 Now ground handling basically is important because of ground movements. So what you do is you attach the airship to some device which can allow it to move forward. It could be by hand for small airship or it could be by some kind of a vehicle if it is not manageable by hand. The need is because it is not so easy even if you have to move a small airship from let us say our department at Jumkhana ground and if the airship is already inflated it is not easy to move it. First of all where do you hold it and how do you ensure that while pulling it you do not tear the envelope. So it is not an easy task and the forces acting on the envelope are extremely large because of the large size which is almost giving as a projection to the side flow. So one important aspect of ground handling is what is, I mean a lift off recovery. So what you do is you support the airship before it reaches the normal operating altitude H OPS and the cruising speed. So till that time you have to support the airship. So one way of doing it is called as a rolled takeoff technique which is like an aircraft. So instead of you know releasing the airship you can allow it to take off like an aircraft. So it will have a rolled takeoff and then it will build up. So what will happen is because of the huge aerodynamic body if you move against the wind at some speed you will get aerodynamic lift. That aerodynamic lift will overcome static heaviness and when it overcome static heaviness you will be able to leave the ground. So a short distance of may be 100, 200, 300 feet the airship can take off rather than providing it aerostatic lift extra or by you know always having to swivel the engine which is also one way of takeoff and we saw that film where the zapper in the engine was able to take off vertically by tilting the engines. Now effect of size, size definitely affects a lot and if it is smaller it is easier to operate it and it adds to the weight of the airship because of that it is very difficult to move it around. So now let us see another video. This will tell you how many people are needed on the ground. This is Hindenburg airship LZ129. You can see now the airship is slowly up look at the grass blades which are moving you will get an idea about the wind. So it is not still condition it is little bit windy you can see the grass blades are moving and here is the airship there it comes. So try to count the number of people in the ground. This is nothing but still this is not the complete lift here there you go this is on one side. On one side on one hook then you have on the nose because it has to be brought and attached to the mast there you go. And on the mast this is a huge mast. On that mast there are people who are attaching the airship to the mast slowly. So they are virtually pulling the airship and you see there is a big drum on which it is being attached and this person with the megaphone is talking to the people on the ground. This is the communication at that time he is telling them do this do that move back move forward okay. So this is what was needed in the past okay. I would like to now show you what is needed today and for that I will again repeat that video which I had shown last time. Now you can count the number of people in the ground. There will be just one central mast man and three people. This is what definitely empty claims round handling by only three people in the ground. Because here the two engines on the side and there is one on the back not visible that is used to provide the required forces. Employing so many people at every location where we will take off and land is a very expensive proposition and that can increase the cost by a large amount. So that is why one of the contributions of Zeppelin empty design is to make the airship completely free of ground handling by so many people. Only three people are needed on the ground. So the mooring mast there are many types one could be called as a single point mooring. This is what you saw in the previous video the airship is moored at just one point at the nose attached to the mast. The mast is supposed to withstand all the loads coming on the airship in all directions and the airship simply aligns with the wind when attached to the mast. So there is a 360 degree freedom in yawing but in roll there is a limitation and roll forces are not expected too much on the airship. Now for low speed control we normally use power plant thrust. So the force of the power plant can be used to provide this low speed. Only people suggested using vector thrust. But vector thrust is very expensive to provide because then you have to go for very special kind of mechanisms on to the engine. It increases the cost and the complexity of the engines. But if you can achieve it such as in Zeppelin empty it can really be used to get rid of many people needed on the ground. And some of the engines can also give you reverse force. So you can actually tilt it and give it. So the thrust vector can be vector from 0 degree which is forward to 90 degrees downwards to 120 degrees and in that case it will move back. So it can be used to give forces in all forward and backward direction. Now to maintain the forces acting on the airship during the mode condition you have to understand first of all what are the causes of these forces. Of course the inertial force of the airship which is coming because of the airship itself. And then you have steady wind flow so that will create a drag force. And then you have turbulence which keeps disturbing it. So this is a paper which came up in 1997 about a new airship ground handling system which they say really works. And this has come from a company called TCOMP which is one of the most ancient companies in the world which makes terroir aerostat systems really large systems. So TCOMP LP is a very good company in the US making aerostats and there is this company called Zeppelin NT which makes airships in Germany.