Aerospace Engineering: Aircraft Aerodynamics & Mechanics | Lluís Foreman | Skillshare

Aerospace Engineering: Aircraft Aerodynamics & Mechanics

Lluís Foreman, Aerospace Engineer

Play Speed
  • 0.5x
  • 1x (Normal)
  • 1.25x
  • 1.5x
  • 2x
13 Lessons (2h 21m)
    • 1. Presentation of the Course

      1:47
    • 2. Forces acting on an Airplane

      6:35
    • 3. Lift and Drag Description

      15:42
    • 4. Lift and Drag: 3D Wings

      18:20
    • 5. High Lift Devices

      14:57
    • 6. Stall

      12:39
    • 7. Jet Engines Overview

      5:45
    • 8. Engine Inlets

      6:33
    • 9. Engine Compressors

      9:40
    • 10. Engine Turbines

      5:10
    • 11. TurboJet vs TurboFan

      20:53
    • 12. Mass and Pressure Centers Stability

      12:52
    • 13. Control Surfaces

      10:13

About This Class

The Aerospace Engineering: Aircraft Aerodynamics & Mechanics Course is a multidisciplinary course where you will study the aerodynamics, mechanics and engineering of Airplanes and Aircraft. My intention is that you fully understand the main topics regarding Design and Engineering of Aircraft and Airplanes.

In this course we will go directly to the topics which define how Airplanes fly efficiently. 

We will focus on Aircraft general Aerodynamics, JET Engine operation and Aircraft Stability. 

I hope you enjoy the course. I highly recommend it to those who are interested in knowing more about the physical behavior of Aircraft. 

