form,it's going to show at the pump.And you'll have the added flexibility for cargo.
Only one way to know!

Thanks for the input, Phil. I value your input here.

Flexibilty & practicality are definitely what I'm shooting for here. I've looked around at what a lot of people have done. Lots of folks around here have done aerocaps of various constructions, however, there don't seem to be very many folks who still use them regularly. The thing is it's not because they don't help FE. Everybody I've seen who has had one has seen a significant benefit. The issue is that people get sick of either not being able to haul stuff, or they get sick of taking the big, heavy thing on and off a bunch of times. That's the issue that I'm trying to address with this concept. It may or may not be the absolute best theoretical aerodynamic design, but if it's not practical, the theory is irrelavant.

I've been floating several ideas around, but haven't actually constructed anything yet. That's just the way my mind works--I need to let my ideas stew for a while before I start--otherwise they come out half-baked :D Hopefully I'll get a chance to actually start turning wrenches here before too long.

I theory, you could make it just like a convertible top. That would be sweet! However, that's too much of a project for me to bite off--I know my limitations :)

fabrication
 

When I did the inflatable boat-tail,I made a full-scale mock-up attached to my bedroom wall ( not married,not an issue).I used the mock-up to tailor the envelope fabric,then sewed the thing up on an old high school gear-drive Singer sewing machine bought well used for $45.00.
You could create an envelope,sew bow-tubes on the inside,just as a headliner in a car has them sewn on the 'outside,'slip the bows in to stabilize the shape.A few of the bows could incorporate overhead door rollers,and roll in overhead door track,attached to the inside of the bed rails.
As the bows were drawn rearward they would force tension on the fabric,and the bows with rollers would stabilize the envelope against vertical displacement.
When it's in the way,unlatch the beast and shove the bows forward to a stowed position and latch.
Goodyear and others have done inflatable airplanes kinda like this.They used collapsible fabric bulkheads to control the shape.The bows would do the same thing for a non-inflated structure.Just thinking out loud.