Pieter Visser's X350

[Pieter001]

We turned the wings over so I can work on the lower part of the spar box. Cut the plywood load spreaders and glued them in with a good bed of flox to bed into.
Checking the holes and areas for the aileron bell crank. Had lovely rain, but I could not sand the wing spar planks. Hopefully tomorrow and I also hope to get the PTFE tape I ordered, as I would like to put a strip on the sides of the wing spar planks where the wing spars come together in the spar box.

Wings turned over for bottom of spar box work

[Pieter001]

I managed to hurt my back when lifting the spar box with both wings attached, not a clever move The result was a couple of very unproductive days and a couple of visits to the chiro.
I did fit the wing tie down long nuts Drilled the holes to 12.5mm and just deeper than the long nut so that it beds about 2mm under the wing skin. I glued the top of the nut closed by screwing a bolt to the required depth. When this had cured (put it in the oven @ 50 degrees to speed it up) I wet out the 12.5mm hole with resin on a earbud. Then made a flox mixture and glued the nuts into the holes while rotating them during insertion. I left bolts in them and filled the 2mm at the top with the flox mixture. During the green phase I unscrewed the bolts and trimmed off the resin around the holes. I'll micro the areas to finish them, but it looks great. I'll use 8mm grub screws to block these holes during normal operation.

Drilled to 12.5mm and 2860mm from the root and 645mm from the aileron trailing edge on the bottom of wing

RH tie down

LH tie down

Grub screw in with breakable lock tite and should be almost invisible once painted

[Pieter001]

Today I cut the 4 layers of 410gr bi-ax E-glass for the spar box. This is because I made the foam spacers yesterday and after I've covered them with packaging tape, I used flox to "bead" them into position in the spar box. As mentioned, the spar box I painfully set up on Monday. With a few hours of day left, I decided to finish the layup All went well

Lower end of spar box bottom section

Finished with peel ply and packaging tape visible through the 4 layers 410gr

Will use a flox bed to even the surface for the plywood load spreader to come

[Pieter001]

Houston we have a problem...

The wing spar stubs are such a close fit with the polystyrene spacers that I could not get the wings out of the spar box

I decided that brute force, tugging, pulling, pushing and all sorts is likely not going to get me anywhere (I tried ). So, I slept over it and this morning I got the car jack and problem solved (without using a big hammer)

Once the spar box is free, I'll clean up and sand the square edges and then fabricate and glue in the plywood spacers and UD.

Getting a gap

Using the car jack to separate the wing from the spar box

Done and polystyrene spacers visible and loose, but I cannot get it out yet as taped to the opposite side too

[Pieter001]

Why does there always have to be a really hard one and why does it always happen to be the last one?

I thought getting the first wing out the spar box was hard, but heavens, number 2 was a dusi! Simply because with the first wing out, there is now no anchor for the jack to push against. I tried all sorts, but to no avail. Eventually I had a Red Bull, sat back and watched this dilemma from another angle... I put the wing bolt back in the spar box on the side where there is now no wing. The idea is to use the bolt as an anchor. I then measured a piece of plank to be 60mm long and inserted that into the spar box so it pushes on the remaining wing's spar stub. Using this method I got the wing free! Maybe Red Bull does give you wings

Personal motivation: Perseverance will give you a Whisper !

No photo of this process, sorry, to few hands to hold and pic all at once
Note: It took considerable force to break this polystyrene and free the wing from the box, an amazing amount

Jippee, spar box finally free and ready for the next steps

Spend quite a bit of time making the plywood load spreader and getting the shape and spacing right

[Pieter001]

Sanded and prepped the spar box bottom section, rounded the square edges and made sure to get a good fit on the plywood spacer. Then glued in the plywood spacer on a good bed of flox. Weighted it down using dive weights, which I've found very useful throughout the build and eventually some will be melted down for the rudder counter balance too. I suggest investing in a couple of these

Cleaned and prepped for the next steps. Toying with a possible rear window...

