Ch 6 Fuselage Assembly

Its been five years since I worked on this chapter. Finally time to flox on the firewall in preparation for doing the canopy and turtleback. I’ve used the access for a while but time to close it up. I’d thought about using something more lightweight than the marine ply and maybe making a slightly better fitting one. Really…. what I have is pretty good and time is not what I have a lot of.

Here you can see the pump I have installed and the relief tubes going into the gear legs. There is the brake lines you can just see too in black tubing as well as the gear leg fairing and engine mounts of course. All this was a lot easier to do before gluing on this firewall.

As usual some creative clamping was required. The clamp and rope up the top was just to move the top part of the piece about 2mm  so it is an exact right angle to the spar. Possibly unnecessary but easy to do and as always I’m trying to do my best where it is reasonable, even if no one ever sees it.

This last pic shows a 1 ply BID tape and peel ply on the inside. I’ll do more 1 ply tapes when the fuselage is next inverted. I have a list of things to do then when gravity and access will make things easier.

Its been a while since this chapter! 5 years… The plywood firewall I have is going to be remade but the current one I did can be used while I setup the canopy so it needed to be installed, be it only a press fit.

Pic 1 is all the trimming I had to do. The top of the turtle-back should be W.L.32.8 with the spar top at W.L.22.0 Maybe it will move +/- a few tenths depending on how the canopy works out. I’m going to see how that goes and then also see if I can make something a bit lighter than the plywood plans firewall. I have some titanium instead of stainless to line it with too.

For now its great to see that firewall sitting there with the engine mount and I’m just a bit closer to getting the final firewall in place.

Trim lines

Fitted for now

A turtleback template

The plans just say to ’round up your Nose box (NB) from a supplier’. I was loaned a mold that was used in the 1980’s to make this part. In fact it is the very mold that was used to make the Long-EZ I am currently flying. So it is fitting that it is again being use for a new build of a Long-EZ.

This is my third attempt using the one and only mold I have for the whole aircraft. The first layup was a bit dry, the second I tried to vacuum bag it only to find that the pressure was deforming the mold so I broke out the wet layup before it did any damage.

The third layup seems OK. Just two plies of BID and some peel ply where tapes will join to the floor. The mold had about 5 layers of wax then I covered it in cheap hair spray as a release rather than the usual PVA. The hairspray dried quickly and as its in a spay can I could get several nice even coats without runs and without using an air-compressor.

While not very thick at only two ply, once taped in place it should do the job. My build will have gear doors so insulation is not an issue for the nose box.

Nose box mold

BID ready for epoxy

NB (Nosebox) part

More picture of the version 2 floor.

This time less dips and very little air in the layup.

Front

Rear Floor

Rear seat back

This step is adding inside tapes to the fuselage bottom joins.

Tapes were added over a couple of days to the front area, Instrument panel and rear seat area. All tapes had half inch peel plied edges and the tapes themselves were laid up on foil as detailed in my first version of the floor.

I’ve left the Instrument panel brace on for now.

Chapter 6 is done and dusted.

Front tapes done

Rear seat tapes complete

Floor Installed!

Layup and join the floor to the fuselage.

This took 12 hours… 14 hours last time so less breaks. I preheated the room overnight and again worked at around 26C. I microed the foam which took a while then let it sit for 15 mts or so.

Next I got the first ply on and the weave at 45 degrees. This is the easier one as its not very wet underneath. Its still very tricky and I might spend even more time in prep next time.

Wetting out still showed some air and it just wouldn’t come out. I might try VERY wet layups next time and then slowly remove the epoxy. Sometimes it just seems harder than others. Maybe the foam was an issue. The second ply was very hard to get the weave straight at 45 in both directions. Once it gets wet you do more harm than good moving things around, It will be OK.

The third ply was a little easier being smaller but still needed lots of attention. Then it was peel ply in the required areas and a short break.

I floxed the floor on and did the required clean up. Wet flox is easy when wet, Once set its a serious clean up job. This was not perfect but will be OK.

Dry glass on micro

All done and with peel ply

Floxed and clamped

A few hours of prep getting all the glass ready for the layup.

Two plies of BID and then one extra piece for the backseat are required. Each full ply needs two pieces which I set up to join at the from seat edge so they will not be visible.

I broke into a new 100m roll of BID. I also have a 100m roll of UND. These are really heavy and it’s something to think this will be in the plane one day.

I labeled the pieces and got the layup on paper and in my head ready for the next day.

Floor on jig

BID roll of 100 meters

Glass cutting

Shaping the floor. This second time I decided to do less areas now knowing exactly what I need and don’t need.

As in the first pic it just takes a while with most of the work by hand after a rough out with a drill and sanding bit. I wanted the sides less steep so that there wouldn’t be the air gaps caused when glass will not lay down.

I now know where the sump tank is going and see no reason to put curves in the back seat feet area at all. Just one for the pilot and PAX behinds and a couple up front for extra ease in getting in.

As I’m not running fuel lines and a valve up to the seat I left out the two front seat little dips.

The third pic shows a trial fit and gluing the bent floor to the jig. I still had all the timber from ver1.

Making the dips

Curves complete

Gluing the floor to the jig

Having cut out my first go at the floor the foam finally arrived from China for a second attempt.

This time it was more straight forward. I knew what to do. Here I’ve cut the foam block in half. Drawn a center line and then placed it on the fuselage with weights and marked out positions as shown in the first pic.

The last pic shows that I’ve lined things up and this time put a straightener on the lower instrument panel as it tends to warp or bow. Just one less thing to think about during the glue process.

Floor marked out

Checking positions

IP Straightener

The floor took over a month and had a lot of expensive parts. However I was unhappy with it as there was air in the layup. This was a non structural fault. It was caused by making the slops on the cutouts too sudden a transition to lowest points. It should or could have been much more gradual.

After all the taping work and doing a repair I decided to cut it out. This took many days as I was very careful and the last pic is 18 days later all ready to go again.

Foam for the floor had to be made and brought in from China so I was in for at least a months delay.

I am committed to the best work I can do without going overboard. This time self imposed quality control required I redo this part. I’m happy with the decision and will do the next floor with alterations.

In the mean time I went on with other tasks and now have the rear seat sump and fuel system roughed out in my head having studied lots of options.

Removing the floor

Lots and lots of clean up

Back to a fresh start

The floor to side joins receive one ply of BID tape at 45 degree bias as is usual. This is in the back seat area.

The longest ones are 45″ X 2’5″ wide. They are first laid up on foil as shown in the first pic and cut out with the rotary blade. The surface is prepared and then painted with pure epoxy and carried over and placed with the foil intact. Hard to see any other way except putting the cloth in dry. This method allow a controlled resin to cloth ratio.

After placement and stippling to remove any air and get it down the edges are peel plyed with a half inch piece of dacron. Very fiddly work and despite having previously cut long strips of the stuff with scissors as a part of the prep. I’d also wiped a very thin line of micro into the edges to help the glass sit down better which worked well..

This completes Chapter 6 except that I have some air under the floor layup to treat. I’ll just use a syringe and very warm epoxy to sort this out. The lesson here is not to ask the BID to do too much and think ahead of possible issues. Another point is to have an assistant for these very big layups.

BID laid up on foil and cut to size

BID with foil still intact

I ply of BID and peel plied

The first pic shows the first lot of inside tapes. All edges are peel plyed. I did this on the 21st. The next pic is the front seat area preped on the 22nd and glassed today (23rd)

These relatively small jobs of 1 ply of BID still take a while and need care and attention to detail.

F22 to IP tapes

Lined up bulkheads

Front seat inside tapes