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Showing results for tags 'consumption order'.
I've encountered what seems an odd phenomenon, that has helped strand a Kerbal in Munar orbit, without a ship. Here's a craft file: Selene 1 Mod 2 I launch this ship with RCS turned off, using main engine gimballing for control until staging. Once I stage away the booster, fairing, and nose cone (above 70 km only due to a spectacular demonstration of the drag still present at 40+ km and 1000+ m/s), I turn on RCS so I can maneuver before igniting the second stage engine to circularize (the second stage also performs transMunar insertion and Munar orbit capture before being deorbited on the Mun). This is where the odd thing happens. It takes a lot of RCS authority to turn the remaining stack at this stage (initially, with full tanks in all modules), and the center of mass is far enough forward that the Lf/O thrusters on the second stage tank get a lot of help from the four sets of RCS quads on the lander and pusher stages. However, the RCS on the lander and pusher stages don't consume fuel evenly from the command pods and RCS tanks, despite crossfeed being enabled on every decoupler and stack separator. Rather, the lander's RCS fuel is depleted first, with the command pod being emptied before the stack RCS tank is used, and both of those being burned dry before any fuel is drawn from the pusher (top module at launch). This doesn't seem to be a case of the game drawing propellant from the lowest tank first, which would make some sense for the usual staging order; rather, the command pod fuel is being depleted first. The only solution I see is to remember to manually disable the command pod and stack tank feeds before launch, and then manually re-enable them before I'm ready to decouple the pusher and turn it around to dock with the lander (a la Apollo, which is the configuration I adopt before Munar orbit insertion so the pusher is ready to maneuver itself and the lander as soon as the second stage is jettisoned). Am I missing something relative to propellant consumption order? I think this is the first time it's really matter which tank empties first -- but this time, it led to a Kerbal launching from Mun without enough RCS propellant left to assist when the main engine's tanks ran dry before establishing orbit. The pusher pilot, meanwhile, was sitting in a safe orbit, with a nearly full RCS tank, and no way to help...