Want to fly on the sky and the sun shoulder side by side?Teach you 3 ways to heaven

"Want to fly to the sky, side by side with the sun ..."

Feitian has always been a dream hidden in human heart. Because of this dream, we have paper kite, hydrogen balloon, and ... modern aircraft.

Looking at the literature related to aerospace, you will find that there are only 3 ways to fly to the sky!

First, it becomes lighter than air

Floating in the air (picture source: reference [1])

We know that under standard conditions, the average relative molecular mass of air is 29. As long as it can find smaller things than the air molecular weight, it can float in the air. Such as hydrogen balloons, pyrum balloons, etc.

The first hydrogen balloon in China was made by Hua Fang, an expert in the late Qing Dynasty. The method of making hydrogen as it seems that it is actually very simple today. In this way, the hydrogen (the chemical reaction equation is as follows), and then the hydrogen is charged into the balloon.

"Dianshi Zhai Pictorial" Hua Yanfang's balloon voyage scene (picture source: reference [3])

The hot air balloon we are familiar with uses thermal gas instead of the lighter hydrogen or staple gas than the air. Because the density of the gas is inversely proportional to the absolute temperature, it can reduce the density and quality of the gas by increasing the temperature to achieve the lighter than the air. the goal of. The ancient Kong Ming lanterns are the earliest hot air balloons.

Hot air balloon (picture source: reference [3])

Either hydrogen balloon or hot air balloon. Although both are good, it is difficult to control their flight direction. In order to better control the flying posture and direction, it is also based on the "lighter" ideological method. airship.

The airship charges the lighter gases (generally used with a better safety of the air) in the interior to provide lift, and then install the engine on the airship to provide power to the airship level and control the flight attitude.

Modern airship (picture source: reference [3])

Second, the manufacturing air pressure difference to lift off

"Manufacturing air pressure difference" is actually when an object is flying in the air, the upper surface air flow rate is greater than the lower surface. According to the Bernunley equation, the place with a large flow rate is small, and the place with a small flow rate is strong.

If the pressure difference between the upper and lower surfaces can be made, the object can get a lift. If this lift is enough to overcome the gravity of the earth, the object can leave the ground!

Bird Flight (Picture Source: References [3])

Birds are the originators who use air pressure difference methods. Birds have natural flying body conditions: clever use of the wings of air dynamics, skeleton structure composed of hard and thin hollow bones Light and smooth feathers and so on.

The main reason for birds to fly is because they master the flying knowledge of "making air pressure differences". When the birds are gliding in the air, the air forms a strong difference in the wings and the lower part, generating a upward lift, so that the birds can be held in the air without falling down [6].

In addition, the birds use active fluttering to generate a certain amount of pneumatic lift. When the wings of the birds are fluttering, it is equivalent to the propeller or jet promotion device of the aircraft, so that the birds can maintain a continuous flight state.

Luban make wooden birds (picture source: reference [7])

Da Vinci's fluttering aircraft drawing (picture source: reference [8])

In fact, in the early days, the wooden birds and Da Vinci's fluttering planes made in Luban tried to imitate the flight status of the birds to achieve the purpose of lift, but their flight plans ended in failure. Cognition of the principles of learning, blindly imitate the geometric shape and fluttering form of bird wings.

However, when people began to understand air dynamics and develop a fixed -wing aircraft like a kite, the modern transportation of the successful flying -aircraft was born. The same principle of aircraft and kites is the same as the speed of the air flow on the upper and lower surfaces of the wing, and the air pressure difference is made to obtain the lift.

Commercial aircraft (picture source: reference [3])

Kite (picture source: reference [3])

All in all, whether it is birds, kites, propellers, jets, or helicopters, they all fly through the method of "manufacturing pressure differences", but they are different in the form of rising conditions.

Third, spraying the substance to get the driving force

That's right, it is it to use this method to heaven -Rockets!

Rockets are lift off (Picture Source: Reference [9])

If the goal of our flying sky is to rush out of the earth, then the first two methods may not be very applicable, because space is a heavy environment, and there is basically no air and the pressure difference can be created.

For the Rockets, because the rocket not only carries fuel, but also carries oxidants, the engine can work without air.

In addition, the fuel and oxidant burned in the engine burning room to generate a large amount of high -pressure gases. High -pressure gases were sprayed out of high speed from the engine in nozzle, and the rocket obtained a reaction force that was opposite to the opposite of the gas, so that the Rockets took off and fly.

In fact, as early as the 17th century, Newton described it clearly as early as the 17th century. ","

The rocket is a spacecraft designed and manufactured in order to rush out of the atmosphere and space sailing. To achieve the purpose of successful flying, at least the spacecraft reaches the speed of 7.91 km/s, that is, the speed of the first universe. However, according to the current technical level, there are no first-class rockets that can reach this purpose. Most of the existing rockets that have successfully lifted off are 2-4.

Therefore, each rocket on the space is multi -class rockets. In their launch live broadcast, we can often see "booster separation", "first -class rocket separation", "second -class rocket ignition", "secondary level", "secondary level" Rocket separation steps such as launch steps. It is the rocket that the Rockets have obtained a steady stream of flying power.

In modern aerospaces, in order to achieve higher target flights, designers do not just use a certain use of these three "flying sky" methods to build aircrafts, but to integrate them. For example, in order to obtain a faster flight speed, the supersonic fighter aircraft uses a stamping engine that can be sprayed backward.

Although, the current way of flying that humans have already mastered is nothing more than "becoming lighter than air", "manufacturing air pressure difference", and "downward spraying substances to obtain flying power", but in the notable future, it will definitely definite More people find more and feasible ways to fly to the sky!

The sky is like the dome, and the cage covers the four wilds. There should be a large piece in our activity territory. There are too many unknown things in the sky. When we work hard to eliminate these unknown, human civilization will have greatly developed!

Produced: Popular Science China

Author: Xiao Junbai (Institute of Optoelectronics Technology, Chinese Academy of Sciences)

Producer: China Science Popularization Expo

Edit: Wang Tingting

references:

[1] From the Chinese Academy of Sciences, https://www.cas.cn/.

[2] Xiaomin. Hua Yifang, an expert in the late Qing Dynasty, and the first hydrogen balloon in China [J]. Aviation World, 2019 (10): 12-15.

[3] From Baidu Pictures, https://graph.baidu.com/

[4] From Baidu Encyclopedia, Kong Ming lanterns,

https://baike.baidu.com/item/ Kong Ming Lantern/82234

[5] I know "What is the principle of continuous flight of birds?" "UPAS000's answer

https://www.zhihu.com/question/355541296

[6] Excerpt from "Flying Like Birds" in the "World of Life" magazine

https://www.cdstm.cn/gallery/media/mkjx/smsj/

[7] Excerpted from the Baijiabian Dream Articles "The Earlier" Aerospace ", the History of the Kite"

https://baijiahao.baidu.com/s?id=1673705650727909520&WFR=spider &FOR=pc

[8] It is taken from Sohu Xin oriental's article "Da Vinci more than 500 years ago described the" aircraft "model. What is the matter?"

https://www.sohu.com/a/355186433_181944

[9] The article "Those Things of the Rocket" Come on ""

http://www.cmse.gov.cn/fxrw/czwhbyzhj/zhxw/202005/t20200503_46375.html

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