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Project APEX has no accounts and no server storage — but everything you need to save and reload your work is built into the toolbar. Configurations are stored as files on your computer, so you own your data completely.
Click Save Config in the toolbar at any time. A .json file is downloaded to your computer containing every current parameter value. JSON format preserves all parameters exactly and is the recommended format for saving and sharing rocket configurations.
Click Load Config in the toolbar and select a previously saved .json or .csv config file. All parameters are populated immediately — no re-entry needed. The simulator automatically handles format differences between older and newer config versions.
Click Template in the toolbar to download a .csv file pre-filled with the current parameter values. This is useful if you prefer to edit parameters in a spreadsheet application before loading them back into the simulator.
The template includes inline comments (rows beginning with #) that explain each parameter, its units, and acceptable value ranges. Edit the values in your spreadsheet, save, and load the file back in using Load Config.
| File type | How to create it | Best used for |
|---|---|---|
| .json — Config | Click Save Config in the toolbar | Saving and reloading complete rocket setups. Recommended format. |
| .csv — Template | Click Template in the toolbar | Editing parameters in Excel, batch preparation of multiple configs. |
After running a simulation, an Export CSV button appears in the toolbar. This downloads a full time-series CSV of the simulation run — every recorded timestep with all computed values.
The exported CSV includes the following columns at each timestep:
| Column | Description |
|---|---|
| time | Elapsed flight time (seconds) |
| altitude | Altitude above launch site (m or ft) |
| velocity | Total velocity (m/s or ft/s) |
| mach | Mach number (dimensionless) |
| acceleration | Axial acceleration (G) |
| drag | Total drag force (N or lbf) |
| thrust | Motor thrust at this timestep (N or lbf) |
| cd | Total drag coefficient at this Mach |
| cp_pos | Centre of pressure from nose (cm or in) |
| cg_pos | Centre of gravity from nose (cm or in) |
| stability | Stability margin (calibers) |
| dyn_pressure | Dynamic pressure (Pa or lbf/ft²) |
| air_density | Air density at altitude (kg/m³ or slug/ft³) |
The Parameter Sweep tab lets you automatically run a full simulation across a range of values for any one parameter. Instead of manually re-running dozens of times and recording each result, the sweep gives you a complete chart of how apogee, velocity, Mach, and stability margin respond to the parameter — in a single click.
The sweep produces two charts stacked vertically:
Top chart — Apogee vs parameter value. The primary performance metric. Look for the peak of this curve to find the parameter value that maximises altitude, or look for the flat region that gives the most stable performance across manufacturing tolerances.
Bottom chart — Max velocity, max Mach, and stability margin. These three traces share the x-axis with the apogee chart, so any point on the x-axis corresponds directly across both charts. Hover over any point to see the exact values.
One of the most powerful features of Project APEX is the ability to load real altimeter data from an actual flight alongside the simulation. This lets you see exactly how well the physics model predicts measured performance — and where to tune it.
The Featherweight Blue Raven exports two types of CSV data files from its onboard logging. Both are loaded from the Flight Profile tab toolbar and can be used independently or together.
| File type | What it contains | Toolbar button |
|---|---|---|
| LR CSV | Low-rate barometric altitude and velocity data. Overlaid on the altitude and velocity charts in the Flight Profile tab. | LR CSV |
| HR CSV | High-rate IMU acceleration data. Overlaid on the acceleration chart. Higher noise than LR — use the Smooth toggle to filter. | HR CSV |
If the simulated apogee does not match the measured apogee from the overlay, the most likely cause is a difference between the modelled drag and the actual drag experienced in flight. You can correct this with the Cd Scale Factor.
If you have an OpenRocket model of the same rocket, you can export its Mach vs Cd data and overlay it on the Aerodynamics tab for a direct model-to-model comparison. This is useful for cross-checking your Project APEX drag model against an existing OpenRocket build.
