WITH THE ENGINE. BUT WITHOUT FUEL

Not so long ago in the journal “modelist-Konstruktor” was published material about model aircraft with pneumatic motor. The main advantage of this engine over any other is that the fuel it is not required. Instead of the usual plastic bottle (they sell carbonated water) to the working cylinder is supplied with compressed air. To resume the supply of such fuel using a car pump or that it is more convenient and easier, portable compressor to inflate tires.

Unusual engine aroused great interest among a certain group of readers — the editors have received many letters asking to tell it about other models that can be made on the basis of such motor. Fulfilling these wishes, we offer our readers a racing car with the fuel tank a bottle and a pneumatic motor.

First a few words about the motor. As can be seen from the figure, according to the scheme, he differs little from the model internal combustion engine with cryoseparators mechanism. In its front and rear parts are the two valve — intake and exhaust. When the piston is at bottom dead center, the intake valve opens, compressed air flows through the crank chamber and pushes the plunger. The piston begins to move, and 2/3 of its stroke, the intake valve closes, and he continues the movement due to the expansion of compressed air. After passing the upper dead point the exhaust valve opens and the piston moving towards top dead center, pushes through it the exhaust air.

Learn more about the motor, its design, parts and manufacturing technology can learn from the article “In the air — pneumonet” (see “modelist-Konstruktor” No. 10 for the year 2000).

The car consists of a tank for compressed air, which is used as a-liter plastic bottle from under sparkling waters of the outer diameter of about 80 mm, aluminum frame, fiberglass fairing front part of the model, transmission of a pair of bevel gears and the front axle and four wheels.

Geometric diagram of the car with pneumatic engine

The frame of the car:

1 — the base (aluminum, sheet s4); 2 — a connecting bracket of the power unit (duralumin, sheet s4); 3 — bolts MZ (4 PCs)

The design of the car:

1 — filling nozzle (Bicycle valve with spool); 2— rubber washer; 3 — tank for compressed air (plastic bottle 1.5 litre); 4,15 — nuts M5; 5—rear axle shaft (steel, stud M5); 6 — frame (aluminum, sheet s4); 7,12 — wheel (from a child’s toy); 8 — fairing (Vileika of fiberglass and epoxy resin); 9— bolts with nuts MZ; 10 — a connecting bracket of the power unit (duralumin, sheet s4); 11 — front axle (steel Serebryanka, stud M5); 13 — engine; 14,16 — bevel gear (i = 1); 17 — mount the spur gear (cylindrical pin d1,5); 18— mount drive gear (nut M5); 19—crown “of the rider-pilot” (foam); 20— visor (transparent plastic)

Pneumatic engine working volume of 3 cm^3:

1 — MZ screw mounting back wall; 2 — crankshaft-spool (steel, rod d25); 3— washer (steel); 4 — motor housing (D16T or AK4-1T); 5 — connecting rod (D16T); 6 — piston (D16T or AK4-1T); 7 — rear wall (D16T or AK4-1T); 8 — spool (steel); 9— gasket (Teflon or hard rubber); 10 — crank pin (Serebryanka 50KHFA); 11 — washer (Teflon or textolite); 12 — element hinge (ball bearing d5,5)

Work should start with the selection of suitable containers for compressed air — you will need at least two identical bottles: one for the cylinder and the other for vyklicky it fairing of the front part of the model. In the thickened back of the bottle-of a cylinder you need to drill a hole and insert the bike valve with a spool designed for the use of the motor pump. The front of the bottle-welling cylinder engine — it is a kind of power unit.

The power unit is attached to the frame, cut and bent sheet of aluminum with a thickness of 4 mm in the front part of the frame is ensured by a connecting bracket. Rotation transmission from the engine to the front drive axle is done using bevel gears — gear ratio pairs is equal to 1. Wheel vehicle models with a diameter of about 120 mm are selected from a suitable children’s toy. It is desirable that they were with rubber tires.

The fairing of the front part of the model wikiepedia of epoxy resin and fiberglass for dummy, made using bottle twin to the one that is selected as the container. For this bottle with foam is brought to the desired shape, after which the idiot cemented clay and glued on an epoxy binder with three or four layers of fiberglass. After polymerization, the shell is removed from the boob, vyshkurivaetsya and podsalivaya, in its lower part is cut in accordance with the shape of the frame, after which the fairing will be painted with enamel of suitable color. Further the model is fixed a protective shield made of transparent plastic and the head “rider-pilot” in the helmet.

To run the model on a rope with a length of 5-8 m, and without it on any of the Playground in “unmanaged” mode. If there are several such models it is possible to arrange a race on the run, on the rate of passage of the measuring area and accuracy is marked on the track gate.

I. TEREKHOV

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