Even a child knows what a parachute is. However, not everyone can imagine just that a parachute can be used not only in the sky, but also under water. This device has been actively used by divers for more than a year. It's time to figure out why he is needed at all in the depths of the sea.
To begin with, the laws of aerodynamics and hydrodynamics are largely similar. It is on this similarity that the use of the dome for solving underwater problems is based. A parachute can be used under water both for movement and for braking movement. Divers usually use special underwater lifting parachutes in order (here's a surprise) to lift something from the bottom. Depending on the size and number of buoys used, either a metal canister or a sunken ship can be lifted. Most often, lifting parachutes are simply pumped with gas directly under the water, after which they rush upward.
In addition, braking parachutes are used underwater. They are used for the most part in submarines in evacuation systems. The fact is that the worst thing people face under water is decompression sickness. It happens when a person is suddenly lifted from a great depth. It occurs due to the vigorous release of nitrogen. In order not to be paralyzed and not to die, divers should ascend slowly and make decompression stops every 10 meters.
The problem is that an evacuation vest for a submariner does not allow a person to control the rate of ascent from great depths with the usual means. Immediately after the evacuation from the submarine, the speed of the vest can reach 56 m / s. For this, the system provides for an automatically deploying parachute at a depth of 100 meters, which slows down the ascent to 0.4 m / s. This is necessary in order to minimize the risk of decompression sickness.
Continuing the topic, there is such "Ten" knives of Soviet and Russian special forces, which are used today and not only.