Who knows the characteristics and uses of hot air balloons, helicopters, airships, fighters and space shuttles?

Helicopter is a kind of airplane, its biggest feature is to provide upward lift with one or more large horizontally rotating rotors. Helicopters can take off and land vertically, stay still (hover) in mid-air or fly upside down, which makes helicopters show their talents on many occasions. The excellent anti-tank capability of helicopters is an indispensable part of modern warfare. The disadvantages of helicopter are high rotor resistance, low speed, high fuel consumption, short range, large radar reflection area in wartime, and easy to be attacked by ground individual combat weapons.

Flight principle

The flight buoyancy of ordinary fixed-wing aircraft comes from the wings fixed on the fuselage. When a fixed-wing aircraft flies forward, the relative motion between the wing and the air produces upward buoyancy. The buoyancy of helicopters also comes from the same principle; But the wings on the helicopter are not fixed on the plane, as the plane advances; But rotating at the top of the machine. So the "propeller" on a helicopter is actually a rotating wing, and the correct name is "rotor". When the rotor provides buoyancy, it will also make the aircraft and the rotor rotate in the opposite direction, which must be balanced by opposite forces. Most practices are to use a small propeller or fan to push in the opposite direction at the tail wing, and some new helicopters rely on the tail wing to blow out air, which is balanced by the thrust generated by the wall-attached effect. The advantage is that the noise is greatly reduced, at the same time, the possibility of damage to the tail propeller is avoided, and the safety of the aircraft is improved. Some large helicopters use rotors rotating in different directions to counteract each other's rotating forces on the fuselage.

history

Humans have longed for free flight since history. Ancient fairy tales tell the early dream of flying. The dream way of flying is to fly in situ. Like modern helicopters, it can fly freely, hover in the air and land at will. For example, the flying carpet of Arabs and the chariots of Greek gods are all vertical take-off and landing planes. However, they only exist in fairy tales. At that time, the level of technology was too low to build a manned plane. It can be said that it was the fantasy period of human flight. Even in the fantasy period, the basic concept of helicopter still came into being, which embodies the principle of modern helicopter. The most valuable and representative are the ancient toy "Bamboo Dragonfly" in China and the Italian Da Da? Finch's painting

Detailed records of bamboo dragonflies can be found in the Jin Dynasty (AD 265-420'). Ge Hong wrote Bao Puzi. It uses the aerodynamic force of propeller to achieve vertical lift, demonstrating the basic working principle of modern helicopter rotor. The ninth volume of The Concise Encyclopedia of Britain wrote: "Helicopter is one of the earliest flying ideas of human beings. For many years, people have always thought that Dada first put forward this idea. Finch, but now we all know that China made helicopter toys earlier than medieval Europeans. " This kind of toy was introduced to Europe in the14th century, which brought the creation of China people. Europeans study and develop it as an airplane. "

George, the father of British Airways? Kelly (1773- 1857) once made several bamboo dragonflies, which were driven by clockwork and flew at a height of 27m. With the development of productivity and the progress of human civilization, the history of helicopter development has entered the exploration period from the fantasy period. After industrial revolution in europe, the mechanical industry rose rapidly, especially the development of automobiles and ships at the beginning of this century, which prepared engines and propellers for airplanes. After brave and arduous creation and experiments by aviation pioneers, the fixed-wing aircraft created by Wright brothers in 1903 successfully took off. During this period, although he made a lot of hardships and efforts in developing helicopters, due to the complex technology and poor engine performance, his successful flight was more than 30 years later than that of the aircraft.

The early 20th century was the exploration period of helicopter development, and many experimental models came out one after another. The diversity of testing machine schemes shows that the technology is still in the exploration stage. After years of practice, these schemes only have tandem type and * * * axis double-rotor type, which are still in use today. The twin-propeller series scheme did not continue in the helicopter family, but it was inherited and developed in the tilt rotor/wing vertical take-off and landing aircraft.

Yulyev, a Russian, found another shortcut, put forward a design scheme of balancing rotor reaction torque with tail rotor, and made a testing machine at 19 12. This single-rotor helicopter with tail rotor has become the most popular form so far, accounting for more than 95% of the total number of helicopters in the world.

