 end by looking at some landing gear of famous aircraft and try to familiar ourselves with their functioning. This is the landing gear of the F-22 aircraft. You can notice here that the landing gear is short and compact and as it retracts inside you have this conformal cover that will fit into the geometry and make the whole aircraft fuselage very much smooth to avoid drag. Here is the main landing gear of the Fokker F-27 aircraft which is now obsolete. It had long main landing gear struts with no side braces. So these were the landing gear struts which are quite long because it was mounted on the wing and the wing was a high wing. So on a high wing aircraft where the wing is above the fuselage when you mount landing gear of course they mounted it below the engine but still it was an example of a long main landing gear strut with no side braces. On a BI-146 aircraft you have to provide landing gear on the the landing gear on the fuselage because it is again a high wing aircraft and when you have turbo fan engines mounted on the wing then mounting the landing gear on the wing becomes a serious problem what we saw in F-27 was an exception. So in this case you have the landing gear mounted on the side of the fuselage but you need to have minimum some minimum wheel tracks so that you can get the where you can avoid the tip off. So therefore you have to have landing gear which is coming out of the fuselage and then when you retract it inside then you require a small blister. So you can see this is a blister in which the landing gear gets compacted and this is the covering for the blister so that the drag is minimized after the landing gear is retracted. The same covering can be seen here also. Let us look at the landing gear of an aircraft called as the Watt F-4U Corsair. This particular aircraft had engines embedded in the root of you can see there is some intake here and in this case the main landing gear retracts rearward into the wing so it goes back. If you look at the DeHavilland-Kalbu aircraft this has got a gull wing configuration and on the gull wing configuration because the landing gear is mounted below the engine and it is a gull wing so therefore you tend to reduce the strength the strut length of the olio strut on which landing gear is mounted. This is the landing gear of Airbus 380 you can see that there are four main legs there are two on the fuselage on the side and there are two on the wings. So there are 20 wheels in total there are six wheels on each of the main legs on the fuselage so 12 wheels here and then there are four wheels on the main landing gear leg which is in the wing. So on each side you have six plus four that means you have total of 20 main landing gear legs and then you have the nose landing gear also which has four wheels. If you look at the landing gear of AN-125 Ruslan aircraft this is a very interesting aircraft it is a cargo aircraft for transporting cargo over long distances so the nose of the aircraft completely bends up and you have as you can see five pairs of landing gear legs on the main landing gear and on the nose wheel you have two pairs on two nose wheels. Now this particular landing gear we can adjust the length of the struts so that the aircraft can be made to mill and that allows easy loading of cargo you can see in this configuration there is a ramp here and you just drive in with the cargo. Then let us look at the monster the largest aircraft that we have seen AN-225 Maria it is one step ahead from the Ruslan it has got seven pairs of main landing gear you can see there are seven pairs and you know in the nose also you have several landing gear. So seven pairs of main landing gear two pairs on the nose wheels two pairs on the nose wheel and you can adjust the pressure of each tire on the main landing gear and you can also retract or extend the each individual struts which allows you to change the tire. Finally we look at the landing gear of Boeing 787 and you can get an idea about the size by comparing with the person here and this particular video will show you how the testing is done. Okay thanks for your attention.