Building the Front Wing & Mounts

Posted by jjludemann on March 24, 2016

Finished front wing on the car (endplates to be added after setting ride height)

: Airfoil profile laser printed on sticker paper, stuck to aluminum sheet

: Airfoil profiles cut from aluminum sheet

: Homemade hot-wire foam cutter cutting airfoil section from styrofoam block

: Laminating outer skin of epoxy resin and fiberglass

: Cutting aluminum jacking points to be laminated into the wing

: Bending wing mounting brackets to be bolted to the nose

: Test fitting brackets on nose

: Test fitting, bottom view

: Trimming front wing airfoil on the bandsaw

: Gluing 3 sections of front wing to brackets

: Reinforcing fiberglass skin across joints

: Laminating end plates with honeycomb core

: End plates cure under vacuum

: Sanding with pneumatic double-action sander

: Laying up endplate mounting points

: Epoxy & microballoon filler to smooth out the spar

: Top coat of 2-part epoxy paint

: Car lifted by front wing

Part Eleventy-seven, In Which We Finally Lay Up a Body

Posted by jjludemann on January 10, 2014

Another view of finished main body.

Time to lay up the first set of body panels. In some photos you can see the joggles laid into the molds with duct tape so the panels will overlap smoothly. Nine coats of mold release wax and there were no problems releasing parts from the molds, although at times I did have to work a bit. Each mold required about a day of finishing work to remove ripples due to waviness in the body buck. As I’ve said before, don’t build a body buck the way I did it. Instead, immediately after completing the X-Y grid of cross sections, lay about 3mm of fiberglass on top to give a good solid surface, then use body putty on top of that. You’ll be finished in half the time it took me. The only place you should use foam is where actual carving is required due to the complexity of the shape, like the sidepod air inlets. Yes, I know the main roll hoop forward braces are still not there. Patience…

One problem I found out the hard way is that a chemical in some brands of duct tape inhibits gelcoat curing. In the end, gelcoat that had been in contact with some kinds of duct tape never fully cured and had to be cleaned out with acetone. Also, the joggles formed with duct tape were too sharp for the fiberglass mat to conform to, resulting in bubbles under the gelcoat that have to be scraped out and reworked. Gelcoat is probably more trouble than it’s worth given its weight, so next time I’ll just prime and paint the body panels to finish them. The sharp joggle corners need to be filled in with fiberglass roving before laying mat on top.

: Leg cover mold ready for layup

: Fiberglass mat for leg cover.

: Finished leg cover, fresh from the mold. No polishing or anything.

: Leg cover test fit onto frame. It fits.

: Engine cover gelcoated

: Engine cover fiberglassed.

: Engine cover test fit on frame.

: Trimming the engine cover.

: Nose and tail molds gelcoated

: Nose & tail fiberglass mat test fitting.

: Nose & tail second layup coremat and fiberglass mat.

: Finished tail fresh from the mold.

: Nose & tail trimmed. Needed some gelcoat repair.

: Tail test fitted onto engine cover.

: Cockpit gelcoated

: Cockpit ridges reinforced with resin and chopped fiberglass mat.

: Fiberglass mat and coremat prepared for second cockpit layup

: Cockpit underside after second layup with coremat clearly visible

: Cockpit removed from mold. A little difficult as it could only be pulled straight off.

: Cockpit so light it’s held up by a pinky finger.

: Test fitting the parts so far onto the frame

: Sidepod mold with gelcoat applied

: Sidepod after second layup, showing coremat.

: Sidepod just released from the mold.

: Sidepod test fitting before trimming.

: Keel mold ready for layup. Note duct-tape joggles for panel overlap.

: Keel mold with gelcoat applied.

: Keel after second layup showing coremat.

: Main body parts all finished and fitted.

: Another view of finished main body.

: Joint between engine cover and cockpit.

: Four body panels meet here. Joggles required some thinking.

: Body from inside the cockpit.

Last of the Molds

Posted by jjludemann on December 16, 2013

Completed set of molds

Since this is the last of the molds, in the photos below I’m showing each of the layups, for a total of three. Target thickness for the molds is 4.8mm, three times the expected thickness of the parts to be molded.

: Keel gelcoated

: 1st layup

: 2nd layup

: 3rd layup

: Mold released. Some sticking on bottom of keel.

: Cleaning the mold. Comes off easily with a scraper.

: Completed set of molds

: Another view.

: Sanity check– test fitting molds on the chassis.

Fiberglass Mold Layup, Parts 4, 5, 6…

Posted by jjludemann on December 11, 2013

Probably the main thing to explain here is how I create the overlaps in the molds. The edge of a mold is marked on the body buck with duct tape, which will leave an impression in the mold for later trimming of the finished part. Then after removing the mold from the buck, I lay in a strip of 1″ duct tape touching the existing tape, then another strip touching that one. I then remove the first two strips of tape, leaving the edge for the next mold with a 1″ overlap.

