I've produced quite a few plans for RCM&E over the past few years, but it occurred to me that these have been aimed mostly at the experienced plan builder. The recent Sky 40 primary trainer (presented as a free plan in the July / August 2006 issues of RCM&E) went some way to redressing the balance by offering a model suitable for beginners, but this is of little help if the novice has no experience of traditional building. Constructing something from a plan introduces a whole new facet to the hobby and practically doubles, if not triples, the choice of model available to you. Take a look at what's available through the Encanta Media Plans Service and you'll find a host of designs at your fingertips that aren't available from model shops in ARTF format. You'll also gain an appreciation of how a model is put together, thus making repairs easier.
With all this in mind it seemed a good idea to write an article that set a few ground rules for would-be plan builders; information that most experienced builders know, yet which the novice only tends to find out through making mistakes.
SQUARING UP
If you've never built a model from a plan then there's no doubt about it, it will appear quite daunting at first. What you're usually faced with is a large sheet (or sheets) of paper showing the full-size outline of the model in both side and plan views. Probably the most important elements to have on a plan are the outlines of the fuselage formers, the wing ribs and, if appropriate, the tailplane and fin ribs. A good quality plan will provide the component outlines to be cut out, information about the type of wood (balsa, plywood etc.) and, where appropriate, the grade or weights of wood. From my own experience of plan building I know that such information can be quite sketchy, and some plans do leave a lot of the decision making to the builder. For example, when the plan provides only the wing tip and wing root templates and expects you to make all those in between. Such omissions can be a real turn-off as well as a disappointment.
Possibly the worst and most irritating problem I've found with plans over the years is drawing inaccuracies: formers and ribs shown on the plan not matching the fuselage or wing outline, left and right wing panels being of different size, etc. The advice here is simple. Before starting any plan build (especially if the plan is hand drawn), check some of the key dimensions and make sure the former and rib outlines (if shown) tie up with their associated locations on the plan views and elevations. Do this and then make any adjustments by redrawing the components onto tracing paper so you can overlay the traced outline on the plan and check for accuracy. This will save a great deal of heartache and annoyance later, believe me!
These inaccuracy problems generally apply to older, hand-drawn plans and not so much those generated using CAD (Computer Aided Design), which most magazine publishers use these days. However, inaccuracies can still occur even with good-looking CAD-drawn plans, so it's prudent to check the drawing irrespective of its visual quality.
SKILLS BASE
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So, how complicated is it to build from a plan? Well, that depends on your modelling ability and experience. It's fair to say that a seasoned modeller who's been brought up on a diet of traditional kit building will have little or no problem as he'll already have gained an understanding as to how a model is constructed. If you've only ever put ARTF models together, on the other hand, you'll need to take things a little more carefully. Clearly, when assembling an ARTF model with ready-built and covered components, the construction of the airframe, the materials used and how it was covered, aren't terribly important unless you damage the thing and wish to attempt a repair. As a large number of ARTFs are traditionally constructed using balsa and various types of plywood, repairing such damage can, however, be a good introduction to understanding how the model was designed and built. It can also confront the ARTF modeller with a few pertinent questions: "How can I replace the broken parts? What glue shall I use, and what material should I purchase to cover the repair?" The learning curve to repair an ARTF may be steep, but it will form a good grounding as and when you move on to traditional kit building or building from plans. There's no reason for the ARTF modeller to view plan building as something that's beyond them, they should see it as a step towards 'true' aeromodelling, a step that I would urge all modeller of all abilities to try, without question.
If you're thinking of building from a plan, my advice is to find a subject (preferably a free magazine plan with pictures and an explanatory write-up) that looks easy to build, i.e:
1. The fuselage should be a simple shape, straight-sided and using a box-type construction.
2. The tail and fin should be from solid sheet balsa.
3. The wings should be of simple parallel rib construction, or (better still) made from solid sheet balsa.
Even if you don't particularly like the look of the model, the practice of building it will be invaluable. Be persistent, and if you make a mistake then just put it down to experience and press on. When you finish the thing (which you will do, of course!), go and fly it. You'll experience incredible feelings of achievement and fulfilment that will surely spur you on to the next project. If at any time during your plan build you're not quite sure what to do next, have a chat to the senior members of your model club and ask their advice. At least one of them will have built from a traditional kit or plan and will no doubt be very willing to point you in the right direction. Okay, all being well I've persuaded you to have a go at building from plan... what's the next step?
WOOD GRADE SELECTION
This generally applies to balsa wood, where there's a need for a softer or harder grade of wood in certain parts of the build. A typical example of this might be the nose section of the fuselage, where additional strength is required if the model is designed to land on its belly. The other benefit of hard balsa at the nose is that it's heavier, and most models ultimately require some additional nose weight. Conversely, the tailplane and fin are usually constructed of a lighter grade to save adding more nose weight.
