Hello from Holland

[Cliffmeister2000]

Further refinement of the design - a sliding hatch instead of hinged. It should save some weight. The panel slides up into the space between the roof and the ceiling. Plastic u-channels as guides. I've also gone to 10-inch wheels instead of 13 inchers for weight saving. My Reliant runs on 10-inchers, so it should look better anyway. Unfortunately the PCD is different (4 inch on the Reliant, 100 mm on the trailer axle), so no common spare!

That looks really nice but I don't understand how it will save much weight. It will be interesting to see how you waterproof it.

[graham17457]

That looks really nice but I don't understand how it will save much weight. It will be interesting to see how you waterproof it.

Regarding the weight issue: The sliding hatch will be a piece of 5 mm flexible triplex with a 0.8 mm aluminium skin. A hinged hatch of the same size has the same piece of 5 mm triplex/aluminium plus a frame with two curved side timbers and at least 4 cross-members of 44 x 27 mm (or similar size). The gas struts to support it would also add weight. My target to to build a sub-250 kg tear, so every kilogram saved helps.

The waterproofing is an issue. Here's my provisional idea. The curvature of the hatch (made from 5 mm flexible triplex with an aluminium skin) gives it some rigidity. Edges are finished with a plastic u-section glued in place. A larger plastic u-section (loose fit over the u-section on the hatch) formed to an arc is secured to the inside of the side panels left and right. These channels extend into the cavity in the roof. A rubber section (normally used in automotive applications) can form a loose seal as shown in the diagram below. A similar construction would be used at the top.

I realize this may not be totally water tight, but since I have no plans for fitted kitchen elements, I can seal the galley area and use waterproof surfaces. Some water entering here will not be critical.

[graham17457]

I've modified the cutaway to show how the hatch would slide between the outer roof skin and the ceiling.

[Cliffmeister2000]

I've modified the cutaway to show how the hatch would slide between the outer roof skin and the ceiling.

It does look sweet, and your CAD skills are over the top!

In automobile sunroof design, it appears they just plan on them leaking and provide channels for the water to flow down and out of the vehicle. Perhaps you could provide a PVC channel without adding too much weight?