Richard Nakka's Experimental Rocketry Web Site

Rocketry Software

  • SRM - Solid rocket motor design
  • METEOR - Solid rocket motor design
  • CASING - Motor casing design
  • IGNITER - Rocket motor igniter design
  • CONVERT - Units converter
  • EzImpulse- Rocket Motor Sizing Spreadsheet>
  • EzRocket- Rocket Design Spreadsheet
  • EzAlt- Rocket Flight Performance Spreadsheet
  • SOAR - Rocket Flight Performance
  • WHOOSH- Water rocket performance
  • ROCCAD- Rocket altitude, Cd and CP estimation
  • AEROLAB- Rocket drag and stability
  • BARROWMAN- Rocket Center of Pressure  
  • Altimeter Correction to Account for Launch Site Temperature  
  • OPENROCKET - Rocket design and performance
  • RASAERO II- Rocket design and performance
  • GUIPEP- Graphic interface for PROPEP program  
  • THERMCAS- Motor casing thermal analysis
  • PARAPAT- Parachute gore pattern maker
  • Parachute gore DXF Generator  
  • LOADCELL- Loadcell designer
  • NOZLBORE- Nozzle Machining Aid
  • PFC-BURN - Pseudo-Finocyl Grain Analysis
  • Ejection Charge Calculator
  • GRAINDENSITY - Grain density check
  • O-RING - Design tool  
  • PDFCreator


    Solid Rocket Motor Design

    SRM.xls is an MS EXCEL spreadsheet that takes user-inputted motor and grain geometry data and computes Kn over the duration of the motor burn, generates a pressure-time curve, a thrust-time curve, as well as performance parameters such as total impulse and delivered specific impulse. Motor performance data is also summarized for easy input into a trajectory simulation software, such as SOAR. Although primarily intended for designing motors using KN-Dextrose or KN-Sorbitol propellant, other propellants may be specified with user inputted propellant properties.
    Solely for cylindrical grain configurations, such as BATES.
    Written by R.A. Nakka.

    SRM_2014.xls is a newly released version. Although similar to the original SRM.xls, this revised version simplifies the design process by allowing the user to specify chamber pressure (rather than Kn) as a design parameter. The propellant choice has been expanded to include additional sugar propellant variations. A nozzle design worksheet has been added to help the user to visualize the nozzle geometry. Drop-down menus have been added to ease selection of parameters.

    SRM_2014.1.ZIP     755 kbytes     Zipped EXCEL 2000 spreadsheet         Freeware
    SRM TIP SHEET   Rev.2020-12-21  178 kbytes     PDF document

    SRM_2014_RU.ZIP     1.604 Mbytes     Zipped EXCEL 2000 spreadsheet         Russian language version of SRM_2014, translated by Vadim Zaharchenko. Freeware

    SRM_2014_BG.RAR     485 kbytes     Zipped EXCEL 2000 spreadsheet         Bulgarian language version of SRM_2014, translated by George Andonov. Freeware

    SRM 1.2.ZIP    Version: 1.2    536 kbytes     Zipped EXCEL 2000 spreadsheet         Freeware

    SRM_RU.ZIP    Russian Language Version    1.08 Mbytes     Zipped EXCEL 97/2000

    SRM-CASTELLANO.ZIP    Spanish Language Version, translated by Guillermo O. Descalzo     550 kbytes     Zipped EXCEL

    SRM_2014_Po    Portuguese Language Version, translated by Phoenix Rocket Tech Team of University of Caxias do Sul (UCS)     930 kbytes     EXCEL XLSM file

    SRM_2014.1_fr .xlsm      French Language Version of SRM_2014    893 kbytes     
    Translated by Jérôme Fouque.


    METEOR is a Java implementation of the SRM.XLS Solid Rocket Motor Design spreadsheet.
    A free-to-use on-line application, METEOR is a convenient, validated tool for designing rocket motors. Includes some useful additional features not currently implemented in SRM.XLS
    Written by Jordan Content and Jérôme Bise of Lyon, France.


    Motor Casing Design

    This is an MS EXCEL spreadsheet that is used to determine the Design Pressure and Burst Pressure of a solid rocket motor casing. Also determines the elastic deformation of the casing under pressure (important for case-bonding consideration). Strength and mechanical properties are supplied for many casing materials such as steels, aluminum alloys, PVC, etc.
    Written by Richard Nakka.

    CASING.XLS    Version 1.03    61kbytes     EXCEL 5.0 spreadsheet         Freeware

    CASING_BG.XLS        70kbytes     EXCEL spreadsheet         Bulgarian language version of CASING translated by George Andonov.

