# IMFD AppA Glossary

## Appendix A - Glossary

AgP Argument of Periapsis. This is the angle between the longitude of the periapsis and the longitude of the ascending node.

Alt Altitude at which the Base Approach program in reentry mode considers you to have started reentry. Also, the altitude of the parking orbit in the Surface Launch program.

Ant Reentry anticipation angle. This is the measure of the angle in degrees (the center of the reference planet being the vertex) between the point at which you cross the Alt number on the Base Approach display screen and the landing site. For example, an Ant of 90 would mean you would travel a quarter around a planet from 120k (if that is the altitude setting you chose) to your landing site.

ApA Altitude of the apoapsis of the orbit measured above the surface of the reference planet.

ApD Radial distance (from the center of the reference planet) of the apoapsis of the current orbit.

Apt Time in seconds until reaching the apoapsis.

ApV Predicted orbital velocity in meters/second at the apoapsis.

BLL The best latitude to launch as dictated by the Surface Launch program. Don‘t worry if your latitude is not this latitude, but do try to launch near the equator (Cape Canaveral is fine).

Bt Estimated burn duration in seconds.

C3 Orbital energy of escape asymptote. C3 = o2 v /1000

Cir The required delta velocity needed to circularize your orbit.

Dis Difference in radial distance from the reference planet traveled during a flight planned by the Tangential Transfer program. Also the distance from the target in the Match Velocity mode of the Orbital program.

dV Delta velocity, the difference in velocity of your ship to match a target orbit or velocity vector.

dVf The x component of a delta velocity vector.

dVp The y component of a delta velocity vector.

dVo The z component of a delta velocity vector.

Ecc The current eccentricity of your ship‘s orbit.

EIn Escape Inclination or Ejection Inclination. The angle between your current velocity vector and that of the target planet‘s or moon‘s velocity vector. Thus, in an off-plane transfer where you do not do a plane change, you must start the flight with an EIn of zero.

EjA Angle between the velocity vectors (tangents) of the ship‘s orbit and the transfer orbit at the time of ejection.

EqI The current inclination of your ship‘s orbit with respect to the equator.

GET Ground elapsed time. This is the ground elapsed time of any significant event in the flight happens. You can set the start date (GET=0 at xxxxx.xxxx MJD or MM-DD-YYYY at HH:MM:SS) via the IMFD configuration page.

Hed The heading that the Surface Launch Program recommends that you fly at in order to achieve a minimum EIn (so you don‘t have to do a fuel-costly burn to fix it later).

Hint The estimated time to Periapsis in the reentry mode Base Approach program. Be sure to get this value from the Map Program, accuracy set at 1.000.

InA Intercept angle. The angle between the velocity vector of ship‘s orbit and the target‘s orbit at the time of interception.

iV Inward delta velocity. A component of the escape velocity vector.

LAN Your ship‘s current longitude of the ascending node.

Lat The latitude of a particular point in the flight (plane change, latitude of a base) with respect to the Reference planet.

LPC Longitude of a plane change with respect to the reference planet.

Lon The longitude of a particular point in the flight (plane change, longitude of a base) with respect to the Reference planet.

Min EqI The minimum equatorial inclination with which a program can generate a target orbit.

Max EqI The maximum equatorial inclination with which a program can generate a target orbit.

Num This is the number of passages over the target landing site at which you execute your deorbit burn. Note that this number is AFTER the insertion burn. If Num is 2, then you should perform your insertion burn as you pass over the base a third time. If Num is 0, then you should do your deorbit burn right as you are passing over it the first time. So basically it is the number of FULL orbits before making your deorbit burn.

oV Outward delta velocity. A component in the escape velocity vector. This is the component that you want to be minimized for a more fuel efficient flight.

PeA Altitude of the periapsis of the orbit measured above the surface of the reference planet.

PeD Radial distance (from the center of the reference planet) of the periapsis of the current orbit.

Pet Time in seconds until reaching the periapsis.

PeV Predicted orbital velocity in meters/second at the periapsis.

PlC Estimated delta velocity required for a plane change maneuver.

Rad Distance from the center of the reference planet.

ReA Estimated reentry angle between your ship‘s velocity vector and the atmosphere at the altitude that you set (default 120k in Base Approach).

ReT Estimated time until you hit the altitude that you set (default 120k in Base Approach)

ReV Estimated velocity at the altitude that you set (default 120k in Base Approach).

RIn Angle between the orbital planes of either the target and the source, the target and your ship, or the target and the hypothetical transfer orbit. Basically, it is the angle between two orbital planes.

TEj Time in seconds until ejection, or time until a burn is performed (Base Approach, Slingshot).

Time The time as displayed by the Surface Launch Program until optimum launch time.

Tin Time in seconds until you intercept your target (closest passage).

Tn Time in seconds until the next node.

TOF Time of Flight, from orbit eject to orbit insertion.

Tot The combined magnitude of the components of a delta velocity vector. So, it is the total magnitude of the delta velocity vector.

TtB Remaining estimated time to burn (assuming that the main engines are at 100%) in seconds