Interplanetary MFD

Project home: IMFD Author: Jarmo Nikkanen Current version: Unknown Compatibility: Unknown

Interplanetary MFD (IMFD) is an Orbiter add-on created by Jarmo Nikkanen. It facilitates travel throughout the solar system by calculating and displaying a vessel's predicted trajectory. It is first released in 2002.

Status

The current version is IMFD 5.1g released on March 28, 2008.

Key Features:

• Map program can be used to display entire solar system and predict the actual course of the vessel with numerical trajectory calculator. The predictor can be also used to predict a hypothetical scenarios as well. This is very useful when planning a free-return trajectories.
• Course program is a collection of minor navigation programs those will let you to navigate through the solar system to other planets, moons and comets. Primary programs are based on the Lambert solver. In the most simplest case only a date of ejection and the Date of arrival is required as an user input.
• BaseApproach program is designed for Apollo style Moon to Earth return missions. It can be used to target a bases on the Mars and land directly without an orbit insertion. The program will also allow to establish an orbit right over a specific base on a planet so that it is possible to continue the descent on the base. That's very useful when landing on the Moon.
• Surface Launch program is usefull when starting interplanetary or lunar missions from the planet surface. The program will compute the time to launch window and required launch heading. This program is the only one that doesn't compute any burn guidance data. A vessel specific ascent profile should be used to reach low orbit.
• Orbit Eject program is required when starting interplanetary missions from the orbit. This program is used in a combination with the other programs to convert the Escape information into burn guidance data.

General Information

Setting values from keyboard

You can setup values in many formats from the keyboard by pressing [Set] button. The exponent format can be used like ”12.4e3” or ”11.45e-2”. The exponent can also be replaced by a letter like ”12.4k” or ”33.2M” or ”22.2G”,where k is equal to ”e3” and so on. ”d”=day will multiply the input value by 86400. ”h” is equal to an hour and ”a” is one astronomical unit.

Time in GET and UT

It is possible to enter dates in UT format like ”UT 14-nov-1969” or with the 24h clock ”UT 4-nov-1969 17:45:21.1” Used names for the months are Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov and Dec (not case sensitive). IMFD 5.0 is supporting GET (Ground Elapsed Time). This feature can be activated from the configuration page. Also the date of launch must be specified. You can enter data in GET format by pressing [Set] button and entering the time ”GET 120:34:56.7”. When flying with AMSO IMFD will receive GET time via interprocess-com link.

Sharing Flight Plans

A Single flight plan can be ”shared” between multible MFDs by seting the IMFD into the remote access mode by pressing [PG] button in main menu. Popup window will ask about an ID code of the MFD being accessed. The ID codes are shown in a top right corner of the MFD. The flight plan will stay resident evenif theMFD containing the flight plan is closed so the other MFDs can still access into the plan. If you want to disconnect the MFD from others just setup an invalid ID. For an example the ID of the MFD itself. When using multible instances of IMFD they must not access in each other. For an example when using two instances only one of them can use remote access.

3D Rotation

Some of the programs are supporting display 3D rotation via mouse. Hold down shift and Z- or L-keys to rotate the display. Only the Left and Right MFD displays can be rotated. 3D Rotation is not supported by all programs.

Version History

0.5 (2002)

• Initial Release

0.6

• Scaleability improved. Using without DG panels
• Bug in Multibody calculations fixed also Calculation speed increased x3
• Map: centering Periapis and Apoapis
• Map: Now mode displaying ship position "Dot"
• Map: Manual reference added
• Map: Hyperbola position bug fixed.
• Ellipse draw fixed

Orbital program added:

• Circulate orbit at any point
• Velocity Match
• Find Target

0.7

• Multi-body calculator rewrote it is now 10-20 times faster than the first one and it is much more accurate.
• Plane change line added to Approach, Zoom, Update
• Intersections are displayed on map
• 50% Gravity Zone Circle
• Information text to Map.
• Continuing updating to approach-program.
• Information display removed
• Gravity references display removed

0.71

• Orbital: circulate fixed

0.72

• Approach: Time stepping improved
• Map: Some Centering problems fixed. When current center is no longer available like apoapis on hyperbola.

