The Custom Window Editor lets you create new windows for MechJeb that display a wide variety of information.
The Custom Window Editor
The Custom Window Editor lets you create, delete, and edit custom windows. To create a new custom window, click "New window" in the upper left. Give your window a name by typing in the text box. Your window will show up, with its given name, at the bottom of the MechJeb menu on the right hand side of the screen.
The "Show in:" toggles control whether your window will appear in flight, in the editor, or in both.
The "Window contents" section shows the current set of items that will be displayed in your window (initially this will be empty). You can use this section to rearrange the order of the items in your window. Click the name of an item to select it, then use "Move up" or "Move down" to move it around within the window. You can also select an item and then click "Remove" to remove it from the window.
The bottom section of the Custom Window Editor provides lists of items that you can add to your windows.
The available items for custom windows are arranged into several categories.
This info items relate to your vessel's current orbit.
Angle to prograde:
Apoapsis: Maximum altitude of your orbit
Argument of periapsis:
Circular orbit speed: The orbital speed you would have to have to be in a circular orbit at your current altitude
Eccentricity: A measure of the shape your orbit is: 0 means circular, between 0 and 1 is increasingly elliptical, > 1 is hyperbolic
Inclination: The angle between your orbit and the equatorial plane
Orbit: A one-line summary of your orbit shape
Orbit horizontal speed: The horizontal component of your orbital velocity
Orbit shape w/ inc.: A one-line summary of your orbit shape, including inclination
Orbital period: How long one orbit takes in your current orbit
Orbital speed: Your current orbital speed
Periapsis: The minimum altitude of your orbit
Semi-major axis: Half the length of the long axis of the ellipse of your orbit
Time to apoapsis: How long until you arrive at your apoapsis
Time to periapsis: How long until you arrive at your periapsis
Time to SoI switch: How long until you reach the edge of your current sphere of influence, if you are on course to leave it
These info items give information about your vessel in relation to the surface of the current body.
Altitude (ASL): You altitude above sea level (this is the altitude displayed by the in-flight altimeter).
Altitude (bottom): Like Altitude (true) but measures from the bottom of your craft.
Altitude (true): Your altitude above the terrain below you, as measured from the center of mass of your craft.
Coordinates: Your latitude and longitude
Latitude: Your current latitude
Longitude: Your current longitude
Pitch: The pitch of your craft (most useful for atmospheric planes).
Roll: The roll of your craft (most useful for atmospheric planes).
Surface gravity: The acceleration due to gravity at the surface of the body you are orbiting.
Surface horizontal speed: The horizontal component of your surface velocity.
Surface speed: Your speed with respect to the surface of the body you are orbiting.
Vertical speed: The vertical component of your speed.
These info items give information about your vessel's capabilities.
Intake air needed:
Intake air needed (max):
Max acceleration: Your craft's acceleration at max throttle (neglecting drag)
Max thrust: Your craft's total thrust at max throttle
Min acceleration: Your craft's acceleration at zero throttle (neglecting drag)
Min thrust: Your craft's total thrust at zero throttle
Part count: How many parts your craft has
Stage stats (all): A stage-by-stage breakdown of stats about your craft, including the delta-V, burn time, and TWR of each stage. When using this info item you can click on a column heading to hide that column, and click "All stats" to restore all hidden columns.
Stage time (current throttle): How long the fuel in your current stage will last at the current throttle level.
Stage time (full throttle): How long the fuel in your current stage will last at full throttle.
Stage time (hover): How long the fuel in your current stage will last if used to hover in the current gravitational field.
Stage ΔV (atmo): How much delta-V is left in the current stage, assuming sea level atmospheric pressure (engine efficiency varies with pressure).
Stage ΔV (vac): How much delta-V is left in the current stage, assuming zero atmospheric pressure.
Strut count: How many struts are holding your craft together.
Surface TWR: Your craft's thrust-to-weight ratio at the surface of the current body.
Terminal velocity: Your craft's terminal velocity at the current altitude.
