Follow the propellant from storage to thrust. Open the hardware, disturb the liquid, and watch the whole system respond.
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Stores the example fuel separately from the oxidizer. Helium occupies the ullage above the liquid and supplies pressure for the fuel feed.
Slosh is an engineering first-mode approximation for a settled free surface. It captures inertia and damping; it does not resolve breaking waves, droplets or microgravity wetting.
Geometry and operating values are fictional teaching assumptions, not vendor data. Tank geometry uses physical dimensions in metres. Liquid mass, density and vessel geometry determine fill volume. The moving surface is solved for that volume as the tank is disturbed.
A damped first lateral mode responds to imposed acceleration and engine settling. Ring baffles increase the assumed damping. The frequency uses the cylindrical-tank approximation ω² = gₑk tanh(kh), with kR = 1.841. Rounded tank ends are included in the volume geometry, not an exact modal solution.
This model describes a settled free surface. It does not calculate breaking waves, droplets, vortices, surface-tension wetting in microgravity, or a coupled six-degree-of-freedom vehicle trajectory.
Fuel and oxidizer remain separate until the injector. Feed continuity and tank pressure determine available flow; liquid mass decreases with delivered mass flow. Finite helium bottles supply regulated operation; their pressure falls as gas moves into the tank ullage. Insufficient bottle pressure causes regulator dropout. The gas model assumes ideal helium and isothermal regulated operation; isolated blowdown uses a polytropic exponent of 1.2. Real-gas effects, thermal exchange and regulator flow limits are not resolved. Pipe tracers show flow direction and are slowed for inspection. Subtle liquid tints distinguish the circuits; plume light is illustrative.
The case contains an inhibited cylindrical grain. Its inner port grows at a prescribed regression speed, with gas production proportional to burning area. Grain volume determines remaining propellant. Chamber transients, pressure-dependent chemistry and structural stresses are outside this model.
NASA · Liquid propulsion feed system design ↗Pressure-fed and pump-fed architectures, regulated supply and blowdown. This lab deliberately uses a pressure-fed spacecraft module and upper-stage example.
NASA SP-106 · Liquid motion in tanks ↗Classical slosh modes, damping and low-gravity behavior. The lab uses a reduced-order, settled free-surface approximation rather than a resolved fluid simulation.
NASA · Baffled propellant tank slosh (PDF, p. 9) ↗Why annular baffle position and liquid level affect damping. The lab’s damping settings are teaching assumptions, not fitted test data.
NASA Glenn · Solid rocket engine ↗Surface combustion, grain geometry and nozzle thrust. The lab prescribes radial burn speed and effective specific impulse.
These fictional vehicle configurations demonstrate propulsion systems. Their dimensions and operating points are study assumptions.