Life extending control of a reusable rocket engine

The goal of life extending control in reusable rocket engines is to achieve high performance without overstraining the mechanical structure; and the major benefit is an increase in structural durability with no significant loss of performance. This paper investigates the feasibility of a decision and control system for life extension and performance enhancement of a reusable rocket engine, such as the Space Shuttle Main Engine (SSME). Creep damage in the coolant channel ligament in the main thrust chamber is controlled while engine performance is maximized. For open loop control of up-thrust transients of the rocket engine, an optimal feedforward policy has been synthesized based on an integrated model of plant, structural and damage dynamics. Optimization is based on the integrated model of plant, structural and damage dynamics under creep damage constraints in the critical plant component, the coolant channel ligament in the main thrust chamber. The results demonstrate the potential of life extension of reusable rocket engines via damage mitigating control. The concept of life extending control, as presented in this paper, is not restricted to rocket engines; it can be applied to any system where structural durability is an important issue.