0.73

Changes are unknown

0.8

• Map: Intersections with hyperbola fixed
• Calculation fixes and minor changes

0.9

• Transfer program is now online. Little different kind of approach to transfers.
• There is no dV. You can specify intersection longitude and that sort of things.
• Hypothetic orbit is shown on the Map. Map will automatically go to HTO mode when transfer program is running in other MFD.

- Course correction program 1 ( Best launch time is when the time required for the burn is minimum )

- Course correction program 2

• Map: Auto Zoom feature
• Map: Mode indicators added
• Map: Interceptions problem with inclination greater than 90deg fixed
• Orbital: Program 7 removed. Same maneuver can be done with transfer programs.
• Approach: Time stepping improved
• Approach: Plane change calculations fixed

1.0

• Map: reference bug fixed.
• Map: auto centering when selecting targets from some where else. Ship orbit will be disabled.
• Transfer: calculation error fixed
• Transfer: reference bug fixed. ( Transfer is now using same reference and target as map)
• Approach: realtime calculation improved, many fixes
• Transfer: Program 1 replaced with new program.
• Transfer: Time to burn added.
• Map: line brightness increased

1.1

• Same programs can be used in both MFDs at the same time. There is still only one trajectory calculator that can be used in a single MFD at a time.

Primary Changes

• MFD won´t lose it´s state when changing between panels.
• Work´s with add-on star systems.
• Advanced Transfer system
• Aerobreaking program
• New layout

Other Changes

• SOI calculation fixed.
• Map: Traget selection fixed.
• Map: Performance improvements.
• Map/Approach: Periapis altitude added (Alt).

1.2

• Transfer program fixed
• Text disappear bug fixed in Aerobrake
• Reference selection improved.
• Few minor bugs

1.4 (April 23, 2003)

• Minor math optimizations
• Some precision errors fixed
• Orbit drawing improved, fixed
• Equatorial geostationary orbit added GEO, Ecliptic & Reference orbits added (g,e,r)
• If no target defined. Ecliptic is targeted
• Input values are checked in transfer programs. No illegal values.
• Low influence warning added to P2
• Ecc, PeV added to Aero-brake (airspeed relative)
• Link option changed to Auto LAN/Manual LAN in transfer program.
• New planets hardcoded Europa, Ganymede, Callisto for aero-brake
• Map zoom limits extended
• Upd/Atm buttons removed from aero-brake. Automatic update begins when mfd is open.
• Int / Slf buttons swapped in a Map. (Int) is used more often than (Slf)
• PeV added to Map (planet relative)
• Interception points (Pe, Ap) added, Interception can be displayed at PeT even if the lines are not crossing
• Plane Change added to orbital programs
• Line draw bug fixed
• Usable range limited in AeroBrake. Update can not be started when the update is taking forever.
• Some problems and bugs fixed in transfer program.
• Interseption information fixed, RAV (Relative Angular Velocity) added
• Transfer program P3 added
• Program flags added
• Better Manual

1.5 (April 26, 2003)

• Orbit change problem fixed in P1
• One crashing bug fixed

1.6 (July 12, 2003)

• Bug fixes

2.0D (September 14, 2003)

D is noted as Devel

• The first release of IMFD containing new trajectory engine.
• Only a map feature is enabled.

2.0 Beta 1 (October 8, 2003)

• Multible fixes and improvements in Map
• Orbit ejection program added
• MFD will save it's state in scenario files
• Manual updated

Course program added (old P2)

• Escape calculation mode added
• Some interseption information added

AeroBrake program added (OLD)

• Automatic atmosphere setup. (Using Hot Dog's 2101AD add-on)

Orbital program added (OLD)

• New "Burn" vector mode added

2.0 Beta 2

• More space for moons
• Mass limiter added to configuration page
• Minor Bug fixed from Orbit-ejection program

2.0 Final (October 15, 2003)

• Orbit draw & calculation disabled from small moons
• Auto reference when selecting target
• Map periapis centering bug when loading a scenario. Fixed.
• Auto zoom fixed
• Escape vector saved in scenario
• Node bug fixed (weak node displayed when it should have been strong one)
• Course program: no interception information for special orbits (impossible)
• Periapis is selected by reference planet (not changing anymore)
• Ecliptic plane is targeted if no other target defined.
• Periapis bug fixed when ship is going away from the reference planet on hyperbolic orbit.
• Ship's orbital data displayed if no periapis information available
• Legsize calculation improved on highly elliptical orbit (apoapis)
• Legs/Frame, LegSize settings limited in usable range
• Different programs may now have a different target and reference
• Graphics syncronation added
• Reference planet of periapis can be centered.
• Centering problem fixed. Caused by changing periapis number.

