 is the physics of flight. So when we talk about flights and aircrafts, how do they take off? How do they land? What are the physics involved? What is the science behind it? We will talk about principles of flight, certain principles that we are going to touch base upon the four forces of flight, getting familiar with the parts of the aircraft. Now an aircraft has a lot of parts, both interior and exterior. However, in this particular module, we'll only touch base on the exterior parts of the aircraft. We'll talk about Newton's law of motion as well as Bernoulli's principle, which is the most important factor which helps us understand the theory of flight, the purpose and the functions of the different airline parts. And that's what is on the agenda today, friends. So let's keep talking about this particular module. So friends, let's understand what exactly is aerodynamics. Well, if you have to give it a definition, aerodynamics is the study of forces and the resulting motion of objects when they go through the air. Studying the motion of air around an object allows us to measure the forces of lift, which allows an aircraft to overcome gravity and drag, which is the resistance an aircraft feels when it moves through the air. Well, aerodynamics is a very interesting study and once you understand that, it will really help you to understand how an aircraft really moves through the air. Well, there are certain principles of flight, so let's take a look at them. There is a flight path, which is what the aircraft takes whenever it has to fly from one destination to another. So there is a particular flight path that the crew that is the captain or the pilot needs to follow. There is a relative wind, which is going in the opposite direction. So the flight path is in the front direction and the relative wind is actually going against the aircraft, making it go towards the destination. There is a thrust, which is the forward movement of a particular aircraft. There is a drag, which is actually making the aircraft go behind and rather making it happen the thrust factor. Component of weight opposed to lift and the rearward component of weight. These, my friends, are certain principles of the flight. Talking about airfoils. Now, what exactly are airfoils and how do they help on the movement of the aircraft? They help to create the force of lift and lift is something which we will talk about in detail. There can be wings or propeller blades, include leading and the trailing edges and cambers and chord lines. Leading edge of the aircraft is towards the nose of the aircraft and the trailing edge of the aircraft is towards the aft or the backside of the aircraft. We are going to talk about the four forces and this is a very crucial part of understanding the theory of the flight. Well, there are main four forces which act on the aircraft. These four forces are lift, weight, drag and thrust. Now, they all act in the opposite direction, which helps the aircraft move through the air and even take off and land in that particular order. The four forces, let's understand are in any level flight, the lift equals the weight and thrust equals drag. When the airplane flies at a constant velocity, maintaining a steady flight requires a balance, often described as an equilibrium of all the forces together. So, when the aircraft is in a motion and is a constant motion, that is the time all these forces are acting against each other and in equilibrium. Upon the airplane, the weight, lift, thrust and drag are acting forces on the aircraft or the airplane. The four forces act on the airplane in the flight and also work against each other. So, it's very important to understand if these forces do not act against each other, the flight will not be able to take off. Hence, they need to be an opposite reaction. Let's understand these four forces in a little detail. So, what exactly is drag? Drag is a movement which actually stops or retards the front movement or the forward movement of an aircraft in the flight. So, it's important that a drag needs to be there for the thrust to happen and that is the backward movement. Lift is an upward force which opposes gravity, supports the waist of the aircraft and that's something which helps the aircraft lift itself off the ground and move forward. Thrust is the force which moves the aircraft forward in the particular direction and weight, as you all know, is something that is holding the aircraft down. It's like the center of gravity wherein weight is always towards the center of gravity and always towards the earth. So, that is weight. It is the force caused by the gravitational attraction of the earth. Let's understand each of these forces in detail now. We'll start with weight. So, let's understand the force which is most familiar to us because weight is something that we feel every single day of our life. Every human being feels the weight. It is always directed towards the center of the earth. For the aircraft to fly, enough lift must be generated to counteract the weight of the aircraft plus the fuels plus the payload or the passengers. Now, for anything