How does helicopter flight work? What is the principle of helicopter flight?

Principle:

1. The power to maintain flight comes from its constantly rotating rotors. When the main rotor blades rotate, an updraft against the air is generated, which naturally creates a lifting force. Then use the rotation speed of the rotor and the angle of each blade to change the aircraft, so that the aircraft can complete a variety of different flight actions such as take-off, lifting, and landing.

2. Flying forward is to manipulate the remote control stick to make the angle of each propeller in different positions according to a certain regularity, and the tensile force generated by the rotor leans forward relative to the rotation axis to pull forward. It's the same thing about making *** fly left or right.

3. When the flight direction changes, the basic principle is to use the variable angle of the tail rotor or generated. Because when the main rotor rotates, the body will produce torsional force, and the torsional force will make the fuselage keep rotating in circles and cannot fly normally. Therefore, a tail rotor must be added to counteract the torsion, and the balance fuselage does not rotate, but the tail rotor alone cannot be balanced, and a gyroscope needs to be used.

According to the swing of the fuselage, it will automatically compensate the server to change the angle of the tail rotor and balance the fuselage.

The principle of bamboo dragonfly is actually the same as ***, which is to use the rotation of the blades to generate lift, so as to overcome its own gravity to achieve the purpose of flight. The blades of the bamboo dragonfly are two symmetrical and angled sheets, the cross-section of the sheet is generally round-headed and pointed-tailed, the upper surface has a certain curvature, and the lower surface is generally straight, which is basically the same as the airfoil used on modern low-speed aircraft. When the blades of the bamboo dragonfly rotate, the air flow through the blades of the bamboo dragonfly will bypass the blades themselves, and because the air flow from the upper surface is longer from the lower surface (between two points, the straight-line distance is the shortest), the air flow on the upper surface is forced to move at a higher speed than the lower surface, so that the air flow converges at the tail of the blade at the same time.

In the low-velocity flow state, the higher the speed of the air flow, the lower the pressure (static pressure), which causes the pressure on the upper surface to be lower than that on the small surface, so that the pressure difference between the upper and lower surfaces is generated, which is manifested as a resultant force pointing to the upper surface on the blade, and this force is the lift force on the blade.

The flight performance of a bamboo dragonfly depends on the following:

1. The difference between lift and gravity, if the lift is less than gravity, the bamboo dragonfly cannot fly normally, which requires the blades to be as thin as possible;

2. The relationship between lift and resistance: lift increases with the increase of the angle of the blade, and the drag also increases, at a certain critical angle, the increase speed of lift is less than the increase speed of resistance, so that the size of the drag reaches an unacceptable level, that is, stall, which will seriously affect the flight performance, therefore, the angle of the bamboo dragonfly blade can not be too large, it is recommended to choose about 15 degrees;

3. The position of the center of gravity: if the position of the center of gravity is not on the geometric center line of the bamboo dragonfly, it will cause the bamboo dragonfly to fly unstable, and it is necessary to ensure the verticality between the vertical bamboo stick and the blade, otherwise it may cause the tail of the bamboo dragonfly to swing seriously when flying, and eventually lose stability and stall.

The flight principle: *** rely on the engine to drive the rotor rotation, and then the rotor rotates to produce tension, because the wing does not need to rely on the fuselage to drive the wing, so it can hover in the air. It can use the rotation speed of the rotor and the angle change of each propeller to cause the aircraft to complete various flight actions, which is also the reason why it is widely used in life.

Brief introduction.

As one of the most distinctive creations of aviation technology in the 20th century, it has greatly expanded the application range of aircraft. It is a typical dual-use product, which can be widely used in transportation, patrol, tourism, ambulance and other fields.

The maximum speed can reach more than 300km h, the diving limit speed is nearly 400km h, the practical ceiling can reach 6000 meters (the world record is 12450m), and the general range can reach about 600 800km. The transfer range of the internal and external auxiliary fuel tanks of the aircraft can reach more than 2000km.

There are different take-off weights according to different needs. The largest heavy *** currently in service in the world is the Russian Mi to 26 (with a maximum take-off weight of up to 56 tons and a payload of 20 tons). At present, the practical application is mechanically driven single-rotor and dual-rotor, of which the single rotor is the most numerous.

Principle: The engine drives the rotor to provide lift, lifting the first propeller in the air, the main engine also outputs power to the small propeller at the tail, the airborne gyroscope can detect the rotation angle and feedback to the small propeller, and the reaction force at different speeds generated by the large propeller can be offset by adjusting the pitch of the small propeller.

At the same time, after the helicopter takes off, the engine is maintained at a relatively stable speed, and the ascent and descent of the helicopter are controlled by adjusting the total pitch of the propeller to obtain different total lift, so the vertical take-off and landing are realized. Historical origin:

Bamboo dragonfly in China.

China's bamboo dragonfly and the Italian Leonardo da Vinci's sketches provide inspiration for modern inventions and point out the correct direction of thinking, and they are recognized as the starting point of the development history.

The bamboo dragonfly, also known as the flying spiral and the "Chinese spinning top", is a peculiar invention of our ancestors. Some believe that China had bamboo dragonflies as early as 400 BC, and another more conservative estimate is that it was in the Ming Dynasty (around 1400 AD). This folk toy called bamboo dragonfly has been handed down to the present.

Although modern *** is ten million times more complex than the bamboo dragonfly, its flight principle is similar to that of the bamboo dragonfly. The modern rotor is like the blade of a bamboo dragonfly, the rotor shaft is like the thin bamboo stick of the bamboo dragonfly, and the engine that drives the rotor is like the hands of the bamboo stick that we rub hard. The blades of the bamboo dragonfly are round and blunt in front and sharp in the back, with the upper surface relatively round and arched, and the lower surface relatively straight.

When the air flow passes over the upper surface of the round arch, its flow velocity is fast and the pressure is small; When the air flow passes over a straight lower surface, its flow velocity is slow and the pressure is high. As a result, a pressure difference is formed between the upper and lower surfaces, and an upward lift force is generated. When the lift force is greater than its own weight, the bamboo dragonfly will take off into the air.

The principle of the rotor generating lift is the same as that of the bamboo dragonfly.

The Encyclopædia Britannica records that this "*** toy" called "Chinese spinning top" was introduced to Europe in the middle of the 15th century, that is, before Leonardo da Vinci drew the design of *** with screw rotors.

Volume 9 of the Concise Encyclopædia Britannica reads: "*** is one of the earliest ideas of mankind to fly the mill potato, and for many years it has been believed that da Vinci was the first to propose this idea, but now it is known that the Chinese made *** toys earlier than the Europeans of the Middle Ages." ”

Painting by Leonardo da Vinci, Italy.

The Italian Leonardo da Vinci proposed the idea and sketched it in 1483.

At the end of the 19th century, an imaginary picture of Leonardo da Vinci painted in 1475 was found in the Milan Library in Italy. It is a huge spiral made of sizing linen that looks like a giant screw. It rotates with a spring as the power force, and when it reaches a certain speed, it carries the body into the air.

The driver stands on the chassis and pulls the wire rope to change the direction of flight. Westerners say that this is the earliest blueprint.