Another Truck Aerocap attempt with sketchup for modeling

[joggerfogger]

Ok, it's 2am and I'm done for the night. I'm getting closer to the shape I want. I don't know if it looks like it, but I started the whole thing from scratch AGAIN and built it with the arcs in the right plane. I'm learning...


The very back of shape where it meets the tailgate looks too wide, but this truck model tapers in at the back and my truck doesn't. Also that taper was screwing up all my geometry trying to match it. Boxy is easier in Sketchup.


I think this is close enough to start building, I just need to figure out how to slice it up so I can get the rib shapes. [sarcasm]I mean, how hard can it be? [/sarcasm]
-Kevin

[KamperBob]

Looking good, Kevin. You get some style points for hips. I believe air likes convex hulls best but pleasing your eyes can be very gratifying.

Are you planning to rake the front forward and curve the sides outward to match the cab?

Rock on!

[joggerfogger]

Bob,

I'm trying to use all convex arcs. I didn't actually plan on any hips and to be honest the end shape kind of (pleasantly) surprised me. I really liked t_vago's design, but I have a problem with squared off bed fender edge. I don't want to take anything away from this design, because I think it looks awesome, and I love the construction ideas.



So all the longitudinal arcs have a chord that runs roughly about the center of the bed floor. And the "transom" curve is going to start with a line tangent to the outside of the bed fender. (I hope I have my geometry terms right).

I plan on extending the cap to the cab, but mating the shape to the cab was making it very difficult for me to draw the arcs. My goal is about 1" gap between cab and cap to match the bed to cab gap. I'd also like to incorporate a tiny little 4 inch, 15 deg. flare at the trailing edge, but I'm still learning with Sketchup. I have absolutely no CAD experience, so I'm kind of muddling through this.

I had to pull out some paper to figure out the basis for the shape, and maybe it explains my idea better:


Next up I'm going to try to build a small (7/8"?) diameter tube frame via sketchup that will be the main support with smaller solid rod as the supporting web.

-Kevin

[KamperBob]

Kevin, my cap project is on hold at early stages of work so what I can share is limited. Sketchup was great for 3D visualization of the concept. I also started using it for virtual build. To check 3D angles I started the base frame. My cab match was empirical using a template. See attached pix. (Sorry for small size; the forum imposes a 127KB limit - shrug.)

These were my next steps. Start with three side-to-side bulkheads. Front and rear being permanent. Middle temporary for construction. Rip strips of thin plywood like lath for a series of front-to-rear arches to define form. They would be flush with the bulkheads. Rip strips of thin poly foam and wrap from one side the the other. Start in the front and work towards rear. Trim as go to achieve orange peel effect. Tape joints with duct or gorilla. Leave excess overhang at both ends. Fiberglass the outside first to capture shell form. After hardened remove middle bulkhead and lath strips from inside. Then evaluate strength. If desired, add more fiberglass. Perhaps glass whole inside too; definitely reinforce joints. Once satisfied with shell itself, separate lid from base and work out details: seals, front hinge, lift struts, latch mechanisms, paint, windows, etc. Hope that helps some.

[Diesel_Dave]

I've been thinking about an aerocap myself.

I really like JRMichler's 1/4"-plywood and epoxy construction. I looks really sharp IMO. See his pics here:
Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - JRMichler's Album: Daily Driver

[skyking]

Bob, where do you get the 1/4" foam like that? is it easier to curve than 4 MM coroplast?

[BamZipPow]

Originally Posted by skyking

Bob, where do you get the 1/4" foam like that? is it easier to curve than 4 MM coroplast?

That's the standard pink/blue insulation board stuff you'll find at Home Depot/Lowes. It's much easier to work with than Coroplast because it's not ribbed like Coroplast.

[skyking]

Originally Posted by BamZipPow

That's the standard pink/blue insulation board stuff you'll find at Home Depot/Lowes. It's much easier to work with than Coroplast because it's not ribbed like Coroplast.

you have something in your eye or what?

[KamperBob]

Originally Posted by BamZipPow

That's the standard pink/blue insulation board stuff you'll find at Home Depot/Lowes. It's much easier to work with than Coroplast because it's not ribbed like Coroplast.

It's also fanfold: 4' wide in 2' sections totaling 50' IIRC. Plenty of material AND you can haul it home in a compact car!

[joggerfogger]

Started to do some front end mods with stuff I found in the garage.
some old Lexan 12x12 sheets that were destined for the garbage made my materials.
Completely blocking the upper grill has only positive effects so far. warms up quicker, and operates at 185-190F more consistently.
I doubt I'll be able to measure any appreciable FE gains just with grill and fog lights.
-Kevin