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Flying the Shuttle - Entry: Difference between revisions
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<b>Since aerodynamical forces push the shuttle into a low AoA configuration, a high pitch angle, once lost, is not easily recoverable. It is best established outside the atmosphere where qbar is low and kept during entry, only to be relaxed in the final phase.</b> | <b>Since aerodynamical forces push the shuttle into a low AoA configuration, a high pitch angle, once lost, is not easily recoverable. It is best established outside the atmosphere where qbar is low and kept during entry, only to be relaxed in the final phase.</b> | ||
== How it feels in FG == | |||
Since the Shuttle is pitched up most of the time, you don't see much except the HUD during the entry phase. Currently there's very little support for displaying ground track or estimating the needed deceleration as function of range to target, so try aiming a track only if you're ambitious, otherwise try to survive. | |||
Important HUD readings to monitor are pitch and roll angle, nose temperature, vertical speed, Mach number and acceleration. | |||
Pitch up and wait for the atmosphere to grab the shuttle. This will be felt initially by a very slow drift of the attitude, trying to reduce pitch. Apply thrusters to keep the nose up. The thrust level needed to hold the 40 degrees will increase with increasing qbar, and eventually the controls will revert to aerodynamical surfaces for roll (qbar = 10 psf) and pitch (qbar = 20 psf). The steering characteristics changes quite drastically - initially it is probably easier to make minute thruster adjustments with the keyboard, in the later phase a stick or mouse is a much better option. | |||
Once the Shuttle is under aerodynamical control, watch descent rate slow and reverse. Once the rate comes back up to about -50 m/s, you can initiate the first careful high-bank roll. Do it gently in order not to lose the AoA! Watch the response of nose cone temperature and acceleration and the slow drift in course. The descent rate will fall again, don't let it fall too fast, or you'll get too hot. Allow for some lag, get a feeling for how the trajectory responds to what you're doing. This is actually piloting, and you can influence a lot of what is happening here. | |||
Monitor Mach number and altitude decrease, feel free to reduce pitch angle later in the flight. Around Mach 3.5, you should finally get the rudder back with RCS jets switched completely off, at which point the Shuttle definitely feels like an aircraft. It can now actually change course and turn, although still sluggishly. Steer the course towards the landing site if you're close. Aim for TAEM interface of 85.000 ft, Mach 2.5, around 60 miles before the runway. Don't try to brake too fast, as the manual has it: | |||
<i>It is better to arrive at TAEM interface with too much energy than without wings.</i> | |||
(NASA has a sense of humor...) | |||
== Further reading == | |||
[http://spaceflight.nasa.gov/shuttle/reference/shutref/events/entry/ NASA human space flight page on Shuttle entry] | |||
[http://en.wikipedia.org/wiki/Atmospheric_entry Wikipedia article on atmospheric entry] | |||