Lightweight platform for rooftent

[jensjakob]

Hi

I am proces of building my own rooftent for my car.

Basic design, 2 hinged plates of 180x120 cm. Total footprint 240x180 cm.

One plate is supported by roofbars.

Other plate is partly supported by roofbars and the steel hinges, partly free hangning and supported by the ladder on the outer edge.

That gives 110x180 cm free span.

My challenge is how to design this as a lightweight structure.

E.g 18 mm marine plywood would give a total weight of 43 kg :-(

Choosing e.g. 9 mm plywood (21,3 kg) and a metalframe (8,5 kg) below will give 29 kg total weight.

Choosing e.g. 12 mm plywood (28,5 kg) and a metalframe (8,5 kg) below will give 37 kg.

But how do I build the most effective steelframe below the plate?

Designgoal is to be able to support 300 kg static load (incl. safety margin).


I guess that by choosing the 12 mm plywood I might be able to design a lighter steel support - maybe even opt for not rectangular tubes of 20x10x1,25 but go for a L-profile of 20x15x1s,15 and save weight.

Any ideas and input and suggestions for the optimal construction are appreaciated.

Best regards

Jens Jakob

P.s pro rooftents are using a aluminium foamcore sandwich - but I cant find any provider with a price that is usefull in Denmark

 

[msquared48]

We do not perform structural engineering services in this forum.

From your post, it sounds like you need to engage the services of a structural engineer in Denmark who will be familiar with the required loading for your structure.

Mike McCann
MMC Engineering

 

[dik]

Have you considered using a 25mmx100mm 'joists' and 5mm plywood glued to form a lightweight base?

The upper structure can be constructed of lightweight ABS piping and fabric.

Good chance to experiment a bit...

Dik