It has been a busy few weeks; The Stratos II propulsion team is working flat out getting ready for a sequence of systems tests and finally a full scale motor test of the Aurora motor at TNO in late April. Production of major parts such as a ¼ size tank for the second tank test at Advanced Lightweight Engineering (ALE) as well as a graphite nozzle is already complete with many other parts underway. The new tank has had the bolt position redesigned to ensure failure over the targeted 120 bar. It will be tested at ALE this coming week.

DHX-200 Aurora Nozzle

DHX-200 Aurora Nozzle

The nozzle is made out of a single block of medium density graphite and weighs in at just over 6 kg. It features a post combustion chamber to improve combustion stability as well as a bell shaped divergent section, a first for DARE. It will be held in the combustion chamber by a ring which sits on the last 60 mm of the divergent section and is bolted to the chamber wall. Thanks go out to DARE alumni member William van Meerbeeck and Senior Lecturer Barry Zandbergen for their help in designing it. This nozzle represents a leap forward in DARE’s design and production and capabilities which will no doubt prove useful in ensuring Stratos II is a success.

The Stratos II propulsion team plans to conduct an igniter test next week at the TU Delft. The test will essentially emulate the ignition sequence to be used during full scale testing. This is done firstly by allowing gaseous N₂O to fill the chamber before a pyro charge is fired. This will ignite the surface of the fuel grain and start combustion albeit at a majorly reduced rate. N₂0 will continue to flow at the reduced rate for an additional 3 seconds to allow the chamber to warm up.  At this point, in the full scale tests, the full mass flow would be allowed into the chamber to produce some real thrust. The igniter test will end after the 3 seconds of pre-heating has been completed.

The purpose of the test is to calibrate the igniter line mass flow to ensure the motor starts properly during full scale testing. Too much mass flow and the igniter may be blown out; too little, and the motor may be too cold to start when the full 4 kg/s of cold liquid N₂O is dumped in the chamber, causing the motor to start roughly or even flameout. This test will also be the first time the new sturdy looking test bench will be used out in the field, although we don’t expect to be producing any significant thrust just yet.

DHX-200 Aurora Nozzle