After hard exploration in the early 20th century, it has accumulated valuable experience for the development of helicopters and made remarkable progress. Several testing machines have achieved short-term vertical lift-off and short-distance flight, but there is still a long way to go.

With the development of aircraft industry, the performance of aero-engine has been improved rapidly, which provides important conditions for the success of helicopters. The first breakthrough of rotor technology was attributed to the Spaniard Ciervao, who invented the rotorcraft by replacing the wing with a self-rotating rotor in order to create a "stall-free" aircraft and solve the safety problem of fixed-wing aircraft. The successful application and development of rotor technology in rotorcraft provides another important condition for the birth of helicopter.

1August 907, Frenchman Paul? Kearney developed a full-scale manned helicopter, which was successfully tested in June of the same year 165438+ 10/3. This helicopter is called "the first human helicopter". 1938, Hannah Reich, a young German, flew a twin-rotor helicopter and gave a perfect flight show at the Berlin Stadium. This helicopter is considered by the helicopter industry to be the first successful helicopter in the world. 1936, after improving the early helicopters in many ways, Fokker Company of Germany publicly demonstrated its own FW-6 1 helicopter. 1 year later, this helicopter created many world records.

1939 Spring, Igor, USA? Sikorsky completed all the design work of VS-300 helicopter and built a prototype in the summer of the same year. This single-rotor helicopter configuration with tail rotor has become the most common helicopter configuration at present.

In the 1940s, Walter Sikorsky Company of the United States developed a two-seat light helicopter R-4. It is a mass-produced 1 helicopter in the world and the first military helicopter used by the US Army Air Force, Navy, Coast Guard, British Air Force and Navy. The company numbers of this machine are VS-3 16 and VS-3 16A. The number of the US Army Air Force is R-4, and the number of the US Navy and Coast Guard is HNS- 1. The British Air Force named it "syrphid fly" 1(Hoverfly 1), and the British Navy named it "gadfly".

By the end of 1930s, France, Germany, the United States, and the Soviet Union all had successful helicopter test flights, which quickly improved to a practical level. The military demand of World War II accelerated this process, which prompted the development of helicopters to enter the practical period from the exploration period, and helicopters began to be put into production lines. By the end of World War II, German factories had produced more than 30 helicopters, and the United States delivered more than 400 R5 and R6 helicopters.

In the second half of the 20th century, helicopters entered the practical period of aviation, and the application fields of helicopters continued to expand and the number increased rapidly. Up to now, tens of thousands of helicopters have served various sectors of the national economy and the military field. Up to today, with the unremitting efforts of 100 years, the helicopter technology has been continuously broken through, improving the application efficiency and flight performance, thus being more suitable for the expansion of uses and gradually maturing in technology.

In 1990s, the development of helicopters entered a new stage, and an armed reconnaissance helicopter with stealth design integrating vision, acoustics, infrared and radar appeared. Typical models are: American RAH-66 and S-92, international cooperation Tiger, NH90 and EH 10 1 etc. These new helicopters are also called the fourth generation helicopters. During this period, the helicopter adopted advanced digital control system and automatic engine monitoring system, which were integrated with the onboard computer management system. Its important features are the adoption of advanced stabilization and control devices, the replacement of conventional control systems by telex and optical control, and the adoption of highly integrated electronic equipment. Computer technology, information technology and intelligent technology. At the same time, helicopter electronic equipment is developing towards high integration. Advanced strapdown inertial navigation, satellite navigation equipment and integrated navigation technology, advanced communication, identification and information transmission equipment, advanced fire control equipment such as target identification, aiming and weapon launching, and advanced electronic countermeasures equipment all adopt bus information transmission and data fusion technology, and are developing towards sensor fusion. The onboard electronics, fire control and flight control systems are connected through redundant digital data buses to realize information sharing. Adopt multifunctional integrated display technology. A small number of multifunctional displays are used to replace a large number of single instruments, and the flight information of helicopters is displayed through keyboard control. Information such as communication, navigation, flight control, friend-or-foe identification, electronic countermeasures, system monitoring and weapon fire control is integrated by the central computer. The use of this advanced integrated electronic equipment greatly simplifies the layout of the helicopter cockpit and instrument panel, simplifies the system components and greatly reduces the weight. More importantly, it greatly reduces the workload of pilots and improves the quality and performance of helicopters.

