From 3d prototype to 2D plans?

[Boomfiziks]

I have both kit built and scratch built some airplanes. I am in the process of drawing up some of my own original plans for a plane. I am curious how Flite Test and other builders go from making a prototype airplane to plans that can be layed out onto a flat sheet of foamboard. I can understand the process of drawing plans and shaping (and reshaping) and further modifying parts until everything fits together. Yet, when they are done making a working prototype of an airplane, what is the process of transferring a 3D airplane into a flat 2D set of plans? I doubt people unglue/cut up their airplanes, lay them out flat, and draw the profiles, score lines, and servo holes where they need to be. Any input would be greatly appreciated.

Thanks,
Dwight

 

[robobob]

This has been a question I've often pondered over for a conisderable amount of time, I am also currently in the process of drawing up plans for a scratch build, (will be making a forum post on that shortly) but for this one I'm using the software autodesk fusion. I'm attempting to make "sketches" of all the ribs, which I well then be able to export as a DXF format. This format can be converted to png, pdf, or even sent to a laser cutter.

(I'm not sure if you're familiar with the software, but in autodesk fusion 360 a sketch is what they define as a 2D drawing confined to a single workplane. Working with multiple planes you can create several sketches at different angles to build up 3D profiles.)

I will admit this probably works best for the style of build I'm going for, being a sheet-depron covered, ribbed structure, similar to a balsa build. However, it still stands that the measurement tools in this software are great, and the ability to export sketches into essentiallly any format is increadibly useful.

So for attempting something perhaps along the style of a flite test build one could certainly create sketches of all the panels required, in 3D, then either redraw, or move/rotate the sketches to their respective positions required for a 2 dimensional format. I would personally guess it is best to redraw multiple sketches into one single 2D sketch using measurements you obtain then from the 3D versions into a 2D plan.

Another tool which I cannot say I have tried for building planes myself but know exists and have played around with for other tasks is pepakura. This would probably be what one could consider a foam plane builders' dream tool, as it does all of the hard work for you. It can take any 3D model, literally unfold it, and turn it into a set of 2D plans. However, this tool was designed for paper, hence the name, and not for foamboard. So in generating a paper template, it adds a load of tabs for gluing, which you would obviously omit, but also comes up with sometimes some rather odd geometry. But as it's obviously assuming it's working with paper and not foamboard, there are several foamboard building techniques that it will not try to emulate. It also means you will probably end up with a thicker model than you bargained for if you follow the plans strictly. So, if you're thinking of using pepakura, I'd reckon you'll be needing to modify the paper template it outputs heavily, before it can be anything feasably usable.

Hope this information is helpful.

 

[FoamyDM]

I use AutoCAD, trace the 3d views. And us reference marks and circles to transfer dimensions of parts... The hard part for me is 3 curved parts. This goes more like pattern making for sewing. But without the body to put the "fabric" around, only dimensions from the view. So the trick for me is to get the top skin Length to make shift from 2d view to 3d part. As there is very little difference between flat distance and the curved surface difference. Maybe a 1/4" on a 8" chord.

Look at my SAM 7 build plans. Or needed been the baby Bugatti, If you can find them, and note the changes. That's what hard to get right. Also making plans then building is much easier than unravelling a model. However sketchup had an add in for that.

Good luck!

 

[Hai-Lee]

when designing I keep a list of all measurements taken from the original model or plan in a spreadsheet all properly identified and then apply my scaling factor. The spreadsheet calculates the required measurements and I round them up or down as required.

From the list of measurements I am able to generate the pieces either by inputting them into the appropriate CAD program, draw them out on graph paper or draw them directly on the FB with a few drafting tools.

From there I cut them out and assemble the plan. The procedure works well for me and often for one of planes I do not even need to male a full size set of plans. Changes are made to the resultant "Rounded" measurements if corrections are required though that is a very rare occurrence.

It is always a good idea to cut to a measurement than to measure what you have cut.

Just what works well for me!

Have fun!