Transcripts

1. Presentation of the Course: 2. Forces acting on an Airplane: Hi, everyone. Andi, welcome to this first class in this section off aerodynamics. In this case, we will be studying forces which are acting on an airplane. Okay, so here you have basically this schematic forces the most basic forces. Okay, that you may encounter in an aircraft. You have, of course, are left. Okay, Which the lift is provided by the wings. You can imagine on allows the aircraft to actually go up in the sky. Right? You have the weight which is related to the whole spacecraft. You have the thrust which is based on the operation off the engines, and you have to track, which is kind of her condition. Just you have just some drag because you're going to a certain speed. Okay. So because of viscosity and because of the conditions off the flow around the wings Onda round the spacecraft itself, you just have some track. Okay, so let's see a bit of a description off these forces and how they relate to the conditions are flight off the aircraft. Okay, so the lift depends mainly on the velocity off the aircraft. Onda also the wing surface. Okay, So for those of you who know a bit more on this case. He will know that it also depends on some other factors. But I just want to point out different elements. The darky Okay to understanding each one off forces. So, as I said, lived depends on velocity, actually, a velocity squared, OK, on the wing surface. The drug also the same way as the lift depends on the velocity on the wing surface. Okay, so these to depend basically on the velocity and the fact that we have wings. Okay, so just some kind of wing surface, right? Also the drag. Um, there's, of course, a drag which is related to the whole geometry off the spacecraft itself. Okay, Andi is that's not what? This depends on the velocity. Also right? What else? The weight. Okay, which I mentioned. There's w is fixed. The idea is that the weight is just a valuable that you will have in any condition. Okay, of course, this converted over time due to the fuel consumption, and the wait may vary a bit. Okay, considering that the fuel is expelled from the aircraft but in generally can be assumed is fixed. Okay, Andi, thrust T, which is this over here will depend on the pilot's attention. Okay, so of course it depends on other conditions. It is quiet. Thrust is usually quiet. Them exhaustive toe analyze correctly. But the idea is that the pilot has control of the fast, as you can imagine. Okay, So one important thing to take into account is the down for the aircraft. We need an equilibrium. OK? So as you may know, Newton's second law states that if you have a difference in forces say that lived okay. This over here is actually bigger than wait. You can imagine that this basement, the aircraft will actually go upwards. OK, so the idea here is that if you want to Nick Librium, so say static flight normal flight at a certain height, you need all of these first forces to be equal, each doing its toe it one Okay, it's important. So the idea is lived. Must be equal toe weight so that we don't have an extra extra force over here, and for us has to be equal to drag on. This is a condition which is completely normal to concede that when doing any kind of operation with aircraft, okay, eso as I mentioned, Newton's second law states that a difference in force okay will imply an acceleration to a certain must. So, as I said, if the weight is bigger than the lift okay, then you would have ah difference in forces and therefore it would result in some kind of force, which is the weight miners left. Okay, which would be different to zero on because it is different. A zero. The aircraft would be pulled outwards. Okay, of course. For instance, when you're taking off, the leaved has to be bigger than the weight. Right? Because otherwise you just cannot take off the agrifood, just stabilize in the in the platform and that we're not where we want. So the idea is just It's okay. So, depending on the operation that you need, you need to kind of adjust the valuables one to China. Okay. Right. So one other thing to know One of the interesting things about is that as I mentioned before, lift depends on the velocity gate. And drag also depends on the velocity. So in take off, you basically have zero lived because the aircraft is still okay. Andi, when you increase thrust all right. You have a completely a very quiet force over here. I had absolutely no track because the velocity zero. So initially, you understand that the aircraft is just pushed, Okay? It has an increase in velocity because there's a thrust, which is a lot bigger than the drag off course. The drag starts to grow. Um, in a way, OK, because we're having higher velocity. But in the end, the idea is that the trust is very bigger or very, you know, increased respect to address, Of course. And in addition, when the thrust operates, you start to have a velocity off the aircraft on. Therefore, the lift starts to grow. Okay, Ondas you can imagine it is when we have a certain velocity that the lift is actually equal to the weight. And in that case, what happens is the aircraft is in my mentality in equilibrium. OK? But as you can imagine, if we increase a bit more thrust and if we increase if we can continue to increase the velocity, then the lift is bigger than the weight on before the aircraft starts to go upwards. OK, so this is what happens. Of course, the thrust is usually bigger than the drag for these conditions, but in general conditions, or when with in flight okay, the thrust will be considered to be equal to dry. 3. Lift and Drag Description: Hi, everyone. And welcome to this new class in aerodynamics and specifically the description off left in drag. So here we have What would be the schematic forces of gay off lift and drag and how they are related to velocity. So, listen, rag depend on the cruising velocity off the aircraft. Depending on the velocity, we will have more lift or less left. Okay. And more drag. Palast track drag has the same direction. Okay. The components asked the velocity, whereas lift is actually perpendicular to the velocity. Okay, this is quite interesting, because as you can see, the pending on the design off the airfoil, we will be able to inform this velocity into lift. Okay? Andi. Andi, Even if we don't want to, we will also have some drag. Okay, so you can see that this design off the air Ford will actually, um, enable us to optimize the relation between the lift on dreck. So f words which are this over here? Okay. On the aircraft is actually the the cross section off the wing, right? Depending on now, requirements our lift requirements on drag, and also we will be defining some kind off airfoil or another. There's, like actually a lot of work in the aerospace industry in designing on optimizing exactly the geometry off thes Voyles. Okay, so some air fold parameters, which are interesting. First of all, the court line, the court line is the distance okay in the line, which relates the leading edge. Okay, on the trailing edge off these. Wherefore Okay, so in this case, it would be something like this. This point over here, the leading edge. Okay, on the trading edge. So you just relate to two points on you. Draw a line on you have the court line. Okay. You also have the Campbell line, which is this over here. Okay. In blue. This Campbell line actually defines the center with respect to the lower surface on the upper surface. So this line is the distribution, OK, off, um, the same distance, perpendicular distance, respect to the lower surface on the episodes. Okay, so it's just the main line or the average nine off thickness. Right. So, as you can see, this is this Linus, just half way to the upper surface and lower surface in all points. Right? Then you have the thickness. Also the thickness just finds the thickness off the off the Air Force. Okay, by definition, that you can imagine, uh, this point for us, that is the maximum thickness. Okay. It's also interesting to note this there's length over here is actually the maximum camba, which is the maximum distance between the Campbell line on the court line. All right, on. Yeah. And also, we have the court. Okay, so this court line is is actually known as the distance on this distance is just the court . Okay. So you would have on interesting geometrical parameter, which is the court, which is this distance on all the other parameters are just defined in order to optimize the radio between lived on drag. Another interesting thing to note is the angle of attack. Okay, angle of attack is the relation the angle relation between the relative wind, which is which is experiencing the aircraft. Okay. On the line. The court line. Okay, so this core line will define a specific orientation right on the relative wind. With respect to that is just the angle off off attack. Okay, this angle of attack vote formula? No. And it's just really important to, you know, to design the airport in itself. So you can imagine that depending on the orientation off the off the aircraft, who will have a specific angle of attack or another one? Okay, no, let's see some more theoretical basis. Respect to the how how are we creating lived? Okay, because we have, um, a specific effort. So what is the computerization off the air Force? What is the geometry off the airfoil on? How is it related to creating left? Right. So most of the time, in aeronautical engineering classes on specifically and aerodynamics, there's a lot of mathematics involved on do what we do is actually can compute the difference in pressure. OK, between the lower part off the or the lower surface. Okay. On the upper surface off the effort. Onda, we usually get something like this. This means that because we have a certain angle of attack, OK? Usually as by the finish in then the wing toiling the wind will actually kind of collide with the with the lower part off the off the Air Force. Okay. And thus some wind will be pointed downwards like this. Ok, so you can imagine that there's a difference in in the direction off the wind. Okay, on this difference, right? Implies that because the wind is actually blown away downwards, it will imply that there's a force, a positive force. Okay. And upwards. Force lifting force. Okay. On the on the wing itself. Right. So this would be the best or the first definition released of what lived ISS. Now, as you can imagine, it's quite intuitive. OK, imagine that you have just plain some kind of plain surface, you know, any kind of plane surface, and you can imagine the depending on the angle of attack. Okay, so if we increase the angle of attack, we'll actually be able to increase the lift. Okay, this is the coefficient off lift. It's just related to the lift. Okay, I'll just explain this a bit later, but the idea is that if the coefficient off lived increases, the lift increases. Okay, so this would be, um, how you define lived because there's some angle of attack. Okay, so it's quite intuitive to understand that an angle of its like implies lived, right. What else are the other? A theoretical approach is actually the Bernoulli effect. OK, which relates basically relates pressure on velocity. Now, balloon Bernoulli effect is quite interesting on describes quite well. Why a specific geometry off the airfoil will actually imply more or less left. Okay, so imagine that you have a specific geometry which is able to change the velocity off the particles on top. Andi on the lower part. Right? So if you can see this, it's quite interesting toe. I will try to explain. This is as well as I can. Velocity on the top will actually be higher. Okay? Because we have thes configuration because we have this geometry. So it's kind off. There's a lot of mathematics on the background, but they kind of derived that. This is the best geometry, Okay, in general terms to create the difference in velocity from the top on the bottom. Okay, um, so if we have different in velocity on the top, off the air, force on on the bottom, velocity and pressure are related. Okay? And pressure is just the amount of force divided by the surface. So you can imagine that if the pressure is high, it implies a high force right high force acting on the Air Force. Andi, if it's off course. If the pressure is is lower, then it implies that the now that there will be probably a poor Okay, push off the air Force towards upwards. OK, so the idea is this In the top, we have high velocity on the bottom. We have low velocity, so low velocity on the bottom implies high pressure. Okay, because all of this parameter, which is the dynamic pressure on de static pressure, should actually be constant. Okay, so the idea is high velocity, low pressure, okay? They are inversely related. Quite pressure, low velocity. Right. So because this has to be constant if this all of this is very high than this has to be spot. Okay, I'm not gonna get into the mathematics, but that's the idea. High velocity, low pressure. So in this case, we have high velocity. So we have low pressure, and in this case, we have, you know, little velocity. So we have kind of pressure on this is just represented like this. Okay, now, the the idea here is that we still have some pressure. Okay? Acting feel. But because we have more pressure on the bottom, there will be a net force okay. Off the airfoil on upwards. OK, so the Bernoulli effect is just that the relation between velocity and pressure and how that implies a difference in pressure OK, on the airfoil. Because yet because the pressure on the other parts is lower than the lower part, and therefore you have a net force on this net forces to lift. Right? So this is kind of what you need to know. Angle of attack in Bannu. Detect. Okay, now let's just discuss a bit off the you know, the relation between left on different parameters. Okay, so for the description off left and for description of drag you need about this letter, which is the rule. Okay, this is density Union velocity, The surface Onda Kardashian off left. So first of all, you will need a wind tunnel, for instance. Andi, you would use you would define some kind of geometry. Okay. For the air Force on you would test it with different angle off attacks. If you do this, you will get this kind of cuff relating the coefficient off lived okay, on the angle of attack so you can see that the lived is a function off the angle of attack pickers. The coefficient of lived is actually a function off high angle of attack. Okay, However, the lived also depends on the on the density, the velocity on the surface. So velocity is just the relative wind with respect to the aircraft, the density is actually the amount of particles that there are in the air surrounding the aircraft. Right. So, of course, if you have ah, very, very. If there's a lot of particles, you would have more lift, right? Because there's more particles colliding with the with the F word. And if you have low amount of particles, then there's lift less left, right. So you can imagine that if you flying at very low altitudes, the density will be high and therefore the lift will be high. But if you're flying, say, at 35,000 feet, for instance, the density is really, really smaller on, Therefore, the amount of lived would be smaller on. Because you need this, you need always to maintain the same amount of lived more or less. Okay, it would imply either speeding up the aircraft or changing the angle of its Ike. Okay, to get more corruption of lift, for instance. So it's the idea is that you had You have to keep the lift equal to the weight on all operation on all of the cruising operation. Okay. On the drag equal to the thrust. Right. So it's just, um you have to you have to design the aircraft in such a way. That is easy to increase a bit, the angle of attack. And you have mawr left, okay? Or you play with the velocity or with a surface. You cannot play right. Because when their surface would be fixed initially, let me just explain this. Also, the surface is the amount off surface that we have with this airfoil, but also with due to the wing. Okay, So the surface would be the airfoil the court. Okay, the court line this distance multiplied by the wing span. Okay, the wing length. Right. So you multiply these