Marijn
Active member
Hello all,
I want to calculate a pressure-dependent isp for use in my spreadsheets. The formula is given on page 437 of the API_Reference manual:
Isp(p) = Isp0(1 - pn); Th(p) = Th0(1 - pn); where n = Isp0 - Ispref / pref*Isp0
When sitting on the runway, I assume 'pref' corresponds to the pressure at sealevel corrected for terrain elevation.
Isp0 is the isp in a vacuum. But I can't figure out what 'Ispref' stands for.
Any help? I want to calculate the value which is displayed by BurnTimeCalc when sitting on a runway for different bases [on different planets].
thnks.
I want to calculate a pressure-dependent isp for use in my spreadsheets. The formula is given on page 437 of the API_Reference manual:
Isp(p) = Isp0(1 - pn); Th(p) = Th0(1 - pn); where n = Isp0 - Ispref / pref*Isp0
When sitting on the runway, I assume 'pref' corresponds to the pressure at sealevel corrected for terrain elevation.
Isp0 is the isp in a vacuum. But I can't figure out what 'Ispref' stands for.
Any help? I want to calculate the value which is displayed by BurnTimeCalc when sitting on a runway for different bases [on different planets].
thnks.