 These are the challenges. Now, we will move to the sizing optimization of the these type of systems in a initial sizing basically in conceptual stage. So, because challenges that you have to take care of all the different aspects of the affecting parameters simultaneously. So, the requirement of there is a design methodology requirement. So, requirement should be such that whenever we feed the operational parameter or design parameter like wind speed because wind speed at that height will be different and even for the it will be different for the different lat long at some the same height say about 20 kilometers the wind speed at the Mumbai will be different from Delhi. So, it should be should we should consider that. So, the radiance will be different at the different location whenever we will talk about altitude latitude and longitude. So, each location at that height will be different power available will be different that will affect our the whole systems because if power available is high you will need a lesser solar cells will need a lesser power storing device. Geometric coverage ratio what is geometric coverage ratio can anybody tell geometric coverage ratio any guess no guess. This simply a ratio of something coverage must be a area. So, the ratio of two areas which are that is simple at basically two areas we have to consider envelope areas and another thing is the solar cell areas area. So, because envelope area will in affect the our structural mass and solar area will affect the power output. So, it is basically a ratio of solar area divided by the area of solar area divided by the envelope area that is called a geometric coverage ratio. Discharging time is the time when the power that power from sun is not available and you have to supply power from the battery that is the discharging time which will be a larger in winter and will be a smaller in a summer and it will vary around the globe due to the latitude and longitude ok. Now, office tender temperature because temperature that height will affect the buoyancy as well as the power output and purity of LTA gas to affect the buoyancy and efficiency of cells that is another major research area as general because the highly efficient solar cells will result a very low system weight. So, it is how much maximum efficiency is nowadays we get a form solar cells any guess maximum efficiency of the solar cells 20% it is 8 to 10% local people are researching in their claim they have claimed that 40-45% so it will be a big search output you know the significance of efficiency so also efficiency to light up a single bulb you will need a larger solar area because larger solar area it will accumulate and 8% of that will be converted and it will light up. So, if the efficiency is high see it is about 100% and the output is how much 500 watt per meter square. So, if we place a 1 meter square we will get a 500 watt but the 8% of that actually a problem. So, a big solar plate is required to light up the small lantern at night. So, the metallurgy requirement is this and it should be such that at the end while we give the payload requirement as well as the power requirement should give the size of airship what is the required size to overcome that payload as well as to power it metallurgy design should be able to give and most feasible shape for different requirement the shape will be different it will vary as I said earlier for the if the power is more power input is more and it is more important then it may might ends with some another shape maybe a 3D because when you will consider only power requirement what type of shape you will proposed any guess suppose we have to bother only about power how we can maximize that power output maximum area but maximum area with the different location orientation will not result a maximum output. So, it should be such that that at over the day the vector of the normal area vector of the profile of the it should be with the 0 degree angle ideally with the solar radiation angle get the point. So, it should be such that at each time it should be the 0 degree and you will get a maximum output otherwise cos theta is involved and it will bring down larger the cos theta minimum will be the output irradiance at least input so, but there is another problem as well drag. So, we have to take care of drag as well we have to take care of payload as well. So, what will be the optimum shape which will maximize the power output as well as payload output payload available payload as well as the minimum drag. So, the shape should be like that and what will be the different mass component with the different mass of the different component like a propulsion systems mass and a structural weight and storing energy battery weight it should be able to give design methodology should be such that. So, basically sizing methodology proposed that we can see it start from here and give some for the given payload and power requirement give some random length and calculate with the given parameter because the location you know and at that location you know that at the particular time as well because over the time over the date it will vary. Suppose at today is the what date of April the energy available at that height in Mumbai it will be different when we consider at some other date. So, for a given location and date the wind speed is available irradiance available temperature pressure and from that we have to calculate all these systems volumes and the volume will drive the payload and other in surface area with the size and surface area of ship will lead to the drag and as well as systems weight and we have to finally check whether the power requirement is met or not and if it is not then you have to go back and change the length and payload and power check both should be fulfilled otherwise you have to go and change the length do the iteration and if all the power requirement of payload are met then end with the calculation that is for initial sizing it is not in optimum sizing. So, for