2.1 (October 27, 2003)

• Bugs fixed from trajectory calculator / Map program.
• Course program: pro/retro-grade selector improved. Planned course doesn't change anymore it has been changeing because LPe is counted in a different direction on pro and retro grade orbits. Now the LPe is counter in pro-grade direction recardless the actual flight direction.
• LanMode: Inclination has been added.
• Apsides Modes: Ap-Line and Pe-Line has been added
• Bug fixed from aero-brake program. Now works with earth also.
• In AeroBrake program longitude and latitude coordinates of periapis added.
• In Map program longitude and latitude coordinates of periapis added.
• Eject position selector added in Orbit-Ejection program.
• Orbiter won't crash anymore when changing a vessel
• Maximum planet count returned to 512
• Launch window added to Orbit-Ejection program
• TEI Trans Earth Injection program added (beta)

2.2 (October 29, 2003)

• GEO-Sync program added
• Minor fixes in TEI program

2.3

Changes are unknown

2.4 (November 29, 2003)

• New features of orbiter release 051103 is in use (planet rotation elements, atmospheric parameters)
• MFD configuration file is used. Allows a color configuration. (Config/IMFD.cfg)
• Bug in a interception lines fixed (founded and reported by Bob Denny)
• EqI added in Map program
• Leg length error fixed form trajectory calculator
• Course/Inclination: now uses a EqI for orbit defination, Alt setting added.
• Trajectory limiter bug fixed.
• Minor fixes in all programs.
• GeoSync program removed. Now available as a GEOSyncMFD
• AeroBrake disabled. (work in progress)
• Auto-intercept feature (Aut)
• Auto repeat when pressing + or
• Automatic program & vector selector

3.0 (January 29, 2004)

• TEI/Approach: Setting of Lon & Lat fixed.
• Trajectory oscillations reduced when transferring to the Jupiter, Saturn...
• Periapis bug fixed allows more than 1 periapis per planet.
• Aero-brake program is now on-line
• GEO has been changed to the LEO (Local Equatorial Orbit)
• TEI/Approach program can now target the opposite side of the base. (automatically)
• Scenario save bug fixed. Now supports names with spaces.
• Interception bug with hyperbolic orbit fixed.
• Experimental trajectory stabilizator added. (turn-on from config page)
• Re-entry zone information added in TEI program
• Some Bug/Calculation fixes in Orbit-Eject program.
• Course jumping problem fixed. Occurs at highly elliptical orbits.
• Some Keyboard issues fixed

Created by Robert B. Denny

• Auto-burn feature in all programs
• Approach Pro/Retro-grade programs. (with in TEI/Approach program)
• Orbit-Insert program. (with in TEI/Approach program)

4.0 Beta 1 (January 15, 2005)

• New Orbit-ejection program. Performance problems fixed in long burns.
• Key-press/repeat problems fixed when using keyboard for (+,-) inputs
• New attitude control code for Autoburn.
• Accuracy / stability improvements in trajectory engine. (Tidal forces included)
• Some scenario load bugs fixed
• New color scheme created.
• Program menu added. Button [PRG] changed to [MNU]
• IMFD can be used in one single MFD screen and optionally the data can be shared with multiple screens.
• Map program will notify the plane-changes maneuvers in prediction.
• Sling-shot program added.
• Auxiliary vector input added in Orbit-Eject and Sling-Shot programs for SBC input parameters. (_V and C3)
• Aerobrake program removed. Will be published as AeroBrakeMFD with some feature enchangements.
• Approach and Orbit insert removed from TEI. (Now included in course program collection)
• New course program containing folowing sub programs:

• Target intercept using co-planar transfer. (Lambert's problem solver)
• Target intercept using off-plane transfer. (Lambert solver)
• Tangential transfer for finding launch windows and low energy transfer orbits.
• Planet Approach program. (efficient change for orbit altitude and inclination)
• Standard dV-program.
• Orbit approach

