 You can see the close up of the Airbus A319 with these positions at which the pilot can or the flight operator can prefix it and this is on Embraer EMB 170 again you have up and down controls on the angle. This is conventional where you have a tail plane here and the wings here. You could have canard in which the tail is in the front like this or like this. These two canards are different, one of them is a control canard, one of them is a lifting canard. Now this distinction I do not want to tell you, I want you to figure out on Moodle and tell me. In fact there are three types of canards, there is a close coupled canard, there is a lifting canard and then there is also a control canard. So you have to tell me what the differences are and how they are. It is a very interesting plane which has got a canard also and a conventional tail also. So we call this as a three surface aircraft, you have canard, wing and tail and we talk about this aircraft a lot in our aircraft design course. I do not want to spend that much time here because in the aircraft design course of course this will be covered in more detail. Then you have elevators, this part is the elevator which is the movable part of a tail. Sometimes we have all moving tails also mostly in military aircraft but transport aircraft normally you have a fixed part called as a stabilizer or a fin and the moving part called as the elevator. So now the interesting thing is that here you have an elevator and you have a small deflecting surface over the elevator. So what is this? A small elevator on the elevator, this is a trim tap, this is a tap which is a small deflecting surface but a fixed surface. So you deflect it at some angle and lock it, it is used to reduce the hinge moment required to operate the stabilizer. We will study about this more when you do the stability. Okay, so trim tabs basically they reduce the force on the control yoke or control stick and they are meant for trimming the aircraft. Alright, this is the vertical stabilizer which is a flat surface sometimes one, sometimes two, sometimes three. On the center line of the aircraft on the rear side in the front it gives directional stability so it gives you the tendency to avoid going into a yoke uncontrolled if there is a disturbance you will fly straight, if there is a disturbance you will avoid going this, you may go and then come back, okay that is called stability we will discuss about it but it also has a small moving part called as a rudder which is meant for intentional motion. So the pilot deflects the rudder to intentionally go into a roll or into a yoke but the fin or the vertical tail is needed for stability, okay so vertical tail can also be conventional like this just a single one, okay directly on the empanage most common, most common configuration but you may also have a t-tail that looks like a t, this is also a tail but that horizontal tail is moved up and away, you can also have a twin tail that means you have two tails mounted at the ends and why do we have them what is the advantage etc that we will discuss in the aircraft design course then you can have again the twin boom twin tail and you can also have something like a V tail this is F117A and this is the beach craft model 35 it has got a butterfly or a V tail here instead of three surfaces vertical one and two horizontal you have just two surfaces so apparently it reduces on weight reduces on dry, okay but read about this more it is a very interesting configuration and there are not many aircraft there are only about four aircraft that I know which have a vertical tail then you have triple tail again I have not seen a quadruple tail although there are some aircraft in the beginning which had multiple tails just for trial purposes like the Louvres, okay now in this picture I want you to focus attention on the part which is required when a tail is not enough then you have to have extra things and that is the ventral fin this is the MiG-23 with the ventral fin, okay what is the ventral fin something mounted at the rear underside of the fuselage it improves responsiveness towards rolling we will see this when we look at the stability glasses and it also improves the directional stability of the aircraft that means if the aircraft has a tendency to go into this kind of a motion it will have a force acting on the back on the bottom it will try to bring it back on itself so it is not common in many aircraft in some aircraft like in Mi-27 there is a very interesting configuration that as soon as the aircraft touches down the ventral fin will bend 90 degrees because if it does not bend it will hit the ground and it may break especially at high angle so we wanted to have a large ventral fin but we did not have space to mount two of them there is only one in the center so they have a coupling system the moment landing gear is hitting the ground it is sensed that it is touched the ground by some pressure and as it is activated the ventral fin becomes 90 degrees bent that is the interesting configuration okay potted engines is basically jet engine inside a pod which is basically a nestle about which we have already spoken there are many many variants you have under wing mounted which is most common and the Boeing aircraft company was the first aircraft company to try out these kind of configurations below the wing potted engines and they made it work very well from Boeing 707 after that every jet engine normally has this and there is a member there is a member which connects the wing to the engine and that is this particular component and that component you can see here also this is called as a pylon okay because it is used to pile the engine on the aircraft that is why it is a pylon that is the way I remember it okay you can also have a pylon for any external store like a bomb or a missile or a rocket pod that will contain the electronics weapon control system and other devices in many aircraft stores