Spar spacing

[edgeau]

Actually, after some similar advice elsewhere, I am in the process of making some curved pieces to go between the spars to get a torsion box effect.

Sent from my ZTE T84 using Tapatalk

[Andrew Herrick]

Actually, after some similar advice elsewhere, I am in the process of making some curved pieces to go between the spars to get a torsion box effect.

Sent from my ZTE T84 using Tapatalk

If you're making a conventional roof - interior plywood ceiling, roof spars with foam, then exterior plywood sheathing, then outer skin - it's hard to imagine getting any real-world advantages from adding curved blocking members. A torsion box is useful because it creates a flat, THIN surface that resists longitudinal warping. Your roof isn't flat. It's curved - hugely so. And unlike a true torsion box, your roof is "bounded" on four sides by the walls and floor. It can't really twist along its centerline by virtue of its geometry and boundaries, and once the skins are installed, it can't rack much, either.

Not trying to insult your intelligence. Just that I can't imagine all the hours it will take to manufacture curved blocking members that fit precisely between the roof rafters, and unless I'm way off in my analysis, I'd rather save you the hassle

Thoughts, anyone else?

[dales133]

If anything id just glue and screw some triangular blocks at the back of the hatch/ spar area

Sent from my SM-N910G using Tapatalk

[edgeau]

No offense taken. This is a learning experience for me. I might know what I am doing by the time I finish. In fact I am enjoying the process as much as I do camping so I can see myself doing another one.

Sent from my ZTE T84 using Tapatalk

[KCStudly]

The skin becomes the diagonal shear member. Essential the skin is the diagonal brace. This is why it is so important to build the hatch in position.

[edgeau]

It turns out I needed to put the centre line in for a completely unexpected reason anyway. When I went to buy my roofing ply they could only supply sheets that bend on the long axis so I am going to have a join run along that centre line.

Sent from my ZTE T84 using Tapatalk

[Andrew Herrick]

What sort of plywood are you using, Edge?

[dales133]

It turns out I needed to put the centre line in for a completely unexpected reason anyway. When I went to buy my roofing ply they could only supply sheets that bend on the long axis so I am going to have a join run along that centre line.

Sent from my ZTE T84 using Tapatalk

Hard to get anything else in aus mate.
I ended up just cutting 2400 sheets to the width and joining 3 from front to back

Sent from my SM-N910G using Tapatalk

[edgeau]

Andrew I am using 6mm marine ply for the roof.

Sent from my ZTE T84 using Tapatalk