I've completed a few successful missions to Minmus, and have always had more than enough fuel to return safely to Kerbin; however, I feel that I could perform the transfer burns better than how I'm doing them now. While it's hard to reduce my fuel load for the upper stages, reducing the delta-v requirement dedicated to the upper stages means I can afford to spend it earlier, meaning I can shed some fuel from my lower stages. My current rocket design has a bit of a weight problem, so if I can cut just 2000 units of fuel, that would be great.
So, if using a Hohmann type transfer orbit, when should I start the burn in order to reduce the overall delta-v requirement (assuming my inclination is correct and that I initially orbit Kerbin at around 125km) for both Mun and Minmus? Should I even bother with trying a low energy transfer, utilizing Mun to get to Minmus?
Best Answer
No. Minimus has an eccentric orbit. Attempting to gain a gravity assist from the Mun that will provide the exact normal/antinormal force to end up in a good Minmus encounter at the exact right point of it's orbit will require some very exact calculations.
The most efficient way I know of is to match the orbital inclination before making the injection burn. From a parking orbit of approximately 100km this just happens to be as it rises over Kerbin.