simplicity we can look at this problem. So, suppose this is actually a in pill shape given by the two parabola you know in pill shape how in pill shape is defined how in pill shape is defined as you say some shapes of the airship you know different shapes of the airship a standard shape profile there are some standard profile of the airship normal airship Gen V are W so it is actually a in pill shape it is a combination of two half ellipsoid with the same minor axis and different major axis. So, here this is different from these length same major axis and it is basically a ratio of root 2. So, we consider that and this is the area required suppose the XF is the final position of the solar cells and XS is the start position. So, the length is will be XF minus XS and angular coverage is zeta rA zeta all psi what used to say. So, whatever this so the angular so complete area can calculate. So, let us these are the design variable a b b is the radius of the airship at maximum diameter a is the same major axis and when you will multiply with a root 2 it will give the other side area length and so 1 2 3 4 and when you add a plus root 2 a it will lead to the L total length of the airship and the psi. So, 5 basically a 5 design parameters a b and zeta rA and XS and XF. So, these are the initial values for initial we have get from initial design now we have to optimize because the location will put XS and XF will affect the output we have to maximize that and coverage how much coverage will be required to fulfill the power. So, for initial sizing what you have said in the design this is the parameters for initial sizing. So, to fulfill the power requirement and payload requirement you will need a length of around 200 meters and with these types of this angle starting and ending total length of the solar cells and the other output parameters for initial sizing you can see for these are the input parameters the other output parameters. So, payload mass of 1000 kilometer 1000 kg and payload payload power of 1 kilowatt the these are these calculations are made and what we are getting is you can see the size of to produce such payload and as power you will need around 137 or 138 meter length of the airship and the thrust and the power required to overcome the thrust will be 31 kilowatt and the mass breakdown as I said a methodology should be able to give the mass breakdown of the systems. So, you can see around 50% of the weight is of the systems is due to its structure that is why the problem whenever we will decrease the GSM with the keeping the same strength it will give a better good result, good output and the storage weight is around third of the total systems it is another problem. So, when will we maximize the storing capacity of the RFC or lithium ion battery it will minimize that it will lower the systems weight and we will get a higher payload. So, these are the sensitivity analysis how different output parameters will be driven with the changing change of the input parameters that is actually a sensitivity of design parameters. So, you can see this is the weight percentage weight due to the RFC and the solar cells. So, whenever we will increase the energy density of RFC that means it can store same energy with the lower weight itself its weight that is the better. So, whenever we will increase the density capacity of RFC the percentage weight of the system will go down this 10 times you can see. Are you able to see this? No, and another thing is the when efficiency of the solar cell will increase the systems weight will go down you get the point systems will weight will go down. Now, see the variation of buoyancy with the length this is the weight of airship and this is the length variation. Are you able to see? No, I should have designed the light background. So, you can observe one interesting thing is that there is a minimum length of the airship required to overcome its own weight and below that length the system will be it will not even overcome its own weight and you have to get extra payload to carry the systems and other systems that is interesting. And another variation is that as simple volume with the payload with the volume as the payload is given by the volume and this is a linear relationship between the payload and the volume. So, move on to the next slide we see the effect of wind speed how much it affects at that height it is for 10 to 25 meters per second for the same size of airship say around 500 length and we are getting a very low drag and when the wind speed will increase to 25 meters per second the drag is about 8 volts that is the significance of wind speed and because the very big size and it is directly the half rho v square right now half rho v square it will go x square with the velocity to overcome the power and because power is required to propel the airship to withstand with the drag and to fulfill the power requirement by the payload. So, there is a minimum requirement of the length or size of the airship which will actually fulfill the power required. So, below that a length around 175 or 190 meters system is underpowered. So, now this earlier it was results for initial sizing and now we have to optimize we put the systems methodology in optimization to get the best result. So, the formulation is such that total mass we have to minimize the total mass of the systems while fulfilling the requirement of payload as well as power required. So, for the baseline case when we have not considered the optimization the baseline case was these for the same power requirement or payload requirement or after optimization we are getting this. So, the change we can see actually the purpose of optimization. So, are you getting our I think you are getting bored not you are not getting a point. So, it is almost so on the last site it is not the least but in last year we have seen in times of India about the high altitude airships. So, research are going on over the globe and it is a very potential area. So, that was talk. Thank you.