classify

Single rotor tail rotor helicopter

The most common helicopter, the horizontal rotor is responsible for providing the lift of the aircraft, and the small vertical propeller at the tail is responsible for offsetting the reaction force of the rotor. Representative models: Mi -26 transport helicopter developed by Miri Design Bureau of the Soviet Union and AH-64 armed helicopter developed by McDonnell Douglas Company of the United States.

Single rotor tailless helicopter

The horizontal rotor is responsible for providing the lift and tail blowing of the aircraft, and the thrust generated by the wall-attached effect is used to offset the reaction force of the rotor. Representative model: MH-6 helicopter produced by McDonnell Douglas.

Twin-rotor helicopter

tandem type

The two rotors are arranged longitudinally in front and back and rotate in opposite directions, which is common in large transport helicopters. Representative model: CH-47 Chinook transport helicopter manufactured by Boeing Company of the United States.

* * * Axis type

The two rotors are arranged on the same shaft up and down, and there is no tail rotor. The advantage is good stability, but the technology is complex, so it is rare. Representative model: Ka -50 helicopter gunship developed by Kamov Design Bureau of Soviet Union.

Side rotor helicopter

Also known as tilt-rotor helicopter, it is a hybrid technology helicopter, which combines the characteristics of fixed-wing aircraft and helicopters. When we take off, we use parallel twin rotors. In flight, the rotor rotates 90 degrees forward to become two real propellers, flying according to the mode of ordinary fixed-wing aircraft. The advantage of this method is that it can reduce flight resistance and improve flight speed, which can exceed 600 km/h at the highest. At the same time, it can save fuel and improve the voyage. Disadvantages are complex structure and high failure rate, which are extremely rare. Representative model: V-22 transport helicopter jointly manufactured by American Bell Company and Boeing Company.

WMJ 007 completed.

(A brief history of helicopter development.

Bamboo Dragonflies in China

Bamboo Dragonflies and Italians in China? Finch's helicopter sketches provided inspiration for the invention of modern helicopters and pointed out the correct thinking direction. They are recognized as the starting point of the history of helicopter development.

Bamboo dragonfly, also known as flying snail and "China gyro", is a strange invention of our ancestors. Some people think that there were bamboo dragonflies in China in 400 BC, and another conservative estimate is that it was in the Ming Dynasty (AD 1400). This kind of folk toy called bamboo dragonfly has been passed down to this day.

Although modern helicopters are thousands of times more complicated than bamboo dragonflies, their flight principles are similar to those of bamboo dragonflies. The rotor of a modern helicopter is like the blade of a bamboo dragonfly. The rotor shaft is like a thin bamboo pole of a bamboo dragonfly, and the engine that drives the rotor is like a hand that rubs the bamboo pole hard. The leaves of bamboo dragonfly are blunt at the front and sharp at the back, and the upper surface is relatively round and the lower surface is relatively straight. When the airflow passes through the upper surface of the circular arch, the speed is fast and the pressure is small; When the airflow passes through the flat lower surface, its velocity is slow and its pressure is high. Therefore, a pressure difference is formed between the upper surface and the lower surface, and an upward lift force is generated. When the lift is greater than its own weight, the bamboo dragonfly will fly. Helicopter rotors generate lift for the same reason as bamboo dragonflies.

Encyclopedia Britannica records that this kind of "helicopter toy" called "China Gyro" was built in the middle of15th century, that is, in Da? Before Finch drew the helicopter design with propeller rotor, it had been introduced to Europe.

The ninth volume of The Concise Encyclopedia of Britain wrote: "Helicopter is one of the earliest flying ideas of human beings. For many years, people have always thought that Dada first put forward this idea. Finch, but now we all know that China made helicopter toys earlier than medieval Europeans. "

A painting by Leonardo da Vinci in Italy

Italian Leonardo da Vinci put forward the idea of helicopter in 1483 and drew a sketch.

