Development of a lean production process for a thermoplastic composite upper stage propellant tank

Abstract

Private space flight disrupted the international launcher industry with an innovative spirit, tremendous funding and the objective to provide low cost access to space. In order to stay a relevant competitor the European launcher industry has to increase its launchers performance while reducing the manufacturing costs. The Center for Lightweight Production Technology (ZLP) of the German Aerospace Center (DLR) in Augsburg developed an innovative and data driven manufacturing process for a liquid hydrogen propellant tank. To account for the complex interior of the tank (e.g. fill level indicators and propellant management devices ) an integral design with thermoplastic CFRP LM-PAEK material was developed. Components were manufactured individually in an automated fiber placement (AFP) process and subsequently assembled by ultrasonic welding. This allows a reduction of complexity in individual parts and ensures easy installation of systems inside the tank. Throughout manufacturing inline quality assurance methods are used, the data is coupled with machine parameters and automatically evaluated. The paper gives an overview of the design approach, processes and methods to manufacture a scaled propellant tank demonstrator.