File Specification

This page describes the specification of OpenRocket’s design file format (.ork), and the OpenRocket component file format (.orc).

OpenRocket Design File (.ork)

The OpenRocket design file format is a human-readable XML format that describes a rocket design. It contains all the information needed to recreate the design in OpenRocket, including the rocket’s components, materials, and simulation settings. The file format is designed to be extensible, allowing for the addition of new features and properties in a backward-compatible way.

Note

Not every parameter in the XML file is explained here. Please refer to the core/src/main/java/info/openrocket/core/file/openrocket package in the source code.

Developer Reference 

The code for reading and writing .ork files is located in:

Reading (.ork → Rocket model):

Main loader: core/src/main/java/info/openrocket/core/file/openrocket/importt/OpenRocketLoader.java
Content handler: core/src/main/java/info/openrocket/core/file/openrocket/importt/OpenRocketContentHandler.java
Component handlers: core/src/main/java/info/openrocket/core/file/openrocket/importt/ComponentHandler.java
Parameter handlers: core/src/main/java/info/openrocket/core/file/openrocket/importt/ComponentParameterHandler.java
Specialized handlers: Various handler classes in the importt/ directory (e.g., SimulationConditionsHandler.java, WindHandler.java, MotorHandler.java)

Writing (Rocket model → .ork):

Main saver: core/src/main/java/info/openrocket/core/file/openrocket/OpenRocketSaver.java
Component savers: core/src/main/java/info/openrocket/core/file/openrocket/savers/ directory
Base saver: core/src/main/java/info/openrocket/core/file/openrocket/savers/RocketComponentSaver.java
Specific component savers: Individual saver classes for each component type (e.g., NoseConeSaver.java, BodyTubeSaver.java, FinSetSaver.java)

File Architecture 

The OpenRocket design file (.ork) is a ZIP archive containing an XML format file and any associated graphics files. While OpenRocket also accepts the .ork.gz extension, the plain .ork extension is recommended.

To examine the contents of an .ork file:

Rename the file extension from .ork to .zip
Extract the contents using any ZIP extraction tool
The main rocket design is stored in the XML file named rocket.ork

Version Control 

The file format uses semantic versioning, indicated by the version attribute in the root <openrocket> tag. The version number follows these rules:

Major version increases indicate backward-incompatible changes
Minor version increases indicate backward-compatible additions
The version is internally stored as an integer, divided by 100 (e.g., version “1.10” is stored as 110)
For maximum compatibility, files should be saved using the oldest format version that supports all required features

The creator attribute optionally specifies the software and version used to create the file.

Version History 

The following table lists the version history of the OpenRocket design file format (taken from fileformat.txt file in the root directory of our repository).

Version	Release	Changes
1.0	OpenRocket 0.9.0	Initial public release
1.1	OpenRocket 0.9.4	Added fin tab support (`<tabheight>`, `<tablength>`, `<tabposition>` elements) Enabled subcomponent attachment to tube couplers
1.2	OpenRocket 1.1.1	Added `<digest>` tag for motor definitions to uniquely identify thrust curve characteristics
1.3	OpenRocket 1.1.9	Added `<launchlongitude>` and `<geodeticmethod>` parameters for simulation conditions
1.4	OpenRocket 12.03	Added `launchrodvelocity` and `deploymentvelocity` attributes to `<flightdata>` Modified motor digesting algorithm Added `<separationevent>` and `<separationdelay>` elements for stage components
1.5	OpenRocket 12.09	Introduced ComponentPresets Added lowerstageseparation as recovery device deployment event Added `<datatypes>` section for custom expressions
1.6	OpenRocket 13.04	Added component Appearances (decals & paint) Added configurable parameters for recovery devices, motor ignition and separation
1.7	OpenRocket 15.03	Added simulation extensions and configuration Added support for TubeFins
1.8	OpenRocket 22.02	Added new components (RailButton `<railbutton>`, Pods `<podset>`, Booster `<parallelstage>`) Added internal appearance options Added PhotoStudio settings Added override CD parameter Added stage activeness remembrance Added nose cone flip parameter Separated override subcomponents Renamed various parameters for clarity
1.9	OpenRocket 23.09	Added component IDs for flight event sources
1.10	OpenRocket 24.12	Added simulation warning priority Added document preferences Added wind model settings Added warning flight events Added maximum time attribute for simulation conditions
1.11	OpenRocket 26.xx	Added `<simulationsteppermethod>` to simulation conditions Added simulation table column visibility preferences Include file preview image (`preview.png`) in .ork zip file Embedded thrust curve motor data as `.rse` (RockSim engine) files in a `thrustcurves/` directory within the .ork zip archive, keyed by motor digest

Root Structure 

The following shows the root XML structure of an OpenRocket design file:

<?xml version='1.0' encoding='utf-8'?>
<openrocket version="1.12" creator="OpenRocket 26.xx">
   <rocket>
      <!-- Rocket definition -->
   </rocket>
   <simulations>
      <!-- Simulation data -->
   </simulations>
   <photostudio>
      <!-- PhotoStudio settings -->
   </photostudio>
   <docprefs>
      <!-- Document preferences -->
   </docprefs>
</openrocket>

The file must begin with the XML declaration:

<?xml version='1.0' encoding='utf-8'?>

Then follows the actual content of the OpenRocket design file, starting with the <openrocket> tag with the following content:

rocket: Rocket definition (see Rocket)
simulations: Simulation data (see Simulation Data)
photostudio: PhotoStudio settings (see PhotoStudio Settings)
docprefs: Document preferences (see Document Preferences)

Rocket 

The <rocket> contains metadata of the rocket (name, designer…), motor configurations in the design, and all the rocket component definitions:

<rocket>
   <!-- Rocket definition -->
   <name>[ROCKET NAME]</name>
   <id>[UUID]</id>
   <axialoffset method="absolute">0.0</axialoffset>
   <position type="absolute">0.0</position>
   <designer>[DESIGNER]</designer>
   <designtype>[DESIGN TYPE]</designtype>
   <kitname>[KIT NAME]</kitname>
   <revision>[REVISION]</revision>
   <motorconfiguration configid="[CONFIG ID]">
      <!-- Motor configuration -->
   </motorconfiguration>

   <subcomponents>
      <!-- Rocket components -->
   </subcomponents>
</rocket>

The <rocket> element contains the following primary attributes:

name: Name of the rocket design
id: Unique identifier (UUID) - automatically generated by OpenRocket
axialoffset: Absolute position offset
designer: Designer’s name
designtype: Design type (e.g., scratch, kit, makeitgo, educational, sport, competition)
kitname: Name of the kit if applicable
revision: Revision information for the design
motorconfiguration: One or more motor configurations
subcomponents: Container for all the rocket components in the design

Motor Configuration 

Each <motorconfiguration> element defines a specific motor setup:

 <motorconfiguration configid="[UUID]" default="true|false">
     <stage number="0" active="true|false"/>
 </motorconfiguration>

Rocket Components 

Common Component Attributes

Most components share these common attributes:

id: Unique identifier (UUID) - automatically generated by OpenRocket
name: Component name
finish: Surface finish type
material: Material specifications including:
- type: (bulk, surface, line)
- density: Material density
- group: Material category
- shearModulus: In-plane shear modulus in Pa (optional)

Position and Offset Attributes:

axialoffset: Position along the rocket’s axis
position: Legacy position attribute
radialdirection: Angular direction for radial components
radialposition: Distance from center axis

Appearance Settings

Components can have appearance settings defined using the <appearance> tag:

 <appearance>
     <paint red="51" green="51" blue="51" alpha="255"/>
     <shine>0.5</shine>
     <decal name="decals/BodyStripe.png" rotation="0.0" edgemode="CLAMP">
         <center x="0.0" y="0.0"/>
         <offset x="0.0" y="-0.2"/>
         <scale x="1.0" y="10.0"/>
     </decal>
 </appearance>

Inside Appearance

Components can have internal appearance defined separately from external (e.g. for tubes or fins):

 <insideappearance>
     <edgessameasinside>false</edgessameasinside>
     <insidesameasoutside>false</insidesameasoutside>
     <paint red="187" green="187" blue="187" alpha="255"/>
     <shine>0.3</shine>
     <decal name="decals/mainBodyWrap2.png" rotation="0.0" edgemode="REPEAT">
         <center x="0.0" y="0.0"/>
         <offset x="0.0" y="0.0"/>
         <scale x="1.0" y="1.0"/>
     </decal>
 </insideappearance>

Component Tags

<subcomponents>

Used in assembly components (rocket, stage, pod set, body tube, …) as a container for child components.

<stage>

Contains components for each defined stage.

 <stage>
     <name>Booster</name>
     <id>[UUID]</id>
     <separationevent>ejection</separationevent>
     <separationaltitude>200.0</separationaltitude>
     <separationdelay>0.0</separationdelay>
     <separationconfiguration configid="[UUID]">
         <separationevent>burnout</separationevent>
         <separationaltitude>200.0</separationaltitude>
         <separationdelay>0.0</separationdelay>
     </separationconfiguration>
 </stage>

<podset>

The <podset> element defines the Pod Set component (added in version 1.8):

 <podset>
     <name>Pod Set</name>
     <id>[UUID]</id>
     <instancecount>3</instancecount>
     <radiusoffset method="surface">0.0</radiusoffset>
     <angleoffset method="fixed">0.0</angleoffset>
     <axialoffset method="top">0.0</axialoffset>
     <position type="top">0.0</position>
     <subcomponents>
         <!-- Pod components -->
     </subcomponents>
 </podset>

Pod sets allow multiple identical assemblies of components (pods) to be radially positioned around the rocket body.

