Hot fire of a fully additively manufactured 10 kN liquid fuel rocket engine: processing a test anomaly

摘要

This paper discusses the complex test anomaly associated with the hot-fire (static-fire) of the first Balerion development engine, a fully additively manufactured, bi-propellant, 10 kN rocket engine. Furthermore, it explores the approach and strategy that guided the failure investigation and learning process associated with this anomaly. The hot-fire resulted in structural damage to Balerion, particularly at the injector and the flange. Moreover, structural and fire damage to the test stand, including the data acquisition system, sensors and electronics, caused the loss of important information. Data that were recovered paint a complex picture, involving irregularities such as a large, instantaneous combustion external to the engine upon ignition, and sub-nominal propellant mass flow rates both before and after ignition. A single, consistent line of events and causative relationships could not be determined convincingly from the data available. Accordingly, it was decided that seeking a single causative explanation was an inappropriate course of action. Instead, each individual non-nominal incidence was considered as a unique and separate failure point. This approach was meant to cast as wide a net as possible, addressing all potential and foreseeable sources of future failure, instead of addressing a single identified problem. An exhaustive list explores and documents all identified failure points and lessons learned in detail, and lays some critical requirements for the next development cycle.