5.4.0 Carbon Beams

After I trimmed each beam to get it to sit as closely as possible to the side of the fuselage, I had to prep them for installation. Doing that includes making some wood blocks that get installed inside of the beams. In addition to an epoxy point for attaching to the side of the fuselage, they are also used to hold various bolts and nuts. A seatbelt hard point and bolt is installed on the aft carbon beams (not shown here - this one is a forward beam). 

I also decided to install grab handles to make it easier to get in and out - just like in a car. The rear beams are fairly flat when the grab handles get installed but the forward beams are curved. In order to get them to sit flat I had to create some mount points. I used some blue foam which I sanded to fit the handles. (You can see the outlines of the handles on the foam.) I then tapered the foam toward the beam. Later, all of this gets covered with a couple of layers of BID to strengthen and protect the foam.

Fuselage - Carbon Beams - Pull Handles

I added some mounting points for the pull handles that eventually get mounted here.

I decided to install all four carbon beams at the same time. I almost ran out of clamps! In fact, I think I used every clamp I had available! Because the beams are made out of carbon fiber in the factory, they are very light weight. Yet, they are also very strong - much stronger than an equivalent fiberglass beam. Because they are so strong they are hard to bend into place. For the most part they lined up properly but I did have to persuade some sections of the beams a bit for good alignment.

There are wood blocks scattered throughout the beams at strategic locations. These blocks are used for multiple purposes - to act as a location to glue the beams down with epoxy and as hardpoints for various hardware, such as bolts for the seatbelts and nuts for the pull handle screws.

Fuselage - Carbon Beams - Installation

It takes a lot of clamps to held these carbon beams into the proper position!

Once the epoxy cures it’s time to add 2-BID layups to all of the beam edges. Before doing that though, I made up a rather thick mixture of EZpoxy and Microballoons which I carefull spread along the edges of the beams. This helps to round out the edges which not only looks nicer but makes it easier for the fiberglass to bend around the corner.

The photo below shows those layups after they were finished. On the forward beam (right side of the photo) you can also see the layups I did over the foam mounts for the grab handles

Fuselage - Carbon Beams - Final Lay-ups

Once the initial epoxy cures that holds these in place, EZpoxy + Micro and 2 BID lay-ups are installed to strengthen and seal the edges.

Once the layups around the edges of the beams are cured, it’s time to add a hard point to the edge of the beam to be used for the door gas spring. More about that in Section 5.5.0. This hardpoint literally gets mounted on the edge so I temporarily had to hold it in place with hot glue. I then packed a lot of EZpoxy + Micro around the hardpoint both for support and to provide a smoothly curved surface for the fiberglass to go over. In this case the factory recommends only one layer of BID so that’s what I applied.

In addition to seeing a closeup of the lay-ups added to the perimeter of the carbon beams, this photo also shows the installed mount point for one of the door gas springs.

Jump ahead a year or so… The fuselage is now upside down which makes it much easier to install all of the beams and ducts and such on the inside of the roof. The first step is to install the carbon fiber cross beam. The door support beams have been in for quite awhile and this beam completes the task. After trimming it to fit between the existing door beams, as well as to adjust the edges to fit the profile of the rood, I installed a couple of wood blocks which are used to epoxy the beam into place. This is the same procedure used for the main beams. See the photo below.

Fuselage - Carbon Fiber Cross Beam Installation

Prepping the carbon fiber cross beam for installation.

Now that the wood blocks are firmly attached underneath, it’s time to glue the assembly to the roof. If you look carefully at the photo you’ll notice that the left side matches up nicely to the door beam. The right side does not! Who knows why? I’m not sure how they mold and trim these in the factory. In any case, a little bit of carved foam along with some fiberglass and the problem on the right side is solved. How do you like my locally sourced weights? They are free and they work!

Fuselage - Carbon Fiber Cross Beam Installation 2

Using my locally sourced weights to hold the beam in place while the epoxy cures!

Once the epoxy cured underneath, it’s time to add a couple of BID layups along each side of the beam to permanently lock it to the ceiling as well as to the two door beams on either side. You can see that I also fixed the gap on the right side.

Fuselage - Carbon Fiber Cross Beam Installation 3

Finished carbon cross beam - lay ups complete!

Section 5.5.0 details the installation of the gas springs. Click here to go to that page.

ui© John Trautschold 2018