<parallelstage>

The <parallelstage> element defines the Parallel Stage (Booster) component (added in version 1.8):

 <parallelstage>
     <name>Booster</name>
     <id>[UUID]</id>
     <instancecount>2</instancecount>
     <radiusoffset method="surface">0.0</radiusoffset>
     <angleoffset method="fixed">0.0</angleoffset>
     <axialoffset method="top">0.0</axialoffset>
     <position type="top">0.0</position>
     <separationevent>burnout</separationevent>
     <separationaltitude>200.0</separationaltitude>
     <separationdelay>0.0</separationdelay>
     <separationconfiguration configid="[UUID]">
         <separationevent>burnout</separationevent>
         <separationaltitude>200.0</separationaltitude>
         <separationdelay>0.0</separationdelay>
     </separationconfiguration>
     <subcomponents>
         <!-- Booster components -->
     </subcomponents>
 </parallelstage>

Parallel stages are side-mounted boosters that separate from the main rocket during flight.

<nosecone>

The <nosecone> element defines the Nose Cone component:

<nosecone>
   <name>Nose cone</name>
   <id>[UUID]</id>
   <finish>normal</finish>
   <material type="bulk" density="500.0">Basswood</material>
   <length>0.22</length>
   <thickness>0.002</thickness>
   <shape>power</shape>
   <shapeclipped>false</shapeclipped>
   <shapeparameter>0.4</shapeparameter>
   <aftradius>0.075</aftradius>
   <aftshoulderradius>0.0</aftshoulderradius>
   <aftshoulderlength>0.0</aftshoulderlength>
   <aftshoulderthickness>0.0</aftshoulderthickness>
   <aftshouldercapped>false</aftshouldercapped>
</nosecone>

Note: Shape values are typically same as editor fields, except: * “power” for Power * “parabolic” for Parabolic * “haack” for Haack series

<bodytube>

The <bodytube> element defines the Body Tube component:

<bodytube>
   <name>Body tube</name>
   <id>[UUID]</id>
   <finish>normal</finish>
   <material type="bulk" density="680.0">Cardboard</material>
   <length>0.3</length>
   <thickness>0.002</thickness>
   <radius>auto</radius>
</bodytube>

<transition>

The <transition> element defines the Transition component:

<transition>
   <name>Transition</name>
   <id>[UUID]</id>
   <finish>normal</finish>
   <material type="bulk" density="500.0">Basswood</material>
   <length>0.11</length>
   <thickness>0.002</thickness>
   <shape>haack</shape>
   <shapeclipped>true</shapeclipped>
   <shapeparameter>0.3</shapeparameter>
   <foreradius>auto</foreradius>
   <aftradius>0.05</aftradius>
   <foreshoulderradius>0.0</foreshoulderradius>
   <foreshoulderlength>0.0</foreshoulderlength>
   <foreshoulderthickness>0.0</foreshoulderthickness>
   <foreshouldercapped>false</foreshouldercapped>
   <aftshoulderradius>0.0</aftshoulderradius>
   <aftshoulderlength>0.0</aftshoulderlength>
   <aftshoulderthickness>0.0</aftshoulderthickness>
   <aftshouldercapped>false</aftshouldercapped>
</transition>

<railbutton>

The <railbutton> element defines the Rail Button component:

<railbutton>
   <name>Rail Button</name>
   <id>[UUID]</id>
   <instancecount>1</instancecount>
   <instanceseparation>0.0582</instanceseparation>
   <angleoffset method="relative">180.0</angleoffset>
   <axialoffset method="middle">0.0</axialoffset>
   <position type="middle">0.0</position>
   <finish>normal</finish>
   <material type="bulk" density="1420.0" group="Plastics">Delrin</material>
   <outerdiameter>0.0097</outerdiameter>
   <innerdiameter>0.008</innerdiameter>
   <height>0.0097</height>
   <baseheight>0.002</baseheight>
   <flangeheight>0.002</flangeheight>
   <screwheight>0.0</screwheight>
</railbutton>

<launchlug>

The <launchlug> element defines the Launch Lug component:

<launchlug>
   <name>12. Launch lug</name>
   <id>[UUID]</id>
   <instancecount>1</instancecount>
   <instanceseparation>0.0</instanceseparation>
   <angleoffset method="relative">19.0</angleoffset>
   <radialdirection>19.0</radialdirection>
   <axialoffset method="middle">0.0</axialoffset>
   <position type="middle">0.0</position>
   <finish>normal</finish>
   <material type="bulk" density="680.0">Cardboard</material>
   <radius>0.0035</radius>
   <length>0.035</length>
   <thickness>0.001</thickness>
</launchlug>

Motor Mount

Components such as body tubes and inner tubes can be used as motor mounts. If they are, a <motormount> element will be present in the XML component block:

<bodytube>
   <!-- Other Body Tube definitions -->
   <motormount>
      <ignitionevent>automatic</ignitionevent>
      <ignitiondelay>0.0</ignitiondelay>
      <overhang>0.003</overhang>
      <motor configid="[UUID]">
         <type>single</type>
         <manufacturer>Estes</manufacturer>
         <digest>22aec01287ea1e3b8c6f66b26fe5fea6</digest>
         <designation>A8</designation>
         <diameter>0.018</diameter>
         <length>0.07</length>
         <delay>3.0</delay>
      </motor>
      <ignitionconfiguration configid="[UUID]">
         <ignitionevent>automatic</ignitionevent>
         <ignitiondelay>0.0</ignitiondelay>
      </ignitionconfiguration>
   </motormount>
</bodytube>

Embedded Thrust Curve Data

As of file format version 1.11, OpenRocket embeds the full thrust curve motor data as .rse (RockSim engine) files in the thrustcurves/ directory of the .ork zip archive. Each motor is stored as thrustcurves/<digest>.rse, where <digest> matches the <digest> element in the XML. This makes designs self-contained when sharing custom or experimental motors.

The .ork zip structure looks like:

mymodel.ork (zip)
├── rocket.ork          (XML)
├── preview.png          (optional)
├── thrustcurves/
│   ├── <digest1>.rse
│   └── <digest2>.rse
└── textures/            (optional decal images)

Motor Loading Precedence

When loading a motor from an .ork file, OpenRocket uses the following precedence order:

Motor database lookup — the motor’s manufacturer, designation, and digest are used to find a match in the local motor database. If found, the database version is used (it may have more accurate or updated data).
Embedded .rse file — if the motor is not in the database, OpenRocket looks for a thrustcurves/<digest>.rse entry in the .ork zip archive and parses it.

This precedence is implemented in MotorHandler.getMotor() (see core/src/main/java/.../file/openrocket/importt/MotorHandler.java).

Fin Sets

<freeformfinset>

The <freeformfinset> element defines the Freeform Fin Set component:

<freeformfinset>
   <name>Freeform fin set</name>
   <id>[UUID]</id>
   <position type="bottom">0.0</position>
   <finish>normal</finish>
   <material type="bulk" density="500.0">Basswood</material>
   <fincount>5</fincount>
   <rotation>0.0</rotation>
   <thickness>0.003</thickness>
   <crosssection>airfoil</crosssection>
   <cant>0.0</cant>
   <filletradius>0.0</filletradius>
   <filletmaterial type="bulk" density="680.0">Cardboard</filletmaterial>
   <finpoints>
      <point x="0.0" y="0.0"/>
      <point x="0.03882760416666667" y="0.056620833333333336"/>
      <point x="0.11000052083333334" y="0.05582708333333333"/>
      <point x="0.07951041666666667" y="0.0"/>
   </finpoints>
</freeformfinset>

<trapezoidfinset>

The <trapezoidfinset> element defines the Trapezoidal Fin Set component:

<trapezoidfinset>
   <name>Trapezoidal fin set</name>
   <id>[UUID]</id>
   <position type="bottom">0.0</position>
   <finish>normal</finish>
   <material type="bulk" density="680.0">Cardboard</material>
   <fincount>3</fincount>
   <rotation>0.0</rotation>
   <thickness>0.003</thickness>
   <crosssection>square</crosssection>
   <cant>0.0</cant>
   <filletradius>0.0</filletradius>
   <filletmaterial type="bulk" density="680.0">Cardboard</filletmaterial>
   <rootchord>0.05</rootchord>
   <tipchord>0.05</tipchord>
   <sweeplength>0.025</sweeplength>
   <height>0.03</height>
</trapezoidfinset>

<ellipticalfinset>

The <ellipticalfinset> element defines the Elliptical Fin Set component:

<ellipticalfinset>
   <name>Elliptical fin set</name>
   <id>[UUID]</id>
   <position type="bottom">0.0</position>
   <finish>normal</finish>
   <material type="bulk" density="680.0">Cardboard</material>
   <fincount>3</fincount>
   <rotation>0.0</rotation>
   <thickness>0.003</thickness>
   <crosssection>square</crosssection>
   <cant>0.0</cant>
   <filletradius>0.0</filletradius>
   <filletmaterial type="bulk" density="680.0">Cardboard</filletmaterial>
   <rootchord>0.05</rootchord>
   <height>0.05</height>
</ellipticalfinset>

<tubefinset>

The <tubefinset> element defines the Tube Fin Set component:

<tubefinset>
   <name>Tube Fin Set</name>
   <id>[UUID]</id>
   <instancecount>6</instancecount>
   <fincount>6</fincount>
   <radiusoffset method="coaxial">0.0</radiusoffset>
   <angleoffset method="fixed">0.0</angleoffset>
   <rotation>0.0</rotation>
   <axialoffset method="bottom">0.0</axialoffset>
   <position type="bottom">0.0</position>
   <finish>normal</finish>
   <material type="bulk" density="680.0" group="PaperProducts">Cardboard</material>
   <fincount>6</fincount>
   <rotation>0.0</rotation>
   <radius>auto</radius>
   <length>0.1</length>
   <thickness>0.002</thickness>
</tubefinset>

