Difference between revisions of "User talk:Tblaxland"

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= ZTC Tether-Sling Transportation System =
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= State Vector MFD =
  
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[[Image:Put some image here|right|thumb|300px|This is the image caption]]
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[[Image:Lgplv3-147x51.png|right|thumb|[http://www.gnu.org/licenses/lgpl-3.0-standalone.html Licensed under LGPL v3]]]
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[[Image:StateVectorMFD.png|right|thumb|300px|StateVectorMFD in action]]
  
 
{{Addon|
 
{{Addon|
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1=[http://www.orbiter-forum.com/showthread.php?t=684 ZTC Tether-Sling at Orbiter-Forum]|
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1=[http://www.orbithangar.com/some_location StateVectorMFD at Orbit Hangar]|
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2=[http://www.orbiter-forum.com/member.php?u=86 Tim 'tblaxland' Blaxland]; [http://www.orbiter-forum.com/member.php?u=163 n0mad23]
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2=[http://www.orbiter-forum.com/member.php?u=86 Tim 'tblaxland' Blaxland]
 
}}
 
}}
  
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The ZTC Tether-Sling Transportation System project uses tethers for propellant free transfers of payloads between solar system bodies.
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StateVectorMFD is basic MFD for displaying a vessel's state vectors at the current time and at a some other time relative to the present time.
  
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It is expected that some propellant will be used by fine-tuning of transfer trajectories. Testing has shown that for lunar transfers corrections of less than 25m/s are typically required.
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The MFD uses the [[Kepler Orbital Simulation Toolkit]] (KOST) to convert the current state vectors to orbital elements and then perform time propagation along those elements. [http://en.wikipedia.org/wiki/Kepler%27s_laws_of_planetary_motion Kepler's Laws] are then solved numerically to obtain the state vectors for the future time.
  
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== Principle ==
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== Operation ==
  
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The basic principle of a momentum exchange tether is to take momentum from the tether's orbit and transfer it into the payload's orbit. The momentum of an Earth based tether can then be recharged over time using solar powered electrodynamic propulsion to allow it to prepare to transfer further payloads.
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=== Loading the MFD ===
  
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== Electro-Dynamic Propulsion ==
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Load the MFD by pressing the MFD "SEL" button and select "State Vector". The MFD will show the current state vectors in a column on the left hand side and the state vectors for a future time in a column on the right hand side.
  
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Electro-dynamic propulsion uses the interaction between an electric current in the tether with the Earth's magnetic field. The thrust generated is a result of the Lorentz force on the electrons flowing in the tether. The Earth's ionosphere is used as a distributed return path for the tether current by way of anodes and cathodes on each end of the tether.
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See [[#Configuration|Configuration]] for the default settings that are used when the MFD is first loaded.
  
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A simplified model of the Earth's magnetic field will be used for the purpose of simulating the electro-dynamic propulsion.
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=== Changing T+ ===
  
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== Tether Locations ==
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To change the time used for predicting the future state vectors, press the T+ button and enter a time (in seconds) in the dialog box. This dialog box also takes SI prefixes in the input, eg, 5100 seconds could be entered as 5.1k. T+ may also be negative. Default value: 0 seconds.
  
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Tethers are planned for Earth (Ananke for lunar transfers and Ananke-MX for Mars transfers), Moon (Khronos) and Mars. Development work is progressing on Ananke at present.
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=== Changing the Reference Body ===
  
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=== Earth ===
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Press the REF button and select a new reference body.
  
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==== Ananke ====
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=== Changing the Numerical Notation ===
  
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Ananke is a 120km long tether for lunar transfers that orbits the Earth in an elliptical (eccentricity approx 0.45) equatorial orbit. An equatorial orbit is used so the regression of the ascending nodes does not over complicate the planning of lunar transfer trajectories. The periapsis of the tether is approximately 340km altitude and this place the catcher mechanism at 250km altitude for rendezvous with the payload.
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Press the NOT button to toggle the numerical notation between SI prefixes and exponential form.
  
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The tether rotates at approximately 1 degree per second. The resulting centripetal force on the payload is approximately 2.8gees.
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=== Non-spherical Gravity Effects ===
  
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The design payload mass is 20-25 metric tonnes.
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Estimated corrections to the future state vectors are added automatically if non-spherical gravity sources are enabled and they are presently acting on the vessel.
  
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One of the key challenges of the system is affecting a successful rendezvous between the payload and the catcher on the end of the tether. The rendezvous is more challenging than a typical space rendezvous due to the rapidly rotating tether forcing the capture window to be very small in both space and time. Specialised guidance tools for the rendezvous of the payload with the catcher mechanism are being developed.
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=== Changing Vessel Focus ===
  
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==== Ananke-MX ====
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When you change vessel focus, the MFD will remember the settings for each vessel and MFD position.
  
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Ananke-MX is a stretched version of Ananke for transferring payloads to Mars. MX is short for Mars eXpress.
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=== Saving/Loading Scenarios ===
  
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=== Moon ===
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This MFD saves its state to the scenario file so all settings will be restored when restarting the scenario. Also included is saving/restoring the settings for any other vessels that have been used with StateVectorMFD in the scenario even though those vessels do not have the focus at the time of scenario being saved.
  
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==== Khronos ====
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== Coordinate Systems ==
  
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Khronos is a rotovator type tether design to be able place and pickup payloads directly from the surface of the moon. Khronos will most likely be placed in a near polar orbit to maximise rendezvous opportunities with payloads coming in from Earth.
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The state vectors are displayed in the Orbiter left-hand ecliptic coordinate system (+X - sun direction at vernal equinox, +Y - ecliptic north). Support for other systems may be added in the future.
  
