CAD Design for Modelers

CAD Design for Modelers

One of the best tools I ever discovered while being involved in RC scale modeling, is Computer Aided Design (CAD) programs. It opened an entirely new segment of modeling to me, while also greatly increasing the precision in which I designed and developed scratch build scale airplanes. I have been using CAD programs now for more than 20 years and this post is an online version of my presentation for drawing 3-views and developing plans to build RC airplanes.

Today, there are several free downloadable CAD programs and several trial use CAD programs. You don’t have to spend a lot of money to see if you like it.

Let’s get started:

Model Airplane News - RC Airplane News | CAD Design for Modelers

Model Airplane News - RC Airplane News | CAD Design for Modelers

 

Model Airplane News - RC Airplane News | CAD Design for Modelers

Be careful! CAD can become an entirely new hobby in itself!

Model Airplane News - RC Airplane News | CAD Design for Modelers

Model Airplane News - RC Airplane News | CAD Design for Modelers

There are several reasonably priced CAD programs intended specifically for modelers looking to start playing with the design and drawing program. Also, there are “Lite” programs you can download from the web to get started.

graphite-logo

I have been using Ashlar’s Graphite CAD program ever since it was first introduced. The program is in my opinion, the easiest and quickest CAD program to learn. I have designed many RC airplanes using Graphite and I am now using version 9.

 

Graphite

Graphite is now available as a “Cloud” download program which you can pay for monthly from: http://ashlar.com/2d-3d-drafting/2d-3d-cad-graphite.html.

 

Model Airplane News - RC Airplane News | CAD Design for Modelers

This CAD Kaos was the first design that I traced into CAD. I then simplifed and added modern hardware to the design. It turned out to be a great flying airplane just like the original Kaos 60.

Model Airplane News - RC Airplane News | CAD Design for Modelers

When it comes to scale airplanes, CAD allows you to duplicate any airplane there is. Just start with simple designs and work your way up to more complicated ones.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Model Airplane News - RC Airplane News | CAD Design for Modelers

Depending on the program you use, you can import, Bitmap, Tiff, JPG or other type of image file.

Model Airplane News - RC Airplane News | CAD Design for Modelers

The other way to produce drawings, is to take direct measurements of the things you want to draw.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Model Airplane News - RC Airplane News | CAD Design for Modelers

Model Airplane News - RC Airplane News | CAD Design for Modelers

For the development of plans where you trace an existing airplane drawing, there are some rules I made that make the job a lot easier.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Learning what your program has to offer is also a first step to using it efficently.

Model Airplane News - RC Airplane News | CAD Design for Modelers

The tools are found in the on-screen tool bar and the pull-down menu windows.

Model Airplane News - RC Airplane News | CAD Design for Modelers

After developing your front, side and top views of your model, you have to make sure they are all to scale with each other. This is important before you start developing the plans’ details and add the spars, formers, ribs etc.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Model Airplane News - RC Airplane News | CAD Design for Modelers

This is a section of a Wylam drawing of a P-40 Warhawk that I scanned and imported  into my program. See below to see the steps in developing the model’s wing.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Instead of using a freehand “spline Line tool” try to use the tool bar tools to develop the various shapes of the wing’s outline and basic details.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Starting to look like something!

Model Airplane News - RC Airplane News | CAD Design for Modelers

Now make a mirror image, flip it around and add it to this one and you have a complete wing plan.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Don’t try to draw the ribs freehand. Just download the airfoils you need and add to your CAD File.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Model Airplane News - RC Airplane News | CAD Design for Modelers

Just like everything else, you develop the ribs starting from the outside of the basic airfoil shape and working inward in steps.

Model Airplane News - RC Airplane News | CAD Design for Modelers

You can also loft ribs if you want to develop your wing with a progressive airfoil shape that changes from the root to the tip. Start with the wing planform, and the rib placement. Make sure the ribs are spaced evenly. The stack the airfoils and divide into a number of stations.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Connect the station lines from the tip to the root rib. Then divide these lines by the number of the ribs you want. If you want 10 ribs, then divide the lines into to 10 equal sections.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Using the spline tool, connect the dots and you develop the individual ribs. Start from the rear end point and work forward on the rib to the leading edge. Remove the station and projection lines and you have the ribs above.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Here’s the wing planform and the ribs. Now you would work inward and add the notches for the spars and the other details like the wing skin and dihedral braces, trailing edges leading edges, etc. Model Airplane News - RC Airplane News | CAD Design for Modelers

The same basic technique is used to develop fuselage formers.

Model Airplane News - RC Airplane News | CAD Design for Modelers

It’s a lot of work but in the end, you have perfectly fitting parts.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Print the parts out, paste them to your wood and start cutting!

Model Airplane News - RC Airplane News | CAD Design for Modelers

Lofting formers is exactly like lofting ribs. The same techniques apply.

Model Airplane News - RC Airplane News | CAD Design for Modelers

So you don’t want to cut the parts out yourself? that’s fine, send the CAD file out and have someone laser cut the parts out for you.

Model Airplane News - RC Airplane News | CAD Design for Modelers

These parts were designed specifically for producing laser cut parts that interlock and form simplified model structures that are strong and lightweight. Often they are self aligning.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Break out the CA glue and kicker!

Model Airplane News - RC Airplane News | CAD Design for Modelers

Model Airplane News - RC Airplane News | CAD Design for Modelers

After designing and building your model, you can still use your CAD program to do other things like figureing out where the CG should go.

Model Airplane News - RC Airplane News | CAD Design for Modelers

It’s all easy if you know what to do. The CAD program helps a lot.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Also, the side view technique for developing the placement of your CG is easy.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Model Airplane News - RC Airplane News | CAD Design for Modelers

Got the weight of your finished model? Great, with the CAD program you can quickly find the wing area so you can figure out what the wing loading will be.

Model Airplane News - RC Airplane News | CAD Design for Modelers

Updated: January 26, 2021 — 2:40 PM

6 Comments

  1. I’m interested in the CAD software.

  2. Does this program also have automatic aerodynamic features like center of pressure, center of gravity etc. do you know any that does?

  3. Am interested in software

  4. Please Send Me Info on how to obtain this software

  5. Could you please send me details of cost and how to obtain this software.

  6. Please send me information on how to purchase this software. Thank You

Comments are closed.

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