Inner Components

<innertube>

The <innertube> element defines the Inner Tube component:

<innertube>
   <name>Inner Tube</name>
   <id>[UUID]</id>
   <axialoffset method="bottom">0.0</axialoffset>
   <position type="bottom">0.0</position>
   <material type="bulk" density="680.0" group="PaperProducts">Cardboard</material>
   <length>0.07</length>
   <radialposition>0.0</radialposition>
   <radialdirection>0.0</radialdirection>
   <outerradius>0.0095</outerradius>
   <thickness>5.000000000000004E-4</thickness>
   <clusterconfiguration>single</clusterconfiguration>
   <clusterscale>1.0</clusterscale>
   <clusterrotation>0.0</clusterrotation>
</innertube>

<tubecoupler>

The <tubecoupler> element defines the Tube Coupler component:

<tubecoupler>
   <name>Tube Coupler</name>
   <id>[UUID]</id>
   <axialoffset method="bottom">0.03175</axialoffset>
   <material type="bulk" density="943.0">Phenolic</material>
   <length>0.0635</length>
   <outerradius>auto</outerradius>
   <thickness>5.0E-4</thickness>
</tubecoupler>

<centeringring>

The <centeringring> element defines the Centering Ring component:

<centeringring>
   <name>Centering Ring</name>
   <id>[UUID]</id>
   <instancecount>1</instancecount>
   <axialoffset method="bottom">-0.05715</axialoffset>
   <material type="bulk" density="657.0">Fiber</material>
   <length>0.00635</length>
   <outerradius>0.016269</outerradius>
   <innerradius>auto</innerradius>
</centeringring>

<bulkhead>

The <bulkhead> element defines the Bulkhead component:

<bulkhead>
   <name>Bulkhead</name>
   <id>[UUID]</id>
   <instancecount>1</instancecount>
   <instanceseparation>0.0</instanceseparation>
   <axialoffset method="bottom">0.0</axialoffset>
   <position type="bottom">0.0</position>
   <material type="bulk" density="680.0" group="PaperProducts">Cardboard</material>
   <length>0.002</length>
   <radialposition>0.0</radialposition>
   <radialdirection>0.0</radialdirection>
   <outerradius>auto</outerradius>
</bulkhead>

<engineblock>

The <engineblock> element defines the Engine Block component:

<engineblock>
   <name>Engine Block</name>
   <id>[UUID]</id>
   <axialoffset method="bottom">-0.0635</axialoffset>
   <material type="bulk" density="657.0">Fiber</material>
   <length>0.00635</length>
   <outerradius>0.008992</outerradius>
   <thickness>7.366E-4</thickness>
</engineblock>

Mass Components

<parachute>

The <parachute> element defines the Parachute component:

 <parachute>
     <name>Parachute</name>
      <id>[UUID]</id>
     <axialoffset method="top">0.032</axialoffset>
     <packedlength>0.042</packedlength>
     <packedradius>0.009</packedradius>
     <cd>auto</cd>
     <material type="surface" density="0.067">Ripstop nylon</material>
     <deployevent>ejection</deployevent>
     <deployaltitude>200.0</deployaltitude>
     <deploydelay>0.0</deploydelay>
     <diameter>0.3</diameter>
     <linecount>6</linecount>
     <linelength>0.3</linelength>
     <linematerial type="line" density="0.0018">Elastic cord</linematerial>
 </parachute>

<streamer>

The <streamer> element defines the Streamer component:

<streamer>
   <name>Streamer</name>
   <id>[UUID]</id>
   <axialoffset method="top">0.0</axialoffset>
   <position type="top">0.0</position>
   <packedlength>0.025</packedlength>
   <packedradius>0.0125</packedradius>
   <radialposition>0.0</radialposition>
   <radialdirection>0.0</radialdirection>
   <cd>auto</cd>
   <material type="surface" density="0.067" group="Fabrics">Ripstop nylon</material>
   <deployevent>ejection</deployevent>
   <deployaltitude>200.0</deployaltitude>
   <deploydelay>0.0</deploydelay>
   <striplength>0.5</striplength>
   <stripwidth>0.05</stripwidth>
</streamer>

<shockcord>

The <shockcord> element defines the Shock Cord component:

 <shockcord>
   <name>Shock Cord</name>
   <id>[UUID]</id>
   <axialoffset method="top">0.044449999999999996</axialoffset>
   <position type="top">0.044449999999999996</position>
   <packedlength>0.019049999999999997</packedlength>
   <packedradius>0.0065405</packedradius>
   <radialposition>0.0</radialposition>
   <radialdirection>0.0</radialdirection>
   <cordlength>0.3047999999999995</cordlength>
   <material type="line" density="0.00297638" group="ThreadsLines">Elastic rubber band (flat 3.2 mm, 1/8 in)</material>
</shockcord>

