cool, i am going to need some help with this one though.... and I apologize in advance, but I will not be able to reply for several days, so for now i will remove my "patch" from kerbalstuff. here is what I have thus far and will be testing for tonight (nov-25) and will add to kerbal stuff once it works.. @PART=[rapierEngine] { @description = The R.A.P.I.E.R. (Reactive Atomic-Propellant Intelligent Engine for Rockets) is a joint venture between C7 Aerospace and the Rockomax Conglomerate. Designed to fill a gap in the design requirements for sustainable single stage to orbit aircraft, this engine combines the best of rocket and air-breathing thrust technology. @MODULE[MultiModeEngine] { @engineID = AirBreathing { !PROPELLANT[LiquidFuel] } @engineID = ClosedCycle { @atmosphereCurve { key = 0 730 key = 1 120 } } } EDIT: I am stuck trying to change the atmos-kurve of the closed cycle engine and do not know how to get MMM to identify and change the varibles. anyone have advice?