Propulsion Systems Definition for a Liquid Fly-back Booster

This paper describes the final design status of a partially reusable space transportation system which has been under study for more than five years within the German future launcher technology research program ASTRA. It consists of dual booster stages, which are attached to an advanced expendable core. The design of the reference liquid fly-back boosters (LFBB) is based on LOX/LH2 propellant and a future advanced gas-generator cycle rocket motor. In focus are the four different propulsion systems and the main propellant feed and pressurization system

Systemanalytische Untersuchung einer Brennkammer in faserkeramischer Bauweise von Raketenantrieben

This work describes an analytic model for evaluation of expected effects of the use of ceramic materials in the construction of rocket engine thrust chambers. An engine of a thrust level around 1500 kN is defined and analyzed. The engine analysis makes use of the DLR tool LRP, which calculates sequentially the changes of fluid properties within the components of a rocket engine. Iteratively the solution fulfilling specific constraints is reached. Varied parameters are among others: chambers mixture ratio, chamber pressure, expansion ratio and coolant mass flow. This report describes the assumptions on which the model is based and lists the equations and methods used to represent the relevant relations of physics

Systemanalytische Untersuchung einer Brennkammer in faserkeramischer Bauweise von Raketenantrieben

This work describes an analytic model for evaluation of expected effects of the use of ceramic materials in the construction of rocket engine thrust chambers. An engine of a thrust level around 1500 kN is defined and analyzed. The engine analysis makes use of the DLR tool LRP, which calculates sequentially the changes of fluid properties within the components of a rocket engine. Iteratively the solution fulfilling specific constraints is reached. Varied parameters are among others: chambers mixture ratio, chamber pressure, expansion ratio and coolant mass flow. This report describes the assumptions on which the model is based and lists the equations and methods used to represent the relevant relations of physics

Konzeptstudie eines lunaren Transportsystems mit Nutzung von In-Situ Sauerstoff als Oxidator

Die vorliegende Studie beinhaltet einen Überblick über Nutzungsszenarien einer zukünftigen bemannten Mondbasis. Ein Transportsystem zur Überwindung von längeren Distanzen auf der Mondoberfläche wird skizziert. Diese Konzeptstudie beschäftigt sich mit einem Transportsystem, welches den lagerfähigen Brennstoff UDMH (Unsymmertrisches Dimethyl Hydrazin) mit dem aus Mondgestein gewinnbaren Sauerstoff als Treibstoffkombination verwendet. Ein Triebwerk mit dieser Treibstoffkombination (LOX/UDMH) kann mit Sauerstoffüberschuss betrieben werden, ohne wesentlichen Leistungseinbußen im Vergleich zu einem mit Brennstoffüberschuss betriebenen Triebwerk. Das vorgeschlagene Triebwerk wird aus poröser Keramik gefertigt, bei der die Wand transpirativ mit Sauerstoff gekühlt wird

Gas Generator Side-Flow Balancing in the Frame of Engine Cycle Analysis

The paper describes the methodology of DLRs new engine cycle analysis tool. The tool KOBRA, which is currently under development, is built on a heritage of cycle analysis software. Compared with its predecessor (LRP), the aim is to improve the component models, especially for turbomachinery and piping. The calculation of combustion processes and general uid properties shall also be improved, providing the user with more options and a wider selection of propellant combinations. In a text input �le the user de�nes the arrangement of the engine components. Changes in fuid properties are sequentially calculated in order of propellant flow direction. Components are linked by user specified constraints and subjected to automatic component parameter variations in order to obtain solutions for steady state nominal engine operation. The paper brie y presents the tool and the implemented methods. The side-flow, which is the exhaust of the gas generator and drives the turbines, is analyzed in terms of mass ow and required gas generator temperature. Parametric variations of gas generator mixture ratio and main chamber pressure are performed

Analysis of Coolant Mass Flow Requirements for Transpiration Cooled Ceramic Thrust Chambers

The long-term development of ceramic rocket engine thrust chambers at the German Aerospace Center (DLR) culminates in compact designs of transpiration-cooled fibre-reinforced ceramic rocket engine chamber structures. Achievable benefits of the transpiration cooled ceramic thrust chamber are the reduction of engine mass and manufacturing cost, as well as an increased reliability and higher lifetime due to thermal cycle stability. The transpiration cooling principle however reduces the engine performance. Due to the transpiration cooling the characteristic velocity decreases with increasing coolant ratio. The goal of the chamber development is therefore to minimize the required coolant mass flow. The wall temperature can be calculated using known heat transfer correlations, for example given by Bartz, and employing a model given in literature for the reduction of the heat transfer coefficient based on coolant mass flow. By this method the required coolant mass flow ratio for different chamber diameters and pressure levels can be calculated. This paper discusses the application potential of DLR's ceramic thrust chamber technology for high performance engines. Parametric variations of engine sizing (such as chamber pressure and diameter) are performed. For large diameters and high chamber pressures the required coolant ratio is below 1%