THE NOVELTY OF THE ICE SEASON | MODEL CONSTRUCTION

Is it possible sensationalism in modern automodelisme? Honestly, the boys of our group were sure that no. It seemed to them that has long been found-perenity all the design options and decisions that the task of the athlete is only to compose the best nodes in one model. But one of the departures on the training time made everyone think differently. It turned out that the young aces, who have had sporting success, I know is not all that possible improvement of even simple models has not been exhausted.

That day on the ice track brought together the best forces of our mug. I must say that kordovye racing models of snowmobiles we are engaged not the first year. Gained a lot of experience, tried in races all the schemes that has ever been held in the magazines, and those that have invented themselves. The boys were able to professionally judge the advantages and disadvantages of each shell. So when they were approached by a little old fellow and asked him to give him some fuel to compete… you had to see our professionals snobs! Barely glancing in his direction, they said to wait until he will bring “wood”, I can’t workout is almost over.

And you should have seen their faces in a minute, with square eyes in surprise! The fact that the stranger pulled out of a shallow pocket of a jacket is something extremely streamlined and beautiful, only instinct athlete can guess the proximity to cordovil. In a few movements he was connected landing gear, propeller and put the model on track. Even once assembled, it could fit in my pocket if that would be a little bigger! Finally, our experts were confounded after the first run of extraordinary machine. It has a top speed of nearly twenty miles an hour in excess of the best results krukowski Champions!

Of course, Nicholas — he introduced himself a little later, the guys dragged in a circle. Probably do not need to explain that he’s a member of our team. And in the classroom on the same day, nick told me how and with whose help he built a great race.

It turns out that last winter he saw our training sessions and never missed one of them, but only to come to meet shy. The self-similar case immediately attracted him, and he decided: “Until you achieve good results in the circle will not go!” And under the guidance of his father, in the past, modelers, and is now working aeronautical engineer, began… No, he did not take from their instruments, as they wanted initially. Father, learning about the passion of the son, was advised to learn the basics of aerodynamics! This is something nick did. You ask, what does so far from avtodela science? This question was the main. And the answer to it and helped to create a truly unique micromachines.

Remember, not so long ago there was proaviation three-point scheme with a stabilizer, they gave a clear speed boost. Due to what? First, is refined from the point of view of aerodynamics the shape of the device (from the scheme were excluded flush screw pylon, “body” turned into a thin rod which connects all model elements in one unit, and the stabilizer function of the frame of the rear axle). Secondly, it is considered that the gain obtained from switching to a single point sliding in the race. But is this win so significant? A detailed analysis of the case showed that according to the theory sliding no make any difference how much the skates moving on the ice, it is only important that they are correctly selected and under each of them formed water “wedge”. The rest of the resistance to slip depends on the weight of the machine. The transition to the scheme with the stabilizer and provided a significant reduction in mass.

Slowly standing the young designer challenge is beginning to emerge, it became clear objectives, which are required to achieve. One of them is the maximum relief model with any number of supporting skate. And this would have… shut down everything else! Indeed, as just. But in this apparent at first glance, the simplicity lies the art of the designer. For an inventor achieves the goal by piling up masses of parts and components, although sometimes a “structure” and looks impressive, but the creation of a unique, simple (and therefore reliable!) machine.

Decided reference scheme — type. In principle, the fourth horse to have something to hold on to, and with the bracket it would give weight gain.

Control line racing model snowmobiles:

1 — front of front skate, 2 — low case, 3 — black, 4 — slot air inlet to the carburetor engine, 5 — “sagging” motor, 6 — housing, 7 — propeller 8 — cook, 9 — engine MK-17 “Junior”, 10 — back horse, 11 — front rear skates, 12 — needle nozzle 13 — cord strap, 14 — exhaust pipe.

Chassis model:

1 — front ridge (PTFE), 2 — the clamp of the skate (steel with thickness of 0.5 mm, solder on the parts 1), 3 — front (wire OVS Ø 2-2,5 mm), 4 — winding thin copper wire (solder), 5 — stand bracket, 6 — front rear skates (made of anodized aluminum with thickness of 1.5 mm).

After that, I went to clean aerodynamics. She suggested that it is much cheaper to abolish completely and stabilizer. After all, when the entire area of 2 DM^{2 of} the surface at a speed of 150 km/h confers resistance, requiring polutorachasovogo engine 15% of its maximum capacity, the growth rate losses grow in the second degree. Resistance to sliding right skate theoretically the speed is not a factor under the same conditions when the mass of the model 300 g “consumes” 20(!) times less energy.