<masscomponent>

 <masscomponent>
     <name>Unspecified</name>
      <id>[UUID]</id>
     <position type="top">0.11</position>
     <packedlength>0.05</packedlength>
     <packedradius>0.0225</packedradius>
     <radialposition>0.0</radialposition>
     <radialdirection>0.0</radialdirection>
     <mass>0.061</mass>
     <masscomponenttype>masscomponent</masscomponenttype>
 </masscomponent>

Simulation Data 

The <simulations> section contains flight simulation data. Each simulation is enclosed in a <simulation> tag:

<simulations>
   <simulation status="loaded">
      <name>Simulation 1</name>
      <simulator>RK4Simulator</simulator>
      <calculator>BarrowmanCalculator</calculator>
      <conditions>
         <configid>[UUID]</configid>
         <launchrodlength>1.0</launchrodlength>
         <launchintowind>true</launchintowind>
         <launchrodangle>0.0</launchrodangle>
         <launchroddirection>90.0</launchroddirection>
         <windaverage>2.0</windaverage>
         <windturbulence>0.1</windturbulence>
         <winddirection>1.5707963267948966</winddirection>
         <wind model="average">
            <speed>2.0</speed>
            <direction>1.5707963267948966</direction>
            <standarddeviation>0.2</standarddeviation>
         </wind>
         <windmodeltype>Average</windmodeltype>
         <launchaltitude>0.0</launchaltitude>
         <launchlatitude>45.0</launchlatitude>
         <launchlongitude>0.0</launchlongitude>
         <geodeticmethod>flat</geodeticmethod>
         <simulationsteppermethod>rk4</simulationsteppermethod>
         <atmosphere model="isa"/>
         <timestep>0.05</timestep>
         <maxtime>1200.0</maxtime>
      </conditions>
      <flightdata maxaltitude="50.605" maxvelocity="29.249" maxacceleration="143.659"
                maxmach="0.086" timetoapogee="3.443" flighttime="15.89"
                groundhitvelocity="4.583" launchrodvelocity="15.366"
                deploymentvelocity="2.634" optimumdelay="2.763">
      <!-- Flight data points -->
      </flightdata>
   </simulation>
   <!-- Other simulations go here -->
   <simulation>
      <!-- Simulation 2 content -->
   </simulation>
<simulations>

Wind Models

OpenRocket supports two wind models: average wind and multi-level wind.

Average Wind Model:

<wind model="average">
   <speed>2.0</speed>
   <direction>1.5707963267948966</direction>
   <standarddeviation>0.2</standarddeviation>
</wind>

Multi-Level Wind Model (added in version 1.10):

<wind model="multilevel" altituderef="agl">
   <windlevel altitude="0.0" speed="2.0" direction="1.57" standarddeviation="0.2"/>
   <windlevel altitude="100.0" speed="3.0" direction="1.57" standarddeviation="0.3"/>
   <windlevel altitude="500.0" speed="5.0" direction="1.60" standarddeviation="0.4"/>
</wind>

The altituderef attribute can be:

agl: Above Ground Level (relative to launch site)
msl: Mean Sea Level (absolute altitude)

Each <windlevel> defines wind conditions at a specific altitude with:

altitude: Altitude value (in meters)
speed: Wind speed (in m/s)
direction: Wind direction (in radians)
standarddeviation: Standard deviation for wind turbulence

Note

Legacy parameters <windaverage>, <windturbulence>, and <winddirection> are still written for backward compatibility with older OpenRocket versions.

PhotoStudio Settings 

<photostudio>
   <!-- Orientation settings -->
   <roll>value</roll>         <!-- Roll angle -->
   <yaw>value</yaw>          <!-- Yaw angle -->
   <pitch>value</pitch>       <!-- Pitch angle -->
   <advance>value</advance>   <!-- Advance position -->

   <!-- View settings -->
   <viewAlt>value</viewAlt>       <!-- View altitude -->
   <viewAz>value</viewAz>         <!-- View azimuth -->
   <viewDistance>value</viewDistance>  <!-- Camera distance -->
   <fov>value</fov>               <!-- Field of view -->

   <!-- Lighting settings -->
   <lightAlt>value</lightAlt>     <!-- Light altitude -->
   <lightAz>value</lightAz>       <!-- Light azimuth -->
   <sunlight red="R" green="G" blue="B" alpha="A"/>  <!-- Sunlight color -->
   <ambiance>value</ambiance>     <!-- Ambient light intensity -->
   <skyColor red="R" green="G" blue="B" alpha="A"/>  <!-- Sky color -->

   <!-- Effects settings -->
   <motionBlurred>true/false</motionBlurred>     <!-- Motion blur enabled -->
   <flame>true/false</flame>                     <!-- Flame effect enabled -->
   <flameColor red="R" green="G" blue="B" alpha="A"/>  <!-- Flame color -->
   <smoke>true/false</smoke>                     <!-- Smoke effect enabled -->
   <smokeColor red="R" green="G" blue="B" alpha="A"/>  <!-- Smoke color -->
   <sparks>true/false</sparks>                   <!-- Spark effect enabled -->
   <exhaustScale>value</exhaustScale>            <!-- Exhaust size scale -->
   <flameAspectRatio>value</flameAspectRatio>   <!-- Flame shape ratio -->

   <!-- Spark properties -->
   <sparkConcentration>value</sparkConcentration>  <!-- Spark density -->
   <sparkWeight>value</sparkWeight>               <!-- Spark size -->

   <!-- Environment settings -->
   <sky>value</sky>  <!-- Sky rendering mode -->
</photostudio>

Colors are specified using RGBA values, each in the range 0-255.

