24/09/26 - Windscreen final install with sikaflex - 06h30
Glue time again... this time we are going to use Sikaflex glue to fixate the windscreen on the top forward fuselage and rollbar.
The product used is this 295 UV. You can easily appy this with a caulking gun. It's very sticky and creates a mess quite easily if you are getting sloppy on the trigger
The sifkaflex is very efficient but needs to be applied on a primed surface. There is a compatibility chart with recommendations on which primer to use on which surface with 295UV glue.
On the tof fuselage surface which is bare aluminum, I am using the sika activator 205 which prepares the aluminum before priming. I think it's an etching product.
After the application of 205, I will prime it with the Sikaflex Multi Marine primer (SMM).
On the rollbar which is already painted with a 2K epoxy primer, I am applying SP-209D primer as well as on the windscreen. The windscreen is made of PMMA and this primer is especially for that material.
First I defined the line where the sikaflex needs to be applied so that I can apply a tape for masking before priming.
Also on the roll bar, I used black 3M tape to define the place where I want to apply the primer. It's hard to remove any sikaflex which comes in contact with the primer. glue that hardens next to the primer can quite easly be remove.
This allows you to make a nice straight line with the glue and fill the gap between rollbar and windscreen with the little fillet of sikaflex.
Taped the windscreen with 3M tape to define the border for the primer. I'm being very liberal on the side of the primed surface but it won't be visible anyway because the epoxy fairing will cover this anyway.
Scuffed the exposed surface with red scotchbrite. Just getting the gloss of is sufficient, no need to go deep with rough sandpaper.
Then taped the forward line on the top fuselage. once taped, I scuffed the surface with scotchbrite for better adhesion of the aktivator and primer.
One of the issues of installing the windscreen over the rollbar with all the sticky goo on it is that it becomes very difficult to place the spacers between the rollbar and windscreen. The black mess will be everywhere and no way to see where exactly the drilled holes were. So I decided to glue the plastic spacers together. Held them togehter and pressed on eachother with some screws and nuts. Once dried, I will glue this in the same way on the right locations on the windscreen so the are already in place when having to position the windscreen in the moment of heat.
I have made a small test piece of scrap lettover of the canopy and glued it on on the rollbar using the primer on the winsdscreen and roll bar. When cured, I stuck to it like you will never be able to remove it again.
I had to cut with a razor blade through the glue and still couldn't get the glue separated from the primer. This stuff stick really well to that primer. I recleaned the bar afterwards.
windscreen fully scuffed now and ready for primer application
Also finished scuffing and matting the rollbar with red scotchbrite.
Same on the front fueselage exposed skin.
Here I have applied the SP-209D primer on the windscreen. This stuff flashes quickly and dries fast. I think it also has some glue in it. Your brush will become useless once you"re done with it.
Same primer applied on the rollbar contact area
Applied the primer SMM (sikaflex multipimer marine) on the aluminum skin after 205 aktivation. For some reason the PMM primer is transparent color. Doesn't matter much as it will all be covered by the black glue stuff.
Once the primer dried, I glued the spacers on the inside of the drilled holes and did a final fit on the rollbar.
Then applied aktivator and SMM primer on the clips.
As the primer was now dry and the windscreen on, I drew a new line under the bottom of the windscreen to see the place where to apply the glue.
And then the mess started. Went all the way around with the caulking gun and applied a big bead of glue about a centimeter wide on the line all around the top fuselage skin and the rollbar.
You have to work quickly as the glue already starts forming skin after half an hour.
I started spreading out the glue on the outside of the windscreen using rounded plastic card in order to to create a nice round filet.
Then started cleaning up the mess by removing the excess glue.
I did not touch the inside. it looked already good and is not visible behind the windscreen fairing.
Then started cleaning up the glue between rollbar and windscreen from both sides.
No clamps needed as I still have the screws in the windscreen around the rollbar and the rest of the windscreen is held in place by the clips.
After all things went smooth. I thought it would be more of a hassle.
