A couple of days ago I came back from work and I had the pleasure of meeting some of my friends that we had several days that we did not see each other. They came to greet me and ask me how I had been and how I was doing with the realization of my goal of being an airplane pilot. After having talked a little, they were interested in knowing what classes I was seeing, what was being talked about and what content was being studied. Speaking a little on the subject, there was a moment where I responded saying: "we also learn why the planes fly"; Then one of my friends made a face of irony and exclaim something like: "that, everyone knows." When I heard this, the only thing that came to mind was to ask, "Why do the planes fly?" for a moment there was a brief silence, and I asked him the same question again, to which he replied by saying: "by the engine". Upon hearing his answer I said no, I had some idea but that was not the right answer. After this he had a second answer and said: "because it exceeds the force of gravity". Again I replied that it was not the right answer either. My friend with an uncertain face told me "then, why does a plane fly?" And I said, "Because it has wings." When he listened to me he laughed thinking it was just a joke on my part; But I ratified that that was the correct answer. Perhaps it is not the answer more technical that we can said but that is the correct answer. Because of this and because it is a topic that I mastered, I encouraged myself to make a post about where and at what moment the art of flying happens, or why do the planes fly?
The first thing I think It´s need to know is: what is the atmosphere?
The atmosphere is the gaseous part of the Earth that surrounds the hydrosphere and the lithosphere, in turn is the least dense of the planet. It consists of several gases that vary in quantity. This mixture of gases forming the atmosphere generically receives the name of air. The 75% of atmospheric mass is in the first 11 km of height, from the surface of the sea. It is composed of oxygen (21%), nitrogen (78%), and 1% of other gases such as argon, neon, helium carbon dioxide, among others. (1)
Now secondly it is important to know the characteristics of how gases behave, since these are the ones that make up the atmosphere; According to the information I received during my studies, gases have the following characteristics:
• They have a cohesive force although it is quite small.
• They have no shape, they take the form of the container that contains them.
• They are compressible and can be easily compressed.
• Because their cohesion force is almost zero, they move with great freedom and are distributed throughout the space of the container that is containing them.
• They exert pressure.
In addition to these characteristics we must take into account Bernoulli's theorem and the venturi effect. Daniel Bernoulli was a mathematician, statistician, physicist and Dutch-Swiss doctor, who in 1738 found that: "The internal pressure of a fluid (liquid or gas) decreases as the velocity of the fluid increases." (2)
On the other hand, Giovanni Battista Venturi was an Italian physicist who also demonstrated in 1797 that a fluid decreases pressure by increasing velocity as it passes through a smaller section area. Resulting:
"The higher the pressure the lower the speed, and the lower the pressure the higher the speed"
(Here I leave a video of Arturo sehrsfgh of youtube, where you can appreciate what was explained about the venturi effect)
Now that we know a little about the environment where the plane will maneuver, let's see a part of it that is where it certainly happens ... The Magic! That is to say; The wings, or as is technically said, the planes.
In the planes is where they originate the forces that make the flight possible, you are: lift, resistance, traction or thrust and weight. The design of a wing varies in size, weight to be supported, aircraft use, desired aircraft speed and ascent rate, ie mainly of the type of aircraft desired.
The planes in turn are composed of what is called an aerodynamic profile.
The aerodynamic profile is a body designed to take full advantage of the forces that originate from the variation of speed and pressure already mentioned above, when this profile is placed in a stream of air.
Parts of aerodynamic profile:
Now, why does the plane fly? As it does? And When does he do it?
When the aircraft's engines make an action, a parallel reaction is generated in the opposite direction (Newton's 3rd Law) which translates as traction or thrust. This accelerates a mass of air particles that are separated through the aerodynamic profile, ones that pass through the intrados and others through the extrados. Due to the behavior of the gases, these particles try to regroup again; It happens that those that pass through the intrados have to travel farther, so they increase their speed and therefore according to Bernoulli's theorem their pressure exerted on the wing profile decreases (some experts think that not only decreases the pressure but more Well there is a suction). In the extrados the opposite happens because this part of the profile has a shorter path and the molecules are not seen in the need to increase its speed but if in exerting more pressure in the wing profile than the ones that move through the intrados . Because in the extrados there is a force greater than in the intrados exerted upwards, it results in the airplane flying or sustaining.
Well in summary you could say simply that the plane flies because it has the planes (wings), without them could not fly. As it does? Accelerating a mass of air that then passes through the aerodynamic profile and occurs what explains Bernoulli's theorem. At what point does he do it? It does so when the air molecules pass through the planes and exert more pressure from the bottom up than from the top down.
I hope you liked the post on this my great passion and have been able to understand everything perfectly. Any questions I would be grateful to answer if I have the knowledge. Regards!
References:
https://es.wikipedia.org/wiki/Atm%C3%B3sfera_terrestre - (1)
https://es.wikipedia.org/wiki/Daniel_Bernoulli
http://www.manualvuelo.com/ - (2)
https://hernanleon1002.wordpress.com/fisica-de-fluidos-y-termodinamica/segundo-corte/marco-teorico/efecto-venturi/
Images Taken:
http://es.avia.pro/blog/bombardier-learjet-85
https://sites.google.com/site/eraselahistoria/home/1o-eso-ciencias-sociales/tiempo-y-clima/la-atmsfera
http://baliaga21.blogspot.com/2010/09/composicion-del-aire-que-respiramos.html
https://albrodpulf1.wordpress.com/2014/10/27/analisis-tecnico-principio-de-bernoulli-efecto-venturi/
https://es.wikipedia.org/wiki/Cessna
http://www.pasionporvolar.com/principios-aerodinamicos-del-avion-aerodinamica/
http://www.proteccioncivil.es/catalogo/carpeta02/carpeta24/vademecum12/vdm02515.htm