The principles that KSP teaches are correct except for the bit where in KSP you're only under the gravitational influence of one body at a time, which doesn't m

The principles that KSP teaches are correct except for the bit where in KSP you're only under the gravitational influence of one body at a time, which doesn't matter for reaching orbit. The specific numbers in the KSP parts are totally fudged to make the game more fun but parts with those numbers would work like they do in KSP if they existed. For instance in real life jet engines have a lower thrust to weight ratio than rocket engines. EDIT: But you can download the realistic solar system mod to get a sense of what real world thrust ratios and orbital delta-v is like. And Children of a Dead Earth has multi-body physics for Lagrange points and so on.