The SG-38 Schulgleiter

Motivation

Why am I doing this? Well, because it’s doable. And I want to explore how far we can push the material „card“.

I stumbled across www.schulgleiter.de by Alexander Görnitz. „Schulgleiter“ is german for primary glider. And Alexander is offering access to a complete set of original plans for the SG-38 primary glider. And he was kind enough to grant me access for this project. And I am goint to use the plans to explore the possibilities of cardmodelling. The SG-38 is somewhat ideal as it was designed to be build by amateurs with limited tools. Therefor no complex compound curves and parts on the whole plane.

Possibilities

So what am I goint to do?

Lasercutting: I am not going to cut everything by hand as lots of the parts will be flimsy
Picking the right material: Usually cardmodels are printed on white 160gr/m² stock. Since all my parts will be lasered I am picking fully coloured card and I will look for a more stable brand
Fittings: All the fittings of the plane i.e. wing connectors, cable connectors, any kind of hardware that is of metal on the original will be made of, well, metal. Have to decide though if it will be laser cut or etched.
Model all the parts of the original glider. Since I have plans for all parts, I will try to model them all.
This should result in a museum quality model, hopefully.

Scale

Since it is going to be a scale model I have to decide on a scale. So what I did, I looked at the most flimsy parts and decided from there which scale would be a natural way to go. This part is the main wing rib:

The ribs are constructed from 4mm x 8mm strips. Yes, true! So a natural scale would be

1:8

This way the ribs can be lasered from 1mm material with 0,5mm thick strips. Should be doable. All the corner enforcements are calculated to be 0,05mm thick. Hm, I’m gonna stick to regular paper here which is around 0,1mm and available in all colours.

The look

The model in 1:8 scale will stand out at roughly 1,2m wing span. The options are

Creating the full model
Creating a half model, cut at the rear spar to be wall mounted. Might look good.

I haven’t decided yet but I liked the look of Alan Rose’s DC-3 in the 80’s. I might become a half model (maybe the rear half? nooo…)

I’ll keep doodling and will update these thoughts…

Design Differences

With such good references it is like designing a cardmodel backwards. Usually the references are limited and you have to build up some kind of raw model and convert this into developable surfaces. These can then be unrolled and put into 2D parts.

This time it is different. I could even use the plans and directly convert them into flat parts. This is due to the fact that the original hardly contains any complex surfaces which need to be split into developable surfaces. However, looking into the details, you need the 3D-model, especially when it comes to finding intersection of parts. Here you need markings where each part is connected to the next.

And on the other hand, the 3D-model looks cool….

Cardmodels.de

Taking cardmodelling to the next level