ops3000/opsrocket

OpsRocket is a Rust rewrite of the simulation core inside OpenRocket, a long-standing program used by model rocket builders to predict how their rockets will fly. The project takes the same .ork design files that OpenRocket uses, then runs the physics in Rust instead of Java. It is a clean-room third party reimplementation, not connected to the original OpenRocket team, and it carries the same GPL-3.0-or-later licence as the upstream tool. The README emphasises two kinds of accuracy. First, the Rust output matches the original Java reference within a few percent on the bundled test fixture, with apogee differing by about 2.9 percent and ground-hit velocity by less than 1 percent. Second, and the part the authors care about more, OpsRocket is checked against a rocket that was actually built and flown with an altimeter. On a C6-3 motor case, OpsRocket lands at 151.5 metres, the same as the altimeter reading, while the Java original predicted 161.4 metres and RockSim 8 predicted 180.1 metres. Under the hood the project covers full six-degree-of-freedom flight simulation with a quaternion attitude model, Barrowman aerodynamics including fin and body interference effects, drag models for friction, base, pressure, and launch lugs, a layered atmosphere model ported from the Java version, motor curves from Estes, AeroTech, Quest, and Klima, multi-stage and clustered motors, and parachute recovery. It can read and write .ork files and ships 50 plus motor thrust curves. There are three ways to use it. A command line tool exposes simulate, inspect, and diff subcommands. A web workbench at ops.sg compiles the engine to WebAssembly so you can open a design and see the 2D blueprint, 3D render, and flight plot entirely in a browser. A desktop GUI built with Tauri, React, and Three.js runs the same Rust core in process. The code is split into focused crates for core geometry, file IO, simulation, the CLI, regression tests, viewer models, the WASM surface, and an HTTP server. Running cargo test --workspace runs the 45 regression tests.