At the end of 19, an imaginary picture of a helicopter drawn by Leonardo da Vinci in 1475 was found in Milan Library, Italy. This is a huge spiral body, made of pulped linen, which looks like a huge screw. It is powered by a spring, and when it reaches a certain speed, it will take the body into the air. The driver stands on the chassis and pulls the wire rope to change the flight direction. Westerners say this is the earliest blueprint for helicopter design.

Man's first helicopter

1August 907, Frenchman Paul? Kearney developed a full-scale manned helicopter, which was successfully tested in June of the same year 165438+ 10/3. This helicopter is called "the first human helicopter". The helicopter named "Flying Bicycle" not only left the ground 0.3 meters by its own power, but also flew vertically for 20 seconds, realizing free flight.

Paul. The helicopter developed by Kearney Company has two rotors, the main structure is a V-shaped steel pipe, and the fuselage is composed of a V-shaped steel pipe and six star-shaped blades, which are reinforced with steel cables to increase the rigidity of the frame structure. The 24 horsepower Antainette engine and the operator seat are installed in the middle of the V-shaped frame. The fuselage is 6.20 meters long and weighs 260 kilograms. A pair of rotors with a diameter of 6 meters are installed at both ends of the V-shaped frame, and each rotor has two blades.

The world's first helicopter with a successful test flight.

1938, Hannah Reich, a German girl, performed a perfect flight show in Berlin Stadium with a twin-rotor helicopter. This helicopter is considered by the helicopter industry to be the first successful helicopter in the world.

1936, after improving the early helicopters in many ways, Fokker Company of Germany publicly demonstrated its own FW-6 1 helicopter. 1 year later, this helicopter created many world records. This is a large twin-rotor tandem helicopter with a fuselage similar to that of a fixed-wing aircraft, but without a fixed wing. Its two rotors are supported on the upper right and left by two groups of thick metal frames respectively, and the two rotors are horizontally installed on the top of the bracket. The plane shape of the blade is sharp, and it is connected with the hub through flapping hinge and dragging hinge. The automatic tilter is used to tilt the rotor rotation plane for longitudinal control, and the yaw control is realized by tilting the two rotors in different directions. The total pitch of rotor blades is fixed, and the rotor tension is changed by changing the rotor speed. Use rudder and horizontal tail to increase stability. FW6 1 Rotor hub is equipped with a periodic pitch changing device, which can change the blade pitch during the rotor rotation. There is also a pitch control lever, which can change the inclination of the rotor surface and realize the flight direction control. FW6 1 ensures its maneuvering flight through this set of periodic range-changing devices and joysticks. The diameter of the rotor of the plane is 7 meters. The power unit is a piston engine with power 140 horsepower. This is the first helicopter with normal maneuverability in the world. The speed of the aircraft is 100 ~ 120km, the range is 200km, and the takeoff weight is 953kg.

The first practical helicopter

1939 Spring, Igor, USA? Sikorsky completed all the design work of VS-300 helicopter and built a prototype in the summer of the same year. This is a single-rotor helicopter with a tail rotor. Equipped with a three-blade rotor with a diameter of 8.5m and a Shuang Ye tail rotor. Its fuselage is welded steel pipe structure, and the transmission device consists of V belt and gear. The landing gear is rear three-point, and the cockpit is fully open. The power plant is an air-cooled engine with four cylinders and 75 horsepower. This single-rotor helicopter configuration with tail rotor has become the most common helicopter configuration at present.

Since the first tethered flight, Sikorsky has continuously improved the VS-300 and gradually increased the engine power. 1940 On May 13, VS-300 made its first free flight, when a 90-horsepower Franklin engine was installed.

The world's first helicopter put into mass production.

R-4 is a two-seat light helicopter developed by Walter Sikorsky Company in the 1940s. It is a 1 helicopter put into mass production in the world, and it is also the first military helicopter used by the US Army Air Force, Navy, Coast Guard, British Air Force and Navy.

