Difference between revisions of "Orbit MFD"

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'''Orbit''' is an MFD mode which is included in the [[Orbiter|Orbiter Space Flight Simulator]]. This mode displays a graphic representing a central body, the orbit of the pilot's ship, and the orbit of a target body, and also includes orbital parameters and elements of those orbits. The pilot can select Orbit from the MFD mode selection page.
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'''Orbit''' is an MFD mode which lists the elements and parameters for the [[orbit]] of the ship's orbit in reference to a central body, and a graphical representation of the orbit. The mode can also show the orbit of a target body orbiting the same body and its orbital characteristics. Orbit may be selected from the MFD selection page.
  
Orbit MFD displays the osculating orbits at the current epoch (its 2-body orbit) with respect to a celestial body. The orbital parameters may change over time due to perturbations from other gravity sources, nonspherical gravity, atmospheric drag, and thruster action, etc.
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The display shows the Keplar, or two-body, orbit of the craft at the current date with respect to the reference body. Any natural body in Orbiter may be selected as the reference body. Because of perturbations to the orbit, it may change over time. Perturbing effects include other bodies in the Solar System, nonspherical gravity, atmospheric drag, and ship's engines, etc.
  
Orbital elements and graphic display is displayed in one of two frames of reference, '''Ecliptic''' (ECL) or '''Equatorial''' (EQU) by selecting the FRM button or {{Key|Shift}}+{{Key|F}}. The current frame is displayed on the top line of the MFD display near the right corner.
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The orbital elements may be displayed in the [[Ecliptic|ecliptic]] or equatorial frame of reference. The plane of the ecliptic is the orbital plane of the Earth and the equatorial plane is the plane of the equator of the reference body. {{Key|Shift}}{{Key|F}} or the FRM button is used to switch back and forth between the reference frames, the 'Frm' value displays the current frame.
  
Any celestial body may be selected as the reference body by selecting the REF button or {{Key|Shift}}+{{Key|R}}, displaying a pop-up window where the pilot may select the reference body. Selecting the NT button or {{Key|Shift}}+{{Key|A}} will autoselect the reference body having the highest gravitational influence on the ship.
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The graphical view can be switched between the planes of the ecliptic (ECL), equator (EQU), ship's orbit (SHP), or target's orbit (TGT) with {{Key|Shift}}{{Key|P}} or with the PRJ button. The radius vector of the ship and target can be displayed from orbit focus (indicated by Rad, ApR, PeR), or by altitude above mean planet radius (Alt, ApA, PeA) with {{Key|Shift}}{{Key|D}}, or the DST button.
  
The display may project a plane to be projected onto the MFD display by selecting PRJ or {{Key|Shift}}+{{Key|P}}. Four planes may be selected: Ecliptic (ECL), Equatorial (EQU), the focus ship (SHP), or target ship or celestial body (TGT).
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{{Key|Shift}}{{Key|T}} or the TGT button opens a popup menu to select a target object, if you want no target, use {{Key|Shift}}{{Key|N}} or the NT button. You can only display orbits for targets orbiting the selected reference object can be displayed.
  
Distance from the focus body may be displayed from the center of the body, indicated by Rad, ApR, PeR, or from the altitude of the mean radius of the body, indicated by Alt, ApA, PeA, by selecting the DTS button or {{Key|Shift}}+{{Key|D}}.
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Press {{Key|Shift}}{{Key|H}} or the HUD button to switch the HUD to display the orbit reference object.
  
The orbit of a target ship or body orbiting the same body as the pilot's ship may be selected with the TGT button or {{Key|Shift}}+{{Key|T}}. The NT button or {{Key|Shift}}+{{Key|N}} turns off the target orbit and data.
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<center>[[File:OrbitMFD.jpg|360 px]]    [[File:OrbitMFDGraphicMode.png|360 px]]    [[File:OrbitMFDListMode.png|360 px]]</center>
  
Selecting the HUD button or {{Key|Shift}}+{{Shift|H}} will set the HUD to Orbit MFD mode and copy the orbit reference object.
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In the graphic mode:<br>
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•The gray circle represents the mean radius of the reference object (Sun, planet, or moon).<br>
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•The green circle, ellipse, parabola, or hyperbola represents the Kepler orbit of your ship.<br>
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•The yellow circle, ellipse, parabola, or hyperbola represents the Kepler orbit of the target.<br>
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•The small open circle on the ship's or target's orbit represents the apoapsis of the orbit.<br>
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•The small closed circle on the ship's or target's orbit represents the periapsis of the orbit.<br>
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•The line from the center of the body to the orbit is the radius vector, the end of the line where it touches the orbit is the ship's or body's current location.<br>
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•The dotted line represents the line of nodes of the target orbit and your ship's orbit.<br>
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•The filled in square at one end of the line of nodes represents the ascending node of your orbit.<br>
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•The open square at the other end of the line of nodes represents the descending node of your orbit.<br>
  
