How it all works.
Applying this principle to the whole propulsion system, it becomes apparent that the complete engine ‘core’ can be tested at ground-level static conditions, right up to its operational design condition of Mach 5, and 25 km altitude. This is possible because of the unique operational characteristics of the precooler, which sits in front of the main engine core to ensure cool ambient air conditions, right up to that high speed operating point. There is thus no need to test the SABRE core at actual Mach 5 conditions.
This core design and development activity is a major undertaking which will culminate in full system testing, at which point the world’s first air-breathing engine capable of accelerating from zero to Mach 5 will have been demonstrated.