In part 1 of “Let me be your wing man.”, I went over the the foam construction, end plate mounts, and mounting plates. The next step is the carbon fiber process. I highly recommend doing this entire process with a test piece of your foam core. You won’t need mounts and end plate mounts for the test, but it will help you fully understand what is involved. Your test piece should be 6″-12″. You’re also going to need a friend to lend you a hand.
You’re going to need materials. I’ve added links to US Composites, where I purchased my materials.
Carbon Fiber. I use 2×2 twill weave 5.7oz carbon fiber. Carbon fiber is sold in yards (3ft) with 40″ or 50″ widths. I personally use the 50″ width. For my 70″ long wing with a 11″ cord, I used a little less than 4 linear yards for my wing element. Link here. Part number FG-DCT57-50
Epoxy. **It’s important that you use epoxy with foam.** Polyester resins will melt the foam. I used medium hardener which gives you plenty of handling time. Link here. Part number EPOX-635313
Vacuum Bag Material. It comes in a 110″ width. I used 1 yard of material. This stuff is pretty inexpensive, so grab a few yards. Link here. Part number VB-VF02110
Bleeder/Breather Material. I used a small amount of this, but 1 yard will work. Link here. Part number VB-BLE060
Sealant Tape. One 25′ roll will be enough for this job. Link here. Part number VB-BT25
Vacuum Bag Connector. This is not required, but if you plan on vacuum bagging more projects, it will help to have this in the tool box. Link here. Part number VB-70400
Vacuum Pump. I use a professional vacuum pump from when I owned my carbon business, but when I was getting started, I used an very inexpensive vacuum pump from Harbor Freight. Be sure to take a 20% off coupon. Link here.
Cutting Shears. Any sharp scissors will do. The longer the better. I used to cut a lot of Kevlar, so I invested in a nice set. Here is what I use. Link here. Part number SHR-KV45
That’s basically all of the materials and tools you will need, so lets get started.
Your first task is to build your vacuum bag. The general rule of thumb is to make the bag 3-5″ bigger around the permitter of the part that you are vacuum bagging.
I typically fold my vacuum bags in half. You will use less tape and there is less of a chance for air leaks. It’s really important that you have a really good seal. For this project, I left the largest run of the vacuum bag unsealed for now. This is so I can place the wing in the bag easily. Once I get the wing in the bag, I’ll seal it up.
Once I was finished with the bag, I set it aside. I then laid out some more vacuum bag material on my work bench. The next steps are pretty messy, so that extra bag material is just for easy clean up. Next, I cut the carbon fiber material. My wing is 70″ long and 11″ wide. It’s best to give yourself some extra working room. I cut the material 74″ long by 24″ wide. 3 layers is best for this construction.
You’re going to want to seal or tape off any of the mounting holes you have. Later I removed the bolt you see in the photo and taped the hole shut. If you skip this step, resin will leak into the threads and you will have to drill and tap them.
Then I mixed up the Epoxy. It also gets messy here. Be sure you have a buddy to help you and make sure you have plenty of latex gloves.
Next, I coated the top of the foam core in epoxy and flipped the wing over and coated the other side.
There’s a lot of mixing up resin and wrapping the foam core in carbon fiber in the next few next steps. You will definitely need a friend to lend you a hand. One benefit with epoxy is it takes hours to dry, so you have plenty of working time, there’s no need to rush. Once I wrapped the first layer around the foam, I “wet out” fabric with epoxy.
Then I wrapped another layer around the wing. Be sure to flip the direction of the weave in the carbon fiber. This will add strength to the construction.
Notice how I have the seam on the tail end of the wing. First, this will create a seamless finish. Second, this will create a stronger part. On goes the final 3rd layer, again be sure to flip the direction of the weave in the carbon fiber.
The wing is a gooey mess at this point, but don’t get flustered.
I put out a separate fold out table set up with my vacuum bag on it. While I transferred the wing to the vacuum bag, my good buddy Mike held it open for me. I placed the leading edge of the wing on the seamless part of the bag.
In the photo below you can see I added 2 layers of breather cloth on the side and tail portion of the wing. It’s important that the breather cloth overlaps the carbon fiber, but make sure that the cloth is only on the excess portion of the carbon fiber and not on the actual wing.
The next step is to add a vacuum bag connector. I’m using a reusable connector with a built in ball valve to shut the air off, but a hose with some sealant tape around it works good too. I cut an “X” slit into the top of the bag. I also added more breather cloth directly under the connector. Be sure to place the vacuum connector away for the part. If it’s too close, you will suck up resin in to your pump.
Then I sealed the bag up air tight and transferred the wing and bag to my work bench. With the wing, it’s important to work on a flat surface. If your bench is curved, it’s likely your wing will be too. I connected the vacuum hose to the connector and turned on the vacuum pump.
Again, I highly recommend trying this out with a sample part first. So now we have to attach the vacuum to the part. It’s going to get very tight VERY quick. With having a ball valve on the fitting, I can adjust the vacuum. You want to have pressure on the wing, but not so much that you can’t smooth out a majority of the wrinkles that are on the part from the bag. Once the bag winkles were smoothed out, I opened the valve to introduce more vacuum pressure. Hopefully you have a good seal on your bag set up, I had to chase a leak on a taped corner. Once I sealed the leak I turned the pump off. I do not recommend running the pump for hours. You can burn your motor up or you could crush / deform your part. It’s a good idea to add a regulator to your vacuum set up.
You will notice that the wing got heavy when transporting it to the vacuum bag. It’s due to how much resin it takes to “wet out” the fabric. To keep the wing light and uniform, you will need to squeegee excess resin and air pockets out of the fabric.
You want to apply with light force. It’s import to not rip or puncture the bag. I worked from the right side of the wing to the left.
As you squeegee the resin to the tail end of the wing, you will notice a lot of excess resin and air escaping to the breather cloth.
Once I felt confident that I removed all of the excess resin and air pockets, I left the wing under vacuum for about 5 hours. To “kick” the resin over quicker, some people use a space heater. I’m located in Florida, so temperatures are not a problem. If you live in a cold climate, that maybe an option.
The next day I came out the shop and removed the wing from the bag.
Once removed, I then cut away the breather cloth.
I took the wing outside for a better photo. You will notice a texture on the wing. That won’t be an issue as I’ll be sanding it down and clear coating it. That being said, I think a denser foam would have resulted in a smoother finish.
The next step is the itchy process where I’ll trim the excess material in part 3 along with sanding and clear coating. Let me know if I need to clear anything up in the comments section. Thanks for the read!