“ASIMMETRIK” COMES FIRST

“Unsportsmanlike! It is helpful to build models, not to bring equipment adult athletes! Not to allow for competition!” These indignant exclamations addressed to our children when they first presented their new microglossary in on a meeting of young modelers. We were convinced opponents and judges that the lightest devices built by the hands of boys, and not only built, but also well-designed by our sportsmen-beginners. Talked about how it was created, the new design scheme, how to construct the model. Gradually distrust, squishie in the eyes of the “enemy”, beginning to be replaced by sincere interest. But honestly, we left with the impression that to fully dispel doubts rivals failed. Especially after it started, when our gliders come with speed only slightly inferior to the results experienced athletes. And this is without the resonance of the exhaust pipes!

What kind of models caused such an unexpected reaction, what innovations inherent in their design? I hope you will be interested to know about it. And most importantly — that the story of the creation of a successful aerolister will help to make yet another step in the development of models of class B1, to design faster (and thus simple and technological) designs.
 
First of all, that led us to new solutions. In the circle a lot of guys do popular among young athletes class B1. Almost everyone is familiar with the basics of constructing aerovision; to thoroughly understand the issues of Aero – and hydrodynamics helped the article by A. Tupikin, published in “M-K” No. 3 in 1983. It described the direct dependence of the aerodynamic drag of the total surface of the model, called the “wetted”. Of course, we wanted to go towards the maximum “compression” of all elements. But here and there were the greatest difficulties. Balsa we have on the model had to be hollowed out lime. What do you think of the thickness of the shell wall can really provide the hands of a boy? In the best case 1,5 mm. Yes, if the individual craftsmen and managed to bring it to 0.5 mm, it would still be pointless: the body would be extremely non-rigid and fragile. But lip thickness of 0.5 mm corresponds to the weight of the balsa wall thickness of 2-3 mm, used on the best models. We have the same fake “pipe” meter length was so heavy that I had to increase the displacement: the airboat with the engine off is required to stay afloat. The increase in displacement caused the growth of volume of the shell, its outer surface and… the Chain is closed — the mass went on. The boys could only dream about first-class machines, weighing 400-500 g.
When at the next session of the circle through the saws screeching came a painfully familiar situation: “if I had balsa, looks like a model I built!”, decided to try my luck at neighbors model airplanes. They somehow believe that without the balsa, you don’t live, and by some miracle manage to get a crop of timber. And then we were lucky. Balsa, of course, we were not given, but we saw a great Tierney model. However, it turned out to be a lot of excess. The wings, stabilizer, keel, the entire bow, the engine But the tail boom of the fuselage! It turned out, the aviators worked and started the production of these beams, completely unaware that they are actually a great case for aerovision. Perfectly smooth, polished fiberglass pipe-cone of a suitable size (Ø 45 — Ø 16 mm, L = 1000 mm) had a mass of only 42 grams) And the strength and stiffness of the beam is beyond praise.
 
Fig. 1. Cord speed sudomodel with a propeller
 
Fig. 1. Cord speed sudomodel with a propeller:
 
1 — sole nasal redan, 2 — body, 3 — fairing plant, 4 — pole, 5 — feed redan, 6 — console stabilizer attachment points for the rear shoulder of the bridle, 7 — stabilizer, 8 — float, 9 — front bracket front shoulder of the bridle, 10 — bonnet, 11 — Kok.

 
Fig. 2. The design of the pylon
 
Fig. 2. The design of the pylon:
 
1 — housing (GRP), 2 — supporting planks (Linden), 3 — the front edge (birch), 4 — longitudinal elements (birch), 5 — window for mounting fuel tank, 6— filler (foam stamps PHV), 7—keevon the junction of the plywood sheathing (sheets of plywood to drive away “on us”), 8—sheathing (plywood), 9—frame (foam stamps PVC), 10—tube insert (aluminum), 11 — lining (plywood).

 
It’s hard to describe what was happening when we returned to his club (I think, to say that the pipe of course, we beg, do not). Ideas fell one after another. Now had a sense of ease and “compressing” all the glider, you can take up the construction for an apparatus) in a couple of days finally* the decision was made, all nodes are traced. And that’s what happened.
 
Body — weight tubular workpiece after cutting it at the ends equal to 36 g. the thickness of the fiberglass walls is 0.3 mm. the Displacement hull of about 520 cm3. With the front broad side of the tube sealed slightly curved steklopaketov plate 0.5 mm thick, joint-fairing is made with a mixture of epoxy resin with sawdust, after curing it is given a fidelity form. The aft end of the closed tube with lime, allowing you to securely attach the stabilizer. Back redan represents a dural plate 0.3 mm thick, installed on the housing using a small wooden bracket-fairing.
 
Stabilizer as easy as possible. Instead of the conventional wood or aluminum, we used the aviation version with the bearing shell, backed by foam filler. However, for its production need to make a small basic bar, but the weight of the stabilizer it is possible to reduce in two times compared with the solid wood with the same strength. Filler — foam stamps SS-4-40, upholstery — birch veneer with a thickness of 0.5 mm. After the imposition of veneer filler on epoxy glue forms a closed design in which a Central non-working layers of wood replaced lightest foam. At the ends of the stabilizer sealed rib for mounting the float and the headstock of the bridle.
 