    CASING_FR.XLS          74kbytes     EXCEL spreadsheet         French language version of CASING translated by Jérôme Fouque


    Rocket Motor Igniter Design

    This is an MS EXCEL spreadsheet that may be used to estimate the chamber pressure that occurs in a rocket motor due to combustion of a pyrotechnic igniter. Use of a properly sized pyro igniter is important for efficient rocket motor design. The motor should reach full operating pressure rapidly without wasting propellant (and thereby reducing Isp). As well, it is important to avoid overpressurization. Although tailored for black powder igniters, this spreadsheet may be used for other pyrotechnic mixtures, as well. The latest version of this spreadsheet (v1.1) also computes parachute ejection charge force.
    Written by Richard Nakka.

    IGNITER.XLS    Version 1.1    74kbytes     EXCEL 2000 spreadsheet         Freeware

    IGNITER_BG.XLS        47kbytes     EXCEL spreadsheet         Bulgarian language version of IGNITER translated by George Andonov. Freeware

    IGNITER_FR.XLSX          68kbytes     EXCEL spreadsheet         French language version of IGNITER translated by Jérôme Fouque.


    Units Converter

    Windows software that converts units for Force, Pressure, Density, Area, Distance, Volume and several other measures. Very convenient and simple to use, highly recommended. Written by Joshua F. Madison. , or download it here:

    CONVERT.ZIP    Version 4.08    168 kbytes     Zipped file         Freeware

    Rocket Motor Sizing Spreadsheet

    This Excel spreadsheet is meant to serve as a design aid for amateur/experimental/model rockets. A simple, easy to use spreadsheet that determines the total impulse of a motor that is required to achieve an altitude goal. Metric units. Written by Richard Nakka.

    EzImpulse_v1.01.xlsm    Version 1.01    40kbytes     Excel macro-enabled spreadsheet         Freeware

    Screen-capture of EzImpulse showing INPUT DATA and RESULTS

    EzImpulse_v1.0_fr.xlsm          39kbytes     EXCEL spreadsheet         French language version of EzImpulse translated by Jérôme Fouque


    Rocket Design Spreadsheet

    This Excel spreadsheet is intended as an easy-to-use design aid for hobby rocketry. Unlike most rocket simulation programs, which predict peak altitude for a given rocket and motor combination, this progam instead considers peak altitude as a design goal. Based on this goal, the program computes what size motor is required to reach this peak altitude. Both English and Metric units. Written by Richard Nakka.

    EzRocket.xls    Version Beta    92kbytes     EXCEL 97 spreadsheet         Freeware

    EzRocket_BG.RAR    24 kbytes     Zipped EXCEL 2000 spreadsheet         Bulgarian language version of EzRocket, translated by George Andonov. Freeware

    EzRocket_fr.xlsx       31 kbytes     EXCEL spreadsheet         French language version of EzRocket, translated by Jérôme Fouque.


    Rocket Flight Performance Spreadsheet

    An easy to use Excel spreadsheet that predicts the peak altitude, maximum velocity, burnout altitude, acceleration and time to peak altitude of an amateur rocket. Intended primarily as a rocket design aid due to its simplicity of use and ease with which variables (such as rocket mass, motor output, drag coefficient, etc.) can be modified, and the effects of such studied. Both English and Metric units. Written by Richard Nakka.

    EzAlt_1.3.xls    Version 1.2    195kbytes     EXCEL 97 spreadsheet         Freeware

    EzAlt_BG.RAR     24 kbytes     Zipped EXCEL 2000 spreadsheet         Bulgarian language version of EzAlt, translated by George Andonov.

    EzAlt_RU.XLS     92 kbytes     EXCEL 2000 spreadsheet         Russian language version of EzAlt, translated by Vadim Zaharchenko.

    EzAlt_1.3_FR.XLSX       46 kbytes     EXCEL spreadsheet         French language version of EzAlt, translated by Jérôme Fouque.


    Rocket Flight Performance

    This program predicts the flight performance of a rocket. It calculates parameters such as altitude, velocity, acceleration, drag force, dynamic pressure, Mach number, and is capable of handling single-stage, multi-stage and clustered rockets. Meant to be accurate, the program utilizes efficient professional subroutines for numerical differentiation and integration. Also meant to be versatile and user friendly, it can handle supersonic rockets with a flight ceiling to 100,000 feet. as easily as low altitude model rockets with commercial engines. Runs under DOS only. Written by Richard Nakka & B.W. Nakka.

