My newest project steps away from building a commercial kit plane, and is more about designing and building my own scale airplane. This includes, using CAD and having final plans sent to a laser cutter to produce my own kit. Then in the workshop it is business as usual. So, to start, I will describe the process to get this multi-part series started. I hope you enjoy it and please, do leave comments and questions. I will reply as we go along.
There’s a bunch of sources around and certainly my choices are not the only ones. First I chose a Sopwith Camel as my project and I based my CAD drawings on the 3-views from William Wylam. I have the book of WW1 drawing from the AirageStore.com website and it is an excellent starting point. You can get this book at: http://www.airagestore.com/scale-aircraft-drawings-vol-1-wwi.html
Plus the Sopwith Camel is right on the cover, so how could I go wrong?!
Here are the scale drawings I used. I simply scanned them so I could import them into my CAD program.
You need to import your scale drawings into a layer in your CAD program to start creating your working plans. Depending on the CAD program you have, you’ll have to convert your drawing file to a compatible format. I use a 2D CAD program called Graphite from Ashlar.com. http://www.ashlar.com/2d-3d-drafting/2d-3d-cad-graphite.html and so, I converted this drawing to a .BMP file and imported it.
Of course there are less expensive CAD programs and some are even free for download, but I have been using Graphite for a very long time and find it extremely easy to use. It is more like a drawing program than a CAD program that’s hard to learn. Here’s a low res screen grab to show my Graphite working drawing for the fuselage and formers.
Here are some links to PDFs of the Camel Plans. These are very early versions of the drawings and not the ones for sale at www.airagestore.com
Along the way, you use the CAD program to produce the parts while simplifying your structures as much as possible. You need and then export the drawings and send to a laser-cutting company. Here again, there are several to choose from. For this project, I used Arizona Model Aircrafters https://www.facebook.com/ArizonaModelAircrafters
Jaime Johnston at the company is very good at checking your drawings for mistakes and if they need a little bit of tweaking, he’ll take care of it. But for the most part, you need to be as accurate as you can with your plans. What you produce is what you’ll get. Here are some pix of the box of wood I got from Jaime.
Nicely packed in a sturdy box. The package has the Trillium Balsa (www.trilliumbalsa.com) label on it! Excellent quality.
Most of the parts are cut from Lite-ply instead of balsa sheet. This keeps costs down and my Camel was designed with this in mind.
To save weight, lightening openings are used to good advantage.
Arizona’s laser-cutting is very clean. Here are some 1/4-inch and 1/8-inch balsa parts.
Even in 3/16 inch birch plywood, the laser cutting is clean and accurate with little to no scorching.
If you take the trouble of making a parts list, Arizona will also supply stick stock for your design. The sticker on my shipping box says the product is from Trillium Balsa LTD. from Canada! Excellent quality. (www.trilliumbalsa.com)
One of the techniques I use to save on time and money, is to incorporate readily available hardware into my drawings whenever possible. I tweak sizes and scales to use off the shelf items like wheels, cowlings, fuel tanks, servos etc. If there is a formed cowling already available, why go through the trouble of forming your own plug and fiberglass layup. So, the same thing goes for placement of model substructures like firewalls, and airfoils. I take the time to draw accurate items like engines, servos, fuel tanks, etc. and place them in the drawings. I use proven airfoils for sport models like this Sopwith Camel. The airfoil here is the Epplar E205 which I downloaded from the web http://airfoiltools.com/airfoil and have used with great success in smaller electric models as well as in 60 to 90 size planes. It is relatively flat bottomed and thin enough to be used with a WW1 design.
Here are some of the hardware items I am using.
For power, I am using my tried and true, very reliable Zenoah G-38 gas engine. It is drawn into the plans so I could estimate the basic firewall location and offsets.
I like to use the aluminum spun cowlings from Arizona Model Aircrafters, and here’s the one I am using for the Camel. Yes I know the dummy engine is a radial, but I will be using a rotary engine in the finished Camel.
Of course you can’t build a WW1 airplane without some William Brothers’ scale accessories. www.williamsbrothersmodelproducts.com/
Two more unusual items in my sport scale Camel are the RotoFlow fuel system and a plug-in aluminum wing tube (and socket) for the lower wing panels. The tank is from www.jlproducts.net/ProductRotoFlow.html and the new QuickFire Fuel filter and balancer is also going to be included.
The wing tube assembly is from TNT Landing Gear, www.tntlandinggear.com .
So here we are, lots to consider and account for in the process of designing your own scale model. Stay tuned as I will be posting the following parts of the series as I continue with my project and start gluing pieces together. One thing to mention here is that being the first model to be built, I am going to use the experience to check and adjust and correct the final drawings. There will be some “on the fly” engineering and I will discuss it as things pop up! Again, if you have any questions or comments, I’d love to hear from you. You can also email me at: Gerryy@airage.com