# State Vector MFD

**Project home:** StateVectorMFD at Orbit Hangar

**Author:** Tim 'tblaxland' Blaxland

StateVectorMFD is a basic MFD for displaying a vessel's state vectors at the current time and at 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.

NOTE: The state vector propagation is Keplerian and is unlikely to be as accurate as a full numerical integration solution.

### Changing the Object[edit]

Press the OBJ button and select a new object whose state vector's will be displayed.

### 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 focus 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/>.