    SOAR.ZIP  187 k     DOS  Freeware  

    Data files of Model Rocket Engines, for use with SOAR program. MROCKENG.ZIP  15 k

    Data files of the Kappa-DX & Kappa-SB Rocket Motor, for use with SOAR program. KAPPA.ZIP  2 k  

    Data files of the B-200 & C-400 Rocket Motors, for use with SOAR program. ENGINE1.ZIP  1 k


    Water Rocket Performance

    This program may be of interest to the slightly less adventurous amateur rocketeer -- it predicts the performance of a "soda bottle" rocket (aka "water rocket"). A water bottle rocket, by the way, is a rocket made from a plastic soda bottle (eg 2 litre) filled with a mixture of water and compressed air (surprising performance!).

    Program calculates parameters such as thrust, jet velocity, and pressure, all as a function of time, as well as total impulse and specific impulse. May be used together with SOAR to predicts the flight performance.
    Runs under DOS only. Written by Richard Nakka.

    Source code (FORTRAN) is available upon request.

    WHOOSH.ZIP  37k   MSWORD 6.0 documentation    DOS  Freeware


    Rocket Altitude Prediction
    & Coefficient of Drag and Centre of Pressure Estimation

    This program predicts the altitude a rocket may fly given the performance parameters of the motor and the physical characteristics of the rocket. The program also determines the optimum weight of a rocket to achieve maximum altitude. Additionally, the program can estimate the coefficient of drag (Cd) and the centre of pressure (Cp) of a rocket, based on the rocket's geometry. Includes performance parameters for the PVC "G", "H", & "I" rocket motors.
    Runs under DOS only. Written by: Charles D. Knight.

    ROCCAD.ZIP  169 k     DOS  Freeware  


    Rocket Drag and Stability

    Aerolab is a very useful and easy to use package that estimates Drag, Lift and Center of Pressure for rockets flying at velocities up to Mach 8. It also estimates the rockets Center of Gravity and Moments of Inertia and performs stability analysis within the entire velocity range.
    Runs under 32 bit Windows. Written by Hans Olaf Toft.       MS Windows   For free distribution 1000 kb


    Rocket Center of Pressure

    This Excel spreadsheet allows the user to quickly and easily compute a rocket's Center of Pressure (C.P.) using the well-known Barrowman method.
    Written by Richard Nakka.

    BARROWMAN.XLS    Version 1.04    57kbytes     EXCEL spreadsheet         Freeware

    Barrowman.xlsx screenshot

    Altimeter Correction to Account for Launch Site Temperature

    Commerical rocket altimeters use a Standard Atmosphere algorithm to calculate the peak altitude a rocket achieves in flight. The drawback to this method of calculating altitude is the Standard Atmosphere assumption that the ground level temperature at the launch site is 15O Celsius (59O F.). If the actual launch site temperature is significantly higher or lower, the reported peak altitude can be in error by an appreciable amount. This Excel spreadsheet makes a correction to account for the launch site temperature to provide a truer peak altitude.

    For more information, visit Altimeter Correction to Account for Launch Site Temperature .

    Written by Richard Nakka.

    Barometric_altitude_correction.xlsx  (U.S.units)
    Barometric_altitude_correction_m.xlsx  (Metric units)
    Version 1.0    150kbytes     EXCEL spreadsheet         Freeware


    Rocket Design and Performance

    OpenRocket is a free, fully featured model rocket simulator that allows you to design and simulate your rockets before actually building and flying them. The main features include:
    •Six-degree-of-freedom flight simulation
    •Automatic design optimization
    •Realtime simulated altitude, velocity and acceleration display
    •Staging and clustering support
    •Cross-platform (Java-based)
    OpenRocket is an Open Source project licensed under the GNU GPL. This means that the software is free to use for whatever purposes, and the source code is also available for studying and extending. Originally written by Sampo Niskanen.

    RASAero II

    Rocket Design and Performance

    RASAero is a combined aerodynamic analysis and flight simulation software package for model rockets, high power rockets, amateur rockets and sounding rockets. I found RASAero to be refreshingly easy to learn how to use. Menus are intuitive and the software provides a nice visual representation of the rocket being designed and good graphics showing the results of flight simulation. Simulation takes into account parameters such as launch angle, wind and parachute deployment, and as such provides results for both vertical and horizontal distance flown by a rocket. Other simulation results include mach number, angle of attack, Cd and Cl, drag force, CG and CP locations, stability margin, flight path angle and rocket attitude, over the full duration of the simulated flight. Results of simulation can be exported to Excel, which is a particularly useful feature.
    RASAero software is free.
    Written by Charles E. Rogers and David Cooper.

