3D/CAD Overview

3D Models Available Now. Click here for the 3D Catalog.

This "Overview" page is a general introduction to the 3D/CAD process. The "CAD Gallery" pages document the specific processes I am using to design and build the 1/6th scale Super King Air B200. The "CAD Tutorial" is a more detailed description of the process, which could be used on any model.

* Something I want to mention before we get started...If you create a nice CAD model for RC, and especially if it is scale, there are other ways you can use it. Check out the freeflightdesign.com site. They're a group of Microsoft™ Flight Simulator enthusiasts, and they might be interested in using your CAD model to create a sim version. (Or, if you've got the expertise, you could do it yourself.)

Back in the late 70s and early 80s, when I was learning to write (primitive) 3D software, a personal computer CAD system for model aircraft design was out of the question.  Only NASA could afford it. The "graphics" on my first (ZX-80) computer were non-existent. I started in 3D with "glorified function plotters" that would create terrain-like mesh surfaces, and that was about it. Photos and high resolution were impossible. Finally, today we all have lots of computer power.

My assistant, busy refining the King Air B200 3D model..

Modern personal computers, combined with very inexpensive CAD software have enabled many of us to give it a try. I know, after seeing the results on some of the RC forums, that there's a lot of interest in using CAD systems for model design. Some modelers just want to create cool 3D images, some use it for visualization, as I do, and some actually want to print plans and/or export designs directly to CNC machines to make parts. Laser cut parts are no longer just for the big companies. This is exciting for me, because I've been waiting for "my time" to come for a while, and am happy to share what I've learned with all of you. Try it... You'll like it!  I use a 3D program to "proof" my designs and help me visualize where equipment will go, etc.. I'm a Mac user, and have been using the same program (currently "Carrara Studio" - previously "Ray Dream Studio 5.02") for several years. Of course, I am a starving artist, so if the fabulous folks at NewTek want to send me a complimentary copy of "Lightwave", I would have to accept!

Seriously, 3D can save you some headaches, as well as providing some cool images. Have you ever hastily drawn up some plans, and gotten part way through construction only to realize that something important (say, an engine, or fuel tank!) won't fit? Careful planning on paper can solve this problem, but 3D gives other advantages. You can revise designs, move components around, try different color schemes, and even get an idea of what the aircraft will look like in flight. I routinely use a 3D model for all my original designs, before I ever draw lines on paper. This CAD model below of the X-36 exists because I considered building one. It could still be a future project.

Boeing/McDonnell Douglas/NASA X-36 "Tailless Agility Aircraft". (Uses yaw thrust vectoring for stability)
This would be a challenge, with no vertical tail surfaces! (Gyros definitely required)

Another view of my X-36 model

CAD lets you dream a little, too! (Done for entertainment, not for reality)

Since both my "Avanti" and the King Air B200 are 1/6th scale, this was a obvious image to make, comparing them. When I decided to do a (1/6th scale) model of the Piaggio "Avanti" P-180, I first made a computer model. As time went on, the computer model became more and more accurate, and eventually I was able to get it published by Viewpoint Digital (Digimation). Click here to view the Digimation 3D Models catalog.

Here are some free files that may help you get started.
Just click the image to download the (2.5 MB) zipped DXF file.

Below, an outline of the process I used on the "Avanti" More images of this aircraft can be seen on my "Projects" page.

It's best to begin with a really accurate set of drawings, and make the model based directly on them. Sometimes those drawings aren't available when I'm ready to start a project though, so I make a rough model, and clean it up as I proceed with the search for drawings. I began with a simple "thrown together" model, to get me started. This wasn't scale, by any means, but instead was "eyeballed" from the sparse documentation I had at the beginning. (tiny little 3-views from "Janes", and a couple of photos)
Like primer, a simple single color can often show you things about the shape you might otherwise miss. So, I made this model "chrome", (and several other color combinations) to help me see imperfections in the shapes, and tidy things up.
Once I'm convinced that the model's exterior is the right shape, I then begin to add interior structures. At this stage, the wireframe model is better, because you're strictly thinking dimensionally, and not distracted by color and texture. This aircraft is built with a lot of typically-Italian compound curves... ...a real beauty.
Following that, I began to visualize where RC components would go, keeping in mind the need for a scale interior. The use of color coding helps separate key structural components from secondary structures. I later settled on the idea of having the main tanks in the fuselage, with only small "hopper" tanks in the nacelles. This makes more structural sense, provides better cooling for the engines, and reduces the outboard mass of the wings. The main tank on the actual aircraft is located in the fuselage at the same position, where the two red bulkheads are located in this image.
At the end, it's always tempting to try and produce some realistic images, emphasizing the quality of the model, scale-wise. You can even try various paint schemes, before the model is actually built!
Sometimes, a 2D drawing program can be used in conjunction with 3D. Here, I'm trying to figure out the "over center" locking mechanism of the nose gear, so that I can have it machined later on. The circles simply show the pivot arcs of all the moving parts. (The geometry shown in this drawing isn't quite right, by the way, so don't build any landing gear based on it!)
The P-180 has slotted Fowler flaps on the outboard sections of the wings. This is a simple drawing showing the flap track arrangement, which will probably be operated via a torque tube, since the wings are very thin, and would make wing-mounted servos difficult.