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Flying the Shuttle - Abort Procedures Overview: Difference between revisions
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Flying the Shuttle - Abort Procedures Overview (view source)
Revision as of 06:24, 8 September 2015
, 8 September 2015→Launchpad abort
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Just as in real life, you have to get out of FG and re-try another time. | Just as in real life, you have to get out of FG and re-try another time. | ||
== Return to Launch Site == | |||
The Return to Launch Site (RTLS abort) procedure is designed for loss of an engine just after liftoff up to perhaps 3:30 into the flight. It aims to bring the Shuttle back to a landing at the launch site and for that reason is very different from the way the Shuttle normally operates. It also is the most difficult abort procedure, as there are several elements which are time-critical and can go wrong easily. The basic pattern is summarized in the following diagram: | |||
[[File:RTLS.gif|600px|Return to Launch Site]] | |||
The abort is declared after SRB separation outside the atmosphere. From there, there are three distinct phases - powered flight, coast and ET separation and final glide. | |||
The powered flight phase starts extremely low on thrust. At that stage, the main aim is to deplete propellant. Pitched highly upwards (up to 60 deg) to vector thrust downward and minimize loss of altitude, the Shuttle continues to accelerate downrange. At a turning point, the Shuttle then pitches around rapidly (about 10 deg/s) and starts to decelerate, still vectoring thrust downward. All the time the trajectory drops, and pitch should be adjusted such that by the time of MECO, it has come down to about 220.000 ft but not significantly lower | |||
After pitch around, the Shuttle eventually reaches a turning point and starts to accelerate back to the range. As propellant depletes and ET weight is reduced, acceleration reaches up to 3 g and the Shuttle becomes very maneuverable again, allowing it to reach up to Mach 7 pointed back towards the landing site. | |||
Timimg for the pitch-around is critical - wait too long and the Shuttle will not make it back to the site, turn too early and the Shuttle will overshoot. The proper indicator for the pitch-around is the amount of propellant remaining, dependent on the time when the engine failed. Refer to the following cue card: | |||
{| class="wikitable" | |||
|+ RTLS cue card | |||
! failure time !! pitch around | |||
|- | |||
| 0:00 || 44% | |||
|- | |||
| 0:30 || 47% | |||
|- | |||
| 1:00 || 47% | |||
|- | |||
| 1:30 || 48% | |||
|- | |||
| 2:00 || 51% | |||
|- | |||
| 2:30 || 51% | |||
|- | |||
| 3:00 || 52% | |||
|- | |||
| 3:30 || 53% | |||
|} | |||
== Further reading == | == Further reading == | ||
[http://spaceflight.nasa.gov/shuttle/reference/shutref/events/aborts/ NASA human spaceflight page on abort modes] | [http://spaceflight.nasa.gov/shuttle/reference/shutref/events/aborts/ NASA human spaceflight page on abort modes] | ||