Solid propellant internal ballistics
Design the motor. See the results.
Enter the motor, nozzle and propellant. BurnSim computes Kn through the burn and predicts chamber pressure and thrust — rigorous enough for research and professional work, direct enough to learn a first motor on.
- Total impulse
- 76,652 N·s
- Burn time
- 25.01 s
- Peak pressure
- 689 psi
- Peak thrust
- 1408.5 lbf
- Designation
- P‑3066
Latest news
BurnSim 3 is officially retired
BurnSim 3 is no longer available for download and is no longer being developed. Version 3.3.10 was the last release. If you already have it installed, nothing changes: it keeps working, and its license still activates. Your BurnSim 3 license carries over to BurnSim 4. Install BurnSim 4 and activate it from Help → Activate BurnSim using the same details you registered BurnSim 3 with. BurnSim 4 installs as a separate program alongside BurnSim 3 and leaves your saved motors and propellant database alone. Download here.
BurnSim 4.0.0.20: bugfix release
Fixed: exporting an ENG file in metric units crashed BurnSim, cored end burners such as the Tapered Core could show huge pressure spikes after the core burned out, uncored BATES end burners could stop partway through a simulation with erosive burning on, and the 3-D tab could cut off its burn-depth slider. Also: the 3-D view now shows the whole motor as a stack of grains, the maximum burn time is a setting, the update prompt lists what changed, and repeat simulations run much faster. Full list on the change history page. Details and download.
What is BurnSim?
BurnSim is a solid rocket steady-state internal ballistics simulation package for Windows, Linux and Mac — a rocket motor simulator and solid propellant grain design tool. You input your motor, nozzle and propellant characteristics, and BurnSim calculates the Kn through the burn and predicts estimated chamber pressure and motor performance.
Once your motor design is in BurnSim, you can tweak parameters such as nozzle diameter or grain
core diameter and instantly see how Kn, chamber pressure and motor thrust are affected. Full data
can be exported in CSV format, or to .eng for RockSim and wRasp.
Grain geometries
Plus Tablet and Tapered Finocyl, and BATES grains with 0‑2 restricted ends. Any number and combination in one motor, each grain with its own propellant. See Grain Types on the wiki.
Features
- Instantly see a graph of Kn, chamber pressure and thrust, and how it changes when you change motor attributes.
- Import test data and graph it alongside simulations.
- Grain erosion visualization, including an interactive 3-D view — orbit, zoom and pan every grain type as a solid, slice it open with a cutaway plane, and scrub a burn-depth slider back through the burn to watch the surface burn back.
- Save your motor designs and propellant characteristics, as well as notes and imported test data.
- Export predicted motor performance to
.engfiles for RockSim or wRasp, or to CSV for Excel and anything else. - Thrust estimations based on nozzle geometry.
- Propellant thermochemistry — compute C*, specific heat ratio and molar mass directly from a propellant's ingredient recipe (ProPEP-style analysis, powered by NASA CEA data), with a searchable, extensible ingredient table.
- Erosive burning simulation — optionally slice each grain along its length and model burn rate rising near the nozzle end where crossflow is highest, instead of a single rate for the whole grain (Lenoir-Robillard, Mukunda-Paul or Ma (2020) models, off by default).
- Custom grains — draw or import your own cross-section (DXF, SVG, raster image, or the built-in shape editor).
- Graph mass flux over the burn, a value that can be used to monitor erosive burning.
- Cross-platform — runs on Windows, Linux and Mac (Linux and Mac support is very new and still in early stages).
Future features
- Command-line mode — simulate a motor file and export results to CSV without opening the UI, for scripting and batch processing.
- Pressure drop (burnout or boost-sustain) transient simulation.
- Your suggestions! Don't hesitate to contact us at burnsim@burnsim.com with any bug reports, suggestions or anything at all.
Please note. BurnSim estimates chamber pressure and performance assuming steady state operation. BurnSim 4 can optionally model erosive burning effects, which can significantly raise chamber pressures in motors with high L/D ratios, but this is off by default — turn it on under Settings if your motor is a candidate for it. Either way, treat all results as estimates, not guarantees. Test all motors in a safe environment, and always assume the motor can fail. Be prepared.
What does it cost?
Free to try
The full program in trial mode, so you can evaluate it on a real design. Full features with a time-limited license are free for the asking — just contact us.
$49 personal
A license entitles one person's personal, non-commercial use of BurnSim, on up to five computers at a time. Your BurnSim 3 license carries over. Purchase.
$149 commercial
The same license, for business and professional use — one named user, up to five computers at a time. See the purchase page for volume and site licensing.
Free for .edu
Student and education licenses are issued automatically to anyone with a .edu email address. No purchase required.
Where can I download BurnSim?
From the download page — installers and portable builds for Windows, Mac and Linux, plus the full change history.
“Can't tell how ya much I've benfited from your new program. Did a lot of mixing the last 2 weeks (over 75 lbs), and every motor I designed with the aide of your BurnSim tool performed as predicted. On one flight I used your .eng import feature for Wrasp, and my predicted altitude of 6281' was off 3 feet per Adept! Ya got a winner there ole buddy, thanks for your hard work. As far as I'm concerned, I still owe ya one....”
— Pat Gordzelik · President, Tripoli Amarillo · L3CC, TAP