Plan of Attack

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 hell 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 Ive 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 youll 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.

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