Headless rocket design, simulation, and optimization using OpenRocket's Java core engine. Includes rocket-sim CLI tool for batch simulations and parameter sweeps, plus an AI-driven optimization loop using Claude. Use when: (1) designing model rockets programmatically, (2) running headless flight simulations, (3) optimizing rocket designs for altitude/stability/velocity, (4) batch-processing .ork files, (5) parameter sweeps over launch conditions, (6) AI-driven design optimization, (7) building a simulation pipeline or API wrapper, (8) exporting designs for 3D printing or laser cutting, (9) user mentions 'openrocket', 'rocket simulation', 'flight sim', 'rocket design', 'model rocket', 'rocketry', 'apogee optimization', 'thrust curve', 'rocket-sim'.
The rocket-sim CLI at ~/broomva/experiments/rocket-tools/ wraps OpenRocket's headless core. All output is structured JSON.
# Prerequisites: Java 17
export JAVA_HOME=/opt/homebrew/opt/openjdk@17/libexec/openjdk.jdk/Contents/Home
ROCKET="~/broomva/experiments/openrocket/core/src/main/resources/datafiles/examples/A simple model rocket.ork"
# Inspect rocket design
rocket-sim info "$ROCKET"
# Run simulation → JSON with altitude, velocity, mach, events
rocket-sim run "$ROCKET"
# Parameter sweep (rod_angle, rod_length, launch_altitude, wind_speed, time_step)
rocket-sim sweep "$ROCKET" wind_speed 0,2,5,8,10
# Flight event timeline
rocket-sim events "$ROCKET"
Validated results (A simple model rocket, A8-3 motor):
Two stage high power rocket (multi-branch):
At ~/broomva/experiments/rocket-ai/optimizer.py. Iterative loop: Claude analyzes simulation results, proposes parameter sweeps, evaluates trade-offs, converges.
export ANTHROPIC_API_KEY=sk-...
cd ~/broomva/experiments/rocket-ai
python3 optimizer.py "path/to/rocket.ork" \
--goal "Maximize altitude while keeping ground hit velocity under 10 m/s" \
--iterations 5
Loop: baseline sim → Claude analysis → sweep proposal → run sweep → feed results back → refine → converge.
~/broomva/experiments/
├── openrocket/ # OpenRocket source (github.com/openrocket/openrocket)
│ ├── core/ # Headless simulation engine (Java 17, Gradle)
│ └── swing/ # GUI (optional)
├── rocket-tools/ # rocket-sim CLI (Gradle project, depends on core shadow JAR)
│ ├── rocket-sim # Shell wrapper
│ └── src/main/java/rocket/cli/RocketCLI.java
└── rocket-ai/ # AI optimizer (Python + Anthropic SDK)
└── optimizer.py
export JAVA_HOME=/opt/homebrew/opt/openjdk@17/libexec/openjdk.jdk/Contents/Home
export PATH="$JAVA_HOME/bin:$PATH"
# 1. Build OpenRocket core + shadow JAR
cd ~/broomva/experiments/openrocket
./gradlew build -x test && ./gradlew shadowJar
# 2. Build rocket-sim CLI
cd ~/broomva/experiments/rocket-tools
./gradlew jar
# 3. Install AI optimizer deps
cd ~/broomva/experiments/rocket-ai
pip install -r requirements.txt
For programmatic use without the CLI, use OpenRocketCore.initialize():
import info.openrocket.core.startup.OpenRocketCore;
// One-line bootstrap (headless, no GUI)
OpenRocketCore.initialize();
// Load and simulate
var loader = new GeneralRocketLoader(new File("rocket.ork"));
var doc = loader.load();
var sim = doc.getSimulation(0);
sim.simulate();
FlightData data = sim.getSimulatedData();
data.getMaxAltitude(); // meters
data.getMaxVelocity(); // m/s
data.getFlightTime(); // seconds
System properties for faster startup:
System.setProperty("openrocket.bypass.presets", "true"); // skip component DB
System.setProperty("openrocket.bypass.motors", "true"); // skip motor DB
At openrocket/core/src/main/resources/datafiles/examples/:
A simple model rocket.ork — single stage, 5 motor configsTwo stage high power rocket.ork — multi-stage, multi-branch simClustered motors.ork — parallel motor clustersSimulation extensions.ork — GraalVM JS scripting demoDual parachute deployment.ork — recovery system demoParallel booster staging.ork — side booster staging