 Alright, so in about hours time I am going to talk about level turn and pull up maneuver. Now these two maneuvers are more relevant and applicable to military aircraft. Transport aircraft also indulge in level turn and they also do a pull up but the critical conditions are applicable mostly for military aircraft. So today you will see a lot of videos of military aircraft. I find them very exciting and very interesting. So this is today's layout. We are going to look at what is meant by a coordinated turn and after looking at a coordinated turn we will define what it is and we will show you what it is. Then we look at turning flight parameters. Such as turn, tightest turn and finally turning in a vertical plane. The previous turns are in the horizontal plane. The last one is in the vertical plane. So I want you to watch a video. Very carefully watch the video. In this video the pilot is going into what is called as a vertical loop which is actually a circle. You can see that by looking at the background but I want you to focus your attention to the extent possible on the glass that he is holding. The pilot is holding a glass of water and as the pilot goes into a turn looking at the background you should be able to make out whether it is a vertical plane on a horizontal turn and watch the water level when this turn takes place. So right now the pilot is horizontal because the clouds are stationary. But later on we saw that the horizon went down. That means the nose of the aircraft went up. But what happened to the water level during this? Did it move or did it, did you see any meniscus formation? Well though it is not very clear. Let us see once again. So the aircraft is going into a non-uniform maneuver but the water on the glass does not seem to be affected. So what is the G force acting on the glass or what is the force acting on the glass is the same as when the aircraft is flying in level flight or even when it is stationary. So how can you do this? The whole aircraft is moving but the level of the water is stationary. That means there are no net imbalance forces acting on the water. So this is done by what is called as coordination although in the example we have shown a vertical motion but the same can also be shown on other directions. So what is the coordinated turn? In a coordinated turn now this is called as, this is basically a level coordinated turn in the horizontal plane. So the altitude remains constant. The aircraft banks in a horizontal plane at some angle and that angle also remains constant during the turn. There is no acceleration either this way or this way to cause what is called as a skidding or a drift. So you turn without side-clip so you do not turn like this and then go this way. Some aircraft maneuvers are like that when you turn and then go this way. That is intentional. When you peel off. So many air shows that you see, that is intentional but in the coordinated turn no side-slip it has to be on a circle and this is achieved by a very nice coordination between the ailerons and the rudders. Ailerons will give you the roll and rudder will give you the yaw. So let us see, we have two small videos indicating, you must tell me now looking at the aircraft whether you think this turn is a coordinated turn or not. The aircraft is in a heavy bank actually, which aircraft is this? One more. Okay. So you have to be very sure. Do you think they were coordinated? Do they meet all these five requirements? Fifth requirement only pilot knows. You cannot comment by seeing. Now even the first four requirements I do not think looking at the video we can be sure. So we are not sure. Let us see. What do we need? We need rudder for yaw and ailerons for rolling, okay. And some people get confused here as to why do we need rudder in a turn? So that we will explain very soon. So to understand a coordinated turn let us first look at an uncoordinated turn. And for the pilot the only visual indication of an uncoordinated turn is a turn and bank indicator, which is a small instrument in the cockpit. We will show you a video. So if the aircraft is in a coordinated turn that means it goes exactly along the horizontal circle with the aircraft always tangential to the circle at all points. Although in a bank then there is no lateral acceleration on any side, there is no vertical acceleration also. And therefore in this particular instrument this ball remains in the center. One option is you may be in a slipping turn, in which case the aircraft is slipping inside because rudder has not been applied that is why we need the rudder. So you go into a turn but you do not apply the corrective rudder so you are going to slip inside the turn. So you will be turning but you will be slipping or you will be skidding, okay. So this as you know this presentation was made by an intern so I wanted him to explain skidding. This is what he came up with. It is completely unconnected to aviation but it is interesting so I left it here. This is skidding, we are going into a turn, going into a turn that is skidding. Now that is skidding on a car but what happens when you skid in the aircraft? So to skid in the aircraft you need to ensure or you need to have a situation where you either give excessive yaw or the roll is not matching. So let us see how we use rudder in the turn and this video will also explain to you some more details about coordinated turn. The opposite direction that it rolls, okay, video done. Okay now it starts. Just kidding. So first let us look at the three directions that an airplane can rotate. This is pitch when we move the nose of the aircraft up and down. This is roll when we move the wings up and down. And this is yaw when we move side to side. A wing is like the fins on this air vent directing air in different directions. As we increase the angle that the wing is moving through the air we start to change and manipulate the air traveling around it. This not only produces a difference in pressure between the top and the bottom but we ultimately get a net down wash of air. Anyway, when a wing is producing lift it is a system doing work on the air and no system that does work on another is 100% efficient. The byproduct of producing lift is induced drag, which is drag that is induced by the production of lift. And usually the amount of lift that each half of the wing creates is equal. However, when we use our ailerons to roll left or right one aileron deflects up causing the wing to produce less lift and the other aileron goes down causing the wing to create more lift. By changing the amount of lift that each wing makes we can roll the aircraft. But since the byproduct of producing lift is drag the wing that produces more lift is also producing more drag. This causes the airplane to kind of slip through the air sideways. The vertical stabilizer will help keep the