The company numbers of this machine are VS-3 16 and VS-3 16A. The number of the US Army Air Force is R-4, and the number of the US Navy and Coast Guard is HNS- 1. The British Air Force named it "syrphid fly" 1(Hoverfly 1), and the British Navy named it "gadfly".

Early piston engines and wooden paddle helicopters

From the 1940s to the mid-1950s, it was the first stage of the development of practical helicopters. Typical aircraft types in this period are: S-5 1, S-55/H- 19, Bell 47; Soviet Mi -4 and Ka-18; Bristol, England-171; Czech HC-2 and so on. Helicopters in this period can be called the first generation helicopters.

Bell 47 is a single-engine light helicopter developed by American Bell Helicopter Company. The development work started at 194 1, and the testing machine bell 30 started at 1943. It was renamed as Bell 47, 1945, and obtained the airworthiness certificate of CAA on March 8, 2006. The machine is a seesaw rotor, single rotor and tail rotor layout, with two blades. There is a stabilizer bar under the rotor, which is at right angles to the blades. Ordinary automatic turning machine can operate the change of total pitch and periodic pitch. All-metal tail rotor with two blades at the back of the tail beam.

Ka-18 is a single-engine dual-rotor light multi-purpose helicopter designed by Kamov Design Bureau of the Soviet Union. /kloc-0 made its first flight in mid-1957, and put it into mass production shortly thereafter. Two pairs of three-blade axial flow rotors with opposite rotating directions are adopted, and the blades are made of wood. Install 1 9-cylinder star piston engine with 275 horsepower. The fuselage is welded steel pipe structure, light metal skin and hard shell tail beam. The cockpit can accommodate 1 pilot and 3 passengers. With four-wheel landing gear, the front landing gear wheel can rotate freely.

The helicopter at this stage has the following characteristics: the power source is a piston engine, with low power, low specific power (about 1.3 kW/kg) and low specific capacity (about 247.5 kg/m3). The life of rotor blades with wood or steel-wood mixed structure is short, about 600 flight hours. The airfoil of the blade is symmetrical, the tip is rectangular, and the aerodynamic efficiency is low. The rotor lift-drag ratio is about 6.8, and the rotor efficiency is usually 0.6. The machine body structure adopts all-metal frame type, and the empty weight accounts for a large proportion of the total weight, about 0.65. There is no necessary navigation equipment, only a single-function visual flight instrument, and the communication equipment is electronic tube equipment. Poor dynamic performance, low maximum flight speed (about 200 km/h), vibration level of about 0.25g, noise level of about 1 10 dB, and poor ride comfort.

Turbine shaft engine and metal blade helicopter

The mid-1950s to the late 1960s was the second stage of the development of practical helicopters. Typical aircraft types at this stage are: S-6 1 from the United States, Bell 209/AH- 1, Bell 204/UH- 1, Mi -6, Mi -8, Mi -24 from the Soviet Union, and SA32 1 "Super. During this period, special armed helicopters began to appear, such as AH- 1, Mi -24 and so on. These helicopters are called the second generation helicopters.

The helicopter at this stage has the following characteristics: the first generation turboshaft engine is used as the power source. The power generated by turboshaft engine is much higher than that of piston engine, which greatly improves the performance of helicopter. The specific power of the first generation turboshaft engine is about 3.62 kW/kg, and the specific capacity is about 294.9 kW/m3. Helicopter rotor blades have developed from wood and steel-wood mixed structure to all-metal blades, and their service life has reached 1200 flight hours. The blade profile is asymmetric, the blade tip is simply sharpened and swept back, and the aerodynamic efficiency is improved. The lift-drag ratio of the rotor reaches 7.3, and the rotor efficiency is improved to 0.6. The machine body structure is all-metal thin-walled structure, and the ratio of empty weight to total weight is reduced to about 0.5. Energy-absorbing landing gear and damping seat are adopted. The fuselage shape began to streamline to reduce aerodynamic drag. The helicopter cockpit began to be arranged in series, which made the fuselage narrow. The performance is obviously improved, the maximum flight speed reaches 200 ~ 250km/h, the vibration level is reduced to about 0. 15g, and the noise level is 100 dB, which improves the ride comfort.

