1/12 scale Spitfire! The Spitfire is probably the most wellknown fighter of WWII. This design is meant to recreate the outlines of this classic warbird, and give you as a R/C pilot the opportunity to fly it! The plans The plans of this fighter are not in fullscale, but you may easily use a copying-machine, to scale them up to full-size. The percentage needed is 141% of the original ones. On the plans, you find rulers that measure both centimeters and inches, to give you a chance of knowing when you "hit the spot". The plan is separated in two halves, you have to make them fit, when you put them together. This should not be any problems. Also, some of the parts of the drawing are overlapped. At a first glance, this may seem confusing, but I think you soon will find out which lines belong to which part. The Spitfire The original aircraft is a beatiful thing, with it's curves and elliptical wings. In model though, these curves may cause some problems. I think I have solved these problems in this design. The main goals of a 1/12th scale fighter, are simplicity, easy and quick to build, cheapness, easy to fly and easy to repair. Keep this in mind when you build your own "Spit". The version used as original to this design, is the Spitfire Mk.XIV, which may be built with "razorback" or bubble-canopy. Also, you may choose not to have the outer wingtips, thus building a "clipped" version (low-level flying...!). The Mk.XIV is a later version, using the bigger Rolls Royce Griffon engine. You may of course easily change this design into an earlier Spitfire, by changing the fin, and maybe also the parts around the engine-compartment, as the earlier Merlin-engined versions have a somewhat different layuot at the front. Keep in maind though, that the earlier fin is smaller, and may give rise to a more instabile fighter. General buildup The design is, as I mentioned previously, made to be very fast and easy to build. The body is built up-side-down, using a flat top. In this way it is easy to assemble the fuselage in a straight manner. To give the Spitfire its rounded upper-parts, a foam-top is added. This top is shaped after the version you want to build - either the razorback or the bubble-canopy. The middle parts of the fuselage is doubled with plywood, to increase strength. Also, the firewall is made out of plywood, to be able to cope with crashes. At a crash, the firewall is meant to break loose, thus saving the rest of the fuselage from the impact of the crash. The most forward parts will in this case act as a deformation-zone, and will be totally broken. The thought behind it, is that you after a major crash should only have to reassemble the firewall plus engine, and the servos, and maybe some other parts, to get your fighter into "service" again. The wing is an all balsa Clark-Y variant. The design of the wing may seem fragile, but I can reassure you that it is very sturdy, and able to take a lot of damage. If you do not want the Clark-Y airfoil, you may instead choose another airfoil, and cut the wing out of foam. This is done by having too large airfoil-formers (especially at the wingtip) when cutting the wing, and having the foam-block elliptical shaped. Use a good airfoil, for instance the Ritz-2, or something similar. If you want a better looking nose (the design is kind of very square), you may either use more balsa-blocks, and sand it into a round shape, or you may mould your own cowling using proper materials. Start building! Start with cutting out the necessary parts, as formers and fuselage-sides. We start with the body: Mark up a centre-line on a 2mm balsa-sheet. This will be the fuselage-top (9). Take all of the formers (1, 2, 3 and 4), and mark their respective centers. Prepare the firewall (1) for you engine-mount and throttle-push-rod. Also make holes for the fuel-lines. In the prototype I used a Radio-active 10/15 size nylon engine-mount. Glue the formers to the top. Be sure to put the firewall (1) pointing a little (about 2 degrees) to the left and upwards. This is to point the engine to the right and downwards (remember - you are building up-side-down!). Adjust the two fuselage-rods (7), and glue them to place. Cut out the fuselage-sides, and sand their rearward edge to make them fit together nicely. Cut out the plywood doublers, and glue them to the fuselage-sides. Be sure to make one left- and a right-hand side! Please note that the plywood-doubler runs in some angle to the fuselage-sides. If you want to make the building easier, you can skip the plywood-doubler, and use 3mm balsa-sheets for the fuselage-sides instead. You can also exchange the plywood-doubler to 1.5mm balsa, thus saving weight. In both cases, you will loose strenght, though. Glue the fuselage-sides to place. Prepare installation While you still may access all of the fuselage, you should prepare for radio-installation by assembling the