airplane from yawing too far but to stay coordinated we have to use a little bit of rudder. When the airplane slips sideways through the air the wind hitting the side of the fuselage creates extra drag and we feel this as a sideways force. This instrument here is called a turn coordinator and the little level looking thing on the bottom is called an inclinometer. It's just a little marble and a curved glass tube and so when the airplane slips sideways the ball gets flung outward and up the tube from the side load on the fuselage. A person in a coordinated airplane will only ever experience downward G forces much like a motorcycle and unlike a car. If you feel a sideways force pushing you into the side of the airplane then your airplane is uncoordinated. There are a couple of different things the aircraft designers can use to try and reduce the effects of adverse yaw. Some airplanes actually mix in a little bit of rudder with the aileron usage and some airplanes like this beachcraft duchess use freeze type ailerons. This is where when one aileron goes up the leading edge of that aileron dips down into the airflow to cause extra drag hopefully countering the induced drag on the other side. Some airplanes like this Piper Aero use differential ailerons. This is where the up-going aileron travels farther than the downward one. And some of the bigger more complicated airplanes use roll spoilers. But even with all this pilots still need to apply rudder pressure with aileron in order to stay coordinated. So I'm going to take up this Piper Aero and see if I can try and demonstrate some adverse yaw even though it has differential ailerons. First I'm going to just wag the wings back and forth without touching the rudder puddles. Notice how the nose of the airplane swings back and forth when I yank on the ailerons. Now I'm going to try and do the same thing except this time I'm going to apply rudder pressure simultaneously with my aileron inputs. Notice how I'm able to keep the nose of the airplane locked on on the same position on the mountains. It's kind of hard but it's like I'm twisting the fuselage in the air. Thanks for watching and I hope you liked it and let me know what you thought. Okay, so I want to just reinforce three or four concepts. So when the airplane slips sideways the ball gets flung outward and up the tube from the side load on the fuselage. So one interesting thing that this author has explained is the fact that when we use ailerons we use them differentially. So one of them goes down, the other one goes up. The one that goes down produces more lift compared to the one that goes up and hence we start rolling in the direction where the one that goes down or opposite to the one that goes down. But he mentioned that along with increase in lift there is also going to be increase in drag because the moment you have more lift you have more induced drag. So there will be a tendency of the aircraft to yaw in the direction opposite to the intended. So like he showed here is an aircraft you roll it this way but because of differential drag it will also yaw this way. This is the opposite direction to the one intended. You would be happy if it rolls this way and yaws this way because that is the way you want it but what will happen is adverse. So you roll it like this it will yaw this way. So to cancel this tendency there are three or four techniques. One technique is to have what is called as a freeze aileron. In a freeze aileron what we want is the side that is producing less lift should also produce more drag to counter the drag that is produced on the other side. So the side that produces less lift is the one where the aileron goes tail up. So what they do is they project the nose down below the wing so that there is a drag created. So the aileron which is going down generates more lift hence more drag. The aileron which goes up the nose produced in the airstream that also produces more drag. So these two drags are kind of cancelling each other. So this yaw tendency is cancelled. This is one way but this is a bad way because you are fighting drag with ultimately the engine has to suffer. The engine has to produce more thrust or your speed will come down. The other way of doing it is differential aileron deflections. So the amount by which the ailerons go up is more than the amount by which ailerons go down. As you saw in the video also we can see it again because that will help you remember. A person in a coordinated airplane will only ever experience downward G forces much like a motorcycle and unlike a car. If you feel a sideways force pushing you into the side of the airplane then your airplane is uncoordinated. There are a couple of different things the aircraft designers can use to try and reduce the effects of adverse yaw. Some airplanes actually mix in a little bit of rudder. So one way is that the moment you deflect the rudder ailerons there will be some automatic rudder deflection. Notice how it is happening. The rudder and ailerons are coupled with the aileron. So this aileron is going up. This aileron is going down. So this side will have more lift. So the tendency will be to yaw towards that side. Look at the rudder. It is trying to bring it to the opposite side. This is automatic. This is just linkages. So the pilot doesn't do anything. The pilot applies the ailerons. The rudders move automatically by some amount. So you can notice the aileron when it is not deflected. It is beautifully matching with the contour of the wing. But when it is going nose down tail up at that time we want more drag because the other side is creating more drag. So we project it below. Where when one aileron goes up the leading edge of the aileron dips down into the airflow to cause extra drag. Hopefully see the air from the front is going to cause extra drag. Countering the induced drag on the other side. Some airplanes like this paper arrow use differential ailerons. This is where the up. So upper aileron has larger movement. Lower aileron has smaller movement. So this is also a way of aileron travels farther than the downward one. So when you deflect the aileron down you create lift but you are creating more drag on the other side. So that additional drag is going to cancel the drag created because of induced. So you can see up is more than down. And some of the bigger more complicated. Now this is more complicated using spoilers. Again not recommended. So here what we are doing is we are creating additional drag by deflecting the spoilers whenever we are going into a roll. This is again not a good way but it is an automatic way of doing things. So you put roll spoilers. Use roll spoilers. But even with all this pilots still need to. Yeah but still with all that also there might be a need. Okay so now once we have seen how it is what is to be done and what is not to be done.