In preparation of the development of new European advanced cryogenic upper stages the need to maturate related technologies has been identified. A German research cooperation involving the German launcher industry, University and DLR research has been initiated to work jointly on various identified key technologies. The partners involved are EADS astrium, MT-Aerospace, various DLR-institutes (Institute of Aerodynamics and Flow Technology; Institute of Composite Structures and Adaptive Systems; Institute of Space Propulsion), and the ZARM at the University of Bremen. All research work is coordinated by DLR Institute of Space Systems in Bremen. In focus are the following key technologies:
Propellant Management Technology: The propellant behavior in cryogenic upper stages demands for specific requirements on the tank system, especially for future upper stages designed for multiple restarts and intermediate long ballistic flight phases. The focus is on the fluid technologies as well as on coupled system Cryogenic experiments at the DLR laboratory will be performed to investigate scientific and technical questions of space technology and to work out technical solutions particularly with regard to reignitable cryogenic upper stages
Extension TAU-Code: The objective in the current study is the further extension of the DLR TAU code for flow conditions within tank systems and feed lines of cryogenic re-ignitable upper stages. The long-term objective is to have a comprehensive design tool for all fluid mechanical problems of space transportation systems.
Simulation of the propulsion system: The time dependant simulation of the entire propulsion system with the consideration of all interacting components is of crucial importance for the upper stage optimization. One aim is the extension of the DLR SART tool Propellant Management Program (PMP) for the needs of re-ignitable upper stages with long ballistic flight phases to calculate the integral dimensioning values and to allow supporting the preliminary upper stage engineering. Further points of interest are the transients during engine shut off and restart
Composite Fibre Technology: With the exception of the propellant tanks, all primary components of advanced upper stages consist of composite fibre structures. The structure has to withstand high temperature gradients together with high mechanical loads. Two topics are investigated in this project. The first topic deals with the connection of cold metal components and composite light- weight construction. The problem is in connecting of hybrid structures consisting of different materials posing specific challenges for the designer. The aim is to optimize the connection technology to reduce weight. The second topic, damage tolerant fibre structures, is driven by the challenge to develop numerical models to calculate the effects of delamination, debonding, and impact on damage growth and the residual strength.
Avionic Technology: This project includes two projects. The first project deals with the development of a flexible, fault-tolerant and high reliable core avionics system. The main issue is the design of a multi-cast capable, intelligent and flexible middle switch core element. The second project is dedicated to sensor technology. Future cryogenic re-ignitable upper stages enable new mission scenarios. The resulting changes on the sensor system requirements will be identified and the need of new sensors will be specified. The aim is to proof and to verify the feasibility of using off-the-shelf-sensors fulfilling the identified need.