Total ΔV (atmo): How much delta-V your craft has, assuming sea level atmospheric pressure.
Total ΔV (vacuum): How much delta-V your craft has, assuming zero atmospheric pressure.
Use SAS if available:
Vessel cost: The total monetary cost of your vessel.
Vessel mass: The total mass of your vessel.
These info items are related to whatever target you have selected.
Closest approach distance: How close you will pass to your target over the next orbit.
Distance to target: The current distance to your target.
Docking guidance: position: The separation between you and your target, broken down along three axes.
Docking guidance: velocity: The relative velocity between you and your target, broken down along three axes.
Heading to target: The heading you should travel at to reach your target (useful for overland travel to reach a landed target).
Phase angle to target: Draw lines from the center of the planet to your craft and from the center of the planet to your target. The phase angle is the angle between these two lines.
Pick position target: A button that, when pressed, lets you select a target on the surface of the current body. This target then shows up on the navball like a regular target.
Rel. vel. at closest approach: The predicted relative velocity you will have to your target during your closest approach to it over the next orbit.
Relative velocity: Your current relative velocity to your target.
Synodic period: If your orbit has a different period from your target's orbit, you will orbit at a different rate. So every so often, either you will lap your target or your target will lap you. The synodic period is the time interval between those laps.
Target apoapsis: The apoapsis of your target's orbit
Target coordinates: The ground coordinates (latitude and longitude) of your target.
Target eccentricity: The eccentricity of your target's orbit.
Target inclination: The inclination of your target's orbit.
Target LAN: The longitude of the ascending node of your target's orbit.
Target orbit: A one-line summary of your target's orbit.
Target orbit period: The period of your target's orbit.
Target orbit shape w/ inc.: A one-line summary of your target's orbit, including inclination.
Target orbit speed: The current orbital speed of your target.
Target periapsis: The periapsis of your target's orbit.
Target SMA: The semi-major axis of your target's orbit.
Target time to Ap: The time until your target reaches its next apoapsis.
Target time to Pe: The time until your target reaches its next periapsis.
Time to closest approach: How long until you will make your closest approach to your target over your next orbit.
MechJeb contains a flight recorder that tracks various statistics since the last mark. By default, the mark is at vessel launch. You can use the MARK item to make a new mark, which resets the statistics and starts recording them from the new mark.
You can use the recorder in a number of ways:
- as a stopwatch
- to remember a location
- to track delta-V expended and various delta-V losses
- to measure the phase angles needed to time rendezvous maneuvers.
Distance from mark: How far you are from the location of the last mark.
Drag losses: Drag losses since the last mark. This is the total amount of speed that has been taken from your ship by atmospheric drag. Drag losses accumulate quickly when you are moving through low dense atmosphere, slowly when you are traveling through high thin atmosphere, and not at all in vacuum.
Gravity losses: Gravity losses since the last mark. This is the total amount of speed that has been taken from your ship by gravity. Gravity losses accumulate quickly when you are travelling vertically upward and slowly when you are traveling more horizontally. If you are falling down, you are accumulating negative gravity losses, since gravity is actually speeding you up.
MARK: A button that resets the recorder and tells it to remember this time and location. All stats will be zeroed. There is an automatic mark at your initial launch at KSC.
Mark altitude ASL: The altitude above sea level of the vessel at the time of the last mark.
Mark body: The body whose sphere of influence the vessel was in at the time of the last mark.
Mark latitude: The latitude of the vessel at the time of the last mark.
Mark longitude: The longitude of the vessel at the time of the last mark.
Mark UT: The universal time of the last mark.
Max drag gees: The maximum gee force due to drag that the vessel has experienced since the last mark.
Phase angle from mark:
Steering losses: Steering losses since the last mark. Steering losses are a measure of how much delta-V your vessel has wasted turning its velocity (steering) instead of speeding up. Steering losses are minimal when you are thrusting straight along the direction of your velocity, because then all your thrust is going into speed up your vessel. Steering losses increase if you thrust at a large angle to the direction of your velocity. Note that MechJeb calculates steering losses using your surface velocity, not your orbital velocity.
