BaBene

Ah, so it's really just I'll use that for my equations and see what happens, thank you very much (Maybe someone should put this formula in the wiki?) Best Regards BaBene

Ok, do you have any more details on the actual function? Where is the upper end of the altitude at which the ISP reaches it's maximum value? How do you know its linear? Observation or do you have any source for this? Thanks and Regards BaBene

Hello, I'm currently working on a little program which outputs detailed information of the flight trajectory of my rocket. It's basically just numerical solving of the differential equation composed of all the forces affecting the rocket. During the creation of the differential equation I've come across a problem relating to the specific impulse. As most of you know the specific impulse is not constant for all altitudes, reaching it's maximum in vacuum. So my question is what is the specific impulse as a function of atmospheric pressure / density? I searched the wiki and forums but haven't found an answer as all calculations presented in the wiki use the ISP at sea level or in vacuum for the sake of simplicity. I wasn't sure where to ask this question but i hope i used the right forum Hope that someone has an answer to this question. Regards BaBene