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Steel Cobra

Basic design

Steel isn't quite the same as paper - although you can fold it, it's not that easy to produce the complex folds required to make up the model. In order to facilitate the construction, a frame will be built, onto which each individual panel will be welded. I've welded before, making a desk for my computer/synth gear, as well as a frame for the back of my car.

The frame will look very much like the 8-bit Elite versions - albeit without the hidden surface removal algorithm.

As luck would have it, I had some sheet steel left over from my car project. This would be ideal for the outer panels, but the question "how big could I make it using what I have?" is the first that needed to be answered (apart from "should I be doing it?").

The sheet I had was bought in an imperial size. This means that what I have is two sheets of 3'x2', and one sheet of 6'x4'. I normally work in metric, but often switch between the two. Anyway, for those of you metricated, it's two sheets of 0.91x0.61, and one of 1.83x1.22.

In order to work out how big a model I could make, I need to put the template for the model on the sheet. If I was making it in one sheet, the biggest I could probably get is around 1m wing span. However, since I'm making it out of individual panels, each panel doesn't have to touch the panel it's going to be next to, so I can take panels from different sheets easily - I could even have some where the panels needed to be flipped.

I chose a size, and carefully layed out each triangle (or, in the case of the back, septagon, and the rectangle plus two quadrilaterals at the bottom) onto the sheets, trying to squeeze in as much as possible.

As luck would have it, the size I chose was fine. It was now time to see how big it actually was.

Before I give the answer, here are some basic figures:

The Whitchspace model I made is 180x85x35 (mm). The Sirocco 1 model is 135x27x63.

On my layout, the steel model is 1500x660x300. Yup, that's 1.5 metres (or 5').

However, that's nothing compared to a life-size model, which is approximately 12x6x2m. I don't have space to build one that big... Note that one you could sit in (enclosed) could be built at about half that size, or a little baby one that you'd end up sticking your head (and most of your body) out of in a model about 1.5 times bigger than mine (although twice the size would be better)...

Facet arrangement

This is the arrangement of the facets on the sheet steel that I have. Note that it was based on the Sirocco 2 model.

Click to download

The frame

Once I'd worked out that I could make a ship with a 1.5m wing span, it was time to work out how much steel I needed for the frame. The frame is to be constructed out of 25x3mm flat bar steel, which isn't very expensive.

Using the Sirocco 2 model, I measured each vertex (not to an incredibly accurate level - I only need a rough answer), and summed them up (being careful not to count a vertex twice), and worked out that I need 8.2 times the wing span to make the frame. This means that if the wing span is 1m, then I need 8.2m of frame. If it's 1', then I need 8.2'. For 1.5m, I need 12.2m of steel. Since I've got plans to do extra stuff (such as a cockpit, legs and so forth), I ordered 20m of steel - for £23 (including delivery and VAT). Well, that's the first item bought.

Extra stuff

Doing a basic model isn't much fun. What I'd like to do is to add:

  • Legs that come out. This will probably involve gas springs (which I have two of already - for an earlier project), or pneumatics (which I have no expertise on). The legs would probably have shock absorber-like qualities, and I'll probably use some VW Beetle valve springs for this purpose.
  • Cockpit. This would have lots of lights, and possibly some LCD displays. I'd like to have an Action Man in it or something similar.
  • Engines. I'm not sure on what to do - I've got ideas ranging from strip/halogen lights to a blow torch. I'll see how big they are, and what can be fitted in the body (the legs may get close to the back).
  • Hinged top. This is so that all the gubbins can be accessed.
  • Missile bay. This could be something as simple as two flaps that open, or something that comes down, like Airwolf's missile pod. It may be like ArcElite, where the missiles are actually hung underneath the wings.
  • Front weapon. This'll probably be a laser, or very bright light through a tube.

Stuff that I've been asked about

I've been asked about the following items:

  • Fuel scoop. This may interfere with the front leg operation, but it's possible to do. It may be a 'bolt-on' extra (literally).
  • Cannisters. I've got enough steel panel to make some cannisters. I'd like to make Radioactives, because they've got the radioactive symbol on it. Or I could make slaves - i.e. a cannister full of Action Men ;-).
  • Radio control. Putting something like a lawnmower engine in it wouldn't be impossible. You'd probably be able to sit on it and move it around...

Stuff for another model

Here's a list of stuff for another model.

  • Flight. I've been planning a model flying vehicle for some time, and using the Cobra Mk III is ideal.
Updated: 2013-03-24 11:47:16 | Comments: 0 | Show comments | Add comment
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