Ch 4 Fuselage Bulkheads

Wow its a while since I worked on this chapter. Now I’ve moved the controls I needed to reset the front seat access hole. I’d previous moved the controls out from the side and this meant that I had to hack into the seat for access. This in turn meant that the outside of the hole showed through beyond the side arm rest which I didn’t like.

Now I’ve moved the sticks I could fill in that access hole a little. I made a piece from a scrap of foam that had plys of glass already on it. Some careful shaping and you see the result in Pic 1.

Pic 2 and I’ve microed it in place using large pins to hold the filler piece in position while it cured. I used peel ply on top of a single ply of glass to secure the ‘patch piece’.

Once cured I fitted the control rods for full movement just removing the minimum foam. I then added micro and peel plyed the edges to seal the foam. I thought about a ply of glass and flox corners but really…. it would have been slightly more weight and no structural advantage.

OK its like moving sideways as far as progress goes but I’d call it a win. Now we are down to the pointy end of making sure everything fits for real.

Make a filler piece

Micro in place

Trim and fit

Sealed the cutouts in the front and back seats with micro. I may have to widen them later so a careful 1ply layup with flox corners would be over the top. The other bulkheads using the thinner foam I sealed with pure epoxy.

Bulkheads completed

Lower IP and Back Seat

Front Seat completed

Cut out the back seat control and wiring holes per plans
Final tidy up of front seat holes.

Note that rudder cable holes still need to go in before Ch5 is completed. I’m using a powered landing brake so extra front seat holes are not required.

Front of back seat

Rear of back seat

Front seat control holes

Lower Instrument panel. Trimmed edges and ‘shelf’ down to 1.1″. Might remove above the leg cutouts but after the bulkhead is installed so it doesn’t warp.

A metal, removable instrument panel will be the upper section using the right angled glass shelf for attachment and as a safety measure so there are no sharp edges at the bottom of the panel that might cause leg injury.

Front seat cutouts are made with a 0.7″ offset to allow for the reclining seat so the channel is parallel with the floor. Still a bit to do here, it will need some glass as it would be subject to the holes being damaged when things are installed.

Made the hole in the firewall to make it lighter per plans. I’ll leave the longeron cutouts untill its time to assemble the sides and bulkheads. I may get a better fit that way.

Front Seat side cutouts

Firewall cutout

Trimmed the edges of the firewall. Now both sides are done. It still needs the center section piece removed.

Firewall trimmed, no hole

Started cleaning up F22. I originally cut out holes in the foam. Then was worried about the glass on the edges drooping so I made foam inserts. It just made a lot more work. All I needed to do was just glass over everything and cut it out later OR deal with the glass buy trimming while it was wet. I was worried about the fibers getting out of alignment although the plans say firbe orientation is not critical here. I still did all the BID at 45 degrees.

Took quite a while to clean up the edges.

The firewall was out of 1/4″ quality birch ply. Easy to cut to shape and 1 ply of bid. I did slurry the wood first but it needed very little and I think this serves to prep the surface and get a bit of resin on it before the glass. Worth doing.

F22 cleaning up

Firewall

Instrument Panel inner layup to reinforce the edge. 2 Ply of BID about 4″ wide. Used an old jig to create an angle to make the layup easier. Worked very well.

I.P. inner reinforcement

F28 reverse side. Prepped glass, cleaned up the other side layup at the edges. Layed up on foil, peel plied the ends again.

F28 Prep

F28 Foil layup

F28 Layups done

This took the previous day to prep the glass, cut to size. There are two large plys over the whole bulkhead then 9 additional per side with peel ply at the end. So 20 plies plus peel.

This took around 4 hours and probably the lower plies were starting to cure while I was doing the upper ones. Big job.

The outside curve of the instrument panel was rounded and 2 plys of BID over the slurred foam. I cleaned up the edges from the first inside layup before this one.

F22 prep then aft face with 2 ply of BID and doubler pressed into place while wet. Then further plys per plans locally over the doubler. Lower edge transitions were peel plied.

I used weights for the cure. Probably not necessary. There is a concern about warping but this is often when external heat is applied and my room was hot enough at 27C.

F22 Prep and IP Prep

F22 with doubler

F22 Doubler