to happen, there has to be a accumulation of certain factors and for weight to happen, it needs to make sure that the aircraft weight is having all the weight of the fuel, the payload, the passengers, etc. Everything together will help to take the weight of the aircraft. Weight acts through the center of gravity. Lift acts through the center of pressure and that's very important to understand. It's not an aerodramatic force but a field force. Weight is not something which is felt suddenly. It's something which is always there and it's like a field force. So, that's important on weight. Talking about lift which is the forward movement of the aircraft. Well, lift happens for two main reasons or two things lead it to happen. The air as well as the motion. Now, these two things are very important for the lift to happen. If any of these either air or motion is not there, the aircraft will not be able to lift itself from the aircraft or rather the ground. How do we explain lift? Lift is very beautifully explained with the help of Newton's law. Now, we're going to discuss three Newton's law and I'm sure you must have read about it in your physics class. Well, let's talk about the first Newton's law of motion. A body in motion tends to stay in motion in a straight line and a body at rest tends to stay at rest unless an outside force causes it to stop and that's Newton's first law of motion. Let's look at the second law of Newton's motion. Newton's second law states that acceleration of an object is inversely proportional to its mass. In other words, it is difficult to change the speed of massive objects and it is easier to change the speed of smaller objects. I'm sure friends, you must have experienced it in your day to day life. When you have to push something small, you don't have to put too much pressure or force but if you have to really push something heavy like a truck or a bus or a big vehicle, you require a lot of force to push that thing or that particular object. Just like a lady out here is trying to push a big bus but it's really impossible to do so. Pushing a smaller object is much easier and that is second law of Newton. The second law of motion has a very simple formula which is, let's understand what the formula is. Force is equal to mass into acceleration. You can use F is equal to NA to calculate exactly how powerful an engine would have to be to supply enough pushing force to accelerate for takeoff. It's important that the force is huge. Even the, you know, more than the weight of the aircraft, the force has to be double or triple the time so that it can really give that kind of push to the aircraft to takeoff. Coming into Newton's third law of motion, let's understand what is that. For every action, there is an equal and opposite reaction. Jet propulsion is an example. For jet planes, I mean why do we say jet planes are very, very fast and speedy because of the fact that they have these propeller blades which help them to really create a swiftness or speediness when they takeoff. Just like you can see on this particular slide, air, when it moves below the kite, it helps the kite to lift up. In the same manner, when we talk about the aircraft, when air goes beneath the wing of the aircraft, it helps the aircraft to lift itself up and that is Newton's third law of motion. For every action, there's an equal and opposite reaction. Let's understand the third force of this particular theory of flight. The third one is drag. Now what exactly is drag? I'm sure, friends, you must have experienced this. When you go in a vehicle, in a car, for example, and you roll down the windows, when you put your hand outside the window, you feel the air passing through your, you know, rather pushing your hand and that is what is drag. It's a resistance. So drag is a mechanical force generated by a solid object moving through a fluid. Drag is a force of resistance that the aircraft feels as it moves through the air. So when the aircraft is moving through the air, there are different parts of the aircraft which are coming out and that is providing the drag to that particular aircraft. Let's look at certain facts with regards to theory. For an airplane to take off, lift must be greater than weight. If the lift is not greater than the weight, the aircraft will never be able to, you know, take off and that's important. So the lift has to be greater than the weight. For an airplane to speed up while flying, thrust must be greater than drag. So if the thrust is not greater than the drag, the aircraft will not be able to move in the forward direction. It will really be lacking behind and trying, you know, kind of falling off, which I'm sure is going to be a scary experience. So for the airplane to speed up, it's important that the thrust needs to be a little greater than the drag. Some more facts. Engines, which are either jet or propeller, typically provide the thrust for the aircraft. When you fly a paper airplane, you generate the thrust. So it's simply said that the engine or whatever the engine of the aircraft, if it is jet or propeller, that is providing the aircraft