{| class="wikitable" style="text-align: center"
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In the list mode:<br>
|-
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•'''Orbit:''' indicates the body about which the ship and/or the target is orbiting.<br>
!MFD button!!Keypress!!Description
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•'''Frm''' indicates the frame of reference, '''Equator''' (ECL) or '''Ecliptic''' (ECL)<br>
|-
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•'''G''' represents the percentage of gravity exerted by the reference body (0-1.00). If the G value is less than 0.8, it will turn yellow, and less than 0.5 it will turn red. {{Key|Shift}}{{Key|A}} will change the reference body to the dominant one.<br>
|AR||{{Key|Shift}}{{Key|A}} ||Autoselect the reference body.
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•'''--OSC.EL.--''' indicates that the list for your ship lists the osculating elements of your orbit.<br>
|-
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•'''SMa''' indicates the semimajor axis of the orbit<br>
|DST||{{Key|Shift}}{{Key|D}} ||Toggle planetocentric distance or altitude above mean radius
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•'''SMi''' indicates the semiminor axis of the orbit<br>
|}
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•'''PeR''' (when selected by the DST button) indicates the periapsis of the orbit from the center of the body.<br>
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•'''PeA''' (when selected by the DST button) indicates the periapsis of the orbit from the mean radius of the body.<br>
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•'''ApR''' (when selected by the DST button) indicates the apoapsis of the orbit from the center of the body.<br>
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•'''ApA''' (when selected by the DST button) indicates the apoapsis of the orbit from the mean radius of the body.<br>
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•'''Rad''' (when selected by the DST button) indicates the current radius of the ship or target from the center of the body.<br>
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•'''Alt''' (when selected by the DST button) indicates the altitude ot the ship or target from the mean radius of the body.<br>
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•'''Ecc''' indicates the eccentricity of the orbit (0 = circular, >0 and <1 elliptical, 1 = parabolic, >1 Hyperbolic).<br>
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•'''T''' indicates the orbital period in seconds (how long it takes to make one orbit).<br>
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•'''PeT''' indicates the time in seconds until the ship or target passes the next periapsis. <br>
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•'''ApT''' indicates time in seconds until the ship or target passes the next apoapsis.<br>
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•'''Vel''' current velocity of the ship or target in meters per second.<br>
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•'''Inc''' inclination of the orbit in degrees (<180° indicates a prograde orbit, >180° indicates a retrograde orbit).<br>
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•'''LAN''' indicates Longitude of the Ascending Node or the angle in degrees between the ship's or target's position to the ascending node.<br>
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•'''LPe''' indicates Longitude of Periapsis or the angle in degrees from the vernal equinox to the periapsis of the ship's or target's orbit.<br>
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•'''AgP''' indicates the argument of periapsis or the angle in degrees from the ascending node to the periapsis of the ship's or target's orbit.<br>
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•'''TrA''' indicates the true anomaly, or the angle in degrees from the periapsis of the orbit to the ship's or target's current position.<br>
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•'''TrL''' indicates the true longitude or the angle in degrees from the vernal equinox to the ship or target's position if the inclination of the orbit were zero.<br>
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•'''MnA''' indicates the mean anomaly of the orbit or the angle from the vernal equinox to the ship's position if the orbit was circular, the ship or target moved at constant speed, and having the same orbital period as the true orbit.<br>
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•'''MnL''' indicates the mean longitude of the orbit or the angle from the vernal equinox to the ship's or target's position if it's orbit was circular and with no perterbations.<br>
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==See also==
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*[[w:Orbit|Orbit]] at Wikipedia.
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[[Category:Articles]]
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[[Category:MFD]]

Latest revision as of 11:56, 4 October 2023

Orbit is an MFD mode which lists the elements and parameters for the orbit of the ship's orbit in reference to a central body, and a graphical representation of the orbit. The mode can also show the orbit of a target body orbiting the same body and its orbital characteristics. Orbit may be selected from the MFD selection page.

