Ch 6 Fuselage Assembly

See the previous entry for a description. These pics show the floor just after it was floxed on showing from underneath.

This layup took 13 hours and next time I’ll find an assistant. Pheeeeewww

First the foam was covered in micro and then this is removed leaving just a film to fill the cell holes. a good couple of hours in the end. Then the first layer of BID is positioned and the end piece nearby.

Then the epoxy work begins. My contours were too deep or at least too abrupt on the bottom and I did my best to get it to lay down. It just wouldn’t in places no matter how I tried so I have a few small air voids to fill later. The bulk is OK it just takes a really long time to do.

Once the floor was glassed then I mixed flox and applied it to both mating surfaces with the bulk on the fuselage. I should have had an assistant to move the floor into position but it worked out OK.

I spent some time ensuring it was straight although I’m 1mm out at the aft end. The fuselage is still straight however. I ensure the top was on tight and cleaned up all the excess flox from underneath .
There are some inside pics of the layup in the next (or previous log entry)

Floor layup begins

Layups done

Clamping the floor

It takes quite a while to get the glass laid out and cut. Couple of days…

I like to get it on the piece dry and line up the bias correctly, then take the outer edges and cut well oversized. The floor needs two plies of BID each with two pieces at 45 degrees. A third ply is also needed for the back seat area.

The peel ply is also planned out and pieces cut ready to go. I write out a layup plan step by step so nothing is forgotten.

The third pic was actually after I laid the glass after the micro the next day but positioned here to show you what things look like. That tiny little credit card in the left foreground is my main tool for spreading the epoxy.

Laying out the glass

After several days the floor contours were completed. I also rough cut the front wheel hole which will be trimmed later.

The alignment of the bulkheads were checked with a laser. As long as these line up and the centre of the floor is pretty close I’II have a straight fuselage. The squareness of F22 and the firewall is already confirmed and set.

A curved jig is needed to hold the floor in a curved shape on the fuselage. It is then removed to the table for glassing. I began setting up the jig as shown in the first pic. I just screwed the timber together which allowed me to easily dismantle it later but be held in place for now.

Looks like a bathroom cabinet!

On the horses

Weights and clamps

Contouring the floor took a good 5 days. I tried different tools and ended up with a router. sanding drum and hand sandpaper finish.

I made templates from the plans to get the curves correct. In retrospect I would have made shallower curves and left the back seat area un-contoured. It would have been easier and better.

Hours of fun

Rotary sandpaper is still slow

A LOT of contours

Using 2″ thick H35 foam obtaining this piece and cutting it to size was quite a task. I first had to disassemble my 2 axis full size flight simulator to make room for the tub on saw horses.

After a trial fit, I laid out all the inside measurements and cut outsides of the foam. It takes quite a lot of weight at this stage to bend it to the fuselage bottom shape.

Any weights do the job

Expensive foam slab

Getting a fit

The support block for F28 is covered in one ply of BID. This required 4 pieces to cover well due to all the angles and a little peel ply as pictured.

The other tapes were cleaned up and overhanging areas were trimmed back to the previous edges.

This completes step 1 of chapter 6. Step 2 is the fuselage floor.

F28 doubler

Front of front seat (inverted)

Front of back seat taped

The tub was placed right side up to install the front and back seat tapes. These are laid up on foil as shown in the pictures and placed into position. About 30 minutes later I remove the foil and treat any air pockets. This works very well for getting the tapes into the correct positions.

The edges are then peel plied with half inch dacron to give a smooth transition.

The third pic shows F28 in position and something that looks like a fuselage for the first time. Its weight would be around 20lbs and its not yet rigid.

Tapes with foil still intact

Back seat with foil

Tub right side up

Adding F28 Bulkhead is 5.9″ from the front of F22 and was better left until now. The bulkhead was carefully fitted and then two small spruce supports were made from left over longeron timber.

The parts were simply floxed in place after pre sanding the already peel plyed areas and lightly clamped.

Taking a few of the main clamps off it was easy to see the movement off the centreline than can be easily achieved. The floor will lock things into place and will need careful positioning to maintain all the alignment work done so far.

F28 and blocks

F28 floxed in place

2″ wide tapes were added to the bulkheads. There are two plys of BID for the front seat, back seat and Instrument Panel (IP). They are layed up first on silver foil with the sizes marked. When wetted out the marks show through and the pieces cut out with a rotary hand cutter to precise shapes.

As the glass is on foil it is easily moved while retaining its shape. I did the I.P. first, both sides and let the foil sit for 30 minutes before removing. It stiffens a little and is less likely to move. After squeeging out any air the edges are peel plied.

The back of the front seat I first added some micro into the join and left it an hour before adding the tapes. I’ll treat around the black straw later with some micro and small tapes.

F22 (front bulkhead) has wider tapes matching the stiffener on the bulkhead in width and uses 4 ply’s. I was very careful to ensure all the air was out doing this layup as two lots of two ply. Again the edges were peel plyed to prevent any chance of delaminating if the edges are knocked in the future. This area carries some of the canard loads so is important.

F22

Instrument Panel (IP) and F22

Front seat (this is the view of the rear of the seat)

2″ Tapes are applied to the back of the back seat. There is also peel ply 1/2″ wide to seal the edges. Probably overkill but just trying to keep the build tidy.

The plans don’t say what to do about the open areas but its clear just to put tapes where I can. Glass to glass is the important area. Glassing onto the timber with tapes is not considered to add much strength and will be at odd angles. Better to do those areas separately if needed.

I’ll add all the tapes I can before removing the clamps.

Nice clean work, if I do say so myself.

Edges peel plied

Worth the effort here

After a successful dry assembly, the bulkheads were removed and all parts to be glued were sanded ready for the flox.

The firewall is not glued in at this stage to make the spar easier to fit later. It is secured with bulldog clips and the other parts and joining places on the sides were then coated with pure epoxy and then flox and assembled.

The backseat has 6 clecos to hold it in place and the front seat has nails which are pre positioned. F22 also has 4 positioning nails. F22 has warped since I made it and the second pic shows a clamping system I added to ensure it was straight and properly seated while the flox dries.

After spending so much time with the dry set up, everything went together quite well.

I’ll leave the clamps on until I have some of the BID tapes done as there is not a lot of gluing surface at this stage.

Its great to have something in 3D now and the beginnings of a fuselage.

Floxed. lined up and clamped

F22 clamped straight

Sitting there curing…