Looking down into it. I used a bit of micro right at the end while curing the front bronze bushings to make it easy to ID the front anytime

Rounded the edge for the 4 layers bi-ax to finish with

Curing while weighted down

[Pieter001]

Due to pretty poor planning I am out of 410gr bi-ax Thought I had another roll somewhere, but it turned out not to be the case. Managed to order 400gr bi-ax here in NZ and should get it tomorrow, which is the day I have off before starting a new contract and I was planning to finish the top of the spar box tomorrow. If my order is delivered early that will happen
No bi-ax delivery today, so this job is standing over for the weekend...

I made the polystyrene spacers from a light type of foam I bought in a 20mm thick sheet. Also used a single layer on suspensions, it is marginal, but less weight... "Tacked" the polystyrene in place with a little (honestly maybe 2 gram in total) for everything. A drop on a part is sufficient!

Suspension pieces of foam to support the top layer for the layups

When all is in place, it is firm and seems great

Left was 65mm high and right side was 60mm

[Pieter001]

I received my bi-ax and it is a very good product indeed, but then it is 3x more expensive than SA per meter

Saturday morning I'll cut the 4 layers needed to finish the spar box and do the layup

Thought I'll share a picture of the cut UD, which is 500gr E-glass, but I'm not sure non-builders understand exactly how much UD is put in one side of the spar box! Both sides get this much, which is then completely covered with another 4 layers of bi-ax 410gr. Simply put, it is a MEGA strong stack of glass! 26 layers UD + 4 layers 410gr below + another 4 layers 410 on top, which makes 34 layers and gives it a thickness after layup of 17mm in total!

But wait, that's not all!!

After all of this the entire middle section of the spar box is wrapped around 3 times with one continuous piece of 500gr UD 180mm wide!

All of this ensures that the wings can handle at least a +4 -4 g wing loading

26 Layers 500gr UD starting at 200mm long and last one at 1100mm long to cover almost the full length of the spar box

[Pieter001]

D-day and the bottom section of the spar box is complete. All the remains is wrapping it in UD, as mentioned.

No matter how well I plan and think things through, I often find that during a job something unforeseen (that maybe even could have been foreseen) crops up

As the spar planks were trimmed at the bottom to a total depth of 204mm we have a fairly long straight section and then it narrows down to the ends. When I did the foam inserts for this layup, I did not consider this and the foam pieces are straight. Thus during the layup I realised that I will have deeper section in the trough exactly where the spar plank starts to narrow from the straight section

With no time to phone a friend, Christiaan in this case of course, I decided to make micro filler and to fill up some of this section. So when I had only the longest 2 pieces of UD remaining, I filled in the low spots with micro, making sure to clean off any micro that got onto the spar plank rounding where the final 4 layers of bi-ax will go over.

This worked OKish, but after I've laid down the last 2 UD layers, I realised that I still have quite a trough and it was not nice and even. The final 4 layers of bi-ax was going to be spoiled by having to go into the trough and then over the sides, which will not deliver the strength desired. Thus, I made some more micro, this time not as much of a paste, but more like mayonnaise so that I can level it out like you would when laying a concrete foundation or floor. This worked well and I was able to get a nice and smooth almost perfect level to lay the bi-ax on

Micro is not a structural material, but it is light and my thinking is that as long as it is completely encapsulated between the last of the UD and the 4 layers of bi-ax with no air bubbles, it should function perfectly as a filler in this application

All done and finished with peel ply. The white areas are the micro visible through the 4 layers bi-ax.

Closer look at the micro filler

Filler before the last 2 layers of UD, which was not sufficient I realised

Laying up the last 4 layers of bi-ax, which goes 60mm onto the sides of the spar planks and the section where the plank starts narrowing is visible

[Pieter001]

Useless bit of information, but just updated my build log and I've now spend 356 hours on my Whisper

"Just keep swimming, swimming, swimming..." - by Dory in Finding Nemo