A Scaled-down Bipropellant Engine
A Stepping Stone to White Giant
White Dwarf was an integral part of CUSF’s research efforts in anticipation of Griffin I. As a scaled-down demonstrator of White Giant, White Dwarf ran on a different combination of propellants, Nitrous Oxide and Isopropyl Alcohol (IPA), but provided a key insight into the test procedures, safety precautions and performance characteristics involved with a larger test of the full scale engine. An end to end propulsion system was built including a test stand, combustion chamber, injgector, feed system, and data and control system were all built from scratch. The small scale development of these systems provided vital experience for the team ahead of the start of White Giant’s development. Another big lesson learned was the importance of implementing integrated testing early – the whole is not just the sum of the parts.
The Propellant Tanks
Static fires of White Dwarf were conducted using tanks for Nitrous Oxide and IPA.
A Graphite bell nozzle insert constrained by high temperature Graphite gaskets.
The injector followed an iterative design and test process. A pintle injector design was chosen.
A thick Copper combustion chamber with milled vertical cooling channels, reinforced with a Stainless Steel outer jacket.
A cooling system to protect the copper wall cycled water through a distribution ring and cooling jacket to simulate regenerative IPA cooling.
A Successful Cold Flow Test at Westcott.
Bigger isn’t always Better
White Dwarf has been designed to test the regenerative cooling system for White Giant. For simplicity, water has been used as the coolant in the scaled test. Crucial information from the hot fire tests, such as temperatures, injector flow and ignition characteristics fed directly into White Giant’s design cycle.
White Dwarf has been developed through extensive use of CUSF’s own Bamboo software. Providing all-in-one capability from modelling temperatures for actively and passively cooled liquid rocket engines to estimating key performance parameters and apogee, Bamboo is the analysis tool to use for anyone looking to design their own engine.
Cold flow testing to determine the optimal injector geometry were completed. Results were used to choose between showerhead, pintle and impinging jet injector designs, as well as to validate pressure drops across the injector. The tests also provided vital data to which Octopus, CUSF’s analytical injector model, can be compared to.