The construction of the first serious model… Immediately raises a whole bunch of problems. Basic: how to use the engine. Now the domestic industry mass-produces three brands of motors suitable for installation on pilotage: “Sneaker” with a working volume of 7.0 cm3, “rainbow 7” and MDS-6,5. The first two need elaboration: setting the desired valve timing, selection of the volume of the combustion chamber and domainservice crank mechanism. However, initially you can apply and serial, well-tested on bench for instance.
Will have to break down and over the choice of material for the construction of the model.
Until recent years, virtually all championship pilotazhki was built entirely out of balsa, and most of this scarce Wood left on the fuselage. But, it turns out, the fuselage can be performed without the use of drevesiny, and new technology developed by the leading Moscow athletes and proven in practice, provides a number of significant advantages. The fiberglass option, and that’s exactly what it is about, first created A. Svejkovsky, balsa is lighter by about 50 grams! In addition, significantly less time is spent not building the fuselage.
First of basswood and pine made a copy of the future of the fuselage without a keel from parts joined with glue dots. Ready disc carefully shpaklyuyut and several times covered with nitrocream AK-20. After drying it is processed to obtain a smooth matte surface” And the bow shall be cut neatly plot (later hood) and blank razdenetsya. The PVA glue each of them is mounted on a flat sheet of organic glass. This also laid solid beech frame-rail, and all surfaces inside of the frame double-covered “Edelvika”, which after drying thoroughly raspeliere cates. Then applied a thin layer of epoxy resin K-153 (a large amount of resin can boil from self-heating, and the work will have to be repeated). He waited until the epoxy is not polimerizuet “to cast”, put in the next layer. Similarly, the form covered by the third time, after which the remaining volume is filled with the wreckage of chipboards or churbachki and filled with epoxy resin. Form-matrix ready. Removing Plexiglas, prostrogat outside and lacquer.
Before running the “crusts” — one half of the fuselage, you need to prepare patterns of annealed glass with a thickness of 0.1 mm, cut and fit to the shape of the packaging is lightweight plastic foam with a thickness of 2-2,5 mm resin (weight must be equal to the mass of fiberglass) and a large plastic bag (it should be free to enter both the matrix form of the fuselage). Last inside are “Edelweiss”, they laid a layer of pre-impregnated on a sheet of Plexiglas, fiberglass, under which carefully remove air bubbles. The forward fuselage is enhanced by the overlay of the next layer, it ends approximately at the rear edge of the wing. The edges of fiberglass are laid on the sides of the matrix and nailed thereto, so that during the moulding-on of the foam he had not moved previously imposed layer. The resin is allowed to solidify to almost “touch”, it remains diluted with alcohol to a liquid state and the resulting solution with a brush cover in a matrix of fiberglass. Forms quickly placed in a plastic bag, and inside it on valaku placed sheets of foam. The package is fastened, and from it through the nozzle of the vacuum pump the air is evacuated. As pumping position the foam inserts should be corrected, pursing through the film. Not glued areas and voids should not be quite. Work carried out on the foam sheet that protects the plastic film from accidental punctures or tears.
The air is evacuated until then, until the resin is cured so that the foam will cease to move away from it. Now the matrix can be extracted from the package and paste the annealed billet of the fuselage is fiberglass with a thickness of 0.02 mm on a parquet varnish. The mass of each “crust” with the right execution of all operations and minimal use of varnish is not more than 50 g.
The next day, “skin” is cut in the matrix, removed from it and adjust to each other. Hood wikiepedia of two layers of fiberglass 0.2 mm thickness in the same matrix, but without the foam. The manufacture of the fuselage of this type takes about 5 hours clear time.
The preparation of one-half to the Assembly is in recess grooves to the outer layer under the two front frame; the first of these sub — sawn peraleja of six-layer plywood with a thickness of 1 mm, and the second — power — of two such layers. They need to prepare the holes for the container of the fuel tank and the outlet channel of the cooling air (the drawing shows the location of these elements corresponding to a self-made engine with the carb on the rear of the crankcase).
