A GIFT TO THE FIRST START | MODEL CONSTRUCTION

It’s been over a decade since then, as avtomodelisty decided to make your sport all season and came up with kordovye model of the sleigh. Now, perhaps, it is difficult to name the author, the first such model: the necessity of introducing the lessons of the circles simple, affordable design that would combine the speed of production and the possibility to use the internal combustion engine, would the creative scope for the budding modeller and, moreover, would not be just “educational” (like, say, contour resonators), was clear to many.

Since then, four classes cord sleigh with internal combustion engines working volume of 1.5 and 2.5 cm³ — speed and copies — have gained a strong place in automodelisme. The growing popularity of the all-Union competition, “arrive” and speed.

However, as it turned out, unpretentious in appearance cord model sleigh is fraught with many opportunities for further improvement. We have not yet reached the stage of purging, but the aerodynamic account when designing, testing, working with the engine long ago entered into practice of work of any group. But most importantly — a model of a sleigh is still very much a creative work. Installation methods of skates, the stiffness of the suspension, the installation of the tank — in any case there are no simple solutions.

Description of “swinging” model, published in this issue is further evidence that the sleigh hold a lot in store, revealing of which could lead to a further increase in the velocity models of these classes.

A distinctive feature of the model of the snowmobile (Fig. 1) — let’s call them “Bear” is a swinging front and rear suspension. Thanks to this constructive innovation of the axis of the motor always remains parallel relative to the surface of the track. Model like is transferred from foot to foot (like a bear). No bumps or cracks is prevented, and the nose looking forward for the course.

Fig. 1. The model of the snowmobile suspension suspension.

Fig. 2. Single-vane propeller with a counterweight.

And how does the model start at the most crucial moment? Typically, a snowmobile under the influence of inertial torque from the rotor trying to hit the circle, unable to gain speed. This negative effect experienced athletes eliminate backspin models in the first laps. (Assistant to the center of the circle creates an additional tension on the cords.) “Bear” at the time of launch like squats on one leg (Fig. 3). The center of gravity is displaced in the outer wheel side, and мoveнт of inertia of the screw is flattened. Not once tested a “Starter fit” models for competition, and always it is justified.

The snowmobiles are easy to make — even for beginners in automodelisme quite a force to build them. The model can be made in the classroom 1.5 cm³ and 2.5 cm³.

The design consists of a frame (fuselage), middle and rear suspension hangers and pylon-engine mounts.

The fuselage is made of aluminium tube Ø 14 mm, which cut the grooves for the pylon and suspension. Front and rear in a tube crammed stub-fairings made of beech.

Front and rear suspension are made from D16T sheet thickness of 2 mm, skating—aluminum corner. Swing system relative to the fuselage is due to the introduced into the cavity of the tube brass rollers.

Fig. 3. Pre-launch installation of the model on the ice.

Fig. 4. Assembly of the model.

Engine mount (D16T sheet with a thickness of 5 mm) is designed integrally formed with the pylon attached to the fuselage with three screws M2,5. Installed on it the engine and fuel tank close the fairing from foam, covered with fiberglass and impregnated with epoxy resin.

Fuel tank — a common type of “drinker” allows you to maintain a constant engine mode throughout the race. And the use of the single-vane air propeller simplifies selection and fabrication, compensates for inaccuracies of adjustment of the engine and increases the average speed on the course in comparison with the usual screw 7.5% (Fig. 2).

For beginners this model is good because it is possible to participate in competitions not only in winter but in summer. Enough instead of skates on the suspension to set axle with wheels (Fig. 4).

Are you going to go for the first start, rookie? We give you the idea and the drawings! Build a snowmobile and make your own gift to the first exit on the track.

N. KOMAROV, master of sports of the USSR

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