SUNFIRE II

Project Sunride's first step into liquid rocketry...

The UK's first student-made engine to include regenerative cooling and additive manufacture

Technical Specification

Discussion

Channel burn through

At approximately 2.7s into the burn, a major disturbance was detected in by both the load cell and pressure transducers in the feed line.

This indicates the instance of channel failure

Addressing this is a key design criteria for Sunfire III

Potential causes:

1) Heat treatment and de-powdering

Powder left in the channels post printing clogged when the engine was removed by wire EDM. This clogged the channels and made the powder to incredibly difficult to remove.

By the time we were due to test the engine at Race to Space Competition, we hadn't managed to heat treat the Inconel preventing the precipitation hardening needed to achieve its high strength properties.

This would have lead to high strain in the channel walls, which may have caused cracking

2) Spray pattern

During cold flow testing, there appeared to be a few minor issues with mixing of jets in from the unlike-impinging elements.

Its possible that imperfect mixing led to oxidiser-rich spray against the wall led to high localised temperatures. This would explain why cracking only occurred at certain areas on the chamber wall.

3) High O/F ratio

with an unknown mass flow rate of N2O, we had to guess a suitable feed pressure.

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