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Phoenix's Interior Ballistic Solver (PIBS)

PIBS solves the interior-ballistics problem for closed-breech and recoilless guns: given a caliber, charge, propellant and barrel, it computes the full pressure/velocity trace from ignition to shot exit.

This wiki has two pages:

• Theory — the full theoretical/numerical model: the reduced-variable ODE system, propellant form functions, the Nobel-Abel equation of state, the three pressure-gradient solutions (why breech/average/shot-base pressure differ), the recoilless nozzle extension, and the numerical methods used to solve it all.
• User Guide — zero-to-hundred instructions: install, run either GUI, a full parameter glossary, and two fully worked examples (a conventional gun and a recoilless gun) using real bundled reference designs — nothing invented.

Both pages are also published as a single navigable page at timeout187.github.io/Phoenix-s-Interior-Ballistic-Solver-PIBS, if you'd rather read them formatted with a table of contents and side-by-side worked-example figures.

Quick answer: does it support recoilless guns?

Yes. Both the desktop app and the web app solve recoilless guns with the same fidelity as conventional guns — see the recoilless worked example on the User Guide page.

Where the code lives

• Source (this fork)
• Upstream project
• docs/THEORY.md and docs/USER_GUIDE.md in the repo are the source of truth these wiki pages are copied from.