I have a bizarre situation with my latest SSTO. It's basically laid out like the Ravenspear Mk4 (stock) with a central body and two outrigger engines, the major difference being the outriggers are separated and supported by 'chime' wings along the central body and I am using Rapier engines. The central body has 2 engines and the outriders have 1 apiece, and each section has an equal amount of Fuel/LOX to support each engine (the center has twice as much fuel as it supports 2 engines.) and some extra fuel in each section for the air breathing part of the mission. The setup works great during the air breathing section of the mission, as each section uses the spare fuel provided there for same. My problem starts after the engines switch to closed cycle, the center uses all its oxidizer (while ignoring the Fuel), and the outriggers use the Fuel up (while ignoring the Oxidizer), and as there is some extra fuel in each section the center engines cut out first (for lack of oxidizer) while the outriggers keep running thanks to the spare fuel from the air breathing part of the mission. There are no fuel lines between the sections, so how the heck is this happening, and how do I stop it?! Thanks for any reply.