    RASAero II download


    Graphic Interface for PROPEP program

    This program provides a user friendly interface to run the PROPEP propellant evaluation program. PROPEP is a program that determines the chemical equilibrium composition for the combustion of a solid or liquid rocket propellant. Additionally, it determines rocket performance parameters such as Isp and C*, and nozzle design parameters. GUIPEPis a must-have program for the rocketry propellant experimentalist.
    Runs under Windows. Written by Arthur J. Lekstutis, GUIPEP is available for download at Arthur's web site, which also has a link to PROPEP.

    GUIPEP and PROPEP       MS Windows   For free distribution  

    ProPep 3 by Dave Cooper, 2012       MS Windows 7/10  For free distribution Expanded data file (pepcoded.daf) for the PROPEP program. Includes entries for Dextrose, Sorbitol, Mannitol, Xylitol, Charcoals, Asphalt, Paraffin and others.
     April 2010    Zipped text file       23 kb

    For details on using GUIPEP and an explanation on interpreting the output, see my web page:
    Solid Rocket Motor Theory -- GUIPEP


    Motor Casing Thermal Analysis

    A thermal analysis package that determines the temperature distribution through the thickness of a motor casing wall that results from convective heating due to propellant combustion and resulting gas flow. The package consists of DOS executable file which outputs a table of results which may be copied into a companion EXCEL spreadsheet for plotting. In addition, the spreadsheet contains thermal and material properties required as input data, as well as a calculator for determining the required heat transfer convection coefficient.
    Runs under DOS only. Written by Richard Nakka.

    THERMCAS.ZIP  112k     DOS  Freeware  Version 1.01


    Parachute Gore Pattern Maker

    This MS EXCEL spreadsheet may be used to create a flat pattern for a parachute gore. A gore is an individual panel that, when stitched together with adjacent gores, forms the canopy of a parachute. The user inputs the basic parachute diameter, as well as the number of gores desired (minimum of 4). The spreadsheet creates a table of coordinates as well as a plot of a single gore. When assembled, the parachute canopy is semi-ellipsoidal in shape (a "flattened" hemisphere). This form of canopy is more efficient than a hemispherical canopy, in that less material is required to provide equal drag.
    Written by Richard Nakka.

    PARAPAT_V1.1.XLS  Version 1.1 (June 2016)    75kbytes     EXCEL 97spreadsheet         Freeware

    PARAPAT_V1.1_BG.XLS        49kbytes     EXCEL spreadsheet         Bulgarian language version of PARAPAT_V1.1 translated by George Andonov. Freeware

    PARAPAT_v1.1_fr.XLSX          42kbytes     EXCEL spreadsheet         French language version of PARAPAT_V1.1 translated by Jérôme Fouque.

    Parachute Gore DXF Generator  

    Parachute Fabrication Aid

    This is a handy, easy-to-use application that generates a parachute gore pattern in DXF file format. DXF is an open-source 2D drawing format. This allows a full-scale gore pattern to be printed using a standard CAD printer. This application plots gore pattern for both elliptical and toroidal parachutes. User can choose number of gores that make up the chute, and can choose either centimetres or inches.

    Written by Eabha Abramson    Case Rocket Team - Certifications Lead, ESRA Payload Subteam Lead.

    Download from Google Drive    50 Megabytes     EXE (executable) file          Freeware

    Parachute Gore DXF Generator screenshot


    Loadcell Designer

    A relatively simple-to-make beam-type loadcell may be designed by use of this Excel spreadsheet. The user specifies the dimensions of the loadcell body (basically, a rectangular block of metal) and the size of hole to be drilled through the body, in order to achieve the desired load capacity. The only other materials required are one or two strain gages, and suitable adhesive for mounting such.
    Written by Richard Nakka.

    LOADCELL.XLS    Version 1.10    210 kbytes     EXCEL spreadsheet         Freeware

    LoadCell_fr.xlsx          47kbytes     EXCEL spreadsheet         French language version of LOADCELL translated by Jérôme Fouque.


    Nozzle Machining Aid

    The most time consuming step of machining a rocket nozzle is the process of boring out the conical convergent and divergent passages. In particular, the divergent passage, which has a greater bore depth and more shallow angle. This step may be eased significantly by first drilling out these passages using a series of incrementally larger drill bits. The required drill bit sizes range from the throat diameter to the entrance (or exit) diameter of the nozzle. This operation results in a "stepped" profile which may then be bored to the final smooth profile with a standard boring bar tool. This spreadsheet is intended to aid this drilling operation by supplying the required drill depth for each drill bit size.
    Written by Richard Nakka.

