Helicopters and airplanes have a metal body, they are heavy, but somehow they can take off and move in the air without falling. The helicopter can also hover over the ground. Why doesn't it fall? It's all about the laws of aerodynamics, in accordance with which these aircraft are designed.
The air medium is not something dense and stationary so that the metal structure of the aircraft can lean on it. But it can act as an intermediary between the gravitational field of the Earth, which prevents objects from rising into the air, and these objects themselves. This is achieved in the following way: with the help of the propeller, the helicopter motor creates a zone of reduced pressure above the body, so that the air particles located under the helicopter, as it were, push it upward, forcing it to stay in the air. It turns out that the gravitational field forms an air cushion under the helicopter. The higher the aircraft rises, the less the air density becomes, as the force of gravity decreases. It would seem that the helicopter should take off with less effort, but in reality, as soon as the support on the gravitational field weakens, the ceiling of the height to which the helicopter can climb is reached. The exact same principle is used by other aircraft, including airplanes, whose wings are designed so that the air flow supports them. The engines create an area of reduced pressure, into which the aircraft moves. Even birds and insects use similar techniques when flying. They quickly flap their wings, reducing the density of air above them, rise up, and then their wings take such a position so that the air flow supports the bird, preventing it from falling. But there are also such devices that can fly in airless space, for example, rockets. How do they do it? The fact is that they contain inside themselves not only the fuel necessary for the flight, but also an oxidizing agent, without which the engine will not work. The jet stream consists of gas, from which a gas cushion is formed, allowing it to interact with the gravitational field. It is on it that the rocket rests, after which the pillow immediately dissolves in the cosmic vacuum.
