Building An Aircraft With Wood (Part 2)

I want to take an opportunity at the beginning of this article to interject a few words of caution and insight to aircraft building in general. It is likely that the person who wants to build with wood already sees the monetary advantages. There are still many pitfalls to watch out for that need careful consideration before spending money. You will find that wood construction has many variables. There are as many opinions as there are designs when it comes to construction techniques. Opinions are great for consideration, but you must remember that this aircraft when completed will be registered with the FAA as (your name followed by the kit manufacturer and model.) You are the builder and you need to be satisfied with the kit manufacturer's engineering, or change it to suit yourself. It is quite likely that the manufacturer's engineer has used approved and accepted FAA practices, but it always good to ask up front so you know what you getting into. Whatever changes you make will still need to be acceptable by the FAA inspector or an FAA Designated Airworthiness Representative who will be signing off on the airworthiness of your completed project.

It is likely that you already have some idea in your mind of what your plane looks like. Choices you make now need focus on increasing the possibility of completing the project. Beyond the fact that you are planning to build with wood are the basic decisions on utility. Are you looking for a single place or a two-place model? Do you prefer high or low wings? Are you interested in a sleek speedy wing or a high-lift wing requiring shorter take-off and landing distances? What engine will you be using? Should an amphibious model be considered? Will you want floats in the future? Do you prefer a tail dragger or tri-cycle gear? A huge problem will likely develop if you change your mind half way through the project.

Purchasing a partial kit does not help to keep you on task and contributes to lack of vision. Building from plans without the benefit of any kit at all only makes your effort that much more complicated and time consuming. "Scratch building" may be a good option for your second plane, but certainly not for a first time builder. You may save money over the cost of a kit, but the actual cost in materials alone (plus multiple shipping costs) may not be that attractive when you consider locating and using your own parts and materials. There are countless examples of partially completed and abandoned aircraft projects in garages, basements, hangers and utility sheds throughout the world. Years of searching leads me to believe that much of it is due to builders purchasing partial kits or "plans only" designs. A partial kit can become a huge obstacle, especially for the first time builder. At the end of the day, you will find that easy access to as many of the materials and as much information possible will only increase your commitment and your focus on finishing the project. If you need to cut back, I suggest it be limited to purchasing nothing less than the entire kit. Choosing not to get the fast build form of your kit will still supply you with enough materials and information to keep you working without interruption until the airplane shows promise of having a day when there will be air under the tires.

Another major consideration is the weight and performance characteristics of your engine. Power plant choices can be overwhelming and certainly deserve some careful consideration from the beginning. Hold off on the engine purchase until you are ready for it, but knowing what engine you plan to use will only help in the building process. Some designs actually require different placement of structural components that hinge on the weight of the engine.

A full size set of drawings are an absolute must for those of us who are not Master Draftsmen. Can you imagine trying to make matching and accurate full size patterns of 13-foot wings based upon sketches done on 8.5 x 11 inch sheets of paper? Unless you are incredibly talented and visionary, I would put this high on the list of requirements. On the other hand, full-scale prints may not be necessary if you are purchasing a quick build kit that has the larger length pieces precut and the cut lines etched on the plywood. There are slight problems with any way you do it and manufacturers all have their own way of getting you accurate measurements. If you get full-scale drawings for patterns and jigs, make sure to keep them in a climate-controlled environment to keep them from shrinking and expanding with humidity.

A very clear and concise set of instructions will generally keep you from getting ahead of yourself. Take time to read all of the literature before uncrating the kit. Chances are the information will be rather abstract, so read it again if you need to. I understand that some manufacturers will send the literature out to you ahead of time for opportunity to comprehend it. When your boxes arrive, you will need to carefully inventory, inspect and mark what you have received. While it is important to know what you have, it is also important to keep track of those things you will not need for a few months. Most kits have a bill of materials to help you complete this step. Inform the manufacturer of any damaged or missing parts as soon as possible.

The fast build kits certainly take less time, but you will miss a lot of the fun in doing the detail work. The money you saved by not purchasing the fast build kit will manifest itself at the very beginning. Depending upon the kit manufacturer, you will likely find yourself cutting and gluing little pieces of wood together from the start. Making a jig and gluing together ribs can be very enjoyable and satisfying, at least for a while. There is always the possibility of making more than one jig to speed the process up, and there is such a thing as needing something else to do on a cold winter night.

One thing you will immediately become very familiar with is making test glue joints. During the build process, you will occasionally take a couple pieces of the wood you have been working with and glue them together in the same fashion, just as you have been gluing parts together for the airplane. After the glue is set, you will need to pull and tug on the joint. A good glue joint will remain in tack while the wood on either side of it will break. Extremely cautious people tend to make test glue joints with every batch of adhesive mixed up while some simply make one test joint every hour or so. Others are satisfied with once a day. You are the person who will be depending upon the structure to remain in one piece, so test your work. FAA Inspectors can ask for evidence of test glue joints, so you may want to save a few and take some pictures along the way.

Source by Tom Lyon

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