two coefficients and you get a surface on equivalent surface. Okay, Right. So this is us how you define the left in the drag. Another interesting thing to know is that the coefficient of lift is just a coefficient. It just relates the geometry. Okay. With the equation basically Andi, you have these coefficient off lift, which usually que zero k minus five degrees is zero. Andi at some points, this 1.51 point six. Okay, but usually you will have coffee lived. Probably around zero. That five and 1.5. Okay, depending on the configuration. And you know the conditions off the hope the crew's flight. Okay, but just around there, which you can understand, is is related to 55 degrees is quite typical. Five degrees angle of attack for a normal cruising flight. Okay, um, what else? Uh, yeah. It's quite interesting to note that you may have seen that this curve is quiet. Kind of linear. Okay, Not exactly linear, but kind of, um, Rania from low degrees, five minus five degrees, for instance, that too high decrease 10 12 degrees. Okay, are kind of acceptable more degrees. You probably going to have problems. Okay, Because this part of the him this is known a store will explain this pattern. Other videos. But the idea is that if you continue to increase the angle of it, actually, then you would actually have stole, which implies that the aircraft, okay, because if you have a very high angle of attack. You would have high turbulence on this part of the off the air Force on. Therefore, you would not be able to transform the velocity into the difference impression. Andi, the following the newly right on. Therefore, you would have ah, decreasing lived. Okay? And actually, it's If you are flying in these conditions, you will lose all stabilization, all control of your aircraft. So it's absolutely essential to fly in some range, which is linear, okay? Or some range which is easily controlled. What else? Yeah, I wanted to point out also that as I mentioned, lift is around zero. That 51.5 drag. The coefficient of drag I haven't drawn here will explain later is around 10 times less than the lived. Okay, so if left is around 0 to 5 to 1.5, drag would be 0.5 or zero dot won five games in front of that. So a magnitude off 10 is the difference between the lift on the track. Um not sure if I'm leaving anything. Otherwise, this is this is all for this video. Okay, I'll will upload more content on aerodynamics and also the other topics. A soon as I can. So see you next class 4. Lift and Drag: 3D Wings: Hi, everyone. And welcome to this new class in the description off lift and drag and specifically how that effects. Okay, how these forces affect three D wings. So let's start by defining some concepts, okay? That we will be talking about three D effects. Basically, we will be talking about the live distribution around wing. Okay, We will see some couple off topics around wintered down, wash on. Also, we will discuss different kind of wind configurations. So let's start by defining waters, the leftist division of knowing. Here you go. Here, you have Ah, what is known as a sail plane, which is just on airplane without motor. Okay. And you can see the different the distribution off the lift. Okay. As a function off the position are doing right, You can see, for instance, that the tip off the wing it is basically a something me a zero. Okay, on the lift is more or less constant around the wing. Okay, but it decreases for those lengths off the wing where the court is actually smaller. So in general terms, as we saw before, the lift is a function off the surface. So if we describe the lift as's function off the wing, Its function off the position of the wing. Okay, we will see that those parts which have ah court, which is bigger. Those parts will have also a higher lift. Okay, so this is kind of the distribution off off a normal wing, right? You also see that the fusion large may have some kind of lift. However, as you may understand, the lift off the fusion edges really negligible compared to that off the wing. Okay. The wings are therefore produce will reduce lift on diffuse largest test. He may produce a bit of lift, but not a lot. Okay, also, you see, the detail is generating lived on the opposite direction, which is word with his cast in previous classes. Okay, so first of all lived distribution depends on the court. Okay. As we saw, depending on the length of the court, we will have more or less left. Okay, that this That is basically the main topic which will decide the amount off lift that we have for one length or another. A. So we also saw the future large may produce, um, some small lived. Okay, Andi Overall, three D leave coefficient. This is quite interesting. Ok, is actually smaller than the two D coefficient. Right? So we discussed for an air Force that this would be the coefficient off lift curve. OK, on. It can be seen that the three D coefficient off lift is actually something a bit smaller. Okay, the you can see the increase off the coefficient off lift as a function off the angle of attack is actually a bit smaller. Okay, on this is due to basically older configuration, the three D configuration, and also due to the down wash, which has produced at the wingtips. Okay, so what is down Wash, right. The idea off down wash is that some induced drag may appear, okay, and we have to eliminate it. So let's describe it a little bit. It's all there will go from high pressure. Okay. To the point of quite pressure, too. Low pressure. As imagine on generic terms in an airfoil. Okay, so let's define any kind of length off the off the wing. What we will have is actually the flow going up on down, okay, with respect to the wheel, right. So the wing is actually some kind of surface, some kind of material which is separating the low pressure on the top on the high pressure on the bottom. Okay, on, because we have, ah, different pressure on the top. On on the bottom on there's a fix material in the middle. Who, actually, or which separates effectively the different precious. Okay, we will actually have the foil being pushed up. So this is the idea again that we discuss before? Okay. Ondas we mentioned pressure is related to velocity and geometry off the air. Four will actually enhance the velocity on the top. Okay, so that we get as much the maximum lived as possible, right? So, as you can see, for all the wing, we will have two separated parts, one at high pressure and one low pressure. Right? So there's no way the actually the wind or the air can move from the upper part to the lower part or from the lower part to the upper part. Okay, because we have the continuity off the weak so it cannot move on the sides, right? It just cannot. It can only move from front to back. OK, So what would happen if we were to discuss the wing tip. Okay, so in the gate, off the wing tip on. In this case, I exaggerated this bit for it to be more clear. Okay, We have high pressure at the bottom, right of the lower part, which is what we discussed on low pressure on top. So we will have a difference in pressure that this is translated into lived, Okay, at any length off the wing. However, at the wingtips there will be a point. Just the little winky. Okay. In which you will have almost at the same point. High pressure and low pressure. OK, on. By definition, what we know is that air will go from high pressure to low pressure. Okay, This is just a fruit dynamics definition. The idea off high pressure would have more internal energy. So if we if the time, so in the fluid will tend to go from high brush into low pressure because low pressure is simply low energy. Okay? And anything in thermodynamics comes from high pressure or high energy. Too low pressure. Okay, so the idea is that we will have the fluid trying to move from quite pressure, too low pressure as we discussed in this case In the case of the wing, this cannot happen unless the fluid actually goes around it. OK? And there will be, in fact, ECA, Librium or pressures. But after the wing. So the wing is an effective way off separating the low pressure from the hybrid. However, in this point, we will actually have the fluid moving around. Okay, so the movie So the vortex. Okay, some kind of fruit vortex will be created due to the fact that we have, in one point different pressures. Okay, so there will be some kind off movement off the fluid around the wing tip, which we must avoid. Okay, we must avoid this because it basically generates induced track. And your strike is just additional drag, which makes the vehicle less optimal. Okay, unless efficient in terms off every dynamic performance. Right. So we can see this in this case, or get back here. Okay. And these this is in a 3 40 enables a three for two on. You can see this kind of vortex generating okay. Due to the difference of pressure on top and on the bottom. Right. You can see it's completely symmetrical. with respect to the airplane on the path off the airplane on it generates on the wing tips . Okay, this is just it generated just when the airplane went through that particular fluid mass. So my question is, why? How how do we solve this? Right. So what we do is we actually add wingtips, right? Is quite a simple solution to the problem on what it does. It just separates the high pressure from the low pressure in this continuum. Okay. And therefore, we will have the same pressure over here, but we will remain with difference with some difference of pressure. Okay, even to the wing tip. And this is the idea off the off the definition off wingtips, okay, Is just this point this geometry, these material over here, which is added in order to separate the high pressure from the low pressure on this, what will allow is actually to have some lived, which is the difference. Bread off pressure, as you know, which is different from zero. Okay, even at the wing tip. Right, because if we didn't have any kind of wing tip, this curve would actually move to zero because the lived is by definition, just a difference of pressure on def. We don't have a way toe separating the pressure on the bottom and on top, we will come to leave equal to zero disappoint. So the wing tip would it allows is to actually improve the lift. Okay, on the armed wing tip, this is the wing tip, okay? And this is why it is used very commonly in many kinds off different aircraft. So let's discuss a bit the several types of wing configurations. Okay. Um, probably the most interesting ones are the constant court wings. Okay, which are these ones of him which will produce a very high down washes you can imagine, because all of this surface all right, we'll actually be needing some kind of wing tip, all right, in order to avoid the difference in high pressure and low pressure. Okay, so it's important for constant court to take into account their effect off down Wash, in fact, is really it is critical and induced. Black can increase a lot, so it is important to take this into account. Constant courts are there for easily manufactured. Okay, because it's just the same wing on at all you know, at all lengths off the wing, we have the same dimensions off the court, so it's very easily constructed, in which we need just the repetition of the same material. Okay, Another very interesting one is the elliptical one, which is actually kind of it can be constructed, of course, but it's kind of the best optimal leaved to drag radio on discounts from equations. This comes derived mathematically. Why? Theological wing configuration is the best one. Okay, but it just comes down to being having, ah, very little wing tip, as you can imagine, and also optimizing the amount off lift for each surface. Okay, It's just optimal in terms off aerodynamic performance. However, the main problem of elliptical win configuration is that it is not easily constructed as you as you may. You may, um if you want to do some kind of into intuition, okay onto how to manufacture this wing, you can imagine that the cord here will actually be specific. Very specific length. This one will be his first Pacific length through this 12 Okay, so you basically need a very detailed construction off the different elements on. Of course, the optimization off the live to drag greater will only take in Well, we'll only be based on a very precise co location off the different elements. Structural lemons off the wind. Okay, in general, in general, terms of gate tepid wings, tepid configurations this one are the most common on the most. Just the simple. Just in general terms, they are the best because they provide good performance. Not as optimal is the elliptical but good performance, reasonably good performance. And at the same time, it's pretty easy to manufacture. Since you have a very specific length okay to cover on it is it is, um, a bit easier to manufacture than the elliptical one. Due to the constraints off the geometry, that's the idea. So in general terms, most of the airplanes tend to go for the tablet. Okay, you can see that there are a lot of different configurations also different elements. Okay, depending alter. You also have to take into account, for instance, the amount off stress that will that the fuse a large will have to withstand with respect to the wing at the wing route. OK, so what points? Well, the wing is actually connected to the to the future Large on. This is also a design parameter which has to be taken to into account. Okay, So sometimes maybe even if the elliptical is the best warning could be a bit different. Or it could be a bit strange how to connect it correctly to the fusion lunch. Okay, the wing, Andi, As I mentioned before, tempered wings are usually the best ones in in all terms. Also, it's interesting to note in supersonic flight hypersonic flight. Okay, we may encounter this kind of delta wings, which have different configurations, And these configurations are just optimized for hypersonic fluid dynamics. Which kind of work? A bit different to the fluid dynamics off supersonic flight. Okay, so this are some examples of wing configurations. Human encounter. Usually as we saw, we have shepherd wings. Okay. This kind off wing, which, which you can see, the route is kind off big. Okay, It's ah, The courts are the root is quite high. It's quite large, OK, compared to the wing tip right on. You can also, um, see that there's some kind of winking used, not march. It's quite small, but it may be in most cases this is enough. So you just need some kind, some little elements, okay. To provide the difference in pressure as we saw before on you can also see that the configuration is optimally. You can see here all the geometry off the structure around this point. The route, OK, which is actually providing the strength required to withstand the different stresses due to the wing. Okay. And actually, because you com'on imagine that the wing is actually providing lived. So this lift will be connected to the fusion large and well. Actually, I think you will be structurally connected to the fuse large only on this service over here . So this surface has to be very very, um, you know, it has to withstand a lot of stress is which is what we discussed before. So this is why sometimes it's just the configuration justice, the kind of configuration this is optimally, there's more surface of contact like this. Okay, on. You can also have the flaps and all of that with which we will discuss later. So this would be the most typical configuration in the Boeing 747 You can see a very similar configuration. In fact, Okay, um you may notice that in some other photos and generally but buying 747 has a very rigid, um body onda Also that I'm the connection between the route, OK, and the fuse large is very strong on this is ah, little aircraft where you can see quite similar leave the It's also accept wing okay on, it's just a bit more uniform on. Do you can understand that the stresses here are lower because the amount off lived which will be produced by this wing, is lower than in this case. Okay, because the whole aircraft is just smaller, So this is a bit the commercial part of it on just to discuss a bit. Also, the wing configurations on another type of aircraft. All right, you have them have this The spitfire, which was one off the Britain's most legendary aircraft. Okay, it has this very recognizable elliptical wing which is mainly one off them. Ah, few aircraft okay with used in the elliptical wings on, but we saw it was optimized for live to drag optimization. However, it was kind of difficult to construct effectively on rapidly. Uh, this is the Mustang will be 61 must only if I remember correctly from the United States. You can see it's just a tepid wig. Okay, So as we saw before, um, it could have some difference in, for instance, in this point, a wing ti would be okay in order to avoid some off the induced drag that we mentioned. This is the first aircraft. I think this is from the Wright Brothers. You can see in this case, it actually has to winks. Okay, Andi. Very first similar toe rectangular. All right. Even it's quite interesting to note that there's no Air Force either. So the airfoil, as you may remember, was optimized in order to increase the lifter dragged radio. Okay, so in this case, there's even know, Therefore, you can see that dumb. Of course, the design at that point was not as advanced okay as it is today, But it's kind of interesting aircraft to see okay, because it costs. Has this, apart from the fact that it has two wings, Okay, It's also kind of rectangular. You can see it. And this is just the Concord, which was Delta Wing. Because as you may remember, the Congo, it was designed to fly at supersonic flights. Okay, so this is kind of another roll off the different wind configurations and three D effects that you need to know in terms off lift and rack. So let's continue to the next class. 