Another Truck Aerocap attempt with sketchup for modeling
 

I'm really amazed with the talent I've found here. I've been spending way too much time reading about modifications over and over again.

I thought I'd take a stab at sketchup to draw out my plans. downloaded the free program, and started to draw some lines. I mean really, how hard can it be??? (line from BBC Top Gear) The truck model I found is the same dimensions as mine, but it's one body style newer.

First attempt:
https://lh3.googleusercontent.com/-H...0prototype.JPG

Second attempt:
https://lh5.googleusercontent.com/-u.../fastback1.png
https://lh6.googleusercontent.com/-k.../fastback2.png

I can't figure out how to stitch the non-planar arcs together. I started with zigzags, but not every triangle produced a shape. I think I need to show the "endpoints" but I can't figure it out and it's about 2am.

The top of the "transom" is now 10 inches up from the tailgate, and it's starting to look close.

Thanks for all the ideas! I'm having a blast with this site.

-Kevin

Much better.

Looks a lot like Bondo's aerolid, but his is more squared off to facilitate a workable lid.

Looks good. :D

What are yer goals with yer aero cap? Windows? Hatch? Access doors? What kind of material are you looking to use?

How are you gonna secure it to the bed?

Goals: aerodynamic.
Windows: no.
Hatch: no/yes.
Doors: no.
Secure: C-clamp to bedrails similar to traditional methods.

I want to build a cheap version with small round steel tubing for ribs and a coroplast skin.
Before I move on, I want to get some data:
1. does it help?
2. does it look like crap?
3. can I deal with it?

I like working with steel, and for me it's easier to make adjustments with steel where I'd have to re-cut with wood. I've seen foam, wood, PVC pipe all on here with varying levels of success. The coroplast will not be perfect because of the complex curves, but it will give me an idea of what it will look like and how it will perform.

About a hatch: I love Bondo's aerolid. I think it perfectly compliments the angles of the the F150 and looks spendid. It doesn't have to be squared off for a hatch though. It would be easier, but the hatch can really be any shape. If this all goes well and I move on to a fiberglass version, I'll try to incorporate a hatch.

About windows: I was a truck driver for +15yrs in my past, and (I assume) from that I really don't use anything but my side mirrors. My diesel programmer actually has a 3x5 color touch screen, but I haven't hooked up a back-up monitor yet; but I plan on it.

I want to make it light enough so that if I want to use the bed I can just lift it off. If I like the whole idea and it makes a difference, then version 2 will be made fiberglass. I suck at fiberglass, but maybe I can do better this time.

My real test comes from the fact that I'm a metropolitan commuter in a very hilly part of town (50' to 1,000' elevation changes) and my average speed is around 25mph. I would think my speed was much higher, but I've been tracking my hrs/miles per tank and battling Portland traffic is unavoidable. With such a slow average speed, I don't know how much it's really going to help me out. If this truck goes on the highway, it either has 2-3 motorcycles in the back or a 24' RV trailer.

I started again tonight after watching some training videos and I still need more training. I'm getting stuck. But at least I found a model of the correct year and configuration of my truck. It's even the right color. Maybe when I get good I'll convert it from a Chevrolet to a GMC.

-Kevin

https://lh4.googleusercontent.com/-A.../fastback1.png

Kevin, that looks really good. If I were you, I'd just go for it.
By saying "go for it", I mean skip building the tube and coroplast prototype, and build the final version.
To get those curves to work out you need slices like orange slices. I'd get the dimensions figured out, and then cut plywood stations and attach them to a keel to keep everything lined up. It is most like a boat hull and that would be easiest; why reinvent the wheel?
The beauty of curves is they become rigid all by themselves without the use of any framework. If you can keep curves in both planes it will be very strong.
Build the bulkhead stations and keel and get them set up about a foot off the ground and straight on a framework. Start cutting your orange slices from long cardboard if you can find it for free/cheap. Fit them with tape.
Get the shell covered on one side. Once you have it looking right, take it back apart and use the cardboard slices for a template to cut your final material. you should be able to make two of each, one for left and right.
Now you can choose coroplast for a core if you wish, or some other material. The strength will come from the epoxy and glass you will put over it, so the coroplast would work fine.
I'm suggesting a method like stitch and glue for lightweight boat building. You could use Okoume plywood and give it a bright finish if you like wood ( I do! )
Coroplast is 5 lbs/sheet for 4MM, $17.50 per sheet. It would do fine and be a good base for a painted shell.
Okoume is 15 lbs/sheet for 4MM, closer to $50~60. Far stronger and you'd be tempted to leave it natural.

