Kit design for the uninitiated

**chris190** · #1 02-23-2020, 11:37 AM

I'm at present using 2d cad to produce my own kit for the Fokker F32 airliner; as it's quite boxy, I'm managing using tech drawing skills acquired long ago but for a more aerodynamic, curvy prototype I'm going to be well and truly stuck.

I noticed a tutorial started by Nobi recently on the subject but can't locate it and I would have to say that at first sight I had great difficulty understanding it (I'm sure it's my fault Nobi, not yours!)

Sorry to be dense - the worst thing about cad is how stupid it makes one feel and I would have to admit to huge difficulties in mastering autocad many years ago - but I've looked at all sorts of tutorials online with growing confusion; there is obviously a quite enormous learning curve in 3d design.

Can anyone please point me in the direction of a simple cad program and tutorial that I might have some chance of grasping, otherwise I can see my modelling career coming to a grinding halt!

**Lex** · #2 02-23-2020, 01:45 PM

For a light-hearted combination, try Sketchup+Pepakura. It makes an intuitive intro into modelling 3D surfaces so you can try the waters before getting lost in the 'how do I do what' question. I was going to suggest Rhino if it didn't cost a fortune though...

**hornswoggler** · #3 02-23-2020, 11:43 PM

Hi Chris190
All 3D CAD programs are complex and therefore complicated to learn.
Rhino3D is a popular choice for many card model designers, because it has inbuild unrolling functions. The purchasing price however is quite high for a hobbyist unless you are a student or an educator. The educational licence is much more affordable, fully functional and does never expire, even if you no longer qualify for a new educational license. Check it out if you are a student or are employed by any educational institution.
If you cannot justify the expense for Rhino or you fear you will not get it to work for your purpose fast enough, consider doing construction the old fashioned way. From your post I take you are somewhat familiar with 2D CAD. So use your skills to draw the formers that define the shape of your model (cross sections, bulkheads, longitudinal formers), cut them out and assemble them into a sturdy skeleton. Then "develop" the skins by temporarily gluing parchment paper (tracing paper, vellum) to sections of the skeleton using rubber cement (fix-o-gum). Mark the outlines of the skin part with pencil and detach the parchment from the skeleton. Then scan the marked parchment and clean up the lines in your 2D drawing software (CAD or other vector editor). Print out and check the fit of your skin part again. Most of the time only small corrections will be necessary for a perfect fit. Once you are happy with the shape of the part you can apply color, markings and so on in a vector editor (Inkscape, Illustrator) or image editor (Gimp, Photoshop). I know of at least two designers who create masterful models using this method.
You are probably aware of the problem that not all 3D surfaces can be developed/unrolled into a perfect 2D part. Surfaces that are curved in two dimensions such as domed or saddle surfaces belong in this category. There is no general solution for these cases, even if you master the most expensive 3D CAD program. You will need to come up with an approximation of the original shape that is developable.
Good luck!
Hornswoggler

**chris190** · #4 02-24-2020, 01:40 AM

Many thanks, will be trying both suggestions; the idea of using a card frame and covering has some appeal as it most resembles what I'm used to but I will also continue my researches into the purely cad route.

**Lex** · #5 02-24-2020, 02:55 AM

Hornswoggler's advice is gold. 3D is never the only way, but just something that speeds up the process. If you manage the analogue technique then you'll probably be one of the few members on this forum who can.

**CMDRTED** · #6 02-24-2020, 05:07 AM

all of the ships I designed, wichitia, hosho, kashima and angstrom were designed with 2d cad. paintshop pro and a very old mgi photoeditor that came with one of my early laptops. be prepared for a bit of beta building, and correcting but it can be done without all the 3d cad programs.

**Lex** · #7 02-26-2020, 10:33 AM

I just realised something, maybe you also want to check out the TBD build here?

Scratchbuilding the Douglas Devastator

**Knife** · #8 02-26-2020, 11:58 AM

Sketchup has the added bonus of thousands of downloadable designs in their online library. I use Sketchup for design, paint.net for graphics.

**Dane** · #9 02-26-2020, 05:27 PM

If you want to approach the matter professionally, I mean you wish make a real good models, you should learn any of 3d CAD programm. I am learning Blender now, because it's give possibility to make 3D model, unfold it and paint it in real colors.
It is very difficult, but there isn't another way to develop quality 3D models. Good luck to all designers!

**chris190** · #10 02-27-2020, 03:33 AM

I've looked at the Blender site and will probably have to try it at least, although on first sight, it seems to assume a good of prior 3d cad knowledge which I don't have.

At the present, getting an accurate 2d drawing of the prototype is absorbing all my attention - comparing different photos, different variations as the design progressed and, even on a fairly simple design such as this, the subtle curvatures and intersections, particularly wing root to slightly sloping body sides.

Will post further as things progress or I abandon the attempt!

Thanks again for the suggestions.

All the best

Chris