4.0 Beta 2 (January 17, 2005)

• Autoconfiguration of Target Intercept fixed while using hyperbolic orbit.
• Button labels changed SBC->AUX as used in manual.
• "Invalid Target" message added in Intercept program. Invalid Orbit is not displayed anymore.
• Intercept Time Bug fixed from Target Intercept programs.
• Time to burn fixed while using pro-grade burn in Co-planar Target Intercept.
• AutoBurn bugs fixed. Shouldn't miss the burn position. Higher time accelerations allowed.
• Other minor fixes

4.0 Beta 3 (January 18, 2005)

• Map program reconfigured for Orbiter 2005
• Removed some unnecessary items from map config
• Course program will display a program menu if no active configuration present

4.0 Beta 4 (January 18, 2005)

• Critical bug fix. Map wont plot when the reference is Sun

4.0 Beta 5 (January 20, 2005)

• Default setup bug fixed from Planet Approach program
• Negative inclinations can be used in Planet Approach program
• Non spherical gravity component J2 included in predictor (Orbiter Update for 2005 Required)
• Data lose while changing panels fixed
• Setup of MJDs from keyboard fixed from Intercept and Tangential programs.
• Solid planet with equator created in Planet Approach

4.0 Beta 6 (February 9, 2005)

• Trajectory plotting bug fixed. Map program will now compute periapis information for reference and target only.
• Ghost item removed from Navigation Menu
• Launch Heading information added in Orbit-Eject program
• Orbit Insert program added
• Equator added in map program. Visible for centered planet only
• In a case of major attitude failure Autoburn will go back in the attitude state engines shutdown.
• AutoBurn Item removed from Orbit-Eject, TEI, Sling-Shot programs. [AB] button added. Now uses same layout as Course program.
• Attitude control code now uses new Thruster Management functions from OrbiterAPI. (Requires 050126_
• Periapis Altitude added in Sling-shot program
• Pro-Grade is now a default mode in Orbit-Eject
• Pro-/Retro-grade selection added in sling-shot program.
• Automatical source object selection added.
• Intersection lines added in Delta Velocity program
• Autoburn wont go on-line in escape mode
• Map Centered in reference planet by default
• Error between Target orbit and perturbated planet position fixed
• New Trajectory Engine added in map program (Runge-Kutta-Fehlberg)
• Burn bug fixed from Delta Velocity program
• Surface launch added in Non-coplanar intercept program
• Plane alignment added in Non-coplanar intercept

4.0 Beta 7 (February 10, 2005)

• LegSize and Legs/Frame used in Multibody predictor. Default values defined in IMFD.cfg. Not saved in scenarios anymore.
• LegSize control improved.
• In Non-coplanar intercept a pro-grade mode can be used when the time to burn is more than one orbit period.

4.0 (April 24, 2005)

• BurnVector/Display mode improvemts

1. BurnVector button [BV] added.

2. [MOD] is now changing display mode (text/graphics).

3. In a future [MOD] will also bring some advanced configuration options for the program.

• Line Of Nodes improvements in map program.

1. Reverse fixed

2. Tn will display negative value after node passage for a while

3. the line between node and referenc is not drawn when the node is under minor SOI

• Critical targeting error bug fixed
• Some bugs with wrror reports fixed. (Return to Menu button added)
• Time to surface launch added in Orbit-Eject program.
• Some AutoZoom problems fixed
• [Find] (Query) Targets button added in map program. Finds available targets from current reference.
• Map projection is now saved in scenarios.
• Orbit-Eject pro-grade mode is saved in scenarios.
• BaseApproach program.
• Many smaller fixes....

4.1 (April 27, 2005)

• BaseApproach: program state is now saved in scenario
• BaseApproach: Time To Eject (TEj) is now working
• BaseApproach: MJD adjust fixed
• BaseApproach: Solution wont be lost so easily after finding one. This should be improved in future.
• BaseApproach: Orbit Insert function added.

4.2 (June 5, 2005)

• BaseApproach: Low Influence warning removed
• AutoBurn: ROLL fixed
• Better support for GlassCockpit addon by Marc Immer
• MJDs can be entered in a date format like 02-Jun-2005 or 02.06.2005
• BaseApproach: Old TEI mode added.
• Vessel specific instance. Only active instance is saved in scenarios.
• "Manual Burn" text removed.
• Planet Approach and Orbit-Eject programs cam be used for Moon to Earth return.

