 So, now we have come to a stage where we look at the various elements of the methodology. I thought this time I will go box by box because last time when I discussed the airship design methodology, I showed you the whole thing and I saw the effect of that in the examination. Very few people were even able to name correctly the elements and what they do. Some of you could name what the elements are but you could not explain what they do. Only one of those students have been able to answer that question correctly. So, I thought this time I am going to go slow. First thing is we start the process and the first block is the input block. In the input block, the values of design constraints, the input parameters are all red so that the methodology can start doing its calculations. Then first thing we do is we use the aerostatics calculation formulae using the ambient temperature, ambient pressure, density of the gas, density of the air. Then there are other things like the effect of humidity, effect of super pressure, effect of lifting gas purity. All those calculations are coded in this particular box so that for any operating condition you are able to get the correct values of net lift available okay. So, this I do not want to repeat, we have already spent probably 3 or 4 classes in looking at all those details formulae right. Once we do this, we now say okay, we have to assume a particular shape. This methodology works only for a given shape. So, let us say we have chosen the shape to be sphere. So, okay, for a sphere, we assume a particular dimension. So, it will be diameter because diameter length are same for a sphere. If you use a shape like GNVR or something else you will say okay length, so GNVR shape of length L equal to 2 meters. You start with some number. With that number and with the geometry of the envelope, you can get the envelope geometrical parameters like max dia, surface area, volume for that particular envelope. Then using the data available regarding the atmospheric properties and the net static lift available under the operating conditions, you can calculate the volume of the ballonet and assuming now in arrow steps we never have 2 ballonet because there is no need to trim. Why not? Because you have a confidence point, it will automatically trim to a particular angle as you will see very soon. So, no need to have 2 ballonet. You normally have only one in the center. So, once you know the volume needed to meet the static, aerostatic requirements, you can calculate the geometry of the ballonet and hence its weight because the weight per unit area of ballonet material is also known to you, you have chosen the material based on available information. Next thing that you do is you locate the confidence point. So, how do you do it? You can say equal to diameter from the nose and diameter below starting point. So, this is not the end point, it is a start point. Once you do that, the next thing is I now know the confidence point location, likely position or the desirable position or I should say the first estimate. I also know the operating height, I know geometry hence the aerodynamics of the data of the envelope. So, I can do the profile calculation which I will demonstrate to you after some time. So, with this you will come to know the actual length of tether needed under the operating condition. Then we carry out fin sizing. So, again for that there is a procedure. One procedure is the fin shape is fixed and look at aerostats which have been designed and they are stable, work out the distance between the aerodynamic center of the fin and the center of the pressure of the envelope and use that to get the relationship. You can scale up or scale down the existing fins or you can do it in the more elaborate method. So, now that you know the size of the fins, therefore you know the fin weight, you know the ballonet weight, you know the tether weight, you know the self weight. So, you can get weight of each component of the aerostat, balance weight will be payload. And remember we have to keep free lift, 15% or whatever number you assume. So, you will come to know how much is the payload which I can carry. Now if this particular thing is meeting your requirement, you stop. If you find that the payload required is 300 kg but what I am getting is only 50 kg, obviously I must increase the size and vice versa. So, you adjust the envelope length as needed, go back and keep on iterating till you come to a convergence for your payload. Everything is clear? So, the same as the energy is now shown in one shot with small variation here. You can do little bit of alteration inside on the confidence point location also which I will elaborate to you.