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[null,null,"What-If Spreadsheet for Latex Balloon with non-elastic constraining outer canopy"]
[]
[{"$nulls":5},"NASA 1962 Atmospheric model – for float height",{"$nulls":7},"at 0C,101 kPa"]
[{"$nulls":5},"Air Density (Kg/m^3)","Air Pressure (kPa) ","Air Temperature (deg K)",{"$nulls":4},"Gas","density Kg/m^3","Molar Mass g/mol"]
[{"$nulls":5},0.03994550567765412,2.482773599017005,216.64000000000001,{"$nulls":4},"Hydrogen",0.08990000000000001,2.01588]
[null,null,"Inputs in Green Cells",{"$nulls":9},"Helium",0.1786,4.002602]
[null,null,"Payload weight (Kg)",1,null,"The weight of the payload mass to be carried by the balloon",{"$nulls":6},"Air",1.205]
[null,null,"Latex Balloon Weight (g)",1700,null,"The weight of the inner latex balloon (typically 10% greater than its balloon size)"]
[null,null,"Desired Float Height (m)",25000,null,"The desired float height for the balloon+payload combination",{"$nulls":6},"R – universal gas constant m^3.kPa/mol.K"]
[null,null,"Thermal Gain (deg C)",20,null,"The estimated temperature of gas inside the balloon above local atmospheric temperature",{"$nulls":6},0.008314472]
[null,null,"Lifting Gas","Hydrogen",null,"The chosen lifting gas"]
[null,null,"Lifting gas Density (Kg/m^3)",0.08990000000000001,null,"The density of the lifting gas at 0C 101kPa (from table)"]
[null,null,"Lifting gas Molar Mass (g/mol)",2.01588,null,"The molar mass of the chosen lifting gas (from table)"]
[]
[null,null,"Mass excluding gas at Launch (Kg)",6.894813180115225,null,"Weight of Payload + Balloon + Fabric"]
[null,null,"Free Lift at Launch (Kg)",0.9,null,"The free lift is the amount of extra lift to make the balloon ascend at the desired rate"]
[null,null,"Gas Volume at Launch (m^3)",6.990236911591091,null,"Gas volume needed to lift Payload + Balloon + Fabric + Free Lift"]
[null,null,"mols of gas (mols)",311.7359656090834,null,"The amount of gas in mols (needed to calculate internal pressure)"]
[null,null,"Internal gas pressure at float (kPa)",3.256664425977358,null,"The gas pressure inside the balloon at float (P = mols * R * T/ Volume)"]
[null,null,"Differential pressure (kPa)",0.7738908269603533,null,"The difference between the internal and external pressures at float"]
[null,null,"Tension in fabric + balloon (kN/m)",1.375938807300316,null,"Calculated tension assuming spherical shape (based on spherical surface tension/hoop stress equation)"]
[null,null,"Material strength (kN/m)",4.3,null,"The working strength of the constraining envelope material – must be significantly more than the tension in the row above"]
[null,null,"Fabric weight (gsm)",22,null,"The constraining envelope material's weight in grams per square meter"]
[null,null,"Fabric total area (sq m)",158.89443864072825,null,"The surface area of the balloon assuming a sphere. (A = 4 * PI() * r^2)"]
[null,null,"Mass of Raw Fabric (Kg)",3.495677650096021,null,"Raw material weight of the envelope based on the surface area and fabric weight (gsm)"]
[null,null,"Fudge Factor",1.2,null,"Factor to allow for seams/joins in fabric."]
[null,null,"Envelope Mass (Kg)",4.194813180115225,null,"Estimated envelope weight based on raw fabric weight and fudge factor"]
[null,null,"Radius at float (m)",3.555898995998323,null,"Radius of the balloon to give float volume – assuming spherical shape (r = cube_root(V*3/(4 * PI()))"]
[null,null,"Balloon Diameter at float (m)",7.111797991996646,null,"2 x Radius- must be significantly less than the latex balloon burst diameter"]
[null,null,"Balloon volume at float (m^3)",188.3374700317245,null,"The volume of air the balloon must displace at the float altitude to equal the mass of the Payload + Balloon + Fabric + Gas"]
[null,null,"Total mass at launch (Kg)",7.523235478467264,null,"Calculated mass of the Payload + Balloon + Fabric + Gas"]
[]
[]
[null,null,"This spreadsheet is a what if calculator for a Super-pressure balloon comprising an inner latex balloon with external constraining fabric envelope."]
[null,null,"The sheet allows calculation of internal and external pressures and hence tension in the balloon envelope & fabric."]
[null,null,"You may enter values in the green cells"]
[null,null,"The values in red cells are calculated from the values you enter in the green cells."]
[null,null,"Things to ensure viable solution:"]
[null,null,null,"Balloon diameter << latex balloon burst diameter"]
[null,null,null,"Surface tension << Material strength"]

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