Design Engineer at AVROS Rocketry
Designing a safety-critical piston for the propellant pressurisation system of a reusable liquid rocket engine, including the O-ring gland sizing that has to hold at 500–800 psi.
I'm designing a safety-critical piston for the propellant pressurisation system of a reusable liquid rocket engine. Its job is to keep IPA and N2O physically separated inside the propellant tank assembly. If that separation fails, the two propellants meet somewhere they were never meant to.
The core of the design is the O-rings. I'm sizing it across squeeze factor, stretch and volumetric gland fill so it holds across a 500 to 800 psi range. Gland fill is the part with no room for error: overfill it and the O-ring has nowhere to displace to under pressure, underfill it and it leaks.
Every dimension starts as a hand calculation before it becomes parametric CAD in Onshape. It keeps the geometry driven by the numbers. I document the sizing process through structured calculation records, so every value traces back to the assumption behind it. That's what makes it possible to verify the design now and reuse the logic on the next iteration.