Tucano (oz12459)

About this Plan

Radio control scale model. Wingspan 39 in, wing area 250 sq in. For electric power with 540, 600 or 480BB motor.

Quote: "Brazil's Embraer aeroplane company has produced some very good aircraft of which my favourite is without doubt the Tucano. It has a very good reputation as an excellent training aircraft and is admired for its elegant lines, and indeed, its sparkling performance. No-one has yet modelled the Tucano for electric flight yet its slender design makes for very efficient aerodynamics and its profile is eye-catching from all angles. In short, its the ideal subject.

Being a little concerned about the wing loading and the resulting performance I decided to build the model with two sizes of wing, one much larger than scale, the other slightly nearer the mark. Anyway, the difference between the two was so negligible that I finally settled on the shortest wing span, which to all intents and purposes is scale... ish! As a result the model is an excellent all round performer, great at high speed aerobatics yet suitably forgiving on landing.

The Build: Begin with the fuselage which is built on its side. Cut both sides from medium 1/8 balsa and mark the former positions on the inner surfaces. Lay one side on a flat building surface and glue in place F3 to F8, F10 to F12 and B1 to B4. Make sure these are square and allow to set. Glue the other side on top of these formers and ensure correct alignment. The next task is to glue the rear half of the fuselage sides together. Pull the two sides inwards with masking tape at the rear and glue B7, F13 and F14 in place. Ensure correct alignment before the glue sets.

Make the motor tube by rolling 1/64 ply (two layers) around your motor to give a tight sliding fit. Cut cooling holes in the tube for the motor brushes. The motor can be held in the tube by any one of a number of methods. Personally, I use a steel clamping band, however, you may well have your own preferred method. Glue the engine tube in place together with F1 and F2 and shape the cooling air slots.

Install the elevator control and aerial tubes through formers F12 to F14. Glue B5, B6 and F9 in place and allow to set. Next, pull the top part of the rear fuselage sides in and glue them to B5 and B6. Glue the two F15 wing seating reinforcement pieces in place and add all ply facings. Make and sand to shape the tailplane and fin and above all be sure to install them accurately. Fit the elevator servo in F6 and remove all dotted areas from formers. These allow air access and cooling. Sand the fuselage to give the required section and add the launching hook and the two dummy turbine exhausts.

These are a nice scale feature and can be made from two 90 degree copper plumbing bends (solder fitting type). To give the correct appearance cut them to shape and tin with solder before fitting. Finally, make the cockpit interior and organise the canopy release system so as to allow access to the NiCads. My own version is held, at the front with a peg and is held in place at the rear by a loop of thin bungee.

THE WING: The plan shows a 1/16 balsa sheet leading edge with the rear half of the structure open. This type of construction tends to favour the heat shrink covering films, however, if you wish to tissue cover and paint the model, modify the wing ribs slightly and sheet the entire wing surface with 1/16 balsa and then use your preferred finishing method. The extra weight involved will not noticeably affect the performance.

Pin the lower spar and aileron hinge line spar in place and add all the wing ribs. Add the top spar and leading edge spar, then skin the upper leading edge and allow the glue to set. Remove from the plan and skin the lower leading edge and also between RI and R2 top and bottom. Cut an appropriate slot and glue the wing brace W1 in place, and when set wrap the centre section join with 1 inch wide nylon cloth and cement. (With one wing flat on the bench the other tip should be
raised 4.5 in'). Note that no washout is required.

Add the wing dowels, fixing bolts and the aileron servo. Small servos are best as the space available is limited. Sand the whole model and cover with your chosen method. In my case the ailerons were hinged with diamond tape although Mylar or proprietary hinges would do equally well. Install the motor, speed controller, servos, Rx and switch. When fitting the battery, adjust the position with sponge rubber to place the centre of gravity 2 inches back from the root leading edge but don't go any further aft than this. Aileron and elevator movements are all +/- 1/4 inch which will give good aerobatic response.

GET AWAY: For launching, I have found that a simple bungee system works extremely well whilst removing the dangers of lone hand launching. The bungee needn't be very long and it really is very quick and easy to make. All you need is 10 metres of 1/4 in shock cord, 5 metres of Nylon string, with a 12 in steel spike firmly screwed in the ground and a key ring at the model end.

Check the controls and motor, have the trims neutral, pull the model back eleven or twelve paces and release! Start the motor just before the model leaves the bungee and you will have achieved a take-off without the struggle of a hand-launch.

Climb away after take-off for some superb aeros just like the real thing. With a good motor it will loop from straight and level with ease and there's little tendency to tip stall.

The model is agile, good in roll and will perform well with 540 to 600 motors and 7 or 8 1700 mAh cells. Another successful 'option is a good quality 480 motor with 8 x 500 AR cells.

The RAF training colour scheme helps with the visibility but stay alert as it has a high turn of speed and quickly disappears into the distance.

The Tucano is equally successful on the slope and nothing could be simpler if you fancy having a go. If you're game there are two ways to approach the conversion: Either remove the prop and fly it with no battery or remove the motor and replace it with the Rx NiCad. In the latter case, attach the spinner to maintain the appearance.

Well, that's it for now, perhaps one day I'll find the time to design a Bandeirante, a twin turboprop aircraft: again another really good looking machine!"

Cyril Carr's electric Tucano from RCME Issue 11, '98.

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