New Rear Window Material

When I tried to order a replacement plexiglass window with Carl, I got a surprising answer:

"I am no longer fabricating the plexiglass window. The cost of shipping, cracking and breakage was the reason I had
switched to a different type of plastic for the rear window. The new type of plastic is called Vivak it is made by the Bayer
Co. of Germany. Vivak is only available in clear, so a tint film must be applied to get the tint required. This plastic is unbreakable
like Lexan but does not have the sensitivity to fuel and solvents that Lexan does."

This new window material lies flat as the Lexan one does, so Van's themselves could replace the fuel-sensitive window with this material. It turns out that this Vivac stuff is also a bit cheaper than the plexiglass and will ship for less as it doesn't have to ship preformed.
I just hope the tinting film will work out ok and stick to the material as I really want to reduce the heat in the cockpit when flying in Arizona's summer.
Carl is going to make one for me this weekend, so we'll soon see how it looks.
To see how fuel resistant this material is, I ordered a 0.1" thick sheet through amazon.com. I'll use that for testing how different solvents are affecting the material.

And On With The Canopy

I tried to avoid it but now I had to continue with the canopy anyway. This task really is intimidating to me and I am far away from feeling comfortable with it, rather overwhelmed I'd say.
So as usual in such situations the standard procedure of Divide et Impera works like a charm. Split an overwhelming task into smaller, controllable tasks and the problem appears less scary.
First I verified that the frame has an even 1/8" gap to the canopy deck. That was not the case. I had to remove some of the cardboard in the front as it wanted to push the frame up where it should match the arch of the rollbar. I held it down good with a lot of blue tape applying the necessary force on both sides.


Clamping the bow to the rollbar with the wooden blocks providing the reference for the distance was the next step. I noticed the the frame is not completely symmetric. One side is slightly shorter than the other which introduces a little warp into the structure when forcing it into an even distance to the rollbar. Nothing significant as I believe the canopy glass will even it out once attached to the frame. At least that's what I hope.


Fluting those little angles that will hold the canopy to the sides of the frame was slow but easy to do. Seems that I haven't done this job in a while and I got somewhat rusty. Much more challenging was figuring out how to sufficiently clamp these angels to the frame for the match drilling. Fortunately I had two clamps that were just big enough to do the job. After two clecoes it's easy to support and fine tune the fit by hand while drilling.


Match drilling, removing clecos, deburring, re-clecoing and then for the fun part. You know it, I LOVE riveting!!!



Then some masking tape had to be attached to some possible scratch points around the canopy frame. This was in preparation for fitting the canopy.


The protective plastic cover in the canopy only seem to be thick and bulky on the front inside where it should fit to the front bow of the frame. That's where I peeled the plastic off to allow a close contact. The rest I left in place for now.




Wow, this looks impressive. Almost like a plane :-).
The fit that Van's produced is breath-taking but it also created a concern. The fit on the rollbar is so perfect that there is no way for me to compensate for a not quite so perfect match drilling and alignment of the rear window to that very same rollbar. I had silently hoped that I could fix that by trimming the canopy but this is now obviously out of the question. As I had also cracked the rear window while opening up the holes (because of the fact that I HAD a hand drill and forgot all about it and didn't use it), I decided to suck it up and order another rear window from Carl. There's is no point to try to fix this mess, it would very likely just get worse.
Now I just have to figure out how to create the tangent line on the front bow. Blue chalk on blue tape doesn't sound so good. I'll see if I can find some green painter's tape.

A Little Bit of This, a Little Bit of That

I finished the rear window installation by tapping the match-drilled holes in the rollbar with a 6-32 drill tap. There's really not a lot of material holding the screws in the rollbar, and the screw is certainly harder than the aluminum, so I better remember not to tighten them too much when installing the window.
I have not yet repaired the crack I caused in the rear window but I received the cement necessary to do so.
Instead I started pulling the parts for the Main Gear section to start assembling the tires. It also looks like installing the upper part of the engine mount would be a possible step to complete next.
In a surge of overwhelming optimism I also checked the Van's website to see if there was an updated Avionics order form available as rumor had it that it should be available around now. Did it really surprise me that it still said that they are working on the SkyView update and that they wouldn't take any orders for now?

Rear Window Done

So I received my clecos on Friday just in time to get some work done over the weekend. Thank you , Avery!

I finished the match-drillling and accomplished a pretty good fit to the rollbar. Not perfect as I wanted to - there's a slight skew over the width of the window which I probably can compensate for when fitting the canopy.


This is how it looks from the inside.





Then I took everything apart and finished the task by opening up the holes in the rollbar and in the rear window. That's when it happened. I honestly despise drilling plexiglass! I already learned this fact when working on the landing light cover. Then at least it was a few holes that were controllable. Not so with the rear window! One of the last holes opened caught on the material and it cracked and broke out a part of the forward flange. I think I'll be able to glue it back in and make it look ok. It's on the top, so not too visible and certainly not a stability issue.
Anyway, when you get to this task, be super careful about the opening part and apply almost no pressure at all with the plexi drill.
I didn't take a photo of that boo-boo but I will do that when I have the cement to fix it.

Now, I am thinking to do some prep work on the Main Gear section as the temps are down again and doing epoxy work is probably not a good idea at this time.

Rear Window Installation

Finally it was warm enough (sounds like we were due, huh? No, we're really lucky this year to get a warm spring-like weather just around New Year's - it was at 78F today!! God, I can so see the envy in your face :-) ).
I didn't feel like finding excuses to not work on the plane any longer and so I just removed the tarp from the fuselage and started fitting the rear window. Remember, I ordered the plexiglass version of the rear window which is provided by Carl Eldridge and is fuel resistant and mine is also tinted to reduce the heat in the cockpit and of the fuel a bit. The Lexan version Van's provides is pre-drilled so you can cleco the window to the rear and side skins before match-drilling the front to the rollbar. Well, it's not that easy with the plexiglass version. First it is not pre-drilled so you will have to align it by yourself as well as stabilize it during the first holes drilled.
Furthermore, there is a section in the center rear that interfere with some brackets on the inside of the cockpit and the window has to get trimmed to clear these brackets. Not too much though to leave enough beef for the screws to hold the window onto the sheet metal.


This shows the right side bracket in question. See the little cut out that allows the window to pass the bracket. That has to be trimmed off. I used the Dremel cutoff wheel and the sander piece to trim this.
The way I marked the area was by sliding the window in place and pushing as much aft as possible until it hit the brackets. Then I aligned the sides to so they were even and then I marked the bracket area which is right around the outer forward screw holes.


The blue marks show what to remove. I repeated this step around 4 times until I had a good and tight fit.

The next challenge was to support the window against the gravitational droop to accomplish a better fit during drilling.
I used a piece of 2x4 to do that.



With these problems all out of the way I started drilling on the rear holes as the front stays well in place just by its own weight. The aft section not so much as it held to the sheet metal by the eventual screws only. Also I used an older #40 drill bit that I drilled into concrete to dull it up enough to not crack the plexiglass.



This is as far as I went on the rear side before I switched over to the rollbar match-drilling. I felt I needed some better support for the front before finishing the sides as I think this will result in a better fit that way.



I couldn't finish the job as I ran out of clecos. Partly because I needed the #40s in the rear to hold the window to the sheet metal (the Lexan takes #30s there as it is pre-drilled) and partly because the plexi is a bit stiffer than the Lexan and likes more screws holding (and forming) it to the rollbar. I'll order some more and then finish the task. It looks really nice so far.