5. High Lift Devices: Hi, everyone. And welcome to this new class in which we will be discussing high lift devices in every dynamics. So first of all, why would we need Okay, some kind of high lived devices, right. So as we mentioned in previous classes, what we usually have is that the lift is more or less similar than the weight. Okay, it has to be equal to the weight at Cruz, but in general terms, we can just assume that it will be very close. Okay, lift on. The weight will be very close. One to a job. So by this definition, the weight off the aircraft will basically be very similar at the beginning, off the flight gate and throughout the flight. It may be a bit different from if we compare the initial conditions to the final conditions off the off the off the airplane, since we will have some fuel. Okay, that we used. But in general terms, we can assume, at least for some calculations, okay, for some instantaneous calculations that the wait is actually constant. So by this definition, okay, the lift can be assumed to be constant at one point, right? So coming back to the equation off the lift on, assuming that the lift east small s equal to the weight and the weight is actually constant . We see that all of this has to be a constant right. So give all of these parameters have to meet a constant then Things means that if the velocity changes, which will happen when we are accelerating on the on the runway. Okay, if when the velocity changes on assuming the density is constant on the surface is constant . It must mean that the coefficient off lift has to change in order to provide more or less. Okay, wait on. Since the weight since constant as I mentioned, if the velocity is small, we need a high coefficient of lived on. If the velocity is high, we need a small questions. No left. Okay, so these two variables will change one with with respect to the other. Right. So imagine is imagine that we have the aircraft on. We warned, actually to take off this aircraft. Right? So why would we know what we do? We need to psych. I lived devices. So the idea is that at low velocities, which is the case at takeoff okay. When we're taking off, we need relatively low velocities in order to take off. Okay. It must mean the coefficient off lift is actually very fine. So, Kylie of Devices, what we'll do is actually increase the car fishing off left, right. This is what you need to know. We will have an increased coefficient off lift so that we can actually lift off okay and take off at relatively small velocities. And why is that? Well, if we had very long runways, okay, would have a long distance in order to accelerate our aircraft. However, just by using us fire coefficient off lived. Okay, It means that we can actually lift our aircraft. Okay, um, at a certainly a bit smaller velocity. And that's the idea on if we actually can take off at a bit. Lower velocity. It means that we need smaller runways. Okay, this is test the idea. So my answer would be this. Why do we need highly of devices in order to have smaller runaways? Right? Because we would where this would imply a high coefficient off lift on, therefore, allow velocity on starting at a given point if we need to go if way will actually be taking off at a smaller distance if our requirement is a lower velocity. Okay. I hope that as we mentioned, the coefficient revered will depend on the angle of attack also right. But we can't just increase a lot. Angle of attack. What we need to do is actually to provide additional lift devices. Now, in this graph, we see how different elements, okay, highly of devices will actually change the coefficient off lift with respect to the angle of attack. Now, first of all, will be discussing flaps. Okay, I'll talk in detail What flaps out in a bit. But for now, I just want you to recognize the different elements. So this would be the normal cuff. Just the generic curve over coefficient off lived with no additional highly of devices. This would be the kerf if we introduce a flap. Okay, So if we actually put some kind of element on the trailing edge off our wing in order to increase the lift, Okay, you can see that basically, what we moving is the curve to the left. Right, Cooper, you concede both ways. I prefer to see it as moving into left. Because this means that if we are at this angle of attack okay, instead, off providing this lift, we will be providing actually deceived, so you can see that the lift coefficient is actually higher. So this is the effect or with flaps, flaps will actually move the coefficient off. Leave curve. Right. Andi, if we introduce also slats, okay, Like in this black line of a here, what will happen is that we actually are able to prevent the curtain that Okay, this curve off the gulf, you know, lived to stall. Okay, So instead of just decreasing, we will actually be able to maintain the increase. The linear increase. Okay, for higher angles of attack. So the idea for slat is that you can continue at higher angles of attack and still be able to provide. Lived without stalling. Okay. Without having the decrease off look professional lived, which happened at high and also no. Let's discuss. There's been in more detail flaps. What they do is basically you have additional surface. Okay, which can be moved from this point over here. Okay. To the back, there's different kind of configurations. Also, you have playing flaps which would be just by finishing constant flap. OK, it's not very optimal. Um, split flaps, which is just some element moving like this on follow flaps, which are the most common. Okay, which is some kind off you can see this kind of little wing. Okay, you would say it says kind of surface which moves from this point. Okay. Like in this case, from this point to the back, right? So what happened with collapse is simply that the there's some kind off down wash because we have the extension off this part of the wing. Okay, So even a zero angle of attack right or something, like zero angle of attack, the air will come. Ons still go down. Right? So there will be a change in the direction off the air, even a dangle zero off angle of attack. So this is what I meant before by changing the angle of attack by changing their the position. Okay. The location off the curve off the coefficient of lived. It's it's simply really the basic idea. The basic physics is simply Don't we have an extra down wash on the east exit down wash, ace transform. You know, related to moving the coefficient of leave cough. Okay, so for instance, zero angle of attack for this probe. For this, um, that boy, we will have this coefficient of lift. Okay, Andi, for this same angle over that, if we add this part off here, which would be the flab, we actually get a higher corporation. So this is what you need to know, right? This is what flaps? Yes. So it is basically equivalent to increasing the angle of attack. So that's what you need to know. This would be the flubs. Another interesting phenomena is Onda. We start all the discussion that we need to do Also a lamb, inna versus turbulent flow. OK, which we will do in the following close. Right now what I need you to know is that there's some kind off, some kind off. You know, the voice. The slats, okay, is designed in order to avoid to be located on the front, off the airfoil. Okay, on the front, off the wing, in this way, we will be able to do is to transform Sam, transfer some off the wind. Okay, which is over here, which otherwise would go down or otherwise, it would kind of behave unstable. E over this point. OK, over this surface over this part of the wing on what we do is direct this air into the slot . Okay, which is that the slot that we have between the slat, which is the physical material? Andi, on the wing. Okay, So by providing it, maybe, you know, it may seem a bit stupid, but the idea is quite clear and it works very effectively. What we actually doing is transferring some off the wind into the top off the wing. Okay on, because we're doing this. We are helping a lot. The conditions off laminar flow on top off. Right. So basically, what we are doing is avoiding the turbulent part off the flow. Right. So how's that transferred to the coefficient off? Live coughed. Those basically, instead, off getting these decrease due to turbulence. Okay, what we will have is that actually, we have, we can provide. We can continue to provide, um, linear increase off the coefficient off lift at high angles of attack. So, by including the slats, we actually are able to increase more the angle of attack on because we can increase more the angle of attack. We will be able to get more coefficient off left. Okay, so we get more lift just by providing a laminar flow on top off the wing. This is what you need to know for sluts. Just taking. Yes. So it is important to relate. Okay, That the turbulent flow is what actually causes these. Decreasing the coefficient off lived at high angles of attack. As I mentioned, we will discuss this and better detail in just the following class. But right now is what you need to know. Slats operate in order to avoid the turbulent flow from appearing. Okay, so some of flaps that you condone you confined in commercial aircraft would be I'm sure you've seen these many times like this once. Okay, this photo is quite interesting because you see the flaps right on this part over here, all of this surface, and you can actually see that There's kind off, you know, a whole physical whole. Okay. Between the wing onda flab, which is what we saw over here. Okay, That it can appear a fold okay on this part of him. And that's not a problem, not a problem, it'll the flow is continuously down washed. Okay, Andi, you can also notes in this photo of a couple of more elements, you can see the spoilers, right? Used on top, which they basically spoil. Okay, relatively, they spoil the flow. So you have specific flow going over here. And if you just, you know, put the spoils in the middle, the flow will actually get spoiled. Or basically, you will have a lot more drag. This can be used in order to slow down the aircraft on the going, you know, when landing, for instance, or in general when you are interested in slowing down the aircraft at any point. OK, so this would be the spoilers. These are the flaps on. Also, you have the guide flap tracks. Okay, Which are quite interesting. Which is the main track where the flaps move. Okay, so you can see that the flaps are actually moving on top off the guide flap tracks, which are this point about Okay, over here. I'm sure you will probably have noticed it am also on aircraft. The idea is that the flap actually moves on top. Okay, off these guiding flap tracks, right? This is the view off. 747 You can see the guarding flap tracks, as we mentioned on also the different level. The different slit. Okay, off the flaps on this part over here. I just like the seven for seven because it has a very distinctive flaps. Andi, you can also see the slats over here. Okay, So yeah. So this would be flaps. I'm sure you already know what flaps looked like on slats are basically this part over here . Okay, So as we mentioned, they are on the leading edge off the wing on they just provide ah, path for the for the wind. Okay, to go from the bottom to the top off the wing. Okay. In order to increase the laminar flow on top off the wing on to avoid the detachment off off the floor. Okay. No, the appearing off off a turbulent flow. Right. So here you can see, for instance, the difference between the slats when they are operating in this part of her here and when they are closed. Okay, So this is the slat configuration on how we discussed already how it will affect. Okay, the laminar flow on top off the way. So this is all we can move to the next class 6. Stall: clear for one. And welcome to this new class in arrow dynamics. In this case, we will be discussing the theoretical part. Okay, off what is stole. So, in terms of fluid dynamics, we need to notice that there's a difference between La Mina on turbulent flow. No, the idea that we need to take into account for aircraft is that we need the most part off their of our flow to be lamb Inna and not turbulent. Okay, so let's say this this over here, which I thought it was quite interesting. Imagine that this is the top off the wing, similar to this case. Okay, You consider the flow at the beginning will actually be lemina. And that means that it will continuously move on top of the wing in contact, in fact, with the wind. So there's a moment just because there's some kind of degeneracy level on the fluids kinetics okay, that we will have a change between a laminar flow on the turbulent flow. And this will happen due to the energy constraints. Okay of the food dynamic in order not to get very theoretical with this, I'm sure you can intuitively imagine that if you have some kind of fluid moving, there will be a moment. Okay, wait. Collapse. Basically, the idea is the flow will kind of collapse on a genetically on become turbulent. Right? So, for our aircraft, in general terms, what we need to maintain is laminar flow as much as possible. Okay, Andi, In fact, we will be talking off detachment off the flow. Okay. When the flow becomes turbulent from Lamia. Right. So this point of care where the flow you can actually see is changing from laminar to turbulent flow. This point is known as detachment off the floor. Now, this is quite in fluid dynamics. This is a very interesting topic which can be applied to many, many different areas. Okay, industrial areas. Andi, it's just essential in order to control our aircraft. If the flow is turbulent, the flow is not connected to the or not very connected. Okay, so the surface andi therefore the turbine and flow will not produce lift. So the idea that productive the production off lift that we have on our aircraft is related to laminar flow. It is not entirely correct, but in for a general, a general idea. You can just intuitively see that laminar flow is the most efficient way to comfort the flow, the energy flow into difference and pressure. Okay. And as we saw in the Bernoulli equation, um, lamps flow the pressure off the flow. He is related to a velocity off flow. So So, yeah, I won't get too much into detail with this. You just need to know that the flow goes generally because of thermal and I mixed of flow go from laminar to turbulent on. What we need to maintain is as much lemina as possible. Okay, So depending on the angle of attack right off our aircraft, turbulent flow will appear. And this is why we actually have this definition off the cuff. We have discussed what would happen, OK, minus five degrees to 10 15 degrees. Whatever