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Bicycle catamaran. Personal transport

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No, not in puddles, but in a real pond! Such an exciting task was set by Leonid Mikula from Donetsk. As a result, a unique amphibious bicycle was born, on which the inventor himself covered 5000 km by land and 2000 km along the Yenisei River in one trip.

On land, it rides like a regular bike, and all the accessories you need for swimming are carried on the rear rack or in a backpack.

When assembled, the amphibian is a catamaran. Its dimensions are 2700x1400x650 mm, and together with the bike, the height is 1300 mm. Gross weight - 25 kg, load capacity - 150 kg.

Modifying an amphibious bike is not difficult. From the bottom of the axis of the pedal drive, two steel ears are welded to the frame, to which a column with a propeller and a rudder is attached before swimming. Otherwise, the bike is no different from the usual one, and when “riding” on water, they use the same pedals and steering wheel. True, the bicycle catamaran is also able to move in reverse, while maintaining good maneuverability. The minimum turning radius on the water is very small. In practice, an amphibian can turn almost on the spot. The stability is so high that even a steep wave from a large vessel passing by will not overturn the catamaran.

Now let's take a look at the design.

Two inflatable cylindrical float cylinders with a diameter of 300 and a length of 2700 mm are sewn from rubberized nylon fabric 0,5 mm thick in the underwater part and from technical nylon with a direct weave - in the surface part. And besides, they are reinforced with sealed inflatable elements made of PVC film.

Along each cylinder, two pockets are sewn on top for attaching longitudinal beams - two for one float. They are made of dural tubes with a diameter of 25 mm. The front and rear transverse beams are attached to them with clamps - pipe segments 1300 long and 48 mm in diameter. Mountings allow the floats to slightly oscillate relative to each other during waves.

Front and rear supports are placed on said beams. In cross section, the center of the bicycle is shifted approximately 40 mm to the left relative to the center of the catamaran (see figure). This was required in order for the propeller and rudder to be located exactly in the center of the amphibian. The fact is that a large bicycle asterisk has just such a "departure" to the right. In order for the bicycle catamaran not to heel, its starboard side should be loaded a little more than the left side.

(click to enlarge)

Cycle catamaran nodes: 1 - rudder blade; 2 - multipitch screw; 3 - drive column; 4 - transverse beam; 5 - longitudinal beam; 6 - front support; 7 - cables - steering rods; 8 - clip stopper; 9 - column lifting stopper; 10 - column lifting lever; 11 - rear support; 12 - rudder stock; 13 - ladder boards; 14 - safety tray.

If the rear support provides for a rigid fastening of the bicycle frame, then the front one is more complicated. It is equipped with a sector that rotates 30 degrees both to the left and to the right, and rests on a pin that acts as the axis of the front wheel, rigidly connected to the sector and the front fork so that the axes of rotation of the latter coincide. A yoke is also rigidly fastened to the swivel sector, from the shoulders of which two swivel control cables extend.

The most complex bike catamaran assembly is the drive column. It contains a two-stage gearbox, where the first, relatively low-speed, stage is a chain drive, and the second, relatively high-speed, is a gear, bevel.

The chain drive is essentially the same as on a standard bike. A small asterisk for it is used from an old car of the same brand. The center distance of this gear is equal to the same size of the original bike. Since the large sprocket has 48 teeth and the small sprocket has 16, the gear ratio for this stage is 3.

The module of the bevel gear is 1,5 mm, the number of teeth of the gear wheel is 80, and the gear is 16. The gear ratio of the stage is 5. Thus, the total gear ratio of the cycle catamaran gearbox is 15.

So many times increases the frequency of rotation of the propeller in relation to the angular velocity of rotation of the pedals. According to the author, the screw can gain from 1200 to 1500 rpm. Scrolling one revolution of the pedal in 0,6 ... 0,75 seconds, you can achieve a speed of 7 ... 9 km / h.

Pedaling on a bicycle catamaran is somewhat different from cycling - the lack of inertia of the flywheel, the role of which in a land vehicle is played by the rear wheel, affects. Therefore, during rotation, both top and bottom dead centers are noticeable. However, the driver quickly gets used to this feature, and it does not interfere.

On his amphibian, Mikula used a ready-made propeller - the so-called multi-pitch propeller of the Chernomorets-1 type. It allows you to adjust the step depending on the conditions and thereby economically expend energy.

The catamaran rudder is mounted on the drive column. It turns with the help of its stock - a remote roller. The latter is equipped on top with a two-shoulder rocker, reminiscent of the front. Both rocker arms are connected by two cables - rods wound under the pedal carriage. They are prevented from moving sideways by ears welded to the bicycle frame. So the cables do not interfere with either the chain or the driver.

If necessary, for example in shallow water, the drive column can be raised. Lever 10 serves for this. It can be quickly used on the go, directly from the driver's seat. Through a flexible rod, the lever acts on the middle of the "breaking" V-shaped link rod, the ends of which are hinged on one side on the rear transverse beam, and on the other - on the drive column. In the intermediate position, the flexible rod can be fixed with a wedge stopper 8, and in the upper position - with a stopper 9, which is a screw protruding outward. The lever handle 10 is simply hung on it.

The stopper 8 is designed so that when the column touches the bottom of the reservoir, a slightly bent articulated rod knocks out the lever 10 from the wedge stopper and the column automatically rises. This eliminates the possibility of damage to the propeller and rudder. So you can safely approach the shore.

The steel input shaft of the gearbox (a small sprocket and a gear wheel are rigidly connected to it) is fixed in a duralumin housing using two bearings No. The input shaft bearings are located at its ends, and the output shaft bearings are located side by side. The shaft is fixed in them cantilever. All bearings and the transmission itself are protected from water by oil seals; The parts of the column casing (see the figure at the top right) are mainly made of fiberglass impregnated with epoxy resin. In addition, the author used parts made of duralumin and foam. In particular, the rudder blade is bent from a single piece of sheet duralumin 1000902 mm thick. It is riveted to a tubular stock, and the feather cavity is filled with epoxy foam. The lower end of the pen is put on the finger-thrust. From above, a square rod is inserted into the hole of a square section in the yoke (tiller) - a continuation of the stock.

For flooring, two ladder boards 13 were used, laid on both sides of the bicycle catamaran. They are fastened with clamps to the front and rear transverse beams A. In the stowed position, a springboard with a sewn-in pallet 14 made of rubberized fabric is stretched between the beams. It protects the pedal mechanism and the driver's legs from water. In addition, payloads are placed on the boards and springboard, for example, wheels removed from a bicycle, a backpack, a sleeping bag.

Author: V.Maksimov

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