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PERSONAL TRANSPORT: GROUND, WATER, AIR
Aerosleigh Triumph. Personal transport
Directory / Personal transport: land, water, air The sleigh that will be discussed is the second model of our joint construction. The first was made a year earlier and was, as it were, a test of strength and capabilities. That "apparatus" turned out to be durable, but heavy - because of the body, for the frame of which we did not find anything better than ordinary steel pipes Ø25 mi. For the same reason, the speed, especially on virgin soil, was much less than we would like. It is known that if the carrying capacity of the snowmobile is set in advance, then the struggle for speed can go in three directions: increasing the efficiency of the power plant, reducing its own weight and reducing the resistance to movement. (The latter consists of slip resistance and aerodynamic resistance.) Therefore, when designing and manufacturing the second model of the snowmobile, we tried to fulfill two basic conditions as much as possible: to make a car with a minimum dead weight and achieve the least resistance to movement. All this is based on an engine with a capacity of 25-28 liters. With.
The overall layout of the machine - the location of the seats, the power unit, skis and other elements that determine the centering - is made in such a way as to ensure that the load on the skis is as evenly distributed as possible, to lower the center of gravity and to bring the propeller thrust line closer to the ground. To prevent the car from tipping over, the rear ski track is large - 1800 mm. The all-metal, load-bearing, one-door body is riveted from sheet duralumin. Its basis is a beam tapering in height in the direction of the front end. Its upper part serves as a floor, passing into the back of the rear seat, the lower part forms the bottom. Power set contains 8 frames and 11 stringers. From frame No. 5, the stringers are doubled symmetrically to the body axis. To facilitate them, holes are made in them, the edges of which are flanged at an angle of 45 ° to increase rigidity. Four holes Ø110 mm in the floor of the body had to be punched in order to bring the riveting tool (support) for fixing work in hard-to-reach places. The bearing part is made of sheet duralumin grade D16T 1 mm thick. To connect the elements, a bent corner profile 16X16X1,5 mm from AMG6 material was used. Since the front and rear ends of the body are double curvature surfaces, they were assembled on rivets from pre-cut elements. Each was preliminarily given a domed shape. The roof is also made convex, but solid: the curvature of its surface is small. Duralumin 0,5 mm thick went to the side skin. To increase the rigidity of the sidewall reinforced with ribs. The "skeleton" is sheathed on the outside with duralumin 1 mm thick, and on the inside - 0,5 mm. Frames and stringers are also made. It should be noted that there are no seats as such. They are replaced by niches in the floor, where seat cushions made of foam rubber, covered with leatherette, are placed. At the front, the backrest is fixed on brackets, allowing it to lean forward for the convenience of passenger landing. The backs are also foam rubber, with leatherette covering. In places of increased rigidity of the body, linings are riveted, to which brackets for attaching suspension pipes are screwed. The horizontal surface of the engine compartment is also reinforced with a 3 mm D16T lining.
Glazing made of organic glass 3 mm thick. The body is painted with two layers of ML-197 enamel applied on a layer of primer GF-020. Combined color: orange bottom, blue top. Body weight with glazing 35 kg. The propeller installation includes an engine, a gearbox and a variable pitch propeller. When using the gearbox, we were guided by the fact that it allows more profitable use of engine power, shifting the propeller speed to the region of up to 2 thousand rpm (max.). The result is higher efficiency than a smaller propeller running at high speeds. The possibility of changing the angles of installation of the blades in the process of movement attracted us because it allowed us to change the tractive effort up to the reverse and carry out aerodynamic braking. The design of the gearbox and the pitch change mechanism is shown in Figure 6. They were designed for the existing Zundapp engine (25 hp). Therefore, later, when using the M-63 Ural motor (28 hp), an adapter flange had to be made to mount the gearbox. With the use of the M-63 engine, the total weight of the power unit decreased by 10 kg and amounted to 65 kg. The gearbox consists of a housing and an extension. A gear is mounted in the housing, and the extension serves as a support for the propeller shaft. The case is welded, steel. It is formed by a flange and a shell welded to it from sheet steel 2 mm thick. Bearing seats are welded inside with stiffening ribs. The body is also ribbed. After welding, it was subjected to heat treatment to relieve internal stresses. The extension cord is made using the same technology. Applied gears are cylindrical, spur; number of teeth Z1= 32, Z2 = 60, modulus 1,75, crown width b = 25. Gears are selected ready-made, modifications are reduced to a minimum. They are seated on shafts with feather keys. Shafts are made of steel 30KhGSA. To facilitate them, they are made hollow, heat-treated to a hardness of 42 ... 45 units, rotate in angular contact ball bearings, the interference in which is regulated by selecting the thickness of the compensators. Torque from the engine is transmitted to the input shaft through an elastic rubber coupling. 100 ml of gear oil is poured into the gearbox. The pitch change mechanism is based on a principle widely used in aviation. The only difference is in the drive: aviation is usually hydraulic, ours is mechanical. The mechanism is mounted in the screw hub and operates as follows. Each blade in the butt part has a shank consisting of a flange and a threaded part (M20x1,5). The shank is screwed into the hub shaft, which also has a flange. After installing the blade, the flanges are tightened with a clamp. Thus, the blade is rigidly connected to the hub shaft, and its angular position will correspond to the angular position of the shaft. The latter is driven by a leash, with which it is connected through the end key. The leash receives rotation from the fork; it, together with the rod, can move translationally relative to the axis of the screw shaft. The rod through a system of levers and rods is connected to the step control knob located to the right of the driver. It has 10 fixed positions, allowing you to change the traction force depending on road conditions. By moving "away from us", we force the fork to move to the left (according to the figure); at its extreme position, the blades will turn a large step. Taking the handle "on ourselves", we transfer the blades to a small step and further to the reverse; its average position corresponds to zero thrust. The nominal stroke of the rod is 30 mm, it corresponds to the rotation of the blade by 60°. All parts of the mechanism are made of 30KhGSA steel. The centrifugal force from the blade is taken up by the thrust bearing. The purpose of centrifugal weights is as follows. When the propeller rotates, centrifugal force acts on the loads, creating a moment that turns the blades in the direction of increasing pitch. This effect creates a tightness in the control circuit and reduces the force on the handle. Steel balls Ø25 mm were used as weights. The figure shows the blade, its geometry and main dimensions. The order of manufacture of each of them is as follows. 20 strips of 135X600 mm in size are cut out of millimeter plywood. The blanks are glued into a bag with epoxy resin in a special device, which provides the bag with a given twist (25 °) and creates the necessary compression. After that, the blade is processed along the contour and the convex side of the profile; the flat side is ready after gluing. The correctness of the profile is controlled by templates. Then the blade is ground, puttied and painted. The geometry of the blades, their dimensions and weight must be strictly the same. Their parameters are selected based on the analysis of existing structures and the study of literature. The speed performance of the snowmobile is largely determined by the chassis, and above all the skis. They must be not only strong and rigid, but also light, have good glide, and be technologically advanced in manufacture.