Third generation helicopter

The 1970s and 1980s were the third stage of helicopter development, with typical models as follows: American S-70/UH-60 Black Hawk, S-76, AH-64 Apache, Soviet Ka -50 and Mi -28, French SA365 Dolphin and Italian A65438+.

At this stage, specialized civil helicopters appeared. In order to deeply study the aerodynamics of helicopters, special helicopter research machines (such as S-72 and Bell 533) were designed and manufactured. Countries compete to develop special armed helicopters, which promotes the development of helicopter technology.

At this stage, the helicopter has the following characteristics: the turboshaft engine developed to the second generation and changed to the free turboshaft structure, so it has better speed control characteristics and improved starting performance, but its acceleration performance is not as good as that of the fixed-axis structure. The weight and volume of the engine are reduced, and the life and reliability are improved. The fuel consumption of a general engine is 0.36kg/kWh, which is similar to that of a piston engine. Rotor blades are made of composite materials, and their service life is much longer than that of metal blades, reaching about 3600 hours. The airfoil is no longer used for reference from fixed-wing aircraft, but is specially developed for helicopters, that is, the airfoil with two-dimensional curve change. The tip of the blade is parabolic and swept back. Elastic bearings are widely used in wheel hubs, some of which are hinged. Efficient and safe ducted tail rotor has been applied to tail rotor. The rotor lift-drag ratio is about 8.5, and the rotor efficiency is improved to about 0.7. The substructure of the airframe is also made of composite materials, and the ratio of composite materials to the total weight of the airframe is usually about 10%, and the ratio of empty weight to the total weight of the helicopter is generally 0.5. For military helicopters, especially armed helicopters, the requirements of bullet resistance and crash resistance are put forward. The US military put forward MIL-STD- 1290, which has become the design standard of military helicopters. In order to meet these standards, military helicopters adopt crew armor protection, and specially design crash-resistant landing gear, seat and fuel system. The electronic system has developed to a semi-integrated type. Helicopters use large-scale integrated circuit communication equipment, integrated autonomous navigation equipment, integrated instruments, electronic and mechanical hybrid control mechanisms, etc. The electronic equipment on board is connected by a bidirectional digital data bus, through which information can be sent and received. The helicopter adopts the mixed layout of local integrated cockpit. The use of the first generation night vision system enables helicopters to fly at night. This advanced semi-integrated electronic equipment significantly increases the communication distance, navigation distance and accuracy of the helicopter, reduces the number of instruments, reduces the workload of pilots, and enables the helicopter to fly on the ground and under bad weather/night conditions, thus improving the overall performance of the helicopter. The dynamic performance is obviously improved. The lift-to-drag ratio of the helicopter reaches 5.4, the vibration level of the whole helicopter is about 0. 1g, the noise level is lower than 95dB, and the maximum flight speed reaches 300 km/h. ..

Modern helicopter

The 1990s is the fourth stage of helicopter development, and an armed reconnaissance helicopter with stealth design, which integrates vision, acoustics, infrared and radar, appeared. Typical models are: American RAH-66 and S-92, international cooperation Tiger, NH90 and EH 10 1 etc. , known as the fourth generation helicopter.