: Left sidepod waxed 10 times and marked

: After first layup

: After second layup

: Right sidepod mold released

: Body buck prepared for engine cover layup

: Engine cover gelcoated

: Rolling out the bubbles

: Catalyzed polyester resin. Color change after stirring vigorously for 1 min.

: Brushing resin onto fiberglass mat

: Engine cover layup finished. Molds are about 6mm thick.

: Released engine cover mold

: Body buck after mold release

: Tape detail showing how overlaps in molds are created

: Leg cover gelcoated

: Leg cover fiberglassed

: Cockpit gelcoated

: Laying out plastic template for cutting fiberglass

: Template is used to precut fiberglass mat

: Resing & catalyst are pre-measured in usable quantities

: Cockpit fiberglass layup finished

: Cockpit mold released

: Body buck after release

Fiberglass Mold Making- Nose, Tail, Sidepod

Posted by jjludemann on November 28, 2013

Time to make molds!

: Starting with the nose. Seal around the bottom with clay.

: Overview of the nose with clay dam and parting board

: Gelcoat applied

: Fitting fiberglass mat

: Fiberglass cloth and polyester resin applied

: Parting board removed

: Bottom fiberglassed to form the second half of the mold

: Separating the mold halves

: Bottom Half

: Top half

: Tail, mold split marked with duct tape

: Grey gelcoat used because the buck is black

: Pre-cutting the fiberglass mat

: Fiberglass mat staged to laminate the second pass

: Lamination finished

: Mold separated

: Right sidepod with split line marked

: Gelcoat applied

: Fiberglass “lock layer” applied over gelcoat

: Test fitting more fiberglass mat

: Spiral plastic tubing used for mold stiffeners

: Final fiberglass mat applied

: Mold released

: Body buck after mold was removed.

Finishing the Body Master Pattern

Posted by jjludemann on June 10, 2013

I ended up applying ten coats of SikaFloor epoxy to try to build a hard base for further finishing. Even this gave me problems, though, as it appears that the two-part urethane foam continues to expand indefinitely. Every time I would finish a section, next time I looked at it, it needed more work. For a long time I just thought my eyes were getting more demanding, but I finally realized the body buck was slowly changing shape, bulging out between the ribs. Once I figured this out, I just tried to finish the molds as fast as possible. I also installed air conditioning in this part of the workshop, and kept it running at night to avoid temperature-cycling the pattern.

If you’re thinking of doing this yourself, a better way to do it would be to just fiberglass straight over the plywood forms, using tape or something to support the first layer of fiberglass while curing. About a 3mm fiberglass shell should do it. Then use body putty right over that, using standard auto-body finishing techniques. That way there’s no foam between the ribs to push outward and mess up the shape. The only time you need foam is when you’re really sculpting something, like the sidepod air intakes. Oh, by the way, plan on about 1,000 hours of work.

After the floor epoxy there were several rounds of primering, puttying and sanding, followed by two coats of black two-part epoxy paint. This was sanded with 400, 800, 1200, and 2000 grit wet-or-dry sandpaper, then machine-polished with rubbing compound. The top layer was 9 coats of “Hi Temp Mold Release”, applied by hand strictly according to the instructions.

When I started to think about how to split up the body panels, I realized that the “horse collar” head surround would be impossible to remove when the car was finished, as it would interfere with the main roll hoop. This necessitated going all the way back to the SCCA rule book, where I took another look at the minimum cockpit opening specifications. I found that I could meet the minimum cockpit opening size with a fixed head surround, but I had to cut the “arms” off it. So, you get to see that surgery in the photos below.

: Many coats of floor epoxy, some puttying in between

: More coats…

: More coats…

: Almost done…

: Finally, ten coats of floor epoxy applied

: Now primer…

: Sanded down…

: Putty applied…

: Sanded down…

: More primer…

: Sprayed on some dark gloss paint to check the reflection

: Sanded down again

: More primer, and a guide coat

: Sanded down again

: Ready for top coats

: First coat of black two-part epoxy

: First top coat, another view

: Sanded down…

: Second epoxy top coat

: Oops, won’t be able to remove the driver’s head surround from the finished car.

: Cut off the arms of the head surround

: Body putty

: Primer

: Voila…

: Perfect. Driver’s head surround is now fixed in place.

: Machine polished but not yet waxed

: Nine coats of mold release wax

: Purty…

: Mmmmm, shiny…

Building the Body Buck: Part 1, Ribs & Foam

Posted by jjludemann on January 23, 2013

Here’s what we’re building, sort of. Rather than build a CAD model of an actual assembly of stringer and rib parts, I extruded cuts into the solid model so that the slots will appear in the correct places when I make cross-section drawings at the appropriate locations. This is actually harder to visualize than you might think. I wasn’t sure it would go together flawlessly, especially since the cuts in both the ribs and stringers went to two different depths depending on the typical height of each region. I didn’t want long floppy sticking up from the cuts: