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Building a simple aero-foil rear wing for a sports car

How to build a simple aero-foil rear wing for a sports car with Bucks-Composites materials

Items needed

  • Design your own wing and get www.foamwings.co.uk to cut your foam cores out of blue foam
  • Bucks Formula GB Epoxy resin with hardener /24 hour cure time and is also foam friendly.
  • Bucks 200g Plain weave woven glass cloth (4 layers on the top and 4 layers on the bottom)
  • Optional eye level rear brake light with homemade housing (the LED rear light could be bought from a car breakers yard)
  • Electrical wire
  • Screws
  • Resin spreader cards
  • Mixing pots
  • Digital scales for measuring resin with the correct ratio of hardener
  • 2” brushes
  • Leg uprights made from metal or wood
  • Sanding pads
  • Vinyl gloves
  • Sharp knife for triming surplus glass fibre cloth
  • 2.0mm Glass fibre sheet for end plates
  • Bucks Thixotropic agent resin additive for making a bonding paste
  • Bucks Super lightweight fairing compound resin additive for making a lightweight strong filler

 

Join the centre section together with Bucks formula GB epoxy resin and hardener with a little of Bucks Thixotropic agent which will prevent the resin bonding paste from running out and weight down to prevent movement on a flat surface also mask the bench where the wing area is to be bonded.

The wing is upside down and the hole for the rear light wiring is visible. Later on once the wiring is in place the slot needs to be filled, I will be using a piece of carbon fibre strip bonded in place to fill the slot.

Rear brake light and homemade light housing.

Optional: When dry cut out the area for the homemade rear brake light housing and bond into position. If any gaps should appear then fill with a mixture of bucks super lightweight fairing compound and bucks Formula GB epoxy resin and hardener.

The two leg uprights are visible here and ready to have fixings made.

Drill the leg uprights square on where the legs will be bolted on. We are going to use three 8mm bolts on each leg. One way is to drill the holes and thread the holes ready for 8mm helicoils inserts and epoxy in place, we use slave bolts coated with wax release agent to prevent the bolts from sticking when bonding in the helicoils and this will keep the Bucks Formula GB epoxy resin and hardener in the right place.

After 24 hours remove the slave bolts from the uprights and bolt onto the car with 8mm bolts. Mark the wing section onto the leg uprights and then cut to shape.

A hole needs to be made for the rear light wire to be passed through the leg upright on one side, we are going to use a long series drill bit to cut the hole.

Once the legs are cut to shape then two plates need to be made (one for each side). Screw the plate down the centre line and the outer holes are for epoxy resin to run through. Have a few dry runs first before final assembly. The metal plate needs to be roughened up and de-greased with pure acetone or similar before final assembly for the Formula GB epoxy and hardener to stick to the plate.

Feed the wire through to the right places and we have used 7 Amp wire. Glue in the carbon fibre strips with epoxy to fill the slot.

Bond the two outer wing panels onto the main wing and remember to mask the bench area.

Support the wing off the bench and cut the glass fibre cloth to shape leaving an inch overhang all around. Mix up a quantity of Bucks Formula GB epoxy resin with the correct ratio of hardener. Using a brush stipple the activated resin into the glass fibre cloth working from one end. Working from the centre line stipple the activated resin to the leading edge and to the trailing edge working your way down the wing until the glass fibre cloth on the wing has been fully ‘wetted’.

Now go back to the starting point and using a resin spreader card as a squeegee remove the surplus resin from the centre line to the leading edge and from the centre line to the trailing edge down the entire wing. Collect the surplus resin back into a pot.

Leave to cure for 6 hours and then trim off the surplus resin and glass cloth while partial cured, now leave for 18 hours.

Sand smooth the leading edge, trailing edge and the two ends of the wing, I recommend the use of a Perma-Grit tool for this job. Repeat the process on the other side. You will need to repeat the process a further time until you have two layers on the top side and two layers on the bottom side. For best results leave 4-6 hours between coats and trim off surplus glass cloth before full cure. Leave for 24 hours for full cure to take place. With lighter weight glass fibre cloth for example on a model aircraft wing it is possible to apply the resin to the glass cloth with a foam roller but on heavier weights of glass fibre cloth the roller picks up the glass cloth so it is better to spread out the resin with a brush and then remove the surplus resin with a resin spreader card.

Remove the two metal plates and mix up a quantity of Bucks Formula GB epoxy resin with the correct ratio of hardener, spoon out the required amount of Bucks Thixotropic agent into a pot and add the activated resin which will make a ‘non-drip’ bonding paste, the control of the viscosity of the mix can be adjusted by adding more or less of the Bucks Thixotropic agent and always remember to stir well, apply to the top of the wooden uprights.

Screw the metal plates back onto the top of wooden uprights. Apply more bonding paste to the top of the metal plates.

Sit the wing on top of the plates in the right place with electrical wire in position, clamp or weight down the wing onto the plates and remove any surplus bonding paste from that area. After 6 hours fill any gaps or voids with the bonding paste and remove the surplus then leave to fully cure. After curing remove the weights or clamps.

Remove the wing from the car and bolt on wooden separators as this will enable you to work around the wing whilst keeping the wing and uprights in the right place.

Seal the area in the brake light housing where the wire comes through with silicone sealer and wait to dry then back fill with Formula GB resin and hardener this will prevent movement of the wire for protection.

Apply two coats of Bucks 200g plain weave glass fibre cloth to the top and the bottom of the wing wetted out with Bucks Formula GB Epoxy resin with the correct ratio of hardener as before. Best results are achieved when laying up the woven glass cloth on top of partial cured resin (4-6 hours) between coats as this will help the layers of woven glass cloth bond better between layers. This will help prevent layers de-laminating later in life.

Apply 3 layers of Bucks 200g plain weave woven glass fibre cloth with Bucks Formula GB epoxy resin with correct ratio of hardener to cover the leg uprights and allow to partial cure to take place (4-6 hours) trim off the surplus glass fibre cloth then leave to fully cure. Ensure there is enough reinforcing between the leg uprights and the wing, if not cut a few strips of glass fibre cloth and build up that area.

Mark and cut out the 2.0mm glass fibre sheet for the end of the wing, cut on the waste side of the line which later will need to be finally sanded to the correct size once bonded onto the wing, I use a jigsaw with a cutting blade suitable for cutting metal as the glass fibre sheet wears out blades suited to wood very quickly, key the surface of the 2.0mm glass fibre sheet with a abrasive tool on the two plates on one side for the bonding paste to grip to.

Mix up an amount of bonding paste (Bucks Thixotropic agent and Bucks Formula GB epoxy resin and correct ratio of Hardener) and apply the bonding paste to the end of the wing and weight down the 2.0mm glass fibre sheet in position to prevent movement and leave to cure. I will bond on one sheet at a time. When fully cured then bond the other end on as before and leave to fully cure.

One way to remove the bulk of the surplus 2.0mm glass fibre sheet on both ends of the wing is to use a power file.

Finishing off sanding with a Perma-Grit tool.

Now fill the wing with a fine easy to sand body filler and ensure surfaces are smooth. Once dry sand with sanding paper.

Seal the hole where the wire comes through on the leg upright with silicone sealer.

Now get in touch with your local car body paint shop
to spray the wing with a high build filler primer then sanded and then top coat of paint applied.

Now bolt the wing onto the car and wire up the eye level rear brake light if you have included one.

Here is the finished aero-foil rear wing for a sports car.

I hope I have given some ideas to you making this simple aero-foil wing.

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