Solid Propellant Internal Ballistics Simulation
Research Rocket Motor Design Software

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Latest News

9/5/2023 - BurnSim 3.3.9 released! Details and Download here.

9/14/2021 - BurnSim is now free for students! If you have a .edu email address, simply click on help > activate and activate your installation with your .edu email address. You will receive an email to validate your address. Once you click the link in that email you can complete your activation and will have a fully-funtional BurnSim!

9/6/2021 - BurnSim 3.2.3 released! Details and Download here.

10/25/2019 - BurnSim beta released! Details and Download here.

What is BurnSim?

BurnSim is a solid rocket steady-state internal ballistics simulation software package for the Windows platform. A rocket motor simulator. Solid propellant grain design. In a nutshell, 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 the parameters such as nozzle diameter or grain core diameter and instantly see how the Kn, chamber pressure, and motor thrust is affected. BurnSim will also optimize your nozzle design. 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!

There is even an experimental feature to do propellant characterization basded on imported test data!


  • 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)
    • Moon or Offset Core
    • D Grains
    • C-Slot
    • Finocyl
    • Star
    • X-Core
  • 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
  • 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
  • Optimize your nozzle design for maximum performance.
  • Propellants can be defined with characterization data that changes over varied pressure ranges

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

  • 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.


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 available for students and educators at a discount.

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

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