Time since mark: How long since the last mark. If you haven't made any marks manually, this is the elapsed time since launch.
Universal Time: A readout of KSP's universal time. This is how much time has elapsed in-game since you started the current save.
ΔV expended: How much delta-V your vessel has expended since the last mark. Delta-V is like a measure of fuel expended, except that its meaning is independent of the design of your rocket. If two craft perform the same maneuver, they expend the same amount of delta-V, no matter what the design of each craft is. For this reason delta-V is a good measure of the cost of a maneuver, and of the capability of a spacecraft.
These items let you toggle various thrust control settings. Most of them establish some sort of upper bound on the throttle. This throttle limit applies to both manual and autopilot throttle control.
Limit acceleration: Provides a text field that lets you type in an acceleration in m/s^2. Then if you turn the toggle on, the throttle will be auto-limited so that the acceleration of your craft is never greater than this value.
Limit throttle: Provides a text field that lets you type in a throttle level in percent. Then if you turn the toggle on, the throttle will be auto-limited always be less than this value.
Limit to terminal velocity: If you turn the toggle on, the throttle will be limited to keep your vertical speed from exceeding terminal velocity. This is useful during ascent, when the most efficient throttle control strategy is to keep your vertical velocity equal to terminal velocity.
Manage air intakes: If you turn the toggle on, MechJeb will automatically open and close air intakes to ensure that you have enough air to prevent jet engine flameouts, but don't have extra intakes open causing unnecessary drag.
Prevent jet flameout: If you turn the toggle on, MechJeb will automatically lower the throttle as necessary to prevent jet engines from flaming out.
Prevent overheats: If you turn the toggle on, MechJeb will automatically lower the throttle as necessary to prevent parts being overheated and exploded by the heat from your engines.
Smooth throttle: If you turn the toggle on, MechJeb will automatically smooth out all throttle inputs to prevent sudden changes in the throttle level. This has little effect on manual throttle and is mostly useful for prevent sudden autopilot throttle controls from damaging delicate spacecraft.
Atmosphere density: The density of the air outside the vessel, measured in kilograms per cubic meter.
Atmospheric pressure: The pressure of the air outside the vessel, measured in atmospheres (Kerbin's air pressure at sea level is 1 atmosphere).
Autostaging: Provides a set of autostaging controls.
Enable 2013-04-01 Joke module: Provides a toggle that lets you turn on Easter eggs that were active on April 1, 2013.
Local gravity: The acceleration due to gravity at the vessel's current location.
Node burn time: MechJeb's estimate for how long it will take to execute the next maneuver node if you use full throttle. This can be useful because the game's estimate of this number can be unreliable.
Node dV: How much delta-V is left in the next maneuver node.
Suicide burn countdown: The most fuel-efficient way to land is a "suicide burn," where you wait until the last second and then throttle up to 100%, ideally braking to zero velocity just as you touch down. This provides a countdown to tell you when to start burning for a suicide burn.
Note that this is a risky tactic: if you start burning a single second too late you will probably crash hard and explode. MechJeb assumes that you will instantaneously throttle up to 100% when the countdown reaches zero. Since it actually takes some time to throttle to 100%, you should throttle up slightly before the countdown reaches zero.
Once you've started the burn, the timer is still useful. If you are on track for a perfect suicide burn touchdown, the counter will continue to read 0s during the burn. If the timer starts to count up again from 0s, you are on track to kill your velocity before you touch down. You can then throttle down a bit until the timer reads 0s again, or perhaps 1s to be safe. The timer often starts to count up again as you burn off fuel, making your craft lighter and easier to decelerate.
If the timer goes negative, you are on track to crash. Good luck!
The suicide burn countdown may be unreliable if you are coming in at a shallow angle. If you are landing in an atmosphere, it may recommend burning too early, since it does not take air resistance into account.
Time to impact: The predicted time until you impact the terrain, assuming you cut all engines and free fall, and neglecting air resistance.
Time to node: The time until the next maneuver node is scheduled.