Our skis fully satisfy the first four requirements, although they are somewhat less technologically advanced than we would like: about 700 pieces of rivets alone are used for each. The structure of each ski is load-bearing, has the shape of a closed box of trapezoidal section and is formed from below by a sole, and from above and from the sides by a bent box-like sheathing. Inside, two longitudinal partitions run along the entire length. All parts, except for the sole and guide undercuts, are made of sheet duralumin grade D16T. Assembly sequence. First, the longitudinal partitions are riveted with corners and reinforcing plates. The latter are made of sheet D16T 3 mm thick, have a length of 450 mm and are located in the middle part of the ski (holes with a diameter of 25 to 50 mm are made in the partitions and overlays to facilitate). Then frames (6 pcs.) are riveted between the partitions. The resulting frame is superimposed on the sole and riveted to it together with guide undercuts. Sole material - stainless steel 0,5 mm thick. (Sheet polyethylene as a material for sliding surfaces was tested by us on the first snowmobiles, it wore out quickly, especially when driving on icy roads.) Ski assembly is completed by riveting the upper skin along four main seams: two lower ones with soles and two upper ones with corners of longitudinal partitions. For riveting the upper seams, a series of holes Ø85 mm were made in the box cladding, and support was brought through them. After riveting, the top of the ski was pasted over with leatherette for sealing. The weight of the front ski was 5,5 kg, the rear, longer ones, 6,5 kg each. Both rear skis are suspended on trailing arms to a truss formed by three pipes attached to the body at three points. Textolite bushings are pressed into the levers, on which they rotate relative to the pin. The shock absorber from the Java motorcycle is attached to the lever at one end, and to the farm at the other. The power truss and levers are made of chromansil tubes. For the levers, elliptical cross-section pipes with a major ellipse axis of 45 mm were used. Front suspension and steering device. Like the rear ski, the front ski is suspended on a welded rocker arm. A system of seven extension springs taken from the rear brakes of the Zhiguli car is connected to the lever by means of rods. Suspension travel 100 mm. To limit it, a rubber buffer is used. The suspension arm swings on a traverse, which, together with the shaft, can be rotated from the steering gear. The latter consists of a steering wheel (automotive type), a steering shaft and a cable system. The cable is laid as follows: in the drum, planted on the steering shaft, a diametrical through hole O3 mm is drilled. A cable is passed through it in such a way that two branches of the same length are obtained. The cable is fixed on the drum with a clamp (not shown in the figure). Each branch makes two turns around the drum in opposite directions, passes through the blocks and is closed on the lever. The degree of cable pressing is regulated by a special device. The bracket is attached to the instrument panel. The steering wheel makes one and a half turns, which corresponds to a 60 ° turn of the ski. Additional equipment includes the following. Suspended gas tanks located on the sides of the snowmobile are soldered from galvanized iron and have internal partitions. Foam fairings. The tanks are connected to each other by a petrol-resistant rubber hose, the filler neck is located in the left of them. On the instrument panel are mounted: a speed indicator, a tachometer, a toggle switch and a signal light for turning on the ignition. Speed indicator - aviation type, home-made tachometer, electronic. Electrical equipment includes a battery ignition system and lighting devices (headlight, position lights). The engine is started only from the propeller. The snowmobiles were made in 10 months, including design. They were tested on snow of different hardness and under different loads. Even fully loaded sledges go very easily on rolled snow at air temperatures of both - 5 ° and - 15 °. The speed in this case can exceed 100 km / h. On virgin snow, the speed reached 30 km / h (when driving without a passenger). It was determined by the speedometer of a car traveling parallel along the highway. Driving on virgin soil is perhaps one of the most difficult modes for a snowmobile: the engine has to work almost to the limit, so a power reserve of 10-12 liters. With. is a must. Therefore, we have now designed and started to manufacture a radial two-stroke engine designed specifically for snowmobiles. A conversation about him, perhaps, is yet to come, after the tests. Authors: O. Yakovlev, V. Bokov
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