4.2.1

• Quick fix for Orbiter 2006

4.5.1-RC1 (August 29, 2006)

RC is noted as Release Candidate. This is for Orbiter 2006 Edition.

• Delta Velocity program is under work and it is disabled
• Plan function of the map program is unlikely working with prograde eject mode.

New Features

• 3D rotation in Target Intercept and Planet Approach programs. Hold Shift+SpaceBar and move the mouse
• New Improved Shared Mode
• Improved pro-grade burn mode
• New Surface Launch Program (Surface launch removed from Orbit-Eject and Intercept programs)

• Launch for Lunar Transfer
• Launch for Interplanetery Transfer

• Background processing for all programs
• Vessel specific instance. Maximum of 16 MFDs
• Display Burns in dV budget includes sum of all dVs required for the transfer.
• Transfer Program: Improved plane control. Now includes 4 transfer types for more efficient flight.
• Transfer Program: Graphically constructed from four stages. Actual transfer part of the orbit is highlighted.
• Autoburn: Final RCS fine tune using translation mode
• Autoburn: New cross-hair tool for attitude control. (roll angle support)
• Autoburn: New autoburn code to support Main, Hover and Retro engines
• Autoburn: Local Vertical based vector components in BurnVector View for Apollo AGC (ft/sec)
• Planet Approach: Target Orbit added, RIn, LAN added
• Planet Approach: AgP value added in (usable for orbit approaches ie. LUNA-OB1)
• BaseApproach: Pro/RetroGrade selector added to fix the "figure 8" problem.

Fixed Bugs

• Autoburn crash fixed when using vessels those doesn't have a dock ports
• BaseApproach: ReEntry Old Mode: MJD/ReT bug
• Critical burn time calculation bug fixed.
• Crash when restarting the scenario from the launchpad fixed.
• Shutdown engines during attitude re-orientation
• OE Headline colors fixed
• Orbital Program: AB button label added
• Find Target - Disable Main Engine burn
• Map: The Change of the selected periapis fixed, (periapis interpolation bug)
• Apogee problem in free-return trajectory
• Vessel count limit removed.
• Tangential Transfer: Rad set
• Planet Approach Auto-config removed (will fail in some scenarios)

4.5-RC2 (August 31, 2006)

This is for Orbiter 2006 Edition.

• Fixes the Apollo AGC information to correspond actual burn position not the current vessel position
• AGC information fixed from circularization program
• Added missing projection and reference in Surface launch program
• Map program "Cir" Orbit circularization fixed

4.6 (September 16, 2006)

This is for Orbiter 2006 Edition.

• Experimental Adaptive Step-size control
• Minimal configuration of dV-program is now online.
• ReEntry information display added in map program.
• Integration of non-spherical gravity fixed.
• Bug: Map lines are jumping under acceleration fixed
• New Encke/Cowell Predictor V1.2 supporting powered flight
• Powered Flight Support added in Map Program. (Powered flight is displayed in white)
• Exact burn time display in BurnVector view "BT". "ABT" is approximated burn time
• "Celbody" config item added in Map. Receives some information from Orbiter's celbody interface.

4.7 Beta (July 15, 2007)

This is for Orbiter 2006 Edition.

• Retro-grade orbit selector added in target intercept
• ReEntry information display fixed from Map program
• Smooth / Period adjusting added in Target Intercept program.
• Fixed TOF setting added in Target Intercept.
• Target Offsetting added in target intercept program (Advanced configuration page)
• Nodal Regression estimation added in PA, TI, OE and dV programs.
• Manual override for PeT (Time To Periapis) added in Planet Approach program.
• Acquire TEj item added in Planet Approach
• New Orbit Insert Program.
• Parking Orbit Altitude Item "Alt" added in Surface Launch
• Rotation key combination can be defined by user. Defaults Shift+Z and Shift+L
• PeA item added in Map-program ReEntry Display
• EIn item fixed form planet approach
• TrL changed to MJD from the planet approach program.
• TrL changed to MJD from the orbit eject program.
• HTO projection removed from target intercept
• Rotation can't be selected with [PRJ]
• MODE bug fixed form Surface Launch.
• "Tot" added in tangential transfer

4.7 Beta 2 (July 19, 2007)

This is for Orbiter 2006 Edition.

