ULTIMATE: Metallic Thermal Protection System for Future RLV'S - Design and Thermo-mechanical Analyses – 2003-01-2469
From the early beginning of space programs metallic Thermal Protection Systems (TPS) have been considered as promising technology to protect space vehicles against the severe aerodynamic heating encountered during re-entry into earth's atmosphere.
The goal of “airplane-like” operations for future RLV's led to a renewed interest in TPS more durable than that developed for the space shuttle orbiter. This triggered developments of metallic TPS recently performed on the X-33.
The same motivation is basis for the metallic TPS development within the frame of the German ASTRA ULTIMATE project since the thermal protection system contributes essentially to the overall mass and defines the operational cost of a space transportation system with its inspection, maintenance and repair capabilities. For these reasons the TPS dictates the overall economical operation of a future RLV.
In Europe considerable effort has been spent to investigate future RLV concepts. One of these concepts named HOPPER has been chosen for further investigations and developments. Mission analyses performed so far for HOPPER identified large areas on the outer surface with moderate maximum temperatures during re-entry into Earth atmosphere.
Nearly 80 per cent of the entire windward surface of this vehicle will experience maximum temperatures are in the range of 800 to 1200°C. Based on these boundaries HOPPER has been chosen as the reference vehicle for ULTIMATE metallic TPS development.
The ULTIMATE TPS is intended for a max temperature range of approx. 850 to 900 °C.
The objective of this paper is to describe the TPS concept selected and the design of the single panels as well as the dedicated thermo-mechanical analyses to refine, optimize and verify design details.
After establishing the overall requirements and needs for an advanced metallic TPS the ULTIMATE development has been started with a review of state-of-the-art technologies followed by an in-depth design trade-off and finally the selection of the most promising concept.
Next, detailed thermo-mechanical analyses of the overall concept as well as design details/components have been performed to optimize the metallic TPS w.r.t its function and especially mass.
During the subsequent detailed design phase emphasis has been given to operational aspects like inspection, maintenance, repair and panel exchange issues.
This paper presents the results of the developments performed thus far and provides an overview of activities to be accomplished in the near future.