The paper describes the methodology of DLR's tools for rocket engine systems analysis. The holistic approach begins with a component based cycle analysis. Parameter variations are performed in order to select the engine reference case. After selection of suitable engine parameters the derived engine performance is used as basis of a high level launcher analysis.The paper provides a detailed description of the tools and the implemented methods. The paper then discusses different variants of open loop cycles. Different propellant combinations are compared and parametric variations of mixture ratio, chamber pressure, and nozzle expansion ratio are performed. Following the engine cycle analysis a launcher trajectory analysis is performed to evaluate the engine concept in terms of achievable payload masses. A generic space launch system is used as baseline for this evaluation.