No abstract

A geostationary stratospheric airship is lighter than air (LTA) platform to be used for several civil and military purposes. In this study, the impact of Helium permeation through the hull and ballonet skin is considered. Mathematical modeling of the system is being done to estimate the amount of helium and air transmission through the hull and the ballonet skin for a general airship system. Impact of permeation mainly affecting its ability to withstand gushes and also to maintain constant altitude is also shown in this study. A method is also devised so as to develop an open loop control system to maintain the altitude of the airship by maintaining the weight of the airship as constant. Both the cases with and without the altitude control are simulated by numerically solving the model using RK4 algorithm. The results obtained are discussed and appropriate conclusions are drawn from the analysis. = area 1 = hull skin area between region 1 and the atmosphere 2 = ballonet skin area in between region 1 and region 2 3 = hull skin area between region 2 and the atmosphere = flux of gas through membrane in m 3 /m 2 /day or moles/m 2 /day = proportionality constant = effusion constant of helium = effusion constant of air 1 = permeability constant for helium for hull skin material 2 = permeability constant for helium for ballonet skin material 1 = permeability constant for air for hull skin material 2 = permeability constant for air for ballonet skin material = molecular weight of air = molecular weight of helium = moles ℎ , = moles of air in region 1 in hull at time t , = moles of air in region 2 in ballonet at time t ℎ , = moles of helium in region 1 in hull at time t , = moles of helium in region 2 in ballonet at time t 1 = moles of gas on side 1 of the membrane 2= moles of gas on side 2 of the membrane = gas pressure = atmospheric pressure = differential pressure across the hull 2 1 = gas pressure in region 1 2 = gas pressure in region 2 1 = partial pressure of gas on surface 1 of the membrane 2 = partial pressure of gas on surface 2 of the membrane = gas constant = gas temperature = time = gas volume = total volume of the airship including hull and ballonet 1 = volume of gas in region 1 2 = volume of gas in region 2