Frames embedded in the grooves of the “crusts” of the fuselage, provide the caliber, it adjusted the length of the container, whereupon the latter ka is glued in place. In the resulting set of forward fuselage cut into two short longitudinal side stringer under them is selected as the inner layer of fiberglass and foam sidewalls. Then “peel” are laid out and propisyvayutsya window under the wing and stabilizer. When marking, it is desirable to use a marking gauge that will provide the necessary accuracy of relative position of the planes of the model. Note that the front edge of the wing at the subsequent Assembly must be joined with the second frame. Now manufactured from foam PVC with a thickness of 4-5 mm in the other frames, adjust them to the “crust”sidewalls.
Before moving on to the wing structure, I want to draw your attention to the seemingly overly simple shape of the fuselage. In addition to the facilities of veclachi “crusts”, this form greatly facilitates the external perception of the figure, running the model in the air. As shown, intricate fuselage, good looking on stationary models, hand turn flying pilotage in the heavy and clumsy apparatus. In addition, the simple shape allows you to transform the appearance of the fuselage in a wide range by changing the shape and location of the lamp, the keel and forces.
The wing model is made of balsa wood according to the classical technology, the well-known modelers. Suitable foam. Recently, the “bezbolesnie” wings have been successfully used in the pilot. They are made in the following way.
4 First sheet of aluminum cut the templates root and conttyh ribs n and borders string, heated by electric current, from a roll construction of the foam are cut out of the console. They are pierced along the scale, the holes are alternately entered string, and it cut the channels of relief. The finished blocks vyshkurivaetsya long (a little more polurama wing) with wooden planks glued to it a strip of sandpaper. Abrasive coating skins pre-test on scrap foam — it should remove material without pulling the individual beads or pieces. The rear edge of the console is enclosed lime 2 mm thick, in places of attachment of the flaps you need to punch extra boss. The block surface is sheathed with veneer — a thin sheet of birch, basswood or even mahogany, viscolene to a thickness of 0.5-0.6 mm. When the thickness of the veneer wing is an exceptionally hard and quite satisfactory for weight. Pre-separate the strips of veneer are joined into whole cloth. For this, thoroughly progruntovav the ends of the strips Amalita, connect them together, shed the joint with acetone and lightly iron with a hot iron. Then one side of the canvas covering vyshkurivaetsya and covered with a thin layer of slightly diluted PVA glue. Giving the glue a little dry, the veneer is applied to the foam of the console, grind and re-iron with a warm iron. The temperature of heat pick up such that only podpravit the foam block. Then set the ending cut out of a foam type PS-4-40, adjust them to the shape of the airfoil and covered with a thin fiberglass.
Ready console are adjusted to each other in the joint, they cut short the grooves for a short rail-side members that serve to strengthen the center wing. Between the shelves of the front longitudinal mounted, fully complete unit of the swing control console are glued together. Strengthening the joint of casings with fiberglass tape with a thickness of 0.1 mm and a width of 60-80 mm, fit an entire wing thin long fiber paper on a parquet varnish. In any case, do not use nitro lacquer: they will instantly dissolve the foam wing! After two or three times coating the outer surface of the consoles vyshkurivaetsya. If done carefully, additional putty is not required. A lot of flaws — mix in 100 g of varnish parquet 30 g of talc and 3.5 g of aluminum powder and cover this part of the wing. After complete drying of the plaster is removed with sandpaper and it only remains in the grooves and sinks surface.
“Bezbolesnie” flaps also have a foam base (foam stamps SS-4-40), along the contour, they are covered with fake wood veneer 2 mm thick. don’t forget to set the root boss for levers the drive flap. Of thick (5-6 mm) Plexiglas cut sheets, plan a little more flaps, RUB “Adelinka” and place them impregnated with epoxy resin fiberglass with a thickness of 0.1 mm. was Left between them to hold the foam flap and wait for the complete polymerization of the resin.
In the manufacture of the tail without the balsa, unfortunately, not enough. The mass of the tail must be minimal, otherwise the increased moment of inertia of the model will adversely affect its flight characteristics. In severe tail pilotage will not stabilize after a run of sharp evolutions. However, it can be quite easy feathering of typing the frame is of reduced cross section to limit lime laths and sheathing his paper, but the reliability and rigidity of such a stabilizer is poor. On my model the skeleton of the stabilizer is made of balsa dams of 1.5 mm thick balsa and covered with veneer thickness of 1 mm.
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