t_vago's compound curve foam board pickup aeroshell

[bondo]

t vago, you're aerocap is looking way excellent. Very nice work! That foam is great to work with and it is strong too.

Bondo

[NeilBlanchard]

Looks great! Will you be able to do so tuft tests?

[t vago]

Originally Posted by NeilBlanchard

Looks great! Will you be able to do so tuft tests?

Not at first. I am going to coat the thing with some sort of epoxy-based coating, and then coat that with fiberglass.

Here are pictures of the finished aerocap. The first three are of me installing the 6 bolts securing the cap to the truck bed.













Yes, the pictures show a huge (~8 inch) gap between the aerocap and the cab. That is slowly being filled in. I expect that fuel economy will rise a little bit once the gap is filled in.

[Varn]

Vago
I would strongly suggest that you do a trial of putting on your composite onto a small scrap before you commit to doing the entire shell.

I would use some super 77 and spray glue on your pink board to stick the fiberglass to it. Don't try and lay it up in one piece rather do it in a 3 sections or more. paint on the epoxy US composites is a good choice. then before it cures lay on smooth strips of either rip stop nylon or polyester cloth.

Once cured you can peal off the cloth and have a nice finish which you can add another layer if you think you need it. I would use 3 layers of 6oz if it were mine.

[Varn]

Oh I would also sand any offsets before your cover.

[jime57]

Very nice work. The 1/4 inch foam looks to be very easy to work with.

I have been traveling so had not discovered the thread. A question - several have spoken of compound curves using this technique, but from the pictures it appears that you are formings single dimensional curvatures in short sections to give an overall compound curvature. Am I correct, or have you found a way to put compound curvature into the thin foam?

Anyway, I'm impressed. This looks like a good technique to get to some quick tuft testing, which is a missing step in some approaches, IMO. Thanks for sharing the pictures. Look forward to some tuft testing.

[Varn]

It actually not that hard to get a 3d shape using 1/4" panels. Just cut in a pie wedge and just pull the ends together with duct tape then glue the edges together with some 2 part polyester foam available from most any place that sells composite supplies.

Here was a fairing I made for a trike using 1/4" pinkboard just about like your tailbox on your truck. it has a single layer of carbon on it.

[t vago]

The compound curve aspect does come from forming one-dimensional curves over a total of 5 sections. This method was the only way of forming curves that did not involve cutting the 1/4 inch sheets in the fashion that Varn described (that's a nice boattail shape).

Once I get the skin coated (I have two cans of Styropoxy coming), I can use Bondo to fashion true compound curves, then coat the resultant mess with fiberglass.

[bondo]

Originally Posted by t vago

The compound curve aspect does come from forming one-dimensional curves over a total of 5 sections. This method was the only way of forming curves that did not involve cutting the 1/4 inch sheets in the fashion that Varn described (that's a nice boattail shape).

Once I get the skin coated (I have two cans of Styropoxy coming), I can use Bondo to fashion true compound curves, then coat the resultant mess with fiberglass.

I hate being used! No, seriously, the foam you are using is an extruded polystyrene foam. Fiberglass will dissolve the foam into a sticky muck due to the styrene chemical in the fiberglass resin. You will never be able to get a bond between the foam and the fiberglass. I just wanted to caution you as to prevent a very disappointing catastrophy, a true resultant mess indeed.

At this point, what I would do, is finish you aerocap in the foam to where it fits the truck bed perfectly and all gaps are filled. Then remove the foam model and set it upon something flat and stable. Then go buy yourself some industrial grade aluminum foil, comes in a big roll and restuarant supply companies carry it. Then go get yourself some 3M 77 spray adhesive and with a sqeegy (sic) cover the foam surface entirely with the aluminum foil. Cover all the foam leaving not a speck uncovered. If you don't the resin will attack it and even a small exposed portion uncovered will dissolve into a gapeing hole.

Then wax the aluminum foil. Three of four coats of wax is best and try to use a wax formulated for Fiberglass use. Then lay up three layers of one and one-half ounce fiberglass mat over the foam shape covered by the aluminum foil. Let it cure and then remove the fiberglas part. You have no need for the foam model anymore. You will now have a light strong fiberglass aerocap. Now develop your compound curves and finish the surface of the fiberglass part with bondo and sand smooth. Then devise a stong mounting system to mount you new cap to your truck bed (camper shell mounting clamps work great) and you are good to go.

Hope this helps,

Bondo

[KamperBob]

+1 on the foil. Before my aerocap project was shelved (indefinitely at this point) my last plan was to laminated the foam with foil to reflect away solar energy as well. Fiberglass the foil, thicken only if needed, then finish to desired color and surface quality. Rock on!