Like an airplane, which is kept in the air by the wings, a helicopter takes off by means of large diameter propellers. Such a propeller is called a bearing propeller. The propeller has blades, each of which has an aerodynamic profile and moves in the air flow as the propeller rotates. As the propeller rotates, there is an aerodynamic force applied to each blade. The force of each blade is summed up and applied to the entire propeller and through it to the entire helicopter. This force is always perpendicular to the plane of rotation of the propeller. In this way the helicopter is provided with a vertical take-off.

Helicopter is commonly referred to as a rotary-wing aircraft of vertical take-off and landing, in which the lifting and driving forces at all stages of the flight are created by one or more rotors driven by one or more engines. Its main advantage is the ability to take off and land vertically – the helicopter can take off and land in any place where there is a flat area of one and a half propeller diameter.

In addition, the helicopter’s strength is maneuverability: they are capable of hovering in the air and even flying backwards. In addition, rotorcraft can carry cargo on the external suspension, even quite bulky, as well as perform assembly work. The main disadvantages common to all rotorcraft are a significantly lower flight speed and increased specific fuel consumption.

The disadvantages are an extension of the advantages.
The disadvantages of helicopters can also include the difficulty in control. Helicopters with jet-driven main rotor have sharply complicated autorotation landing, because when the engines are off, the large drag of the engine nacelles quickly slows down the rotation of the main rotor, as well as high noise and high visibility from the flares of the engines. But how high can a helicopter climb?

The French Aerospatiale SA 315B Lama, designed for the high altitude areas of India and Nepal, holds the record since 1972: 12,442 meters! However, during the flight the engine stalled and the pilot unwillingly set another record – the longest descent by helicopter in autorotation mode. And the altitude record for horizontal flight was set a year earlier on the American Sikorsky CH-54 Tarhe helicopter – 11,010 meters.