LOX-Propane Rocket Burns Well, Despite Also Being On Fire (Space Enterprise at Berkeley)

April 29, 2023
UC Berkeley's SEB continues to test fire their liquid bipropellant rocket motors. This vertical stacked static fire is meant to put the propulsion system through its paces in as close to flight configuration as possible. Thanks to the rapid testing program and the group's mastery over 3D printing techniques from HP (The printer company, who have been rather generous contributors to rocket propulsion lately), a new flight vehicle may be ready to fly soon enough.
This test features hardware that is typical of SEB, but a rocket can always produce unexpected results. This is why repeated testing is important for any campaign. In dealing with probabilities and risks, failure modes are hardly consistent, and determining what can go wrong, and how to mitigate it, will be all the more important during a flight test, where aborts are more difficult, and a ballistic return a hazardous alternative.
This particular test encountered an anomaly early on, when a leak towards the top of the motor caused a secondary combustion event. An abort was called, but this did not shut down the motor. Whether this was intentional, or if connection was lost, it can be argued that letting a rocket drain and burn is safer than letting a compromised system hold onto its dangerous and warming propellants. Despite the extra fire, the chamber maintained its integrity, before eventually showing signs of nozzle burn-through towards depletion, where the mixture may have turned LOX-rich. With less fuel to burn, the oxygen will tend to find other things to burn, like ablative chambers, nozzles, and aluminum. Despite a violent and fiery appearance, this result is promising, and the causes can be resolved fairly readily with procedure. The nozzle burn-through may look like a problem, but it may well be more of a symptom of other issues further back.

[@user-vz9lc5xk6y]

The abort is designed to leave our main propellant valves open to allow the dumping of propellant to safe the vehicle, so that was intentional. When we aborted we closed our pressurant valve, meaning the propellants were in blow down. Since lox has a higher vapor pressure, we were very lox rich.

[@jacksonboone8396]

nice

[@alexanderpatrus9588]

Did the description get cut off? Its the next best thing since the derek blog posts

[@nabilibensobih2632]

Hi, which purity of propane are you dealing with? Are you subcooling it to cryo temepratures?

[@slowrider8680]

this just poped up on my recomedended and I know nothing about this, but are you planning to fly this engine?

[@DerekHonkawa]

The SEB team flew one of these last year. The video can be found on this very channel.

[@user-qo4hc6jf1l]

Combustion chamber can’t handle the pressure don’t know just a guess flames speeds to upwards camber can’t handle it