 Flaps as you all know are used at high lift devices and during landing we have a very large deflection as can be seen here there is a very large deflection typically between 30 to 60 degrees and the CL at landing is normally the CL maximum and the aim is to lower the landing distance. During takeoff the flaps are deflected at lower angle as you can see here the deflection angle of these flaps are lower than that you see in the landing typically the angle of flap deflection would be 15 to 30 degrees. So one can assume that the CL at takeoff is going to be 80% of CL max because the deflection of the flaps is at a lower angle and the purpose of using flaps during takeoff is to have a better climb performance. But there are also many different type of flaps and each of them has got a different effect on the lift coefficient these are some of the standard flap sections that you would use. So for example if you have a basic flap basic aircraft suppose you have a basic wing whose CL max is equal to A this is our baseline. Let us see how the usage of flaps and that to different type of flaps increases the value of CL max from A. So with a plane flap you can have 50% higher value of CL just by deflecting a plane flap. If you have a split flap you can get slightly better up to 60% higher this is because we are not spoiling the flow on the upper surface we are only creating a deflection of the flow on the downward surface as compared to the plane flap. If you have a slot in the flap then you are allowing the air from here to actually go and flow over it so you can get slightly higher you can get maybe 65% higher value of the CL. And if you use a fouler flap in which not only does the flap deflect down with a gap but also moves backward resulting in an effective increase in the surface area then you can almost double the CL lift coefficient up to order of 1.9. And if you have a basic wing section like this if this is the lift cover of the basic wing section using a flap is going to lead to a parallel line and at all angles is going to affect the increase in the lift. Similarly if you look at the CD versus CL curve so if you have a basic wing line as shown here then you go for a tilt when you include flaps in the aircraft. Now if you want to sequentially look at the effect of different type of flaps so if the basic aerofoil you know this is the same information but now placed in a more detailed fashion. And as I mentioned the fouler flap can lead to almost 90% increase in the lift coefficient. Notice that these are only approximations because the actual increase depends on the geometry of the aerofoil also. If you go further and if you start putting now slots in fouler flaps you can go for higher increase. Let us look at now some leading edge devices so by using a Kruger flap which is basically a flat curved plate with some kind of a rounded leading edge you can get 50% if you put a slot you get 40% a fixed flat with a gap in between can give you around 50% increase. And as you keep on moving and as you keep on increasing the complexity of the system you get more and more benefits. For example if you look at this configuration where you have a flat and you have a double slotted fouler flap you can get around 120% increase in the lift coefficient. But this is basically a complicated system so you have to be careful about use of flaps because improvements do not come without any problem. Improvements always come with some kind of a compromise. So this table sums up the typical values of the maximum lift coefficient. So if you do not have the actual data available and if you just know the type of the flap for example if you are told that the aircraft is using double slotted flaps and slats you can just use this value as a good starting value to calculate the to estimate the lift coefficient. This graph from Reimers textbook shows two things. It shows that different flaps types have higher values of CL max and also shows how these values reduce with the increase in the quarter chord sweep. So you can use this graph for wings of moderate aspect ratio only and with this graph you know you can probably get something like if the sweep is 40 degrees and if the flap type is fouler then you can get the value of CL max that you can take from the graph. Thanks for your attention. We will now move to the next section.