Document Preferences 

The <docprefs> section contains document-wide settings, including material definitions:

 <docprefs>
     <docmaterials>
         <material>BULK|My Custom Material 1|680.0|1.2E9|Custom</material>
         <material>BULK|My Custom Metal|0.0018|7.5E10|Metals</material>
     </docmaterials>
 </docprefs>

Material string format:

{type}|{name}|{density}|{inPlaneShearModulus}|{group}
Older files may omit inPlaneShearModulus and store {type}|{name}|{density}|{group}

OpenRocket Component File (.orc)

The OpenRocket component file format is a human-readable XML format that defines standard rocket components and their specifications. This file format allows rocket components to be stored in a database, making it easier for users to select pre-defined components rather than entering specifications manually.

Developer Reference 

The code for reading and writing .orc files is located in:

Reading (.orc → ComponentPreset objects):

Main loader: core/src/main/java/info/openrocket/core/preset/xml/OpenRocketComponentLoader.java
Root DTO: core/src/main/java/info/openrocket/core/preset/xml/OpenRocketComponentDTO.java
Component DTOs: Individual DTO classes for each component type (e.g., BodyTubeDTO.java, NoseConeDTO.java, ParachuteDTO.java)
Material DTO: core/src/main/java/info/openrocket/core/preset/xml/MaterialDTO.java
Base component DTO: core/src/main/java/info/openrocket/core/preset/xml/BaseComponentDTO.java

Writing (ComponentPreset objects → .orc):

Main saver: core/src/main/java/info/openrocket/core/preset/xml/OpenRocketComponentSaver.java
Uses JAXB marshalling from the same DTO classes listed above

Note

The .orc file format uses JAXB (Jakarta XML Binding) annotations for serialization/deserialization, while the .ork format uses SAX parsing for reading and direct XML writing for saving.

File Architecture 

The OpenRocket component file (.orc) is a plain XML file that contains component definitions. When OpenRocket is built, these files are serialized into a single binary file (system.ser) that is included in the OpenRocket jar.

Root Structure 

The following shows the root XML structure of an OpenRocket component file:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<OpenRocketComponent>
    <Version>0.1</Version>
    <Materials>
        <!-- Material definitions -->
    </Materials>
    <Components>
        <!-- Component definitions -->
    </Components>
</OpenRocketComponent>

Materials 

The <Materials> section defines materials used within the component database:

<Materials>
    <Material UnitsOfMeasure="g/cm3">
        <Name>Material Name</Name>
        <Density>0.0</Density>
        <ShearModulus>0.0</ShearModulus>
        <Type>BULK</Type>
        <Group>MaterialGroup</Group>
    </Material>
</Materials>

Material properties: - UnitsOfMeasure: Density units (supported formats):

Bulk density: g/cm3, kg/m3, lb/ft3

Areal density: g/cm2, oz/in2

Line density: g/cm, oz/in

Type: Material type (BULK, SURFACE, or LINE)
Group: Material group for categorization (optional)
ShearModulus: In-plane shear modulus in Pa (optional, defaults to 0.0 when omitted)

Components 

Common Component Attributes

All components share these common attributes:

<Manufacturer>Text</Manufacturer>
<PartNumber>Text</PartNumber>
<Description>Text</Description>
<Material Type="BULK" Group="MaterialGroup">Material Name</Material>
<Mass Unit="kg">0.035892</Mass>
<Filled>true</Filled>
<Thumbnail>base64EncodedImageData</Thumbnail>

Common attributes:

Manufacturer: Manufacturer name
PartNumber: Part/model number
Description: Component description (optional)
Material: Material definition with Type attribute (BULK, SURFACE, or LINE) and optional Group attribute
Mass: Component mass with Unit attribute (optional)
Filled: Boolean indicating if the component is filled (optional)
Thumbnail: Base64-encoded PNG image data for component preview (optional)

Component Types

Body Tube

<BodyTube>
    <InsideDiameter Unit="m">0.0657352</InsideDiameter>
    <OutsideDiameter Unit="m">0.06604</OutsideDiameter>
    <Length Unit="m">0.36195</Length>
</BodyTube>

