“SMARAGD” ON A CURVED COURSE

Today we want to introduce the adherents of model shipbuilding with the successful development of Czechoslovak athletes. Interestingly, they have created a small motor boat “Smaragd” is designed based on the highly successful hull of sports “train” subclass E7 (construction of which our magazine introduced to its readers in No. 5 of 1992). I hope you will be interested to know how the target pure sports car can turn into a spectacular polyopia. By the way, except for the external transformations, the new model simultaneously received and other power equipment much more affordable for the average modeller. Long-term experiments allowed the authors to find the optimal combination performance.
As in a purely sports version, most body parts are made from balsa. The use of scarce wood is justified, because at small speed model each saved gram mass of the shell can be transferred to mass energy (batteries). For those who can not find the balsa, we can recommend technology vyklicky power shell housing made of fiberglass, is well known among modellers. However, the properties of the body, the more close to the balsa, can be achieved with the available materials conventional paper or cardboard. Because balsa is very light, only by itself: most of the advantages of this wood is lost after finishing the internal and external surfaces. In the case of, for example, the use as plating pre-glued with liquid epoxy resin panels of two layers of paper of average quality you get from the material is not only water resistant (resin impregnates the paper through), but are ready for painting without additional putty and sanding. Not only saves weight, but also dramatically reduces the complexity of the model as a whole. However, similar advantages have and fibreglass body. However Vilana technology is very demanding on the professionalism and experience of using it, and make full advantages of fiberglass are manifested only when high precision compliance of the subtleties of the processes (which, unfortunately, in the practice of modeling the average level is almost impossible).
 
Based on the foregoing, when reading the recommendations for the production of model boats you will be able to make their own adjustments on the materials used. We give the original description zelenoborskoe option.
 
The housing is assembled on a flat Board bench on the classic version of the “keel up”. Frames one through five and fore end are cut from regular plywood with thickness 2.5 mm. the Frames connect to the keel rail cross section 2×6 mm and four stringers cross-section of 4×4 mm (pine). Between the frames 2 and 3 are also spacers of strips 3×3 mm. the nasal cavity of the housing until the fourth frame is filled with foam. Finished the frame body is sheathed with sheet balsa 2 mm thick. Outer surface of the plating is polished, and the whole interior, including parts of the carcass, after removal of the housing from the slipway covered by a two-component synthetic varnish. At the upper edge of the sides is glued on the casing rail (RUB rail) section of 2×4 mm.
In the bottom with maximum precision drilled and then are adjusted to exactly the right size holes for stern tubes and pipes bearings stock. After the control of placing on the model of the propeller shaft with stern tube in the hull and put the motor to check the alignment of rotating parts. The motor is easiest to fix using a wooden cube-cradle, glued to the bottom of the hull, and two poltroncina ties are cut and bent from sheet brass with a thickness of 0.8 mm. Together, these parts are compressed by four screws as shown in the figure.
 
After checking the ease of rotation of the shaft power plant of a stern tube sealed in the casing, rack spacers and frames also put glue on the bottom of the compartment out of plywood with a thickness of 1.5 mm, and the entire deck surface is sheathed with balsa with thickness of 2 mm. While the inside of the hull should remain uncovered only the side wall of the compartment, and the deck — window approach to internal volumes indicated on the drawings by the letter “a”. The outline of this window is framed with overhead outside rails cross-section of 4×4 mm.
 
The superstructure is glued of the front and rear walls, bulkheads, windshield frame, rear frame (all these parts are sawed out of plywood with a thickness of 2.5 mm) and the horizontal panels with the sidewalls of the cutting (plywood 1 mm). Openings in the front and rear frames serve for cooling strongly heated power resistors.
 
When working it is better to adhere to the following order. First wall of the dock with pine stringers with a cross section of 3×3 mm, resulting in a frame, which tightly clasp the fitting framing for the deck opening of the housing. Then glued the side supports and all other parts of the superstructure. With careful work all felling during drive models reliably held in place only by friction and additional fixing is not needed. The joints between the sidewalls and horizontal elements is helpful to reinforce the slats with the cross-section 3×3 mm. the Side window openings on the bridge after varnishing and painting are covered on the inside with plastic tracing paper is of medium thickness.
 
Small scale details of the model, the boat is easy to carry, plastic, wire Ø 1 mm and thick sheet. Imitation cleats well get aluminum rivets.
 
The basis of the power plant is a powerful electric motor (60 W), the rotating propeller with a diameter of about 30 mm. of Course, this is not the only solution, but in the specific case, the choice of engine may be very different from the one proposed. The same applies to the power source of the motor, which on the original is composed of four Nickel-cadmium “AA” batteries with a capacity of 1.2 A-h. the Author recommends to equip the control system with engine speed discrete two-stage switch with reverse polarity, a well-known engaged in radio-controlled boat. Included in the switch resistance is 4.7 Ohms (10-watt) are included in the scheme of parallel pairs. The author does not recommend to include in the switch resistance values of less than 3.3 Ω, as due to the high supply currents of the motor and overheating of the resistances themselves there is a threat of fire on the model. If possible it is better to equip the boat with electronic speed controller with variable characteristics. In the proposed variant of the plant the time course of the model at full speed is approximately 10-13 minutes.
 
Regarding design: the case itself is covered with trains and sports “train” (it is possible to apply additional tinting “marine” varnish) and painted white cabin complemented by a black strip around the edge of the junction with the deck. Minor elements of the model and its trim is also black.

 
From the editor. Of course, the RC version polyopia speed boats is the most attractive. However, in the absence of the control apparatus of the model can nicely serve young athletes. Low weight housing with efficient planing hull will provide high speed and accuracy retention rate difficult to increase due to the dismantling of the keel plate. By the way, the lack of equipment and regulators of course will dramatically reduce launch mass of microcamera, so it will be very fast at low engine power (at the same time it will allow you to browse for available dry batteries).
R / C model boats with electric drive on the basis of the case sports model
RC model boats electric based on body sport model:
1 — rear steak add-in, 2 — bulkhead auxiliary, 3 — main bulkhead, 4 — the bottom compartment, 5 — rear deck part of the superstructure, 6 — rear frame, 7 — roof, 8 — front frame, 9 — front deck part, 10 — front side, 11 — a fore end, 12 — side panel of the cabin. 13 — spacer Reiki compartment, 14 — stern tube, 15 — wooden wedge strengthen the junction of shaft tube with the shell plating.
In the model view and the side shell plating is not shown.

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