As for the whole model, the laws of aerodynamics say: the least resistance to the air flow creates a body having a minimum size, the greatest streamlining and moving through the air with minimal speed.

The first requirement (minimum size) to ensure it was not too difficult. Harder to coordinate it with the flow. After many sketches of Nikolai managed to find a good solution. Reference confirmed srebreno shirt engine cylinder can be zakoptelova only from the front, it will give quite a sufficient reduction in resistance. At the same time improve thermal conditions pereohlazhden in winter conditions motor. Carter will be completely closed by the compressed casing. Chassis — without a single cylindrical element, perpendicular to the oncoming flow of air. This is important! If you put a regular wire as done on the front of the front of the skate, its resistance will decrease by 5-8 times. Because the relative flow cross-section of the cylindrical body will be elliptical, and hence fidelity. Otherwise, the resistance of the wire would be equal to the pterygoid plate with a chord equal to 20 diameters of microcalendar!

No less attention was paid to the other elements. Thus, the cord strap is not rectangular, and wing-shaped cross-section; similarly profiled front and rear skates.

Gradually the project was completed. But when dad reminded Cole about the third requirement of aerodynamics — the requirement for minimum ow velocity had to put everything on the head… a Small racing propellers to create the required thrust will have to drop the jet at a speed far exceeding the speed of the car. So, everything that is located beyond the screw will create increased resistance, the energy of the engine will be used not for traction, and the senseless blowing of the body.

After that, the engine immediately “flipped” back shaft, propeller from pulling became pushing. But there is a new problem: where to get such screws? The hands of a boy not yet able to carve the perfect precision and quality of the propeller. And to use the standard, it is necessary to get the engine going in the opposite direction. Nicholas and spit that way the engine until I got the idea to deploy the rear slide wall at 90°. This was the solution. Indeed, the timing is almost the same as the serial engine, only adapted, they now reverse the direction of rotation of the crankshaft. Now able to use industrial plastic screws 200X200 mm, cut to a diameter of 145 mm and tapered blades. By the way, the last operation is best done not at the rear, and the front edge of the blade, gradually going deeper into the material and making it the end of perhaps more subtle. The transfer engine in the tail of the model allowed to find another original design decision — to carry the tank in the form of a airplane cockpit. Tinted translucent tank-lantern, it turns out, was not only a tribute to beauty. It is logical! Why the extra wall of the housing, hiding the rectangular shape of the ordinary tin can of a tank? Tank-lantern lighter in weight, it fits well with the faired model, and the condition and amount of fuel is easy to follow.

Form factor:

1 — power plate (plywood 2.5 mm thick), 2 spacer (plywood 5 mm thick), 3 — frame (plywood thickness 2.5 mm), 4 — motor mount (plywood 5 mm thick), 5 — fairing of the hull (Linden), 6 — contour of the hole under the needle of the nozzle in the normal position of the rear wall of the engine and specially make a pusher air screw, 7 — low of the body (basswood), 8, 10 — tube of the engine and drain (wrap the yarn, gluing to the epoxy resin in the holes of part 9), 9 — rear wall of the tank (acrylic glass thickness of 4 mm), 11 — tank-light (plexiglass in the thickness of 1-1,5 mm).

Remained to implement the project in the material.

Comparing the original with microsemi krukovskii (immediately became prohibitively bulky and clumsy!), the guys just shrugged — as simple as that. But when someone tried to check balance, our aces indulgently smiled — finally found the bug. Well cannot be so that some rookie beat them on all counts. Alas, it turned out all right. Eyelet for cord strap going ago shifted from the usual position on the axis of the center of gravity. But the need for such a bias try to understand themselves. I can only suggest that when this issue will again need the knowledge of aerodynamics and that there is a pattern: the lighter the model, the greater the shift the strap back. We theory gave PA the idea of a basic machine that turns the start-up of the most capricious of snowmobile enjoyment. But while the device of the machine will stay on a little secret that we will reveal as soon as will pass the first test.

That’s it, I guess. You just have to carefully discover the drawings and to appreciate the elegance, simplicity and justification for new design. Just want to add that since the advent of microsania in the circle of the textbooks on aerodynamics became our reference books. This science at the present rate of self-similar race often determines many important parameters of their movement.

I hope that the publication of drawings of this model will give rise not only backup, but also help to create a more perfect technique, will allow you to break the frame of traditional schemes and structures in the classroom cord racing snowmobiles.

The basic data model

Length, mm: 250

Width with cord strap, mm: 335

Height with the air screw, mm: 160

Maximum zero-fuel weight, g: 240

Engine capacity, cm³: 1,5

Air screw (Ø x pitch) mm: 145X200

V. DIMA, head of the self-similar mug

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