on you can see that the flow is continuously increasing. OK, on all of this flow of here, I can tell you is completely level. However, when the line starts to diverge from this linear continuum okay, from this linear direction defined at low angles of attack, you can see that some turbulent flow is actually appearing. Now this turbulent flow is relatively small. Okay, Andi, it won't effect the overall lift because it is a small proportion to the total amount off flow which is flowing around the airport. However, there's a point where the turbulent flow actually, um, expanse in somewhere another or the detachment line. Okay, The transition point is actually closer to the front edge. Okay, so basically another way of saying this is that for all of this part of a here, we have completely laminar flow. But at some point over there, over here, more or less something like this, some turbulent flow starts to appear and it starts to get on. It starts to move to the front. Right? So if we continue to increase the angle of attack, the transition point will actually move from to the further edge. Okay? To the front edge off our aircraft of our way. Now, just an interesting way to say this is actually with streamlines on. You can see that lamb Inna. It's just the idea. Awful. The flow being connected on, you know, kind off geometrically very well described around the Air Force. Okay, this is what happens with laminar flow. However, in turbulent flow, you can see the death. A complete detachment. Okay, off the energy off the fluid around this point around the you know them after the trailing edge, off the all the way. However, in this example, you can see that it starts by a turbulent flow. A transition point around here. And if we continue to increase the angle of attack, it moves up to here. Right? So you consider detachment allowing something around here. This is La Mina. This is not This is turbulent. And if we increase it, it becomes all turbulent. Right? So you can imagine what happens in this case, this is known as stole. Right? So stole is when all turbulent flow actually moves to the front on you have a completely unstable flow around the F word. You can imagine that this is related to this limit of their on the decrease off the lived the you know, the latter decrease off the lyft due to their high angles of attack. Right? So stole is not a joke. You have to really take into account stole when defining any kind of aircraft. And it's one of the main hassles. Okay, for aerodynamic performance, Andi, Indeed, for the geometry definition of our wing. Okay, So as we mentioned at high angles of attack, the flow will detach from the wing. Okay, so the flow, the turbulent flow, will actually move from the back off the wing to the front, off the wing. Andi, Once it is in the front, we can say that the wing is all the. The flow is completely detached from the wind, meaning that it will not be able to produce much lift. Okay. In fact, in this case, it will be completely unstable. Right? So at very high angles off attack, the flow will become completely turbulent and completely unstable. And this means that we will not be able to provide. Apart from not providing lift, we will probably have a severe fall off our aircraft due to the loss off lift. Okay, you can. You can take them into account that the weight will be constant if it's some safe. If it's stump stage, the lift is decreased. In this way, we have control loss off the off off the airplane itself on the airplane will start to fall . So stole is a very important topic which I thought it was important to cover. Okay? And it affects to the air fall. And it is, Ah, very important topic to discuss when defining the effort. That's what you need to know. It's also interesting to note that the stole okay, we actually discussed it in two dimensions. In this case, however, it doesn't appear the same way or at the same point. Okay, depending on the geometry. So if you have, for instance, an elliptical wing in general terms of the detachment off the off the flow or the appearance off the stole Okay, well, actually happen in kind of in the middle. Off the off the wing, on the back part of the wing, as we mentioned before, the turbulent part becomes okay, start off on the trailing edge and kind of moves to the front. Right. So this is the same that happens, kit. The stall starts at the trailing edge and then starts propagating to them. To them front. And these may your cure naturally, or it may a cure due to the UN increase off the angle of attack. Okay, So you do. You shouldn't just assume that it won't happen. It could happen, OK? Even if you are kind of I relatively low on goals off attack in may happen to so as you can see, the elliptical wing should be It's actually quite good. It forms in this point, which means that it is distributed well around all the all the wing in a rectangular wing. It will tend to propagate more on the on the route. OK, on the route off on the wing root, Another kind off high type of wings eaten probably will lock your more towards the wing tips. Not exactly. The wing tip itself more to awards that on. Do you know different kind of geometries will have different impacts on the appearance off them off the three d stop. Another thing that I want to take for you to know is that stole generally means losing control of office surface. Andi, this means that if we have clearance Okay, we will discuss this in mechanic um you know, in some mechanical terms, on terms, off maneuvering and that. But if we have some clearance to change the direction off the off the aircraft, if we actually have stole okay on the clearance light itself, then even if we moved the Isla rinse. We are unable to control our aircraft because we have store. So what? I mean, when I say that stole is related to losing comptroller's office surface. It means that if we have stole at some specific point where we are controlling the aircraft , say, like the ill E rinse, then we may have a problem. Okay on. We need to recover from the stole in a way which is not using the islet because the islands are not useful because the flow is completely detached. So there's no way to recover from that. Okay, it will lose control of the islands, for instance. We will probably lose control off the aircraft on. Would we need to do is have active systems or passive systems which are able to control in a very effective way. Okay. And you know, be sure that there are plenty off different systems on on on normal commercial aircraft in order to recover from store. Okay, but however you have to take into account that these systems are needed are now required in order to maintain the stable conditions. Okay, off our aircraft, otherwise stole, just blow it in all senses right. So stole is a thing to take into account when designing on aircraft. Okay, so I think we can go to the next topic. 7. Jet Engines Overview: Hi, everyone. And welcome to this new section in engine propulsion. In this case, we will be discussing jet engine properties. So definitions on over you. First of all, we should consider different variables such as temperature, which would be discussing dusty pressure p on the velocity off the fluid. OK, so the idea for jet engine is actually that you have some air from the surroundings off the aircraft which is in taken. OK, which is put inside off the off the engine. Andi. Then it is compressed. Okay, this is done by the compressor. We will discuss this in further detail in a bit. Okay, but the idea is that the air is in taken, then compressed. Then in the combustion chamber, we get a higher temperature. Okay? Because off the mix with a fuel. Andi, After that, we have the turbine where the mixed year, which will be air on some fuel, okay, is actually expanded. So this means that we the pressure is actually reduced in this case. Okay. Compressor increases The pressure on the turban decreases the pressure. Okay. And finally we have that the mixture is expanded again through the north, right? So the idea in this case is that we obtain actually higher velocities. All right, let's see the different competence. So we have the inlet, which is basically this part of a here in a tour. Projet, we have, ah, kind of a basic in lead. In a tool for fun, we would have more complex inlet. OK, which we will discuss in a bit. Then we have the compressor where we have an increase off the pressure as we mentioned the combustion chamber over here, which is this part of a here? Okay, the turbine on finally the nozzle. Right. In addition, we have a shaft in the middle. Okay, which actually relates the movement of the rotation over turbine to the rotation off the compressor. So the movement off the turbine because of the off the combustion chamber, we get a higher temperature off the fluid. All right, so this implies higher thermodynamic status, and therefore we actually gain some movement on the turbine. So, as a consequence, off the combustion chamber, we get a rotation in the turbine on the turbine. Therefore, because it is connected to the compressor, actually moves the compressor. Okay, So the idea initially would be that the compressor is stopped. It's completely still. Okay, then we have the combustion chamber in this combustion chamber. We get more or higher properties. Thurman, I'm incorrect properties. Therefore, the turbine starts to move on because it is connected to a compressor. Compressor starts to move again. OK, so this is the kind of cycle on one's. The compressor starts moving. As you can imagine. The the machine, The engine works optimally. Okay, Now, the idea off the thrust that is generated by this kind of engines is actually that exhaust velocity. Okay, So the velocity which is expelled, is related directly to the thrust on also the mass flow. Okay, which is propelled is also related to arrest. So another way of saying this is that the thrust is a direct consequence off the amount off flow propelled, which implies the air on the fuel. Okay, the mixed here that we had here. So the amount off mass, the amount of kilograms per second Ok, that we are expecting multiplied by the velocity off rejection. Here we have the velocity of rejection miners the velocity off the aircraft because this velocity will be relative to the velocity which we took in. Okay. In the inlet off our engine. So the idea is just this. Okay? The difference off velocities multiplied by the amount of flow, which is probably OK, This is the thrust. This is the basic definition of first. Okay, here. Just the Nova view over the different kind of jet engines. We will speak off each one. Okay, we will discuss several off the properties that each 1/2 okay? Yes. You can see the two budget is like the basic model. Then you have the two profile, which is kind of a combination. As as you can see, it's to budget. Okay. It has kind of a tube rigid structure. Andi Also, it has an additional fund which is common in all almost all commercial aircraft used to define okay, because it's more efficient. Ondas, you can see there's a fan. Okay, which acts also as kind of a compressor. Andi, this on air which goes on the outside and an air which goes in the inside. Okay, so we're distinguish between call there on. All right, this is kind of more complex machinery, as you can imagine compared to the two Bridgette and Finally, we have the turbo prop, which is kind of similar to the tour was yet. But the idea is that the amount of thrust is actually not as a consequence off the exhaust itself, Not as a consequence of the velocity off a section, but rather because we're moving the shaft. As we mentioned before, we are able to move a propellant. Okay, A propeller. So this is war generates the most amount of thrust. 8. Engine Inlets: Hi, everyone. And welcome to this new class in engine propulsion and specifically the design off the England's. So in, Let's basically what they are is a way for the flow for the airflow. Okay, for a new specific air, given a certain velocity off the aircraft to actually enter to the engine. Okay, through these device. So through these inland, right, the ended itself would not produce any work to the which means this is a physical definition, which just means that there will be no change in pressure due to the inlet. It will just allow the flow to get from the inside to the inside off the engine. Now the flow will smoothly enter the inlet, okay, at a specific temperature which is actually related to the velocity off the aircraft. Meaning that the temperature at which the flow will enter is not the same temperature off the ambient. It's not the same temperature off the exterior bird, rather a temperature which is increased due to the velocity off the over the aircraft itself. Okay, so we will have a small increase off the temperature now, In general terms, this would be a gas turbine which you can see is just in this case, it's a tube to will fund. You can see the fun. Okay, over here on. You can also note that inlet is just supersonic in this case, okay, on most off the aircraft commercial aircraft will actually have this kind of king. Let because this kind of inlet is optimal for subsonic regimes and this means flowing at a velocity lower than the speed of sound. Okay, also, you have in leads which are different for supersonic. Now, this is interesting because it's a bit different on the idea for supersonic aircraft is that we need to provide some kind of inlet which allows shockwaves Okay, which appear due to the fact that our aircraft is going higher velocity off speed. So short waves OK have to be absorbs in somewhere another before entering the engine. Because if the shockwaves answered the engine themselves, then they can easily break some of the elements off the engine. So in let's in case of supersonic aircraft and more are more important. Okay, are more relevant because they have to comply with this mission off, actually kind off reducing the energy off the shock wife due to the supersonic flight. Okay, so we have different ways of doing this. There's in this accurate, for instance, you have some this kind of geometry, which is just like this, kind of it's known as internal compression. What it does is the shock wife will actually enter at a certain angle. Okay, this angle of them off the shock wave is usually given due to the velocity off the aircraft on what it will do is actually absorb the energy off the shock wave and converted into some kind off normal shock which will behave, Um, dynamically. It would behave as, ah, normal flow. Okay, so the idea is that we are able to actually provide some kind off way too absorbing the amount of energy off the shock wave, okay? And reducing it for it to be, um, you know, introduced to the engine. Andi correctly converted into additional energy for thrust purposes. Right. So that's why we need the engine. Okay, so this is a way to do it with an internal compression, like in this case, in this aircraft, other ways to doing it is just by in this is usually the case for very high velocity aircraft. Okay, So very supersonic or even hypersonic. We usually what we do is we actually put like this counts. Okay, Over here. You can see that these cones would they do? Is they break the shock wave on. They make it break in such a way that the Shoko wave is actually this stop Andi separated on will not enter directly to them to the inlet, which would be these part of a here. Okay, this is a schematic view off. How these woodwork? The idea is that because we're flying and very five velocities, the shockwave will actually have a very high angle. Okay, Andi, Due to this angle, we need something to be disturbing the shock wave in order for it to disappear. What? Least, um, not appear a strongly okay on Indian live himself. So the inlet in this case would be the zone over here. The surrounding off the cone. Okay. On the inside of the engine. Right. So, in a similar way to the to the case before, what we do is we reduce the energy off the shock wave in order to transform it into kind of a normal shock, which is just that particular flow right on this pumpernickel flow will then be able to or will be transformed, um, into additional energy, which is what we need from the from the thrusters from the engines. Okay, so this is some examples also that I wanted to include. You can see here the difference between subsonic. Okay, So velocity slower than the speed of sound, which is basically all of the off the commercial aircraft apart from the Concord. Okay, on you can see the distinguishable to both funds in this case. Right. And here you can see the dean lead is that we saw before an internal compression one. Andi. It will provide a way to absorb the shock wave that will appear the two supersonic flight. Okay, so we can move to the to the next topic. 