The float is similar to the case for its production may be approached front a scrap of fiberglass beams. The sole of the float and feed a slice — flat plate fiberglass, pre-shaped on the glass. Its thickness is 0.3 mm. Before sewing the soles in the junction of the stabilizer with float inside first unit last small plates of mm plywood or the area is filled with foam.
 
Pylon-engine mount unconventional designs. In their power scheme it is similar to the stabilizer, which gives a considerable gain in weight. The only difference in materials and shape. Sheathing— plywood with a thickness of 1.2 mm, a filler is Styrofoam brand PVC. Boss, the leading edge and trailing frame ribs sawn from birch. The bulkheads of the hull and lining are securely reinforce the junction of the pylon with a fiberglass tube and the tube near the slit under the pylon are cut from foam and lime.
 
Engine brand CSTOM-2.5 K. You’re lucky a new scheme for mounting the motor. Due to its possible to save a lot of weight, but 20-25% decrease midsection of the plant. The engine is mounted on the pole using a small dural corners, privernutyh to the rear of the crankcase extra long screws. Regiments of corners swaged plate of the pylon in which the sealed aluminum tubular lugs. Regular legs are cut crankcase, cylinder head and the crankcase can be filed so that the overall width of the motor becomes equal to 26-27 mm.
 
The force of the engine was conducted, only clarified the timing and the volume of the combustion chamber. In addition, before running the new motor made a “cosmetic” surgery. Recommend any engines, with the exception only of KMD-2,5, to start with them. As a rule, all Windows have casings after hardening and grinding, are significant leslieanne burrs with a length of 2 mm. Often when you run they fall off, leading the pair into complete disrepair. Remove burrs better thin abrasive bar. Not less damage, it can be detached from the crankshaft or the sleeve scale. Remove this firm abrasiveness “coverage” sandpaper. Particularly close to attention to the processing cavity, the distribution channel of the crankshaft.
 
The engine and close the tank with a light hood, laminated of fiberglass on the foam disc. Pole it is closed up tightly, the upper part is cut off to form a lid, in the sides of the bonnet are vents approach to the lower screw of mounting the motor. In the cover cut two small Windows under the tides of Carter. With careful execution vyklicky width may be reduced to 29-30 mm., a Significant reduction in noise is achieved with extra tail fairing, shown in a General form of the model as a dotted line. It should fit to dock with the main hood. In this embodiment, it is useful to divide the volume of the silencer and the cooling channel of the thin bulkheads.
In conclusion, I want to say a few words about the scheme the glider. The displacement of the axis of the propeller and the whole plant to the left from the axis of the body gave the opportunity to return to widespread earlier odnopetlewoj design. Despite the undisputed win in mass and aerodynamic resistance, the athletes refused it because of unstable motion of the model asymmetric schemes during acceleration. Our lightest boat starts easy, after the engine has sunken cord thread not reverses the model. Reliable starting is ensured by the modern system of suspension of the bridle. The front node is moved nose almost on the center of gravity, and now even asymmetrical the glider does not deploy in a circle with moving have not stretched cords and water. With the rear shoulder of the bridle is weakened, the model is slightly shifted to the front. Useful can be small steering surface is located on the bottom for melting and unfolding the apparatus to the left. After exiting the glider on re-press the wheel does not generate extra resistance as the float moves away completely from the water. For this, he raised unusually high above the level of the main redan. Useful and occurs when the engine idle roll to the left.
 
Fig. 3. The fastening parts on the rear of the modified engine.
 
Fig. 3. The fastening parts on the rear of the modified engine.
 
Fig. 4. The design of the aft model
 
Fig. 4. The design of the aft model:
 
1 — housing (GRP), 2 — tube (Linden), 3 — a bracket aft of the redan (Linden), 4 — feed redan (aluminum), 5 — trim (birch veneer), 6 — filler (foam stamps SS-4-40 or packing), 7 — reinforced rib (Linden), 8 — float (glass), 9 — a lug (foam).

 
Fig. 5. Templates for the manufacture of a propeller.
 
Fig. 5. Templates for the manufacture of a propeller.
 
Those who are going to build such a device under a less powerful motor, can be recommended to move the pylon with the engine, and therefore the center of gravity forward. The fact is that the proposed model santaana for a significant thrust of the screw, otherwise it can not tear away from the water by the tail.
 
And finally, about our plans for the future. Aerolizer created the base of the tail beam of the timer model, fully met our expectations. Now we are going to improve them. How? First of all, by practicing the shape of the hull. Getting rid of unnecessary displacement can significantly decrease the value of the full external surface of the device and its resistance. Immediately reduced the weight of the body. Hence the ability to “compress” bow rednow part, totally unsatisfactory from the point of view of aerodynamics, and to make narrower the redan “clinging” to the water. The transfer of node attachment of the bridle from the nose to the pylon almost completely unloaded I-beam-frame from the tremendous centrifugal load of a massive plant, so its diameter fiberglass vyklicky can be reduced fearlessly. Especially after the transition from glass cloth backing to carbon fiber.
 
So we managed to get out of the design closed-loop “deadlock”. I hope that the future model of class B1, called the boys “Asymmetrical” not fully exhausted its possibilities.
 
WEIGHT DATA MODEL
 
Case ……. 43 g
Stabilizer 8 g
Float…… 11 g
Engine with air
screw and parts . . 158 g
Pylon fairing 43 g
The attachment point of the bridle . 9 g
The exterior finish . . . 22 g
Fuel tank . . 18 g
The model Assembly . . . 312 g

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