Here is the stitch and glue method I'm suggesting.
Stitch-N-Glue

That 20' long triple cockpit boats weighs in at 64 pounds :D

The final product will still appear to have slices and slight corners but it will mimic the curves very well.

You can choose to attach to your bulkheads permanently, and then use a sabre saw to cut almost all of it away, leaving a 2" bulkhead ring for example.

I guess you've looked at my aero cap thread?
http://ecomodder.com/forum/showthrea...dea-15137.html

Compared to my cab high topper/camper, my first version did improve a little on the MPGs. Once I tapered the sides towards the rear, the MPGs did improve more. :D

Making a hatch wasn't as easy as one might think. There's support, weather seals, latching, weight, flexing, and fit.

Is this yer daily driver truck? Being that mine is my daily driver made it rather "fun" to git certain phases done before I had to pick up my son at school each day.

Is security one of yer goals fer yer aero cap? It isn't one of my current goals fer my testing phase. Makes it easier to keep things out of the truck bed. :D

Does yer truck have a rear sliding window? If so, are you going to have access to the bed through front of the aero cap? ;)

My current aero cap weighs about 50lbs (just a guess). I'll be taking mine off later this week so I can revamp my stake pocket brackets. One of my goals is to make mine into 4 sections. Hatch, front frame, and both sides. Should make it easier to take apart and store if I need to. I know I have to install a brace on the back end so I can take off the current aero cap in one piece.

I love it. I do like the wood idea. Those boats look awesome and I too would go for a natural wood finish if I went that way. But I don't think it fits with what this truck is about. maybe if I was a woodworker for a profession? Although I do use biodiesel and it would fit in with a "natural" theme.
I think I'm going to use the same basic construction technique. wood or metal ribs and coroplast for the skin. I'm hoping that once I figure out sketchup better, I can derive the "orange peel slice" shapes so I don't have to fit, trim, fit, trim, fit, trim.

• I did read your thread. I acutally found it on the Toyota? site first by accident from a google search, and then read more here. Really cool stuff.
• The hatch would be only if I liked the whole idea and moved on to Ver. 2 made of fiberglass. But yea, I hear you on the difficulty.
• Yes, daily driver. I also have a 01 Golf that I use, but it's shared with my whole family- just stored at my house, so it's not always available.
• Security, no. bed is empty when not in use. (motorcycles, yard debris, gravel, barkdust, firewood, camping equipment)
• No rear slider in the back window.
• Storage is not an issue. I have a shop and 1/2ac. for stuff to sit around.

I gave it another stab on sketchup. I'm learning slowly. :turtle: very slowly. I think my most common command is Ctrl-Z (undo). It takes me about 10 mistakes to make one good move. I'm going to keep trying until I get it the way I envision. I've found myself attempting tutorial objects like chairs and tables in order to learn the tools. It's amazing what you can do with sketchup.
This is version 3. I would expect that I'll get it by version 5. :)
https://lh3.googleusercontent.com/-6.../fastback3.png

I *think* you can stitch and glue the coroplast the same way, then glass it with epoxy the same way. I am going to give it a try on my first fairing on the 5th wheel trailer. It has an ugly fan housing and it is the perfect size to try it out. I hope to build it with just coroplast, epoxy and 4 oz fiberglass cloth. Use coroplast for the bulkheads as well.
It will be at least a month before I give it a try though.

I think you would have better success with mahogany panels and wood glue. 4mm Coroplast is rather difficult to bend in the right shape and gluing it up isn't much easier. I've tried silicone, polyurethane glues like Gorilla glue, hot glue, Gorilla tape, duct tape, and painter's tape. Mechanical fasteners seem the best method of keeping Coroplast in place in the long run. Tape/glue fer the short term. ;)

Do a search on "recumbent bicycle fairings" and you'll git an idea of how they worked the Coroplast to their fairing. ;)

Also, check out Coroplast containers and how they're constructed...like the USPS containers. ;)

None of those adhesives is epoxy. The adhesive joint is only there to keep it together until lamination with glass. That is where the real strength is. I'll do some tests unless somebody else has already done so.