9. Engine Compressors: Hi, everyone. And welcome to this new class in engine propulsion and specifically the design off compresses. Okay, so first thing we need to know is that compresses are used in all cases. Okay, as a za noun has the same name. Okay. Introduces to actually compress the flow. And this means increasing the pressure off the flow. Now, this is the first states that we encounter after the inlet. Okay, on the idea is to get the flow to a very high pressure state. Now, mechanical work on the flow okay, results in the increase of pressure. So the idea is that the compressor is actually moving and very high speeds on this high speeds allow the flow or force the flow. Okay. To go from a low pressure state to a higher pressure state throughout all off this status. Okay, so imagine the flow is coming this way on. Actually, the flow is started is rooted in this way, and the pressure will increase due to the the conversion from the velocity to pressure into you toe the geometry off thes several parts off the compressor. Okay, so that's the definition by itself. Off how velocity is converting in depression comes from but no release equation, OK? And its just related to the fact that the compressor is rotating on the compressor. Therefore has an internal energy has a very high energy which is converted or is given or provided to the flow on the flow becomes, therefore Kylie pressured. OK, so we just get the flow at high pressure due to the movement and velocity off the compress itself now mechanical work. Okay, The rotation off the compressor, as we mentioned before I think, is actually the result off the rotation. Okay, off the turbine which is located on the back on because the turbine is moving, we actually have the compressor moving on. The fact that the compresses moving actually allows for the fluid to be compressed. Right? Okay, so there are several types of compressors on Mainly will discuss axial compressors and centrifugal compressors. So the idea for actual compresses is that the flow will go parallel to the rotation access . So you can imagine that the flow is actually the rotating rotating access would be the centre, right? The sex is over here because it is the the compresses, rotating really in regards to this access on the flow will therefore go parallel to the axis throughout the compressor. Now, this is this kind of compresses. The actual compresses are actually very common modern to push its on tuba funds. Okay, Also to be prevalent, tobel propel us because there seem a very effective way to increasing a lot. The pressure off, the off the fluid. OK, but each row okay, we will actually be able to provide something like 1.15 to 1.6 times the UN enquiries off pressure. OK, so this means that the pressure over here will be actually 1.5 times. For instance, the pressure over here. Okay, So multiply this by all the stages on. You have a pretty decent increase off the pressure. We can actually link several stages. In fact, a lot of stages on there are some new engines which I think they are up to 40 times. Okay, So they in general terms, the pressure on the on the last one is actually 40 times bigger than the pressure at the beginning, which is a very fine rate for pressure. Ok, as we mentioned before, the airflow goes in this direction and what we have is a rotating wrote of road. Okay, Andi, this is actually translated into pressure by using a stationary vein rope like this. Okay, which will You can see that the airflow is forced to rotate, and then it is forced to maintain some kind of steady direction. And then it is rotated again. Okay. And this is continues. Um, you can do this. As we mentioned for several stages on Indian, we get very quiet pressure fluid. OK, apart from the actual compressors which are the most common, I would say in mode and engines on, specifically in commission on commercial engine, we also have centrally centrifugal coming compressors, which, in fact, the flow instead of going parallel to the axis right, it will actually move centrifugal. So it starts pretty close to the center off rotation. Andi, due to the rotation off the off the compress all toe, it will kind of move to the side on this will give on increase of pressure. Right. So it's also interesting to will use centrifugal compressors. However, the main is advantages that due to the geometry, you can imagine that you can just use only one. Okay, Andi using one. You may get a four times increase of pressure, but you can't get something like 40 times the amount off increase of pressure. Okay, so this is the main distinctive fact between axial compressor Isn't centrifugal compressors . Centrifugal compressors are You may find them in in very or relatively small aircraft, which don't demand that much compression. Okay? Or you can also find it in our C radio control aircraft. Okay, on on other kind of engines, but at least not for now. It's not that common. Right? So, common lead. Right now we have actually compresses. Okay, so a Z we mentioned before actual compressors, what they do is rotating airfoil. Okay, um, which will basically create different in pressure is the same as the wing similarly to the wing. Okay, but page stage will will be able to actually increase the pressure a bit on. Therefore, the pressure will be very much increased. The fluid is parallel to the X rotation. There's a continuous flow of a compressed gas. Okay, so the gases at each stage, it is compressed a bit more, and in general terms in that it has high efficiency, okay, and large mass flows so it can cover a lot off mass flow in just 11 road like this. Okay, on different stages. You congee just have a lot off pressure on increasing pressure, which is very large on also for large mass flows. In additional to that, as we mentioned before, we have several rows off air foils. Okay, on this is also combined to the fact that we have several, you know, compresses lines of compresses. So each row okay, it's circle over. This one's is actually composed by many Air Force on these Air Force actually create some difference impressions we mentioned on because we have a lot we are able to gather a lot off are high mass flow, okay. And we are able to pressurize these large match flow throughout the flight. Often aircraft. Okay, Andan centrifugal compressors, as we mentioned before with what we have is a rotating compressor again en tests in the axis of rotation, Okay, Only in very close to the axis of rotation, but has a big radial component when exiting the compressor. So basically it will go in this direction and then it will end up. Today it will end up going in this direction Almost. Okay. So especially useful for high volumes. But little pressure come Little pressure compression. So it is also useful for large must flows even more. Okay, But the pressure given as we saw before, it's like four times and not 40 times. Andi, this kind of compressors are actually very common in other industries, so specifically in for industrial purposes. Ah, lot of compresses are based on this kind of geometry, which is it's interesting because it's just simpler to design its implementation in general terms. Okay, on it can be useful if you need just four times the amount pressure, which is mostly, um, you know enough for a lot of industrial purposes, but in the case off aircraft, we just need a verify compression in order to provide the maximum thrust possible. Okay, so this would be all we can go now to the next class 10. Engine Turbines: Hi, everyone. And welcome to this new class in engine propulsion and specifically the design off turbines on the nozzle. So let's begin by doing a little overview off What the turbine us. So turbines would they do is decrease the pressure. Okay, so expand the flow, which means the same mess decreasing the pressure in order to accelerate it to accelerate the flow to higher velocities. So the turbine converts basically convert pressure to velocity. Using Bernoulli equation, you can see that the pressure is always related to velocity on. If we have higher pressure in means low velocity, low pressure in means high velocity so away to increasing the velocity off rejection off our fluid. What we need to do is decrease the pressure. Okay, so the flow going through the turbine has also ah, high temperature. And this is due to the reaction in the combustion chamber which has taken part okay between the compression part, the compression zone onda the turbine. So when the flow arrives to the turbine, it is actually high temperature. Okay, due to the combustion chamber on high pressure due to the compressor, right. It's also interesting to note that one off the main, um, objectives off the turbine is not only to accelerate the flow, but actions to provide rotation through the shaft to the compressor. Andi, By providing this rotation to the compressor, the compressor will be able to pressurize the fluid. Andi therefore reacting correctly in the combustion chamber on optimizing the complete engine cycle. Now, another view over the nozzles is pretty straightforward. The idea of a nozzle is that the flow is furthermore accelerated. Okay, It's not only accelerated due to the turbine, but also accelerated a bit more due to simple geometry. Okay, by using a conversion nozzle in case off supersonic flight. So you can see that this is just a graph that I found is quite intuitive. You have velocity going, a mass flow going in this at this velocity. Okay, on, due to the conservation off the mass flow, we will have higher velocities just because the total area east decreased. Okay, so we will have an increase of the velocity due to jail men. Geometric constraints, that's all. So you can see a bit off the off the nozzle it doesn't have. The idea is that you cannot do it too much because off the properties, the energy properties and kinetic properties off the gas. But you can actually provide a bit more velocity due to a converting all. Okay, as before us happened in the same case as the nozzle. There's no work. There's no difference of pressure on the fluid. OK, do it to the normal. So it is simply a way to accelerate the float with no difference. Oppression. Okay, one on one topic that I want to discuss. Also are the after burners with some of you may know from aircraft specifically mostly from military aircraft, which is kind of, you know, interesting to know that you can actually provide on additional propellant. Okay, so an additional burning part off, you know, but you can actually provide more energy to the fluid by burning the fluid on the nozzle. And this is actually known us after burning. So my definition would be that some aircraft introduce additional propellants, okay, So that the flow at the nozzle is burned again, and this would actually does, as you can see is create this kind of interesting, you know, fact that some off the fluid is seen as if it were burnt okay or after burnt. Andi, it's well, you know, you're probably seen it for supersonic flight. Andi, these kind of afterburners I am quite usual in supersonic aircraft on what they do is provide additional thrust. However, the main drawback is fuel efficiency because you're basically burning more fuel, you know, to get a bit more thrust. In general terms, you won't find this in commercial aircraft. OK, It could be done. It could be done. But it's not efficient. It's not fuel efficient. And so this is not the case unless we need extra thrust or we need verify thrust, which is what usually happens for supersonic aircraft. Okay, so I think we can go to the next topic. 11. TurboJet vs TurboFan: Hi, everyone. And welcome to the new class in engine propulsion. Specifically, will they discuss with greater detail turbo jets, aunt over funds. So we discussed in previous classes the difference or the main differences between turbojet to over fund on global proportions. So turbo jets, basically they get some kind off air. Okay, the exterior air, they get it from the exterior, they compress it. After that, the temperature is also increased on the combustion chamber. Then all of these energy is transformed in the turban to velocity on. Finally, with a nozzle, we get higher velocity. Okay, which compared to the initial velocity, will give ah a certain amount of thrust to the engine. This is a main how interpreted mainly works turbofan. The difference off the turbo final turbojet is that instead of having only one flow, we will have to kind of flows first. We will have something very similar to the turbojet in the interior. But we also have some kind of flow on the exterior like this which will actually be named. It's called flow. OK, so this will be hot flow because, you know, the exhaust is hard temperature. Where's this Will be named the cult float. The idea is that we have greater efficiency at supersonic flight due to a fund. And finally we have a turbo propeller which instead off generating thrust due to the difference in velocity on the exhaust on the inland, we will actually have the creation off thrust due to the movement off the compressor and turbine on. Therefore, the shaft on that, given a gearbox, will be transformed into a propeller on kinetic energy. So this means a velocity are given specific velocity for the propeller, will actually be able to generate some thrust No, to get more into detail and to just, you know, get into a lot the topics on for you to get to know exactly how this work. We will make a bit of ah, greater discussion. Okay, some more detailed discussion. So as I mentioned jet engines, turbo jets work based only on one float on this flow is initially called at low pressure. Now pressure will be increased at the compressor in several stages, as we saw in the part of compressor. Where we will have is an axial compressor with different stages. Andi, this different stages will actually improve or increase the pressure part step. All right. So in the combustion chamber, we will get actually a very high pressure food. The combustion chamber will hit the flow to a high temperature. So not only will have five pressure fluid, but actually very quiet temperature and high pressure. High pressure food. Then the turbine over here will accelerate the flow boy expanding it. And this means that the turbine will actually decrease the pressure. Andi, therefore, accelerate the flow on DWI will have the flow at Kaya acceleration at high velocity. Okay, Onda at high temperature. So the flow you can imagine at this point has energetically speaking has great conditions. Okay, In this case, it will have the conditions off. The floor will be greater than those in the initial conditions. So the velocity will actually be very much higher velocity in doing it. And this would provide the thrust Also, it's interesting to note to remember that the compressor is moved by the turbine. So when the turbine starts to operate, it will translate movement with the shaft to the compressor on the compressor will start compressing okay or pressurizing the flow to the combustion chamber in order to optimize the the phone engines. Um, finally flow is further accelerated by the nozzle. Okay. And you to the jail metric conditions off the nozzle Onda, we actually can use also an additional after birth, right as we discussed in previous classes. So the idea is that the final flow is hot. Okay, It will have quite a high temperature. Andi will become also low pressure. So this flow is basically optimized in order to be at high velocity. Now, Turbo finds on the main difference between turbofan interpreted is that we have to flows named, caught and called. The hot flow is basically the same or very similar. Or the configuration of the internal part of the engine is very similar to the turpitude. However, in