Designing Curves The Old Way

[Cami]

Ok, here is something I should have done a while ago, a tutorial (kind of) on how to design curves the old way. I will try to explain it the best I can, but most of you will probably remind some geometry basic lessons. Let's design a panoramic windshield as an example:

1- First step is to draw the basic shape of the windshield in each of the three views.

2- Then, draw a rounded contour line.

3- Now you have to simplify this line into straight sections.

4- Each of the straight sections then becomes the base of a triangle.

Most of you probably have already realized that I'm describing step by step in a few minutes what an unfolding software does in thousands of a second.

To work in 3d, you need 3 points in space and that is why we are working with triangles. Any shape, no matter how curved, can be simplified into triangles (the surface beetween the 3 points in space). The more surfaces you have, the more accurate is the end result, but too many surfaces may also lead to hard-to-assemble parts so I personnally go for a compromise beetween simplicity and realism and limit the number of surface I am working with as much as I can.

5- Ok, back to the windshield. The surface A in this example is flat so I simply adjust its height from the side view.

6- The A surface now is the starting point to unfold the windshield. The next surface to draw is the green B triangle, starting with its base. When you look at the front view, you note that the base of the windshield is flat. This means you need the base side of the B triangle from the top view because its lenght is not affected as if it was in an angle.

7- Now you have the base of the green B triangle and the side from surface A so you need the outer side of the B triangle which is highlighted in magenta. The problem is that this one is in an angle position!

8- Easy, figure it out as the side of a rectangle triangle on a flat surface in the front view.

9- Then, if you take a look at it from the top view, you see the base of your rectangle triangle.

10- As in step 5, all you have to do is to adjust the base of the rectangle triangle from the front view to that of the top view.

11-12- Here you are, match the sides you have and you get the green B triangle.

13- You have to repeat this for each triangle and to completely unfold the windshield.

14- Now that you have unfolded your parts, you should draw a rounded contour line, to make it more realistic.

15- Ready to cut and shape with any object that has the desired radius!

Hope this helps those who do not work with 3d softwares! If any of you feel the need to add some explanations or clarify some points, feel free to do so.

Cami

[thorst]

Cami,

that's a very nice tutorial! i'm working in a very similar way, with just minor differences (I don't adjust the triangles but draw them new for the unfolded part). Great that you found a way to explain it here!

And great that you incuded step 14, in the times of Pepakura, this is unfortunately not usual anymore...

Best regards,
Thorsten

[stickers11]

This is a great tutorial....but I'm still over my head.
Practice...

[chrisstahl]

The theory seems plausible, but is this technique practical? I once tried something similar and it didn't work out. I also wonder if this kind of calculation works for round and oval fuselages. Any thoughts?

[thorst]

Yes it does. See for example my shuttle:
1/48 Space Shuttle orbiter under construction

All parts are drawin in a way quite similar to what Cami described. It's the same as any 3D-program does internally. The only difference is the time that has to be invested.

[Art Deco]

Thanks for the nicely-illustrated tutorial!

[Cami]

You welcome guys! As Thorst mentioned, it takes a lot of time to unfold parts this way, but I believe you have a better control on the end result. It is just my opinion though!

Cami

[Retired_for_now]

Nicely done! Same basic idea as expanding a boat's lines drawings into (canted) frames or expanding a transom - with the added complexity of a curved part. Best "how to" I've seen on this topic.
Yogi

[Cami]

Originally Posted by Retired_for_now

Nicely done! Same basic idea as expanding a boat's lines drawings into (canted) frames or expanding a transom - with the added complexity of a curved part. Best "how to" I've seen on this topic.
Yogi

Thanks Yogi!

Cami

[chrisstahl]

Originally Posted by thorst

Yes it does. See for example my shuttle:
1/48 Space Shuttle orbiter under construction

All parts are drawin in a way quite similar to what Cami described. It's the same as any 3D-program does internally. The only difference is the time that has to be invested.

This is incredible. Congratulations on your work, Thorst.

I also work without 3D, but usually adjust my parts through test-building. I use a similar strategy as cami's for the paintjob where it has to cross glue-seams.