Exoscientist

Hello, newbie here. I have some spacecraft proposals that I want to create simulations for that I discuss here: The Coming SSTO\'s. http://exoscientist.blogspot.com/2012/05/coming-sstos.html How do you use the kerbal program to simulate a space launch? Also does kerbal have accurate trajectory calculators where you can get a good idea about how much payload your rocket can get to orbit? Thank You, Bob Clark