this case, we have a high pressure turbine. Okay, this one over here. Ah, high pressure compression. A low pressure compressor on a low pressure turbine. Okay. And you may ask why, while the idea is that high pressure turbine will actually move the five pressure compressor, So you know that the turbine will actually move on because of the movement off the turbine , we actually are able to move the compressor. So high pressure turbine will move high pressure compressor. And apart from that, the low pressure turbine. Okay, so it just doesn't remind you know that pressure this point is relatively low than it increases on. It continues to increase. So this is why this is the high pressure compressor. And this is why this is the low pressure complex. Okay, because of the flow at this point is at lower pressure conditions. Now, as I was mentioning that low pressure turbine. So this part of the hair, the exterior part okay will actually move the low pressure compressor. Andi, Also the fund. Now, what's interesting off this on The main difference between the turbofan and turbojet is that we have the separation off high pressure elements, okay, and low pressure elements. And this is interesting because because we have, ah, low pressure turbine. We are able to move also, the fan and this fan would will do is create home induce to the flow to the cold flow on the exterior, some kinetic energy, and you to the movement off the front. And this will be transferred in the end as an increase off the velocity, not a lot of increase, but just substantial, a bit off increase. And as you know, the thrust is just the the product off the mass flow times the velocity or the doctor that difference off velocity between the, you know, the nozzle on the inland. So if we have a lot off mass around the cold, OK, so a lot off cold mass, a lot off called flow, which means a lot off mass flow but with little different in velocity. That's enough to cover a lot off thrust. Okay, just because we have a lot off the mass flow. So even if the difference in velocity is not that high, the fact that we moving with this compressor, we are able to move all of this flow will actually make the engine a bit more efficient. And this is just the idea off the turbo fun. So turbo funds are a bit more efficient in terms of subsonic flight because we also count with a family, okay, and this fan will generate a bit more velocity to the mass flow on because there's a lot of mass flow. This will be converted to an extra part over thrust. Okay, so overall thrust can be higher due to high mass flow, Right? So combining the hot flow on also the called flow, as we mentioned now, efficiencies in this case is in turbo. Funds are higher than turbo jets for subsonic flight. There's actually are mathematical derivation that had very high hypersonic speeds. Actually, turbo jets work better than number funds. So this is why you won't see turbo funds for, you know, supersonic aircraft. It usually is turbo jets because of the efficiencies. Okay, it's simply more efficient in subsonic flight, Andi, In case of the supersonic flight, a turbojet will meet more efficient. So what else? Here you have some examples of what turbojet engines look like. So I would like you to check on, Do you know, be able to determine the different elements on this one? For instance, this one is, um, this engine. You can only see the exterior, so it's not that obvious the different elements, but you can see all the connections all down further determine our dynamic connections on electric connections. Okay, that are required in order to fulfill all off the corrective mystics that all of the potential okay that this engine could get so you can see different elements, some revision, some just different elements off the off the engine, Which quite interesting. To be honest, Andi, which can be, you know, it can be off your interest to determine the different elements. However, in this cause, I will just focus on the different concepts. Okay, that we can see over him. So first of all, you see that inlet on this part? Ah, you see the different compressor stages. Okay? You you can also determine that these ones are bit different than following ones. In fact, to conceive the air foils in these cases are quite larger compared to the latter cases. And this is because the pressure in these and in you know, in this stage, off the aircraft or off the engine is actually lower than in these cases. This is high pressure are conditions. So due to the difference in pressure, we will need some collectivization or some other off the air foils. Okay, that composed the compressor. So this is actually quite interesting. Do not All of this will be the complex stages. Okay, Andi, you have the inland. As I mentioned, this is the shaft Andi. In this case, you can see that combustion chamber is actually radio is on the outside due to the fact that the flow will will move in this direction and it will be introduced in this point with the combustion chamber. Andi, As you know, the combustion chamber will increase the temperature. And after that, you can see the dust combustion chamber will move the flow towards the end towards the turbine. The turbine would expand the flow so it will decrease the pressure on, therefore, create a high velocity. Right on. After that, you just have the exhaust. You have not. All right, so this would be a typical configuration off a turbojet. I wanted you to see a real case. Okay? So that you can analyze the different elements if you're interested in that. Now, turbojet examples are mostly as I mentioned. Supersonic flight. Um, you can see this woman's in this case. You can see it has after burners. All right, with with, you know, it looks like fire is coming out. In fact, you can also see that different all of this. You can see that there's this this continuous kind off burning. Can you see that That is related to the velocity at which the you know the speed at which the fluid is coming out from the from the engine itself. And you can see that is supersonic. Okay, the speed off this fluid is supersonic because we have kind off shock waves. And this our little shockwaves. Okay, that will appear a different, you know, a different time. Rates due to the velocity, the actual velocity over there. Engine. So if you if you see some, you know, if you see this kind of element you condone, you can determine it is related to shock waves. So it actually you can actually determine the velocity at which them the speed at which the home lost in the story, the speed at which the flow is actually coming out. You to analysis off the floor. All right, so this is the first example. This is Blackbird from NASA. Um, this is, um actually, this is quite interesting to note. Okay, I like this photograph because you can see that there's also more technology going on in the nozzle. Okay, depending on the amount off off thrust that you need, you can actually, uh close. I'm not sure if it's very visible, but you can see that this is closer. OK, this surface is a bit smaller than this one over here, so you can actually have a difference in the amount of thrust that one motor or one engine is given with respect to the other, which will may serve for some kind off. You know, mechanics. Some kind of rigid body mechanics can be useful to orient the spacecraft in one way or another. Okay. And it just means that the nozzle can perform on, probably will automatically perform in the best optimal way. Okay, so you can imagine that there's a lot of computers going on here, Okay, In order to optimize how these is cloaked. So how the novel is actually focusing the fluid going out off the off the aircraft. Okay, so it's quite interesting to note this technology is, actually, um, you know, it is being developed on. It is quite useful, to be honest, in order to optimize the amount of thrust given by an engine on this one. I like also, you can see that them I'm not sure if it's very visible, but this is them the main access Okay, off the off the engine. But you can also see that there's a change off the axis on this part of its kind of looking downwards, isn't it? On this is this is usually known as thrust vectoring. What it means is that you can actually point the nozzle toe one direction or another in order to get thrust in one direction or another on this can be also used in order to orient your aircraft and in some specific way or not. So if you need to make a quick rotation off the aircraft equipped maneuver, you can actually and probably automatically the whole computers In the in, um, aircraft will be capable off orienting the fluid in one specific direction in order to get an impulse buy Newton's third law okay by reaction in the opposite direction. So this is how complex Okay some of these engines can actually get. And this is the technology we actually looking for, right? Also, I wanted to include some turbo find examples sober find. I'm sure you're probably more familiar with. If you ever flown with an aircraft with a commercial aircraft, your half almost for sure seen one of thes fun. Um, engines. Okay, you just get to see the exterior. But this is all the interior. It's quite interesting to note that this is the fun. All right, on you get all the different compressor stages. Onda also, you know the shaft on dumb. Yeah, it's very It's difficult to note, but there's a combustion chamber here. Okay? View to the high pressure you get here the combustion chamber. And then it has expanded with the turbine on. Therefore, you actually able to transform, um, the low pressure from, you know, velocity and actually accelerate the fluid as we mentioned before. This is quite similar to the turbojet Andi. It is also interesting to note all off this space. Okay, All off this part over here, which will be covered afterwards with, you know, with some kind of mechanical element on what we'll do is actually have a cold flow right around the engine. So you have the combination of both on this is the idea of all that. This is the dimensions off control, which motiveless is. I think it's the motor for them for 787 on this engine is quite efficient. Um, Yep. So you can just see the different elements as we saw the fan. In this case, this is covered. Okay. And this is the exterior. You can also see all the refrigeration, different elements, key points, Elektronik connections, all of that off the offer to define itself on. Finally, this would be the example of what you would see on a term fund. You just get to see the external cover. Okay? Onda fan. Usually eso the force of the funny wouldn't see the fan on the cover, That's all. But you must know that the interior is what with this crab reform. Okay, so the interior off them off. The engineers actually like this on day. One thing to you know, I like this photo because, apart from the dimensions, okay, which is quite interesting to compare with her with a person who was walking about, Um, it's quite interesting to note that you can determine the cold flow. Okay, Where would will go? Because there's actually, um, you can see it's avoid, you know, there's no there's no, there's no structure in this part. You can see the funding, but in this part over here you can see the defining is actually empty on the on the mysterious. So you get the fun and you get the cold flow flowing on. That's all Andi on. Also, you get cold. So they called the hot flow on the middle. Okay, in order to generate the maximum thrust. So well, it's a combination of both, right, Just like a turbojet on this part and you actually have Also the fan on the final wouldn't move the cold flow on the surroundings. So this is all right. Um, if you want to know also this, you may be interested in knowing why this is used. They usually use this in order to recognize even engineers working on art. It's to kind of imagine that your long distance from an aircraft and you don't know if that aircraft is moving or not while moving. If the engine is operating so you can know easily, you can easily know that if the engine is operating just by seeing if this element in the center is actually moving or not on therefore you can see if the engineers operating this can be useful for, you know, control purposes from the tower station or whatever. Okay, So I think this is all, um, as always, if you have any questions, let me know on in addition to that, um, I tried to build a lot of effort into getting the most material. If I would appreciate it if you if you feel like this content is is good and useful for you , I would appreciate it A good, you know, a good review on your part on. I'm willing to listen to all the reputations. Okay. And I would like to provide the best material for you. So just let me know if you have any questions. If you have you have any doubts, let me know, and I'll try to look for a solution for those. Okay, so let's go to the next class. 12. Mass and Pressure Centers Stability: Hi, everyone. And welcome to these new class, these new section regarding flight mechanics. In this case, we will be studying a bit off the ideas on the fundamentals off stability, often, aircraft. So let's start by the finding. What is the center of gravity? Okay, most of you, I guess, already know. But it's kind of an important concept, so just checking. Okay. This center of gravity is actually defined as the average point off all the mass distribution off a given aircraft. Okay, so you would have the tail, you would have the cockpit, different passengers and cargo and all of that. And if you add all these masses, you would get a center off mass. Okay, on overall jail metric gravity center. Okay. Now, the limits for the center of gravity must always be met. Okay? Andare they find in the flight manual. What I mean by this is that you cannot consider, um, sent off mass, which goes further to the back off further to the to the start of the off the aircraft. Because if there were to be the case, the aircraft night become completely unstable. Okay, so if you are, for instance, allocating different passengers in the aircraft on There's not a lot of passengers you cannot consider putting them all on the on the front. Okay, on the back. Because that would statement would stabilize the aircraft, possibly due to the current the position off the scent off. So it is really an important concept to take into account on pilots. Andi and all the staff have to rig are required to check with the flight manual all the allocations off their passengers. OK, this is important stability. Okay. Depends on the allocation off the center off mass. Okay. The center of gravity, as I mentioned. So as we said, passengers must be seated in a specific way. Now, let's go find another concept center off pressure. This Ah, really interesting topic. Which is ah, well discussed in or papers regarding aviation, okay. And regarding the stability off aircraft and it's basically the center or the position at which all the force, all the lift, the dispirited by a wing can be considered to be applied to. Okay, So the idea, as you can imagine, is that if we have ah, big wing, we would have different amounts off lift on different points on top of the wing. OK, but as a novel as, ah kind of an average, we can consider just one point on the total amount off. Lift off that wing. Okay. On one specific position. All right. This is Ah, quite interesting topic, because it is kind of a simplification, as you may understand, but it is quite useful to understand this, Dan, in terms of stability off the aircraft, so usually it should be around 1/4 off the court off the wing. Okay, on this also depends on camp. So what I mean with this? The idea is that the court is the line which unites the front off the wing on the end of the wing. Okay, so if I say it should be on 1/4 this means that it should be allocated quite on the front. Okay, As you can see, 2/4 would be in the middle. 