The display shows the Keplar, or two-body, orbit of the craft at the current date with respect to the reference body. Any natural body in Orbiter may be selected as the reference body. Because of perturbations to the orbit, it may change over time. Perturbing effects include other bodies in the Solar System, nonspherical gravity, atmospheric drag, and ship's engines, etc.

The orbital elements may be displayed in the ecliptic or equatorial frame of reference. The plane of the ecliptic is the orbital plane of the Earth and the equatorial plane is the plane of the equator of the reference body. ShiftF or the FRM button is used to switch back and forth between the reference frames, the 'Frm' value displays the current frame.

The graphical view can be switched between the planes of the ecliptic (ECL), equator (EQU), ship's orbit (SHP), or target's orbit (TGT) with ShiftP or with the PRJ button. The radius vector of the ship and target can be displayed from orbit focus (indicated by Rad, ApR, PeR), or by altitude above mean planet radius (Alt, ApA, PeA) with ShiftD, or the DST button.

ShiftT or the TGT button opens a popup menu to select a target object, if you want no target, use ShiftN or the NT button. You can only display orbits for targets orbiting the selected reference object can be displayed.

Press ShiftH or the HUD button to switch the HUD to display the orbit reference object.

OrbitMFD.jpg OrbitMFDGraphicMode.png OrbitMFDListMode.png

In the graphic mode:
•The gray circle represents the mean radius of the reference object (Sun, planet, or moon).
•The green circle, ellipse, parabola, or hyperbola represents the Kepler orbit of your ship.
•The yellow circle, ellipse, parabola, or hyperbola represents the Kepler orbit of the target.
•The small open circle on the ship's or target's orbit represents the apoapsis of the orbit.
•The small closed circle on the ship's or target's orbit represents the periapsis of the orbit.
•The line from the center of the body to the orbit is the radius vector, the end of the line where it touches the orbit is the ship's or body's current location.
•The dotted line represents the line of nodes of the target orbit and your ship's orbit.
•The filled in square at one end of the line of nodes represents the ascending node of your orbit.
•The open square at the other end of the line of nodes represents the descending node of your orbit.

In the list mode:
Orbit: indicates the body about which the ship and/or the target is orbiting.
Frm indicates the frame of reference, Equator (ECL) or Ecliptic (ECL)
G represents the percentage of gravity exerted by the reference body (0-1.00). If the G value is less than 0.8, it will turn yellow, and less than 0.5 it will turn red. ShiftA will change the reference body to the dominant one.
--OSC.EL.-- indicates that the list for your ship lists the osculating elements of your orbit.
SMa indicates the semimajor axis of the orbit
SMi indicates the semiminor axis of the orbit
PeR (when selected by the DST button) indicates the periapsis of the orbit from the center of the body.
PeA (when selected by the DST button) indicates the periapsis of the orbit from the mean radius of the body.
ApR (when selected by the DST button) indicates the apoapsis of the orbit from the center of the body.
ApA (when selected by the DST button) indicates the apoapsis of the orbit from the mean radius of the body.
Rad (when selected by the DST button) indicates the current radius of the ship or target from the center of the body.
Alt (when selected by the DST button) indicates the altitude ot the ship or target from the mean radius of the body.
Ecc indicates the eccentricity of the orbit (0 = circular, >0 and <1 elliptical, 1 = parabolic, >1 Hyperbolic).
T indicates the orbital period in seconds (how long it takes to make one orbit).
PeT indicates the time in seconds until the ship or target passes the next periapsis.
ApT indicates time in seconds until the ship or target passes the next apoapsis.
Vel current velocity of the ship or target in meters per second.
Inc inclination of the orbit in degrees (<180° indicates a prograde orbit, >180° indicates a retrograde orbit).
LAN indicates Longitude of the Ascending Node or the angle in degrees between the ship's or target's position to the ascending node.
LPe indicates Longitude of Periapsis or the angle in degrees from the vernal equinox to the periapsis of the ship's or target's orbit.
AgP indicates the argument of periapsis or the angle in degrees from the ascending node to the periapsis of the ship's or target's orbit.
TrA indicates the true anomaly, or the angle in degrees from the periapsis of the orbit to the ship's or target's current position.
TrL indicates the true longitude or the angle in degrees from the vernal equinox to the ship or target's position if the inclination of the orbit were zero.
MnA indicates the mean anomaly of the orbit or the angle from the vernal equinox to the ship's position if the orbit was circular, the ship or target moved at constant speed, and having the same orbital period as the true orbit.
MnL indicates the mean longitude of the orbit or the angle from the vernal equinox to the ship's or target's position if it's orbit was circular and with no perterbations.

See also[edit]