The NACA ducts that I installed nearly two years ago need to be reinforced from the inside. So a couple layers of BID around the edges of the NACAs and the fresh air duct.

Now comes the big stuff. I’m not going with the diagonal shoulder belt system that the factory sells (and is found in most cars); a lap belt and a diagonal shoulder harness. Instead, I’m going with a 4-point style with a lap belt and two shoulder harnesses that connect to a center buckle.

The problem here is that with the fast build, the factory puts in the hardpoint for a diagonal shoulder harness (this is the stuff that you don’t think about when you’re starting all of this). So I’m going to have to completely remove the B-pillar/overhead beam.

This is looking up at the roof. At the bottom-center is the top of the pilot side door opening. Top-center is the top of the co-pilot door opening. On the left side of these door openings is the overhead beam. This overhead beam (and the B-pillars which run down the side in back of the door openings) are made of carbon fiber. In order to get a hardpoint for the shoulder harnesses to mount to, I was going to have to remove this, install the hardpoint and re-install it. That’s when I made a couple discoveries. 

• The B-pillars and overhear beam are not a single unit. They are three separate pieces.
  
• Where they are tie in is not the most impressive union I’ve ever seen.
  
• The roof has a layer of carbon fiber BID… but only one layer. (Notice in the previous picture that instead of solid black, you can see some “tan” between the rear beam and the windshield.)

Here’s the joint between one of the B-pillars and the overhead beam.

And here’s a closeup. No reinforcing layups. Just some epoxy.

The first thing to do is remove the overhead beam. To do this, I scored the 2-BID layup where the beam meets the roof. Then using a putty knife, I separated the BID from the beam at one end and then literally peeled it away from the beam. Then repeat for the roof. Next I made a couple small cuts at the joints on each end, a couple whacks with a chisel and the beam came right out. 

Next I smoothed out any rough areas and sanded the entire forward roof area and lay down an (additional) layer of carbon fiber BID.

Once that cured, I decided to do an additional task. Most builders have a hard time getting the doors to fit after installing the engine. This is due to the weight of the engine causing the fuselage shape to change slightly. A few builders have installed some diagonal layups on the roof from the rear to the front to prevent the distortion. I used two plys of a fairly thick carbon fiber UNI that will help with the distortion and will add to the strength of the roof. 

Next I needed to locate where the hardpoint for the new (improved) shoulder harness will be. I did this with a plumb bob and a tape measure. The hardpoints for the diagonal shoulder harness is a piece of 2″x4″ wood. Two problems with that method for the new hardpoint. #1 is that the B-pillar is much deeper than the overhead beam (the beam is only 5/8″ deep) and #2 is the factory hardpoint uses a bolt sticking out. So I’m going to use a 3″ x 4″ x 1/2″ piece of aluminum that’s drilled and tapped. For most hardpoints, they use 2″ x 2″ x 1/8″ so mine will be much more substantial.

Here’s my hardpoint and the standard sized hardpoint.

Once the hardpoints are secured with structural epoxy, I drilled and tapped them.

Before installing the beam I glued down a small square of titanium on the ceiling where the bolt for the hardpoint would come through. Just in case a too-long bolt was used, I didn’t want it going through the skin.

I need to bond the beam in place. I want the overhead beam to become part of the of the B-Pillars to create a seamless rollcage. So I took 2 layers of leftover carbon UNI and inserted them into the ends of the B-Pillar. I then stuffed some foam under the layups to force it into contact with the inside of the B-Pillar.

Then I applied some structural epoxy to the bottom edge of the beam and pushed into position. The foam under the layups will also force it into contact with the inside of the overhead beam. I then put the beam in place with a couple bricks on top to hold in place while the epoxy setup. Then I used some more leftover carbon BID over the seam with the B-Pillars and over the beam and onto the roof.