Scale Soaring UK

managed to get the canopy vacuum formed but was only successful on the third attempt. The first two had lots of folds everywhere so I was a bit disappointed. On these attempts I had the vacuum cleaner on before I dropped the frame with heated clear Vivac on the plug.
the third time I dropped the frame over the plug without the vacuum on The plug was formed for say 80% by its own weight without folds, then the vacuum was switched on and it all came good. Maybe this is how it is supposed to go but I do not have much experience with this
With the vacuum switched on before dropping the plastic it may go all to fast and the plastic does not get time to stretch were required.
Maybe somebody in the know can give us some light on this

When at Sarik hobbies and watching them pulling canopies, the vacuum pump comes on after the plastic is pulled over the mould so, yes get the plastic down over the mould as far as you can before turning on the vacuum. Perhaps Barry from Sarik could advise.

Jilles,
How do you heat the PETG?

the PETG is heated by an old Oven grill. on attached picture you see the top structure of my vacuum machine, the grill is housed in the timber structure.
The knob shown is the on/off and thermostat. The aluminum window frame with PETG is hooked to the top. It forms then a closed box. With the thermostat the heating is controlled by increasing the heat slowly. This way the PETG sheet is evenly heated.
When the PETG comes down from the frame half way the plug during heating I lower the frame. With the K8 canopy it was the first time the frame was lowered completely to the foam seal on the bottom before applying vacuum.
It was the first time I made a canopy this big and using PETG. Previous material I used for smaller canopies was not satisfactory. During heating it formed small air bubbles inside the plastic regardless of slow or fast heating. These bubbles stayed visible in the finished product.
This PETG is perfect. I use 1mm sheet.
Before I get any smart comments, the picture of the frame shows the PETG with cover film still attached. This is to prevent damage to the surface when fitting the PETG to the frame, And yes it was removed before the heating process.

Thanks Jilles, that explains it well.

Hi Gents,

The build is looking fantastic and I am pretty impressed with the PETG canopy forming doohiccie thingymabob.

We are still just about to move house here so no progress from me for a few months, damn COVID.

Have a great day everyone.

Steve

All major components are completed. Today I had the first total assembly. all fitted as was intended, not so difficult with Laser cut parts.
The elevator has a sort of working trim, it moves up or down opposite to the elevator movement like the full scale. It is not used to trim the model the TX will have to take care of that. The nose cone and wing tips are 3D printed. A decent sanding job and some detailing will have it ready for the cover film, fabric or Ikarex. Not sure yet what to use

Very nice Jilles.
You’ve made a good job of that

As usual, very nice Jilles.

The covering of the K8 has started. I use Icarex. There is 10m of red and yellow in stock so just as well use it. It is1.4m wide so plenty of area.
The fuselage sides and bottom were simultaneously covered with a one piece of Icarex. There are no formers at the surface to make overlaps so it had to be in one go. SIG Stix-it was used, the last I had . Fortunately by the end of the week I will have an other tin from the hobby shop. I did try the Deluxe Materials Cover Grip ( formerly known as balsalock)
It works fine but I think Stix-It works better with Icarex. The red is not the final color. The plane will be mainly sprayed white or off-white with a red bottom