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PERSONAL TRANSPORT: GROUND, WATER, AIR
Water jet propulsion. Personal transport
Directory / Personal transport: land, water, air Among the thousands of drawings, drawings and sketches made by the hand of the brilliant artist and engineer Leonardo da Vinci, there are many very interesting water sports equipment and devices. For swimmers, divers, so that they can swim for a long time and breathe freely, while not raising their heads out of the water, he came up with a breathing tube. The idea of flippers, peculiar gloves and stockings with elongated fingers and membranes between them, worn on the hands and feet, also belonged to him. But quite recently, researchers of the great Italian’s work discovered in the archive a sketch of a strange-looking apparatus, fixed on the swimmer’s chest. The device was fundamentally different from all of them mainly in that it was powered by the power of the legs alone and did not have fins. The sketch was shown to the engineers, they were surprised: after all, the device was supposed to work due to jet propulsion - the return of a jet of water. Usually a swimmer puts on both foot and hand fins at the same time. This allows you to increase the swimming speed by about one and a half times. But just like that, nothing in nature is given. It is known that a swimmer with fins gets tired faster. Even 500 years ago Leonardo, if he did not know, intuitively guessed about this feature. It is not by chance that on sketches with technical devices invented by him, he very often drew insects, birds, fish, marine animals, analyzing the mechanics of their flight, swimming, and movement. It is likely that the way the squid moved, which was drawn on the same sketch, suggested to him the idea of \uXNUMXb\uXNUMXban unusual apparatus.
The American engineer Robert Cunningham got acquainted with the drawings of Leonardo. Without changing the essence of the idea of the great Italian, Cunningham built the apparatus in such a way that during operation he threw out a water jet not pulsed, but continuous. He achieved this by alternating the work of not one, but two water cannons, or, more simply, ordinary piston pumps. Let's turn now to the drawings. The new water sports equipment requires not only strong legs, but also a developed sense of balance, the ability to control one's body, courage and accuracy of movements. Its base is a foam board, and under the board are two piston pumps that work in the same way as I do a bicycle pump, although they are structurally different.
Board 1 must be made of dense, fine-meshed radio-technical foam. This foam is strong enough to support two cylinders and a block bolted to it. The length, width and thickness of the board are shown in the figure. Don't forget to round the edges and corners. Belts with buckles 5, with which the board is pressed against the swimmer's belt, chest and shoulders, it is better to take ready-made, canvas ones, having previously measured their length according to your height. The situation will be more complicated with pump cylinders 2. If you cannot get thin-walled duralumin pipes of the sizes indicated in the figure, we advise you to make them yourself. To do this, cut out blanks from a sheet of duralumin 0,5-1 mm thick - cylinder reamers. Roll them into a cylinder on a wooden mandrel, or better on a steel pipe. Insert a bottom 9 into each cylinder. Secure the bottoms with countersunk screws. To make the cylinders airtight and more durable, wrap them on top with two or three layers of fiberglass, previously lubricated on one side with epoxy glue. When the glue dries, drill two holes in the bottoms: one in the center, the other closer to the edge. Insert nozzle 8 into the last hole. With the rest of the details, you will have less difficulty. You will need two more pistons 4. You can turn them on a turning flock of Teflon or textolite. Please note: the pistons are not solid, but hollow - holes must be drilled parallel to the axis for each, the purpose of which will be discussed below. Fix the pistons on short rods through which a steel cable 6 with a diameter of 1,5-2 mm passes. The middle of the cable covers block 7 twice, and its ends are passed through the holes in the cylinders and end with stirrups - foot rests. Clamp nuts hold the cable against the pistons. Each piston is equipped with a petal valve 3 having a disk made of rubber or other elastic material. The discs are attached to the rods with washers and nuts. When installing the block and cylinders on the board, do not forget to secure them with clamps 10 more securely. Otherwise, the nuts will quickly loosen, and the projectile will become naughty and rebellious in control. The device is ready. But even those who do not know how to swim can safely put it on and enter the water: after all, the volume of the foam board is taken with a margin - it will keep you on the surface. Enter waist-deep water Put the stirrups on your feet and lie down on the board. Now begin to make alternating movements back and forth with your legs in the same way as if you were climbing a ladder. If you push off with your left foot, and pull your right foot to your stomach, the right piston moves forward, the petal valve opens, the cylinder is filled with a portion of water. At this time, the left piston moves back, the valve closes, a jet of water is pushed through the nozzle, creating jet thrust. The alternating operation of the two pumps provides continuous thrust, the swimmer swims. Of course, the device will not work reliably the first time. You will have to adjust the cable tension, pick up a nozzle, because the speed of movement also depends on the diameter of the hole through which the jet escapes. But do not despair, the projectile will reward you both for good workmanship and for the first failures. Author: A.Ivanov
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