or armament you need to have an ejector so that you can push the store down to avoid the store hitting the aircraft you know if you release a bomb a bomb is an aerodynamic body and it is a body which can actually start floating up because of the aerodynamic forces so much so that it may hit the aircraft which launched it there have been such cases where you have damaged your own aircraft by launching an armament the worst offender are the drop tanks because drop tanks are basically external fuel tanks which are mounted generally on the bottom of the fuselage or on the two wings below the wing they carry extra fuel so if you want to have larger range especially in military aircraft what they do is they mount one or three drop tanks and then they consume the fuel from drop tanks first and then you release them and then you switch over to the internal fuel so by the time you take off climb and reach some place you now have full internal fuel for the mission now these drop tanks are lightweight now because fuel is gone large aerodynamic bodies they float and they may hit there have been many studies one of the last things I did when I was in HAL Nasik was to look at the aerodynamics of store separation and today also it is a very big area of study okay but you could also have engines over the wing like these two examples there are also more examples and then you can have engines over the wings or halfway over the wings in the front this particular variation is called as the upper surface blowing or USB where the exhaust of the engines is used to flow it over the wing so this is called as powered lift you combine the propulsion with the aerodynamics by using the exhaust of the hot engine flowing over the wing okay again there are many variations you could have engines mounted on the back with pylons coming out such as in this particular example okay. Now the question is why are these configurations normally seen only on small jet planes do not answer it now read about it and answer on the model page why is it so that most large transport aircraft they will have engines below the wing but most or many small jet engine aircraft especially business jet luxury jets they may have engines mounted in this fashion okay so what could be the reason you have to figure out by looking at the model again more variation single engine mounted above with a butterfly tail yes yes yes MD90 see MD80 there are there is one variation which has got one in the tail and two in the fuselage okay yeah that is not a very small jet but generally you will find large jets we do not have like MD90 normally they are mounted below the wing it is only in the small jets that you basically have examples of this okay this is the most useful thing as far as the pilot is concerned in case of any emergency the pilot uses this to save life this is the ejection seat I do not know whether we have a video of this embedded in the skies over Calgary and F-18 pilot practices maneuvers for an air show would be cheating death had he failed when the plane was still horizontal he might have floated but when one pilot gets a signal crossed team with a daring high-speed pass whoo breaking it in two seconds after the collision Sergei ejects all these scenes as we watch again we can see that Alexander was able to eject from the firing piece of our just in time but after a turn out of the square loop in the midst of slow flight at 500 feet something suddenly and dramatically went wrong with the right engine earlier crash landing nose broken pilot is still waiting the plane is on fire but when the fire reaches there then the pilot will eject very risky to wait for so long till the fire is coming in the front so all these are ejection seats and many a times they happen accidentally also while doing maintenance some mechanic or someone does something and then another mechanic is launched it has happened we are laughing but people have died I know of cases in HAL where there was a false ejection like this and the poor mechanic hit the ceiling and he was literally unrecognizable because of the sheer force okay. So one ejection took place by Winkamata Rakesh Sharma when I was there and he was coming into land and 10 kilometers before the Osir runway there was some problem which was further investigated but he was able to eject after rejecting he came down and he got stuck in a tree and then from the tree he had a fall so he broke his ankle he was without flying for about 3 or 4 months but then obviously he came to the HAL and there was a huge party for the ejection penalty because the ejection seat worked and saved his life okay right I would like to just spend very few minutes about while collecting data for this particular course I came across this very nice documentary of the first female fighter pilot in Asia okay Lieutenant Mariam Mukhtiar who was from Pakistan so there is a very interesting story that this is the FT-7PG is a Chinese aircraft you can see there are two what do you see two ventures are mounted and what about the intake it is a nose mounted intake so this is an authorized license to version of a Chinese aircraft which was a copy of a Russian aircraft okay it took off with one modern leader as their teacher and Mariam Mukhtiar as the flying officer and you know there was a crash and there is a very beautiful documentary documenting her life and also this whole incident the most you know nice thing to know is that she could have saved her life by ejecting early but she decided to divert the plane away from the population and in the process save the life of people on the ground there was she was going to hit a school and she said there are going to be many casualties of young children and instead of that she tried to steer the plane which is having a mile function her captain has ejected and he saved his life but she ejected late and she gave her life for the welfare of the people on the ground okay so this was the first Martyr also