Nose Cone

<NoseCone>
    <Shape>ELLIPSOID</Shape>
    <ShapeParameter>1.0</ShapeParameter>
    <Filled>true</Filled>
    <OutsideDiameter Unit="m">0.06604</OutsideDiameter>
    <BaseDiameter Unit="m">0.06604</BaseDiameter>
    <ShoulderDiameter Unit="m">0.064922</ShoulderDiameter>
    <ShoulderLength Unit="m">0.0381</ShoulderLength>
    <ShoulderThickness Unit="m">0.003175</ShoulderThickness>
    <Length Unit="m">0.1016</Length>
    <Thickness Unit="m">0.003175</Thickness>
</NoseCone>

Supported nose cone shapes:

CONICAL
ELLIPSOID
HAACK
OGIVE
PARABOLIC
POWER

Note

HAACK, OGIVE, PARABOLIC, and POWER types support a shape parameter that can be set in the UI but cannot be specified in the .orc file.

Transition

<Transition>
    <Shape>OGIVE</Shape>
    <Filled>true</Filled>
    <ForeOutsideDiameter Unit="m">0.067056</ForeOutsideDiameter>
    <ForeShoulderDiameter Unit="m">0.064973</ForeShoulderDiameter>
    <ForeShoulderLength Unit="m">0.0254</ForeShoulderLength>
    <ForeShoulderThickness Unit="m">0.003175</ForeShoulderThickness>
    <AftOutsideDiameter Unit="m">0.03175</AftOutsideDiameter>
    <AftShoulderDiameter Unit="m">0.0</AftShoulderDiameter>
    <AftShoulderLength Unit="m">0.0</AftShoulderLength>
    <AftShoulderThickness Unit="m">0.003175</AftShoulderThickness>
    <Length Unit="m">0.1524</Length>
    <Thickness Unit="m">0.003175</Thickness>
</Transition>

Centering Ring

<CenteringRing>
    <InsideDiameter Unit="m">0.0187452</InsideDiameter>
    <OutsideDiameter Unit="m">0.0240792</OutsideDiameter>
    <Thickness Unit="m">0.003175</Thickness>
    <Length Unit="m">0.00635</Length>
</CenteringRing>

Bulkhead

<BulkHead>
    <Filled>true</Filled>
    <OutsideDiameter Unit="m">0.028701999999999995</OutsideDiameter>
    <Length Unit="m">0.038099999999999995</Length>
</BulkHead>

Engine Block

<EngineBlock>
    <InsideDiameter Unit="m">0.013131799999999999</InsideDiameter>
    <OutsideDiameter Unit="m">0.017983199999999998</OutsideDiameter>
    <Thickness Unit="m">0.003175</Thickness>
    <Length Unit="m">0.003175</Length>
</EngineBlock>

Launch Lug

<LaunchLug>
    <InsideDiameter Unit="m">0.0055626</InsideDiameter>
    <OutsideDiameter Unit="m">0.006096</OutsideDiameter>
    <Length Unit="m">0.0508</Length>
</LaunchLug>

Rail Button

<RailButton>
    <InnerDiameter Unit="m">0.008</InnerDiameter>
    <OuterDiameter Unit="m">0.0097</OuterDiameter>
    <Height Unit="m">0.0097</Height>
    <BaseHeight Unit="m">0.002</BaseHeight>
    <FlangeHeight Unit="m">0.002</FlangeHeight>
    <ScrewHeight Unit="m">0.0</ScrewHeight>
    <ScrewMass Unit="kg">0.0</ScrewMass>
    <NutMass Unit="kg">0.0</NutMass>
</RailButton>

Parachute

<Parachute>
    <Diameter Unit="m">0.6095999999999999</Diameter>
    <DragCoefficient>0.80</DragCoefficient>
    <Sides>8</Sides>
    <LineCount>8</LineCount>
    <LineLength Unit="m">0.7493</LineLength>
</Parachute>

Streamer

<Streamer>
    <Length Unit="m">0.5</Length>
    <Width Unit="m">0.05</Width>
    <Thickness Unit="m">0.00005</Thickness>
</Streamer>

Tube Coupler

<TubeCoupler>
    <InsideDiameter Unit="m">0.0</InsideDiameter>
    <OutsideDiameter Unit="m">0.017907</OutsideDiameter>
    <Thickness Unit="m">0.003175</Thickness>
    <Length Unit="m">0.019049999999999997</Length>
</TubeCoupler>

Units of Measure 

OpenRocket supports various units of measure for component specifications:

Length: mm, cm, m, in, in/64, ft
Distance: m, km, ft, yd, mi, nmi
Velocity: m/s, km/h, ft/s, mph
Mass: g, kg, oz, lb
Angle: deg, rad, arcmin
Force: N, lbf, kgf
Impulse: Ns, lbf*s

Important Notes 

Material definitions only have scope within the current datafile.
When a component is first created in a .ork file, the material definition is copied from the .orc file. Subsequent changes to the material definition in the .orc file will not automatically update existing components in .ork files.
To update a component’s material properties, you must manually reselect the component preset from the database.
The XML schema for .orc files is not formally defined in an XSD file.