You also need to be aware of grain direction, particularly if you have to roll or bend the wood during construction, and here again a grade that's too hard will prove difficult to bend. When rolling / bending, the grain needs to run longitudinally (i.e. along the length of the balsa). Try to do this with the wood at 90° to the longitudinal (known as 'cross-grain') and the wood will surely split. Producing a shallow, rolled curved shouldn't present a problem using soft grain longitudinal wood, but make the curve tighter and the wood will split. To overcome this you should first dampen the outer surface only, thus causing the surface of the wood to swell slightly and start to curve, whilst the gluing surface stays dry. Should the side you're gluing become damp then the balsa can still be stuck in place using either PVA or cyano', provided the balsa isn't waterlogged. Bear in mind that moisture is a cyano' activator, causing a much faster-curing joint than might otherwise be expected.
TOOLS OF THE TRADE
When building from plans the three most important tools are a sharp knife, a sharp razor plane and a 12" long sanding block. These will form the backbone of your tool collection, and you'll find yourself using these constantly. I also have three power tools that are invaluable: a small electric hand drill, a table band saw and a table-top belt sander. Add these essential items to the standard tool range of screwdrivers, pliers etc. that most modellers already have at their disposal and you'll be well equipped to tackle building from plans.
CUTTING OUT
With some modern plans there's an option to buy a CNC-cut component pack, and this really does take some of the hard work out of the task. Mind you, if you're building from a plan without the aid of a CNC pack then you'll need to transfer the outline of the parts (wing ribs, fuselage formers etc.) onto the wood surface ready for cutting out. You could simply cut the plan about, pin the paper parts on to the wood and then cut around them with a hobby knife or saw, but, of course, the drawing would be destroyed in the process, which seems a shame. My suggestion here is to photocopy the relevant parts to be cut out, lay them face down on the wood and, with a hot iron, iron the paper firmly onto the timber. As the black photocopy toner is heat-fixed to the paper, applying heat with an iron transmits some of the toner onto the wood surface, leaving a perfect outline to cut around.
So, we have the outline imprinted on the balsa, but what's the best way of cutting the components out? For balsa and thin grades of liteply a sharp modelling knife will suffice, but if you want a little more control and the ability to cut multiple components (e.g. a parallel set of wing ribs) then a cheap table-top band saw will prove invaluable.
When all the parts are cut out you've effectively produced your own kit which, of course, we now have to put together.
CONSTRUCTION
If there's no written guide associated with your plan to point you in the right direction then you could always follow my lead and start with the fuselage, move on to the tail surfaces and finish with the wings. Why this sequence? No particular reason, in fact one of the nice things about building from a plan is the very fact that there's no 'wrong' order of assembly. When you've decided what part to make first, try and understand how the construction works. If there's little or no written information about the construction on the plan then it may be wise to make a list, scheduling the steps to take. For example:
Step 1. Line fuselage side, top and bottom edges with 12mm triangular strip stock.
Step 2. Fit fuselage / engine formers 1, 2 and 3 to one side of the fuselage.
Step 3. Fit the other fuselage side.
Doing this before you start can highlight potential problems, saving you from making mistakes during the build - mistakes that you only usually realise after the glue's dried!
Assuming you're cracking on nicely with your build, there are a few little tricks that can help the process run a little smoother. For example, Step 1 mentioned above is a classic construction step. Fitting triangular balsa to the fuselage edges reinforces the internal corners of the construction along its length and also allows the fuselage to be rounded into a 'cigar' shape by razor-planing the corners. Once glued in position this triangular strip can cause the fuselage to distort slightly during the remaining construction. To overcome this I leave the strips out and only install them once all the fuselage formers have been fitted and the fuselage sides are glued to the front former and at the tail end.
Another tip concerns the covering of open framework wings with thin sheet balsa planks. I used to glue each plank to the wing panel separately, but when I tried butting the plank edges together there would always be a slight ridge, which was almost impossible to remove completely and would often show through the covering. The way to overcome this is by butt-gluing the planks together on a flat work bench, joining enough sheets to cover the whole wing. Careful use of a large sanding block will then give a smooth, seamless sheet of balsa ready to be glued to the open framework.
CLASS DISMISSED
That's it, lesson over. Building from plans may seem quite daunting at first, but it doesn't necessarily have to be so in practice. Choose the right plan to start with, follow the advice above and there's no reason why you shouldn't enjoy the total R/C aeromodelling experience. Seeing that model fly, a non-ARTF model that you've built from the ground up, will give you an unparalleled sense of achievement and, what's more, it'll be totally unique.
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