THE AMPHIBIAN ON THE ICE TRACK | MODEL CONSTRUCTION

The prototype model has served as a snowmobile amphibian created in 60-ies a group of young professionals under the leadership of the Soviet aircraft designer A. N. Tupolev. This car attracts the severity of the contours (see “M-K” No. 11 of 1978), do not break any complex suspension system of the ski or tubular enclosure of the propeller. And this is a significant advantage Because each protruding element design increases the aerodynamic resistance. It is better to have a bulky, but streamlined body than compressed to the limit, but with the “stork” legs of the undercarriage. In addition, the housing of such a model creates the effect of aerodynamic unloading, manifested even at low speed. Amphibians have relatively small diameter propeller.

This allows you to make copno moderate dimensions, focusing on the optimum propeller diameter 160 mm for the engine with working volume of 2.5 cm3. Hence selected, and the minimum allowable scale of this model — 1:12 on the prototype.

The case of the model can be applied to the wall of the fiberglass, but easier to make from plastic. It is extruded from a heated Plexiglas, alternately stamping the four parts that form the outer skin. The case weighs just 400 g. Details adjust to each other, glued, pre-cutting hatches and doors. There is a saving of time and effort. Imagine how much trouble would it Vileika of fiberglass, not to mention time-consuming operations for surface preparation of fiberglass “crusts” for painting. And cut the “glass” in them requires a lot of effort. Housing made of plexiglass after stamping is immediately ready for painting. He has a good gloss, and the “glass” is inserted. They won’t fly out when you shake or to form prominent ledges PRN imprecise fitting.

Thus, the material chosen. Now you need to make a wooden disc-punch for each part. Such blanks will need three: for the body (it can be used with the hood top and bottom), torch n of the engine hood. The shape of these punches you need to understate 2 mm, considering the thickness of the plexiglass. A plywood thickness of 15 mm on the exact contours cut out of the matrix window. Wooden parts lubricate with machine oil, heating it to 50 — 80°. Acrylic must be heated to 115 — 135°, to impose on the matrix and push the top of the punch. This work should be performed together — so it turns out faster. The cooled semi-finished products cut to size limits saw with fine tooth. After adjustment, the parts with a jigsaw, cut out holes, separated hatches and shutters of the lantern.

The basis of the frame power frame formed by the back and weight the frame, bulkhead and engine mount dural. Before Assembly on the wooden blanks of the punches is marked the section of the frames and removed them from the cardboard templates. From six-millimeter plywood template cut out of the power frame, the bulkhead, and chetyrehkilometrovoy rear frame. Examples of the power frame to the pieces of the body, collect it on with epoxy resin. Is the membrane that protects the cavity of the model from contamination of fuel, is fitted and mounted fuel tank, metal engine mount and the Latter is useful to additionally attach to the frames with dural corners.

Collecting model, it is better to connect the parts of Plexiglas and wood with a special glue — chip solution of Plexiglas in dichloroethane. With its help the body is connected with the power unit. Then fix the front frame (plywood thickness 2.5 mm), cavity of the trunk, the floors and walls of the cabin (thin cardboard) and lastly glued the bottom of the case. The internal space of the cab is painted. It also mounts the foam chairs, celluloid dashboard, steering column. Trunk lid, fold the lantern after painting hung on hinges, they fit the simplest model locks.

Fig. 1. Model-copy of the snowmobile-amphibian:

1 — rudder, 2 — the keel 3 — hood, 4 — membrane, 5 — bulkhead, 6 — tank, 7 — rear frame, 8 — screw, 9 — front frame, 10 — loop 11 — cavity of trunk, 12 — castle 13 — trunk lid, 14 — housing, 15 — fold lamp 16 power frame, 17 — cord strap, 18 — Board, 19 — mine, 20 — stern frame, 21 — propeller 22 — the lantern 23 — cabin floor, 24 — horse, 25 — engine mount.

Then install the keels, cut from plywood, the aft bulkhead and a tubular shaft for access to screw kontrpartiya. Finished, “real” view of the model will give small details of design: edging glass, handles, headlamps, stiffeners and junctions of the panels of the body, the nodes turn rulen. The best material for densely srebrenik cylinder layout plant — ebonite. Polished dural tube and the notched sticks mimic cover heads and various nozzles. Mount all the parts on the aluminum “housing”, complete layout brass tubing (wire) and bolt heads (epoxy resin with aluminum powder, applied with a needle).

Before the first runs you must check the alignment of the device. The length of the model DH — cord under the strap, fixed on the bulkhead of the power frame. If the center of gravity, it will take “baggage” placed in the baggage, nose compartment of the housing. To shift the cord the bar and the center of gravity back is not necessary — the model will tend to approach on track. When specified on the drawing, centering it perfectly goes the distance, relying mostly on the Central ridge. Even with significant irregularities track snowmobile jump only, without changing the tilt of the body, the impact from bumps falls exactly under the center of gravity, and unfolding its up and down moments arise.

N. MAROV

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