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=== Mars ===
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== Configuration ==
  
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== Vessels ==
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A configuration file (StateVector.cfg) in located in OrbiterDirectory\Config contains the settings for the MFD. The following items can be configured.
  
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=== Tortoise Class Lunar Transfer Vessel ===
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=== Colours ===
  
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The Tortoise Class Lunar Transfer Vessel is designed to be transferred from low Earth orbit to the lunar surface and back again. Capture and landing at the moon is by way of the Khronos tether. Capture at Earth is by way of aerobraking.
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NOW_COLOUR - colour for the current state vectors in the left-hand column.
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T_PLUS_COLOUR - colour for the predicted state vectors in the right-hand column.
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See the config file for valid colour values.
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=== Numerical Solver ===
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MAX_RELATIVE_ERROR - the maximum relative error in the mean anomaly when solving Kepler's equation. Smaller number = more accurate.
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MAX_ITERATIONS - the maximum number of iterations used when solving Kepler's equation. Larger number = more accurate.
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=== Defaults ===
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T_PLUS_TIME - the default T+ value (in seconds).
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NOTATION - the default numerical notation.
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== Credits ==
 +
 
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This MFD uses the [[Kepler Orbital Simulation Toolkit]] (KOST) by CJ Plooy and Tim Blaxland. A copy of KOST is included with the source code.
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It also use the built-in Orbiter pop-up menus for selecting the reference body. Thanks to CJ Plooy for his work in making this functionality available.
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Two functions from [http://www.orbithangar.com/searchid.php?ID=3609 FreeOrbitMFD by CJ Plooy] were used for formatting the SI prefixes. See source code for details.
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== Copyright Notice ==
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Copyright 2009 by Tim Blaxland (tblaxland@gmail.com)
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StateVectorMFD is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
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 +
StateVectorMFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
 +
 
 +
You should have received a copy of the GNU Lesser General Public License along with StateVectorMFD. If not, see <http://www.gnu.org/licenses/>.

Latest revision as of 05:33, 1 February 2009

State Vector MFD[edit]

Licensed under LGPL v3
StateVectorMFD in action

Project home: StateVectorMFD at Orbit Hangar
Author: Tim 'tblaxland' Blaxland
Current version: Unknown
Compatibility: Unknown


StateVectorMFD is basic MFD for displaying a vessel's state vectors at the current time and at a some other time relative to the present time.

The MFD uses the Kepler Orbital Simulation Toolkit (KOST) to convert the current state vectors to orbital elements and then perform time propagation along those elements. Kepler's Laws are then solved numerically to obtain the state vectors for the future time.

Operation[edit]

Loading the MFD[edit]

Load the MFD by pressing the MFD "SEL" button and select "State Vector". The MFD will show the current state vectors in a column on the left hand side and the state vectors for a future time in a column on the right hand side.

See Configuration for the default settings that are used when the MFD is first loaded.

Changing T+[edit]

To change the time used for predicting the future state vectors, press the T+ button and enter a time (in seconds) in the dialog box. This dialog box also takes SI prefixes in the input, eg, 5100 seconds could be entered as 5.1k. T+ may also be negative. Default value: 0 seconds.

Changing the Reference Body[edit]

Press the REF button and select a new reference body.

Changing the Numerical Notation[edit]

Press the NOT button to toggle the numerical notation between SI prefixes and exponential form.

Non-spherical Gravity Effects[edit]

Estimated corrections to the future state vectors are added automatically if non-spherical gravity sources are enabled and they are presently acting on the vessel.

Changing Vessel Focus[edit]

When you change vessel focus, the MFD will remember the settings for each vessel and MFD position.

Saving/Loading Scenarios[edit]

This MFD saves its state to the scenario file so all settings will be restored when restarting the scenario. Also included is saving/restoring the settings for any other vessels that have been used with StateVectorMFD in the scenario even though those vessels do not have the focus at the time of scenario being saved.

Coordinate Systems[edit]

The state vectors are displayed in the Orbiter left-hand ecliptic coordinate system (+X - sun direction at vernal equinox, +Y - ecliptic north). Support for other systems may be added in the future.

Configuration[edit]

A configuration file (StateVector.cfg) in located in OrbiterDirectory\Config contains the settings for the MFD. The following items can be configured.

Colours[edit]

NOW_COLOUR - colour for the current state vectors in the left-hand column.

T_PLUS_COLOUR - colour for the predicted state vectors in the right-hand column.

See the config file for valid colour values.

Numerical Solver[edit]

MAX_RELATIVE_ERROR - the maximum relative error in the mean anomaly when solving Kepler's equation. Smaller number = more accurate.

MAX_ITERATIONS - the maximum number of iterations used when solving Kepler's equation. Larger number = more accurate.

Defaults[edit]

T_PLUS_TIME - the default T+ value (in seconds).

NOTATION - the default numerical notation.

Credits[edit]

This MFD uses the Kepler Orbital Simulation Toolkit (KOST) by CJ Plooy and Tim Blaxland. A copy of KOST is included with the source code.

It also use the built-in Orbiter pop-up menus for selecting the reference body. Thanks to CJ Plooy for his work in making this functionality available.

Two functions from FreeOrbitMFD by CJ Plooy were used for formatting the SI prefixes. See source code for details.

Copyright Notice[edit]

Copyright 2009 by Tim Blaxland (tblaxland@gmail.com)

StateVectorMFD is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

StateVectorMFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with StateVectorMFD. If not, see <http://www.gnu.org/licenses/>.

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