elevator- and throttle- push-rods. After that, attach the wing-saddle (8), and the bottom fuselage-covers (10 and 11). Please note the fibre-direction of the bottom-cover - it should be directed in 90 degrees angle to the fuselage. Now you can drill holes for the rubber-band rods (12), and attach them. They should stick out some 1-2cm from the fuselage-sides, to be able to draw rubber-bands around them, to mount the wing. The next step is to attach stabilizer and fin. Attach the stabilizer (15) to the fuselage. Cover the elevator (16) with the covering you wish to use for the model, i.e. some iron-on tex, and put it in place in the hatch in the fin (14). Now, glue the fin to its place, be sure not to forget the elevator! To get the rounded Spitfire-look, you must add the foam-top (13) to the fuselage. First you must choose what version of the Spitfire you are building: An "ordinary" or a "bubble". Then cut out one (or several, it does not matter) piece(s) of foam that fit in to the fuselage top-view. The foam can be a bit too wide, as it is easy to sand it to proper shape later on. Then shape up the foam according to the side-view you find on the plan (and of the version you are building). Then glue the foam-top to its place. When the glue has dried, you can sand the foam-top to proper, round shape. If you do not want to make a transparent canopy, you can use the foam-top to shape the canopy too. The wing You start by adding the sheets of balsa that makes the wing-covering. You do this by using tape to fit the sheets together, and then dipping glue into the gap between the sheets. Let the sheets dry under pressure, to keep them straight. After having cut out the wing top and bottom covering, you may start assembling the wing. Please note that the top-covering must be made a little bit wider, as the top of the wing is curved. You start by attaching 25, 26, 27, 28 and 29 to the bottom covering (23) of the wing. Do the same to both wing-halves. Please note that spar 25 are in two versions, with different hatches. The one with biggest hatch is to be placed at the wing-root. This spar can be aded later on, when asembling the two winghalves together. Also attach the pieces of balsa that are to be placed between 26, 27, 28 and 29, where the ailerons are to be attached. Now, attach the winghalves to each other, using 22 to get the proper dihedral. Be sure that 22 is properly attached to all of the spars nbr 25! This is vital to the strength of the wing. Now you can start installing an aileron-linkage of some sort. After that, you may cover the top of the wing. Before you do this, you must put wash-out to the wing. You do this by pinning down the leading edge of the wingtip, and having an 8mm piece of balsa under the rear edge of the wingtip. Then you glue the top covering to its place. Be sure to use a lot of needles to secure the covering while the glue dries up. This is to keep the balse down on all the spars of the wing. Do the same to the other wing-half, and be sure to give the same wash-out to both of them. Sanding Now, you should sand the leading- and rear edges of the wing. Sand away all unecessary balsa, and give the leading edge its characteristic rounded shape. The rear edge, where the ailerons are to be attached, you should sand as straight as you can. The leading-edge (31) is attached in two layers of 3mm balsa. The reason for this, is the sharp bend of the leading edge. If you want to have a very strong leading edge, you could always put a 1mm plywood string in-between the two 3mm balsa layers. Sand the wingtips (32) into reasonable shape, and glue them to their places. When the glue is dry, you should sand them to proper shape. Meanwhile you could sand the ailerons to proper shape. Be sure to let them follow the shape of the wing, which is pointing more upward the further to the wingtip you get (due to the wash-out). To be able to hand-launch your fighter in a safe manner, you should add a scoop to the middle of the wing-bottom. The scoop is built up by parts 18-21, and it should be placed about 1cm from the leading edge of the wing. After that you have covered the wing with iron on material, you should glue some sanding-paper to the sides of the scoop, to give you a good hold even when the model is slippery of oil. Finish Preferrably you cover your model with iron-on covering, that should be in some scale-like colour. By using iron-on tex, your model gets tougher to break, and you save weight in comparison to painting the model straight on the balsa. The foam-top is sensitive to iron-on tex, as it melts by heat. It is no problem, though, if you are careful. If you want to be sure not melting your foam-top, you could cover it with "brown-paper", that is, the kind of paper used to cover mailed parcels. Wet-room wall-paper glue has proven to be a good glu...
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