Align MFD

AlignMFD is an MFD mode designed to allow the pilot to align the ship's orbital plane with that of a target orbital plane. It indicates orbital elements of the ships current and target orbits, relative inclination of the two orbits, the angles of the current radius vector from the ascending and descending nodes and estimated burn time to zero out the relative inclination. The target plane can be the orbital plane of a target body or vessel, or another orbital plane.

Screenshot of Align MFD mode

AlignMFD is called by selecting it from the SEL button below the desired MFD display or by the hot key LeftShift+A for the left display or RightShift+A for the right display.

Control buttons

• REF:Brings up a menu list of reference bodies.
• AR:Automatically selects the body with the highest gravity potential on the ship as reference, usually the body the ship is orbiting.
• TGT Shift+T:Allows the user to select a target's orbit to align with.
• ELS Shift+E:Allow the user to input a custom orbit to align with.

On screen data

• Inc: Orbit inclination of Current (your ship) and target
• LAN: Longitude of the Ascending Node of Current (your ship) and target
• RInc: Relative inclination between current and target orbits, in degrees
• Rate: How fast the current orbital plane is changing, in degrees per second
• AN: Ascending node
• Tn: Number of seconds until the next node
• TthA: estimated number of seconds until alignment during the next burn at the next Ascending node
• TthD: estimated number of seconds until alignment during the next burn at the next Descending node

Alignment burns should be done near the nodes. Near the Ascending node (AN), rotate the ship to Normal- (antinormal), and near the Descending node (DN), rotate the ship to Normal+ (normal).

Operation

• Using the SEL button on any MFD display, select 'Align Planes (Shift+A.
• Using the TGT button or Shift+T, select a target from the menu or type in a target name.
• Note RInc, just under "Relative". Looking at the graphics, if your ship is approaching the DN node, rotate the ship to Orbit Normal (NML+), if your are approaching the AN node, rotate to Orbit antinormal (NML-). The way to remember this is Ascending node and Antinormal both begin with the letter A.
• Note the Est Thrust T - TthA is for near the ascending node, TthD is for near the descending node. When your Tn reaches half of the TthA or TthD value, engage full thrust, the message box at the lower left of the display will also tell you to engage thrusters. After you pass the node, continue thrust until either RInc reaches zero or node line begins to move rapidly, or the message in the lower left says KILL THRUST, stop firing. At the next node, rotate to NML + or -, then burn again about half the remaining thrust time required. You can also use retros to correct an overshoot and RCS to fine tune the RInc.
• Once you zero the RInc or near to it, you are done with this MFD mode.
• If you are chasing a target, the next MFD mode is Sync MFD, Transfer MFD, or your favorite autopilot, such as TransX or IMFD.

See also

Orbiter\Doc\Orbiter.pdf, Orbiter User Manual, 15.8 Align orbital plane, page 85, Martin Schweiger.