with the thrust, the movement or the forward movement of the aircraft. A propeller is a spinning wheel that generates the lift in a forward direction. Well, friends, now we're coming to a very important aspect of this particular module, which is understanding the different parts of the aircraft. As we mentioned before, we'll talk about these exterior parts of the aircraft. Let me introduce you to this exterior part of the aircraft. Well, you have a lot of things written out here. I'm going to take you one by one. We have the propeller, the engine of the aircraft, the fuel tank, which is located right at the wing, the ailerons, the radio antenna, the elevator trim tab, vertical stabilizers, flashing beacon, the rudder. We have the elevator and the horizontal stabilizer. We have the flaps, navigation light, landing gear and the fuselage, which is the body of the aircraft. Well, do not worry because we are going to explain what these parts are and how do they really function in an aircraft. Let's quickly look at what we will cover in detail. We'll talk about the wings of the aircraft, rudder, ailerons, flaps, fuselage, elevator and last, the spoilers. These aircrafts help the aircraft in the forward backward side movements. So let's look at them. Let's understand the role of different parts. So what do the wings do? The wings of the aircraft generate most of the lift to hold the airplane in the air and that's the reason why wings are there. They hold the aircraft up in the air. To generate lift, the airplane must be pushed through the air. I'm sure when you travel by airlines, you see the part when the aircraft is in a full takeoff role before taking off and that's the kind of speed which is required because if the aircraft doesn't have that speed, it will not be able to lift. The jet engines which are located beneath the wings provide the thrust to push the airplane forward through the air and that's what we have studied a little while before that you need the engines to give the thrust so that the aircraft is able to move forward. To control and maneuver the aircraft, smaller wings are located at the tail of the plane. The tail usually has two parts which is the vertical stabilizer and the horizontal stabilizer. Let's understand what the roles of each of these stabilizers are. The stabilizer's job is to provide stability for the aircraft to keep it from flying straight and do not lose its balance. The vertical stabilizer keeps the nose of the plane from swinging from side to side whereas the horizontal stabilizer prevents an up and down motion of the aircraft. Well, the hinge part of the vertical stabilizer is called the rudder. So on the vertical stabilizer, there is a part which is known as the rudder. Now what does the rudder do? It is used to deflect the tail to the left and right as viewed from the front of the fuselage. So the rudder is actually making sure that the tail goes from the left to the right whenever the requirement is there. The hinge part of the vertical or rather the horizontal stabilizer is called the elevator. Now what does an elevator do? It is used to deflect the tail up and down. So a rudder helps in the left and right movement of the aircraft and the elevator helps in the up and down movement of the aircraft. The outboard hinged part of the wing is known as ailerons. It is used to roll the wings from side to side. I'm sure when you travel by airlines you must have seen that the aircraft goes from you know side to side that's called as yawing. Now how that does happen? It happens with the help of ailerons which help the aircraft to move from side to side. Most of the airlines can also be rolled from side to side by the use of spoilers. Well, what are spoilers? Spoilers are small plates that are used to disrupt the flow of the wing and change the amount of force by decreasing the lift when the spoiler is deployed. The airline crew meaning the cockpit crew the pilot has the button in his particular cabin wherein he can remove the spoilers as and when it's required. So spoilers are there which will help the aircraft kind of you know change the speed of the aircraft whenever it's the possibility is there. The wings have additional hinds rear sections near the body that are known as flaps and I'm sure you must have seen it again when you fly. The flaps are there which are deployed downward on the takeoff and landing to increase the amount of force produced by the wing. So flaps are there on the wing both the wings of the aircraft and when you take off and land these flaps come up which helps to really give the thrust to the aircraft. So well friends that makes us come to an end on this particular module on theory of flight where we have understood so many things on this particular module right from understanding the principles of flight to the forces of flight and also understanding the different parts of the exterior aircraft. I do hope you have enjoyed listening to this particular module and I'm sure you have taken a lot of values from this particular module. Keep watching more and more videos coming your way. Till then thank you very much.