BurnSim - Solid Propellant Internal Ballistics Simulation - Research Rocket Motor Design Software

BurnSim
Solid Propellant Internal Ballistics Simulation
Research Rocket Motor Design Software

7/22/2026 - BurnSim 4.0 public beta released!
A ground-up rewrite: BurnSim now runs natively on Windows, Linux, and Mac, with a redesigned interface built on a modern cross-platform engine. New in 4.0: one-page PDF motor reports with direct printing, an improved test-data workflow (editable imported data, measured-vs-calculated thrust). All your existing grain types, propellant characterization, and simulation features carry forward, including the graphical eroder, which models grain burn-back on an actual pixel-based cross-section instead of relying purely on mathematical formulas.
Details and Download here.

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. In a nutshell, 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.

Motor designs in BurnSim can be saved and recalled for later use. In addition, test data can be imported and graphed alongside simulation data to compare sims to results. BurnSim allows you to make notes about your propellants and motor designs, all saved in one convenient location.

Once you're happy with the your motor design, BurnSim can then export a .ENG file for use in RockSim, wRasp or other rocket flight simulators. You may also export the data to a text file (comma delimited) for use in virtually any system. You can estimate your motor's performance and rocket's flight before you even cast a grain!

Features

Now cross-platform! Runs on Windows, Linux, and Mac (Linux and Mac support is very new and still in early stages)
Supports the following grain configurations in any number and combination:
- BATES grains with 0-2 restricted ends
- End burning grains (defined as BATES grain with zero diameter core)
- Tablet (uninhibited BATES)
- Moon or Offset Core
- D Grains
- C-Slot
- Finocyl
- Star
- X-Core
- Custom Grains - Coming Soon!
Different propellant types can be specified for each grain
Instantly see a graph of Kn, chamber pressure, thrust, and see how it changes when you change motor attributes.
Graph Mass Flux over the burn, a value that can be used to monitor erosive burning
Grain erosion visualization
Import test data and graph it along side simulations
Save your motor designs and propellant characteristics, as well as notes and imported test data
Export predicted motor performance into .eng files for use in Rocksim or wRasp
Export predicted motor performance into .csv files (comma delimited text files) for use Excel or any other program.
Thrust estimations based on nozzle geometry

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

Future Features

Custom grain cross-sections via 2D file import
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
Erosive burning simulation
Your suggestions!

Dont hesitate to contact me at BurnSim@blastzone.org with any bug reports, suggestions or anything at all.

PLEASE NOTE!

BurnSim estimates chamber pressure and performance assuming steady state operation. BurnSim (currently) does NOT take into account erosive burning effects which can significantly raise chamber pressures in motors with high L/D ratios. Test all motors in a safe environment, and always assume the motor can fail. Be prepared.

What does it cost?

BurnSim is free to download and try in trial mode. Full features with a time limited license are free for the asking, just contact me. Education licenses are free for .edu users.

A Personal license for BurnSim is only $39. The Personal license entitles one person's use of BurnSim version 3.0. For multiple users, volume discounts are available. Please contact me for details.

Please download BurnSim and try it out. Thank you for your support, license fees cover the costs of continued development and improvements to BurnSim.

License fees may be purchased with via Paypal, or with a credit card, or check / money order. Please go to the Secure Payment Page to purchase your license.

Where can I download BurnSim?

The download page is here