The Corsair82: 82% F4U-1A Corsair

Here you can see the process of creating the molds.

The first step to building the molds was to outline the sections. This will be a three piece mold. I want each section to have a flange that mates to it's neighboring section. I used a good quality masking tape to outline each section.
I used masking tape because I knew I would be able to remove it when I needed to. Over the masking tape, I applied a two sided tape. Then I applied a length of "J" channel. This is used for siding on houses. It's vinyl, so the resin won't stick to it. I cut the small side off so I was left with an "L" instead of a "J".
I cut the vinyl vertically in places to allow it to bend around curves. I bridged the cuts with aluminum tape. Then I waxed the tape, so the resin would not stick. A bead of model clay was added to seal the gap at the bottom.
A tongue depressor helps to make the clay bead clean.
In some places foam was used to make the flange.
With the flanges in place, kraft paper was used to make templates for cutting the fiberglass.
After each piece of glass was cut, it was rolled up in it's template. This kept the fiberglass clean. It also made it easy to identify which piece would be applied next.
It's important to have all of your materials and supplies ready for your lay-ups. If you mix your resin and don't have the essentials ready, it will set up before you get to use it. I learned this the hard way. And resin is expensive.
At this point the mold is ready. It has been waxed four times. It was then sprayed with PVA mold release. The next step was to spray a gel coat on the plug. This will put a hard finish on the outer layer of the fiberglass.
A layer of 3/4 oz. fiberglass mat is applied over the gel coat.
A second layer of fiberglass mat is applied before a layer of core mat is applied. Core mat is a spongy cotton like material. It is available in many thicknesses. I used 2 mm. It is a great core material when weight is not a big concern. It absorbs a lot of resin, but it is a nice way to make a mold ridged without a lot of bulk. It also contours well, as does the glass mat.
A final layer of fiberglass mat covers the core mat.
This picture shows how well the fiberglass mat and core mat contour. Also not the flanges on top, on bottom, and in the front. The vinyl will now be removed and the flanges waxed. This will allow the next mold part to be made right up to the existing flang without sticking to it.
Now the process starts for the left side mold.
Gel coat.
Templates. You may have noticed that the right side mold is smaller than the left side. I didn't want to join the fuselage parts along the spine of the aircraft. That is because it will take some body work to fill the joint. I felt it would be easier to do on a flatter surface than on a curve.
Here Al Muscella is applying the last layer of glass to the left side mold. Al knows the faster I get this thing flying, the faster he can build one of my kits! He's like a rocket scientist or something at NASA.
The core mat is hard to work with on a vertical surface, so I figured it would be impossible to put it in place on the bottom of the plug. I modified the stands so I could roll the plug inverted. I figured it was stiff enough with all the glass and the molds in place and would not bend. It worked well.
Secret weapon! Chris uses an air injected wedge to help separate the molds. I got it through a company called Fibreglast. They are on my reference page.
Proper preparation! That's the key to having the molds separate from the plug with ease. I've heard so many horror stories about how hard it would be to do it, but mine came off like peeling a banana.
Getting a little crowded in here.
I wanted to assemble the molds to se how well they fit. Here the top mold parts are assembled, and I decided to see how well I fit!
Looking in from the front. Nice fit and surface. The effort paid off.
A view from the other end.
In this digital video I show the start of the process of strengthing the molds. While the molds were disassembled, I felt they were too flexible. I put the molds back on the plug and built an external skeleton to make the parts more ridged.
Here you see the reinforcing completed. The tubes are completely glassed. I used two or three layers of glass and on some I used core mat to make them more ridged. The tubes work well and can be had free from carpet shops. (They are happy to let you haul them away.)
In this digital video I show the cross brace I had to add to the front of the mold to keep it from deforming.
I thought the cardboard tubes might even make good legs for the molds. It looks weird, but they work well, and are light and strong.
Click on any photo to see an expanded version.
(Click on the QuickTime logo to go to the page to view the associated video.)

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