Installing the Snoopy's (OH-XEA) roof window

Suomeksi

There was a plexiglass roof window above the seat in the Snoopy’s cockpit. That window has not survived. From the existing photographs and the material list we know that the window was made from green acrylic sheet. The photos also show that the acrylic in the roof window had already cracked. Acrylic is, in fact, prone to cracking or splintering when it is sawn to shape. The cockpit roof window was attached with small bolts to the brackets welded onto the roof frame tubes. Two of these brackets are missing, having come off at some point.

Differing from the Snoopy’s original roof window, we decided to make the new roof window out of polycarbonate sheet, which is easier to work with. However, thin and transparent green polycarbonate sheet was not available. Therefore our approach is to make the roof window from 2 mm thick polycarbonate sheet and add a transparent green film to its surface.

We began constructing the roof window by making a cardboard template. We measured the size of the window and cut a piece of cardboard accordingly. We then fitted the cardboard into the roof window opening, trimming it to its final shape. Using this cardboard template, we purchased from Etra a piece cut from 2 mm thick polycarbonate sheet.

We fitted the polycarbonate sheet into place. There is something unusual about it, as the frame has mounting brackets for the roof window sheet on only three sides. There are no brackets on the cross tube beneath the front edge of the roof window. We have no information on how the window sheet was originally fastened at its front edge to the cockpit roof cross tube.

However, photographs taken of the Snoopy show that at this cross tube, the roof window and the windscreen meet. Presumably, at the cross tube, the rear edge of the windscreen rests on top of the front edge of the roof window. This way, the airflow passes over the roof window sheet and cannot enter the cockpit.

What kind of joint there was between the roof window and the windscreen, is not clear from the photographs taken of the Snoopy. The photos do show, however, that this joint is covered by some sort of trim strip. How it was fastened is unclear, as there are no indications of it on the cockpit roof frame tube. However, the connection between the front edge of the roof window and the rear edge of the windscreen will need to be resolved at the latest when we bend the windscreen, made from polycarbonate sheet, into shape and fix it into place.

We continued fitting the 2 mm thick window sheet into place so that the edges of the sheet lined up with the rows of mounting brackets. Next, the holes in the brackets were marked onto the plexi sheet by shining a light underneath it. This way, the bracket and the hole for the mounting screw were clearly reflected onto the surface of the plexi sheet and could be marked with a marker pen. Once all the holes were marked, holes for the mounting screws were drilled at the marked locations. In fact, these are small mounting bolts with nuts.

We wondered how well the 2 mm thick polycarbonate sheet would bend to match the curved profile of the roof window. We first fastened the sheet to the brackets at its rear edge. Then, the sides of the plexi sheet were fastened bracket by bracket. We were pleased to discover that the 2 mm thick polycarbonate sheet bent surprisingly well to match the shape of the cockpit roof.

It was noted that the left edge of the plexi sheet protruded about half a centimetre beyond the line of the frame tube. Obviously, the sheet had been fixed slightly further to the left than intended. So a line was drawn on the plexi sheet to indicate the excess, and the extra material was removed using a fine-toothed bandsaw. After this, the sheet was put back into place.

It was still necessary to solve how to proceed with the two missing mounting brackets in the cockpit roof structure. The solution chosen was to fasten two small perforated angle brackets at the positions where the brackets were missing from the cross tube of the roof. The positions of the holes in these brackets were then marked onto the sheet. Once the holes had been drilled, the two mounting bolts could be put in place.

The front edge of the sheet has not yet been fastened to the cross-frame tube beneath it, as the method of attachment has not yet been decided. For the time being, the front edge of the roof window sheet is held in place on the frame tube with small clamps.

The roof window plexi sheet for the Snoopy is now in place. Protective film still covers both sides of the sheet. These will be removed when the roof window is eventually fastened into place after the restoration of Ressu has been completed. Before that, a thin transparent green film must be found to be glued onto the surface of the roof window sheet.

Photos: Lassi Karivalo

Translation to English: Erja Reinikainen