    NOZLBORE.XLS    Version 1.11    375kbytes     EXCEL 2000 spreadsheet         Freeware

    NOZLBORE_BG.RAR        308kbytes     EXCEL spreadsheet         Bulgarian language version of NOZLBORE, translated by George Andonov.

    Nozlbore_fr.xlsx          311kbytes     EXCEL spreadsheet         French language version of NOZLBORE, translated by Jérôme Fouque.

    nozzle step drilled
    Step-drilled divergent passage of A-100M nozzle.
    A boring tool is then used to finish the contour.


    Grain Geometric Analysis

    This spreadsheet computes the Kn (burning-area to throat-area ratio) for a Pseudo-finocyl propellant grain. A Pseudo-finocyl grain configuration consists of a cylindrical grain with a circular bore, from which a number of fins extend radially (similar to a star-grain). Five independant geometric variables allow for great freedom in tailoring of the Kn profile. Such a grain may be fabricated by casting with a suitable mandrel, or by drilling the core, then cutting the fin slots.
    Written by Richard Nakka.

    PFC-BURN.XLS    Version Beta-1    165kbytes     EXCEL 2000 spreadsheet         Freeware

    PFC-BURN.RAR        72 kbytes     Zipped EXCEL spreadsheet         Bulgarian language version of PFC-BURN, translated by George Andonov. Freeware

    PFC-BURN_fr.xlsm          176 kbytes     EXCEL spreadsheet         French language version of PFC-BURN, translated by Jérôme Fouque.

    Pseudo-finocyl grain cross-section  
    Pseudo-finocyl grain cross-section. Example Kn chart.

    Delaney/Nakka Ejection Charge Calculator

    Simple to use Windows calculator that computes the mass of Black Powder needed to produce a specified pressure within a rocket parachute compartment. The resulting force tending to eject the nosecone or to separate the rocket sections is also computed.
    Software written by J.Delaney
    Help written by Richard Nakka    Version 1.3    1.4Mbytes     MS Windows         Freeware


    Grain Density Check

    This Excel spreadsheet computes the actual mass density of a sugar-propellant grain based on user input values of grain geometry and mass. This is compared to the ideal mass density by computing the ratio of the two densities. This provides the experimentalist with a "densitometric quality" assessment of a propellant grain. A good quality grain, one with minimal porosity and few voids or other flaws, will have a ratio close to one. A porous grain or a grain with hidden voids, for example, will be marked by a significantly lower density ratio. The usefulness of such a check is apparent when one considers that propellant burn rate and Kn profile can be strongly affected by such grain deficiencies. In extreme cases, a CATO could result from a grain with degraded densitometric quality.
    Written by Richard Nakka.

    GRAINDENSITY.XLS    Version 1.00    40kbytes     EXCEL 2000 spreadsheet         Freeware

    GRAINDENSITY_BG.RAR        13kbytes     Zipped EXCEL spreadsheet         Bulgarian language version of GRAINDENSITY, translated by George Andonov. Freeware

    GRAINDENSITY_fr.xlsx          33kbytes      EXCEL spreadsheet         French language version of GRAINDENSITY, translated by Jérôme Fouque


    O-Ring Designer

    The use of o-rings is an ideal means to pressure seal a rocket nozzle or bulkhead. O-rings are inexpensive, simple to incorporate, and are highly reliable. However, it is important to choose the correct size o-ring for a given application, and to have the correct size gland (groove) into which the o-ring is seated. This Excel spreadsheet selects the appropriate sized o-ring based on user input values of casing and nozzle diameters, based on ARP 1232 specifications. Updated for 010, 100, 200 & 300 series (1/16", 3/32", 1/8" & 3/16") o-rings .
    Written by Richard Nakka.

    O-RING_2.4.XLS    Version 2.4    872kbytes     EXCEL spreadsheet         Freeware

    O-RING_2.3_fr.xlsx          33kbytes     EXCEL spreadsheet         French language version of O-RING, translated by Jérôme Fouque.


    Document converter

    An extremely useful "open-source" (GNU GPL) software for reliably converting documents to Acrobat PDF format. Excellent for publishing articles for on-line format or for e-mailing. Can be used with any document software (examples: MS Word, MS Excel, Paint Shop Pro, etc.). Easy to use -- instead of printing to a device, you simply print to PDF Creator.

    PDFCreator    Version 0.9.3

    Last updated

    Last updated September 15, 2022

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