Beginners learn how to swing diving duck fins.

The flippers are the product of bionics. In the long-term practice of water sports, human beings made flippers by imitating duck flippers, frog flippers and fishtail wings. Jet fin is a classic of traditional fin. This flipper was first designed and manufactured by the French company Beuchat, and was patented for the first time on April 25th, 1962. During the period of 1964-1965, the French company Beuchat sold this patent to the American company SCUBAPRO. Since then, jet fin flippers have been widely used in commercial diving and military diving all over the world, and have been popular for nearly half a century. The basic design has not changed and has been used ever since. It can be seen from the appearance that the webbed surface of Jetfin flippers is very wide, extending from thick to thin. When the flippers kick up and down, the wide front along the moving direction will produce huge wave-making resistance, and the wide back along the moving direction will produce corresponding eddy current resistance. These two resistances will consume most of the diver's physical strength. Judging from the movement direction and reaction force of the water flow, when the flippers are kicked down, most of the water flows downward, and its reaction force is 180 with the direction of the water flow, which not only produces upward thrust, but also a small part of the water flows backward along the upturned edge of the flippers, resulting in forward thrust. Therefore, the trailing edge of this flipper can be called edge effect surface or dynamic surface. To put it simply, the diver's physical strength is mainly spent on swinging the flippers up and down, and some forward thrust will be generated in the process of swinging the flippers up and down. Although this part of the forward thrust is very small, it is exactly what we need. In practical application, the experience of new students learning snorkeling can best illustrate this problem. When freshmen float on the water and kick their flippers up and down, they first feel that their feet are floating up, not moving forward, so the swing range is very small and they walk slowly. Only when the diver holds his head high and overcomes the upward thrust generated by the flippers, it is possible to increase the swing range and improve the forward speed. This shows that when swinging up and down, the upward thrust generated by this flipper is much greater than the forward thrust. Frog kick does not kick water like a frog, but separates the flippers to the left and right at an angle of about 40 degrees and then clamps them together. What happens at this time is completely different from when it swings up and down. First of all, the flippers move along the narrowest edges on the left and right sides, which avoids the wave-making resistance and eddy current resistance caused by the wide front moving against the current. In addition, opening and closing the water clamp at a certain angle actually takes the whole fin surface as the power surface, so that the direction of water flow generated during clamping is backward, and its reaction force is just the forward thrust. Frog kick effectively eliminates the resistance surface and increases the strength surface. How can such a kicking method not be easy and inefficient? It is for this reason that jet fin flippers are favored by professional divers and have been used ever since. In fact, all these professional divers are proud of their beautiful breaststroke. It is really a wonderful enjoyment to enjoy their relaxed and beautiful swimming in the water.