• CTD problem fixed
• RCS activity reduced (quick fix only)
• Linear RCS translation during Autoburn disabled with AMSO
• Minor SOI bug fixed

5.0 Beta (August 21, 2007)

• New Configuration Program in main menu
• New Attitude Control Autopilot for AutoBurn
• Some bugs related to CelBody interface fixed.
• Ground Elapsed Time GET and UT
• Off-Axis guidance mode in target intercept Off-Plane/Target Plane modes. (Designed for Apollo)
• Off-Axis guidance in Orbit Eject program
• New Thrust monitor program (BurnVector View)
• New Delta Velocity program accepting velocity setup for all 3 axis.
• Offset Vector setup relative to velocity vector
• Bad Plane Warning removed from orbit-eject
• Numerical ignition state vector propagation in TgtInt, Delta-V and Orbit Eject programs (Off-Axis mode)
• Docked vessel mass included.
• One Trajectory stability bug at TEj=0 in realtime mode fixed. (Some still remains)
• Engine selection bug fixed.
• RCS Only Option added in engine selection.

5.0 (August 30, 2007)

• New AttitudeController supporting some special thruster configurations.
• AttitudeController Drift Velocity Added
• Negative Periapis Altitude Setting in Planet Approach
• More engines added in engine selection.
• one Off-Axis Enable bug fixed.
• GET/MJD of reentry/periapis added in BaseApproach
• PlanetApproach: PeT override in GET/MJD format added
• Target Base alignment value added in map program.
• Burn guidance modes "Off-Axis" and "Prograde" saved in scenarios (Course, Orbit Eject programs)
• Error message "Missing IMFD.cfg" changed to "Missing IMFD5.cfg"
• Multiple minor fixes

5.1 Beta (October 16, 2007)

• New Apollo P30 compatibility mode added.
• Accuracy of the multibody predictor increased a lot
• CelBody Interface used for lunar position computations
• 1800s Powered Flight intergation limit increased atleast into 5000s
• Burn dara written in inter-process-comlink IPC

• Reliable LAP data in Target Intercept, Orbit Eject
• LAP data not tested in Base Approach, Planet Approach
• LAP Data not available in Delta-Velocity or Orbit-Insert

• Accuracy of the display variables increased in burn vector view
• Added a time of landing in config page and map program

5.1 Beta 2 (October 24, 2007)

• Lockup problem of the delta velocity program fixed
• Delta Velocity: orbit flashing bug fixed

5.1 (November 11, 2007)

• Minor corrections in Attitude controller
• Autoburn Status display removed from Menu screen.
• One unknown CTD problem during scenario reload fixed
• Minor text alignment proglem fixed from Thrust Monitor (BV)
• Removed obsollete SBCalc from SlingShot program
• New Orbit Insert program accepting ecc/ApA/OPe/SMa input, also working with elliptical source orbits

5.1b (December 10, 2007)

• Precision of the Lambert Iteration increased.
• Removed some IMFD-Log output

5.1c (December 15, 2007)

• Thrust monitor bug fix. (Change of "Required" velocity under time acceleration and attitude control)
• IPC Configuration for lambert aim point Offsets for NASSP.

5.1d (December 16, 2007)

• "True" fix of the Thrust monitor program.

5.1e (January 20, 2008)

• Orbit Insert Lockup fixed

5.1f (March 27, 2008)

• Fuel Efficiency factor alert. (IMFD doesn't currently work with factors other than 1.0)
• Trajectory jump bug in target-intercept fixed
• Plane change delta-v calculation bug fixed
• Map CTD with incorrect target name fixed
• GET sync problem with AMSO fixed

5.1g (March 28, 2008)

• Fuel efficiency factor implemented.
• Alert removed

5.1h (April 14, 2008)

• Minor change in Lambert iteration.

5.1h (May 2, 2008)

• Configuration File Fix. AB Throttle Down and RCS Level treshold changed.

When using IMFD with Apollo "AB Throttle Down" setting can be decreased down to 1 from configuration menu.

Future

5.2

• TODO: Apollo TLI, TEI program (auto-offset) (work in progress)
• TODO: Orbit Insert Fix
• TODO: Copy fuel-efficiency code from 5.1g
• TODO: Attitude Control problems in rdenny Europa->Callisto scenario

External Links

http://koti.mbnet.fi/jarmonik/sc2.gif

Jarmo Nikkanen's Orbiter page