3/4 over here. Right? So 1/4 is over here. The idea this convey that used to mathematically, Andi is usually approached for many problems. But the idea is that this kind of similar or kind of very, very close to 1/4 off the court. Okay. This especially depends on the on the geometry off the wing itself. Okay. Depends on the camper. So, actually, the form the German tree off the wing. All right, what's stability? Okay, Depends on the allocation off the center off pressure. Andi. It actually depends by comparing the center of pressure. The position off the center of pressure with Okay, the center of gravity. So, basically, you have to compare one to another. Let's see this. Okay, so here we have some are illustrations of what these would look like. Okay, let's see. The center of gravity should be located closer to the front for stability purposes. Okay, this is kind of a definition off stability. I'll just take a minute to talk about stability, but before I want to, I want to kind off relate what the Tail Onda lived actually do. Ok, so first of all, in an aircraft, as we mentioned before, we need a new equilibrium of forces. We need the lived. We need the weight we need the drag on. We need the thrust. Right. So all these forces should be completely liberal. No. The aircraft should also consider a naked Librium in terms off moment. Okay? What I mean by this is that a moment? I don't know if you know this, but the moment is they find us the force multiplied by the distance off the force. Okay, The perpendicular distance off the force. Respect to the center. Off rotation. So, as I said, rotation okay, off the aircraft actually takes place around or respect to the center of gravity. So this is why the center of gravity is so important. You can imagine this aircraft okay, moving in any way but respect to the center off us. Okay, Now, the idea here is that if we need moment, Liberum, we need all the moments to compensate one another. Okay? The same way that the lift and the weight had to be the same so that the some off the lived on the weight would be zero. Now, what we need is that the product off L A times the distance of l Okay, which I defined as d l should be actually equal to t alright multiplied by the distance off . So first of all, you may notice that our T has to be defined in the negative direction okay, Because the left is defined in this way on the left would actually imply that the aircraft moves in this direction. However, if we need to compensate for this movement because of the lived okay, we have to compensate it with a tail force. Okay. A tale lived, which actually goes in the opposite direction. Why is this what? Because if you had the tail going up also, you would have a very severe movement off the A graft. You will see that it is completely unstable using so you need one to compensate the other on the second idea care is that the lift is very bigger. OK, it is much higher then the then the tail in the lift on the tail. Why is that? Well, the idea is that you have to compensate for the moment. Okay, so l times d l should be the same as tee times. DT. And as you can see in this image, D l is very, very lower compared to DT. Okay, so in the end, you end up with a lived which is very big on a deal which is quite small on a T, which is kind off small, okay, but our duty, which is very large compared to the year. So this is kind of over. You need to know in terms off. Can you promote the moments? Okay, let's see an alcohol. How? How this actually affect stability off the aircraft now, depending on the position off the center of gravity, our aircraft will be stable. Okay. So as to understand this, what I propose is that you actually look for the silver. Okay, imagine that you have a point. All right? Or that you I don't know. This could be a ball. Could be a heavy ball. Could be some metal. Okay, Bolt. Andi, you're holding the ball from this point. So imagine your fingers over here. Kind off supporting the weight off this ball. Okay, you can imagine that and these works has abandoned them. OK? So you could actually move the bull and it would be stable regarding the sensor off rotation over here. Right, Gatewood, move this way. Now imagine that you have that. You actually you know, you're the ball is over here on the top, okay? And you're holding the ball on this point, which doesn't really make sense, does it. Right. Okay. So the idea would be considering that this would be solid beam. Okay. In this case, you would actually have completely unstable movement. Okay. And why is that? Well, the idea would be that if you're trying to called this poll from below, if you try to move the ball a bit, the ball will completely fall and move to the other part. Right. Move to the lower part again, would start rotating here. And why is this? Well, this is the basic off stability. So it depends on where you're holding the ball on where the ball is actually moving. Okay, this would be completely unstable, this element over here, as you can see, as you can imagine, OK, on this one would be stable because it would rotate, but it would be in, you know, it would be kept in Ah, certain range off angles. Okay. So it will rotate, but it would be stable, and this one would be unstable. Okay, so why am I? Why am I talking about this? Well, the idea is that the position of the center of mass is actually where we would be actually called ing the ball OK, so we would kind of imagine that we can. We are calling the aircraft in this point of here. So if we have a perturbation Okay, off the lift, for instance. So if the lift where to increase a bit for one moment, you can see easily that the aircraft would actually move. But since the center off mass is on the front, right, respect to the velocity. Okay, respect the velocity. That would be coming off here. You can see that automatically. Kind of stabilized. All right, over here. So this is the same ideas. This one over here? Okay. In addition, as you can see, the lift on the tail would be would have the different, um, directions. Okay, because we have to compensate the aircraft. And if there's a perturbation in the lift, the most possible probably detail will automatically compensate for that. Okay, Now, let's see the other case in the case that we have to center of gravity, actually, um, positioned farther away from the front off the vehicle. Okay, then the lift. Okay, so let's say now the lift increases a bit, So if you imagine that you're holding the aircraft on this point. What would happen is actually, the aircraft would start to rotate on unless the tail can provide stability, which probably wouldn't Okay, the aircraft would just completely unstable E. Okay, just move around in the same way that we defined this over here. Right? So imagine taking the aircraft on this point, holding the A graft in this point. Andi actually putting an additional force to this so the aircraft would be completely unstable, considering the velocity right, it's pretty clear, I think if you have any doubt regarding these, just let me know and I'll make sure to send to you some more examples and ideas on stability. Okay, because it isn't interesting topic. And it is very important, of course, for aircraft that they're stable. In fact, if you wanted to know, there's also a military aircraft which are designed for them to be unstable, OK, naturally unstable. And this is because it may improve of the man off ability. Okay, off the aircraft itself. So sometimes it may be interesting for us to make the aircraft and stable, but as you can imagine, there's them, as in terms of a commercial aircraft off course we needed to be incredibly stable. Okay, What else? Um yeah. So if we do find the center of gravity is we mentioned after the sense of pressure? OK, then The aircraft is naturally unstable, even though the same may try to stabilize it, but the aircraft is in stable. Okay, so this is what you need to love. 13. Control Surfaces: Hi, everyone. And welcome to these new class in flight mechanics and specifically, control surfaces. So let's bidding by defining water control surfaces. So this are basically mo buying surface used on an aircraft in order to maneuver the aircraft itself. So, basically, we will be talking about three types of control surfaces. We have a clearance, which are these control surface is located on the wing tips. Okay. We also have elevators, which are located on the horizontal stabilizer off the tail, right on their located on the part off the back. So on the trailing edge off the horizontal stabilizer. Okay. And we also have ruedas, which are located on the vertical stabilizer over our aircraft. Right. So, again, a clearance on the wing tips. Okay. It's important that they are as far from the center as possible in order to produce maximum moment off the aircraft. Then we have elevators on the horizontal stabilizer on routers on the vertical stabilizer. Right. So what do we get with these control surfaces? So because we can move, the pilot can actually move these control surfaces. Okay. We will be able to produce some moments, some angles on the aircraft itself. Right? So the first thing we can do is actually roll the aircraft, so create an angle off role. This roll angle is oriented on the X axis. Now, this on this axis is actually the axis which relates, you know, the propeller off the aircraft, the first part of the group to the tail off the aircraft. Okay, So instead, our external of the aircraft itself, now rotating on the roll axis, can be done using the eyelid Rinse. Right. So if reproduce an extra lived in one part of the island Onda, we actually decreased the lived on the other part, we will be able to create on a rotation our role rotation okay to the left. In the same way, on a similar way, we use the elevator in order to create a pay channel. Now, this peach angle is related to the angle of attack with respect to the wind. Okay, so by pitching by creating a pitch which can be done by a pilot, as I mentioned before, what we do is control the aircraft by going upwards for going that words right. We also have the your angle, which is an angle which will be defined as as the angle on the vertical axis off the aircraft. Andi, In order to produce a your angle, what we will do is actually produced some extra lived additional lift toe one direction or the other direction off the aggregate in order to change the orientation off the Now here we have, um, another example. OK, we'll have to see this. Um, you can see that we have the roll angle on which will be produced because we actually used the Islay rinse in order to produce more lived in this part of the wing on less lived in this part of the wing on this will create a rotation on the X access to the aircraft. Right. So this is the role. The your, as we mentioned before, is the rotation with respect to the vertical angle off the aircraft. So by changing the direction off the router, we will be able to create additional left in one direction or the other direction on this will rotate in as your angle the aircraft with the respect of the vertical axis. In addition, you also have a pitch pitch will be related to changing the direction off the elevator. Okay, so the pilot will control the elevator on by this, you will be able to create additional lived in order to go downwards or to go ab words. Right? So the aircraft will be controlled by this different control surfaces, and therefore we will be able to produce any kind of maneuver by combining these rotations . Now, what is the physics? Why thus another Le'Ron produced more or less lift. So it's pretty similar to the case that we discussed before, which is the flaps and earlier in works very similar to a flap. In this case, as we discussed in the case of flaps, we actually increase the lived when we put an additional ah wing. Okay, so we put an additional part of the wing which will be the ill here in Ondo. It is facing downwards they so it is directed downwards. In this way, we will be able to do is actually two down wash the wind in the surrounding off the wing. Right? So, by doing this by actually down, washing their wind will be able to produce a net force to which is in the opposite direction to the down wash off the wind on the surrounding or the F graft gets so by 1/3 law, Andi, the third law off Newton We are well able to justify that. The fact that the wind is down worst will produce a positive net force on the positive Lived to the well, Okay, so in this case, we would be able to produce on increased lived Just because we are moving the Islay room in this direction, it actually makes sense, right? It is quite intuitive. So in this case, you can see that the island is down washing the wind, okay on, therefore will produce an additional left on this additional lived will actually make the aircraft rotate in the same way. But in the opposite way, I would say we are actually able to rotate the yet, um, the I live in this way in order to up wash the wind on the surrounding off the wing. So in this case, we will be able to produce a net lift decrease okay to these parts off the wind. So in this way, we'll actually be able to produce a positive lived here on the negative. Lived here on this will, you know, produce the balance on could use the rotation off the aircraft itself. So this is the main physical idea. Okay, on the on how I Le'Ron work now, Ruedas work in a very similar way. If we actually rotate the router in this direction, as you can see, as you can imagine, the wind will be Director will be washed in this direction to Okay, So because the wind is going over here, Andi, when it reaches the ruder will actually being washed on one specific direction. This wash will make the aircraft rotate in the opposite direction because off Newton's in the third law. So it's basic physics, Okay, It is applied in many different areas. As you can see, the Islay rinse are able to produce a net difference in lived. Also, the ruler will produce a difference in lived on the specific lift off the rueda. Okay, And this will actually rotate the aircraft on in the same way. The elevator will actually provide aversive Milam, um, forces okay, but applied to the tail. So if the elevator is in this case, washed like this washes the wind to the top right up bushes, the wind as in this case, So you can imagine that the lived will decrease. And if the lift decreases in this point, you can see that the aircraft will rotate towards upwards. OK, so there will be a change in direction off the aircraft. Right? So I wanted to see um um example of this. Okay, So first of all, would you want you see, Here is the appearance which you can see are very similar to the flaps flaps out here on the flaps in these gays are not extended. Okay, on also, the island is not extended, but this would be the control service. Right on. I wanted to show you this video, which I like, because you can see them. How the Isla rinse are actually used by the pilot to control the aircraft when landing. Okay, so he actually uses the Isla rinse in order to stabilize the direction. The role rotation Okay, off the aircraft when landing. You can see that in this case, we had cross winds which are winds that come at a certain direction with respect to the vertical plane off the aircraft. So coming from this direction on, he has to stabilize it in some way. Another using the Islanders. Okay, you can see here how the allowance change, right? Andi, how he tries to stabilize it. Andi aircraft won't stabilize because there's a lot of cross weight. In this case. What else elevates earned ruler are quite easy to see to some to determine in various spacecraft. In this case, you can see in this aircraft. You see, the This is the rueda, right? Okay. It can be seen a bit. This is a control surface which can be directed by the pilot as we mentioned before on we also have the elevators located on the horizontal tail. Right. Okay, so these are quite easy to see. You can also see. Um it's not as easy to see in this case, but in this case, which this is a fighter, this a Russian fighter. And as you can see, we have two routers. Okay, because the airplane is designed in a way that it has kind of two tails or two vertical stabilizers. So two routers to control the direction Your access direction. Onda. We also have elevators which are not very clear to see, but they are over here, okay? And are used for ph controls. In addition, you also have this image, which is from on old aircraft. You can also see the elevator over here on the ruder, which is thes geometry of here. Okay, so with this, we can move to the next class.