The helicopter at this stage has the following characteristics: it adopts the third generation turboshaft engine. Although this engine still adopts the free vortex shaft structure, it adopts the advanced digital control system and automatic monitoring system of the engine, and is integrated with the airborne computer management system, which has remarkable technical progress and comprehensive characteristics. The fuel consumption of the third generation turboshaft engine is only 0.28kg/kWh, which is lower than that of the piston engine. Its representative engines are T800, RTM322 and RTM390. The blade is made of advanced composite materials such as carbon fiber and Kevlar, and its life is infinite. There are many new blade tip shapes, among which BERP blade tips with parabolic swept back and forward swept back are more prominent. The common characteristics of these new blades are that they can weaken the compressibility effect of the blades, improve the aerodynamic load distribution of the blades, reduce the vibration and noise of the rotor and improve the aerodynamic efficiency of the rotor. Spherical flexible bearingless hub has been widely used. The hub shell and the blade connection part are made of composite materials, which makes the structure more compact and greatly reduces the weight and resistance. The lift-drag ratio of the rotor reaches 10.5, and the rotor efficiency is 0.8. At this stage, the tailless reaction torque system has the advantages of good control response characteristics, small vibration and low noise, and there is no need for tail transmission shaft and tail deceleration, which greatly reduces the number of parts, thus improving maintainability. Composite materials are widely used in helicopters as never before. Helicopters began to use composite main structures, and the application proportion of composite materials increased greatly, usually accounting for 30~50% of the weight of fuselage structure. During this period, the empty/total weight ratio of civil helicopters was about 0.37. Highly integrated electronic equipment. Computer technology, information technology and intelligent technology have been applied in helicopters, and helicopter electronic equipment is developing in a highly integrated direction. During this period, the helicopter has adopted advanced stabilization and control devices, replaced the conventional control system with telex and optical transmission control, adopted advanced strapdown inertial navigation, satellite navigation equipment and integrated navigation technology, advanced communication, identification and information transmission equipment, advanced fire control equipment such as target identification, aiming and weapon launch, advanced electronic countermeasures equipment, and adopted bus information transmission and data fusion technology, which are developing towards sensor fusion. The onboard electronics, fire control and flight control systems are connected through redundant digital data buses to realize information sharing. Adopt multifunctional integrated display technology. A small number of multifunctional displays are used to replace a large number of single instruments, and the flight information of helicopters is displayed through keyboard control. Information such as communication, navigation, flight control, friend-or-foe identification, electronic countermeasures, system monitoring and weapon fire control is integrated by the central computer. The use of this advanced integrated electronic equipment greatly simplifies the layout of the helicopter cockpit and instrument panel, simplifies the system components and greatly reduces the weight. More importantly, it greatly reduces the workload of pilots and improves the quality and performance of helicopters. The lift-to-drag ratio of the whole machine reaches 6.6, the vibration level is reduced to 0.05g, the noise level is less than 90 dB, and the maximum speed can reach 350 km/h. ..

(2)

The flight principle of helicopter

There is a big propeller on the helicopter head and a small propeller at the tail. The small propeller is used to counteract the reaction force generated by the large propeller. The helicopter engine drives the rotor to provide lift and lift the helicopter into the air. The rotor can also drive the helicopter to tilt and change direction. The propeller speed affects the lift of the helicopter, so the helicopter can take off and land vertically.

The invention of the helicopter

1939, American Sikorse invented the first helicopter. The fuselage shape is not much different from now, and it is still adopted by designers.

The use of helicopters

Helicopter is widely used because it has many advantages that other aircraft can't or can't do. Helicopters can take off and land vertically without a large airport, and are mainly used in various departments of the national economy, such as sightseeing, fire rescue, maritime first aid, anti-smuggling and drug trafficking, fire fighting, commercial transportation, medical assistance, communication, spraying pesticides to eliminate pests, and resource exploration. The world helicopter fleet is gradually growing.

References:

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Interviewee: wmj 007- Commander of the Guard Corps,1level 312-1821:08.

Because if the helicopter has only one large propeller, the fuselage will rotate according to momentum, so the helicopter must have a device that can stop the fuselage from rotating. At the same time, in order to prevent the tail rotor from touching the rotor, the helicopter fuselage must be lengthened, so the helicopter has a long tail like a dragonfly. Fourth, energy pattern analysis. according to ...

References:

Helicopter Baidu search

Respondent: Mr. Dae Jang-jin-first-class probation12-2116: 49.

Reply to the revision: Your reply to the revision is as follows: The integral rule is closed.

Because if the helicopter has only one large propeller, the fuselage will rotate according to momentum, so the helicopter must have a device that can stop the fuselage from rotating. At the same time, in order to prevent the tail rotor from touching the rotor, the helicopter fuselage must be lengthened, so the helicopter has a long tail like a dragonfly. Fourth, energy pattern analysis. according to ...

/kloc-answer within 0/0000 words.