Advanced Question Space Shuttle Reentry Problems

[wllmpeek]

I'm a little concerned with the realism of the Space Shuttle reentry. Both Standard Orbiter version and Space Shuttle Ultra. I'm having difficulty maintaining the proper reentry attitude. As soon as you hit semi-dense atmosphere the nose pitches down to almost level. No amount of aileron or RCS will null these rates.

When flying the XR-2 you have variable center of gravity control to maintain the proper attitude which is very effective. A great flying machine.

All the internet and NASA literature I can find on the Space Shuttle are very vague about how the Shuttle maintained a high reentry pitch up to 40 degrees necessary.

The only mention I can find, is about the Body Flap on the rear of the Shuttle shielding the Main Engine Bell's.

From NASA website:

"Body Flap"

"The body flap thermally shields the three SSMEs during entry and provides the orbiter with pitch control trim during its atmospheric flight after entry."

And here's a reference from Wikipedia regarding STS-1:

"The orbiter's heat shield was damaged when an overpressure wave from the solid rocket booster caused a forward RCS oxidizer strut to fail.[11] The same overpressure wave also forced the shuttle's "body flap" – an extension on the orbiter's underbelly that helps to control pitch during reentry – into an angle well beyond the point where cracking or rupture of its hydraulic system would have been expected. Such damage would have made a controlled descent impossible, with John Young later admitting that had the crew known about this, they would have flown the shuttle up to a safe altitude and ejected, causing Columbia to have been lost on the first flight."

The standard Space Shuttle offered in Orbiter does not have this feature and the Operations Manual for Space Shuttle Ultra say's this feature is disabled.

So, my question is, after all these years of Orbiter, why is this feature not represented and how do you reenter realistically??????????:huh:

 

[GLS]

I'm a little concerned with the realism of the Space Shuttle reentry. Both Standard Orbiter version and Space Shuttle Ultra. I'm having difficulty maintaining the proper reentry attitude. As soon as you hit semi-dense atmosphere the nose pitches down to almost level. No amount of aileron or RCS will null these rates.

When flying the XR-2 you have variable center of gravity control to maintain the proper attitude which is very effective. A great flying machine.

All the internet and NASA literature I can find on the Space Shuttle are very vague about how the Shuttle maintained a high reentry pitch up to 40 degrees necessary.

The only mention I can find, is about the Body Flap on the rear of the Shuttle shielding the Main Engine Bell's.

From NASA website:

"Body Flap"

"The body flap thermally shields the three SSMEs during entry and provides the orbiter with pitch control trim during its atmospheric flight after entry."

And here's a reference from Wikipedia regarding STS-1:

"The orbiter's heat shield was damaged when an overpressure wave from the solid rocket booster caused a forward RCS oxidizer strut to fail.[11] The same overpressure wave also forced the shuttle's "body flap" – an extension on the orbiter's underbelly that helps to control pitch during reentry – into an angle well beyond the point where cracking or rupture of its hydraulic system would have been expected. Such damage would have made a controlled descent impossible, with John Young later admitting that had the crew known about this, they would have flown the shuttle up to a safe altitude and ejected, causing Columbia to have been lost on the first flight."

The standard Space Shuttle offered in Orbiter does not have this feature and the Operations Manual for Space Shuttle Ultra say's this feature is disabled.

So, my question is, after all these years of Orbiter, why is this feature not represented and how do you reenter realistically??????????:huh:

In SSU, alpha is kept +/- at the correct value when pitch is in AUTO, and in MAN it's "easy" to keep it stable (at least at 40º).
Yeah, in SSU the body flap doesn't work... yet (don't know why as I'm not familiarized with the "aero part" of SSU), but even with the "missing parts" and other problems that it might have, I still think SSU has a pretty good entry performance.
Could you provide more details on when is SSU "failing" (scenario/speed/altitude/alpha)?

 

[DaveS]

In SSU, alpha is kept +/- at the correct value when pitch is in AUTO, and in MAN it's "easy" to keep it stable (at least at 40º).

A note on this: You need to have loaded the entry software into the GPCs for this to work. This done by entering OPS 304 PRO on the GPC keyboard some 5 minutes prior to Entry Interface (EI).

 

[STS]

A note on this: You need to have loaded the entry software into the GPCs for this to work. This done by entering OPS 304 PRO on the GPC keyboard some 5 minutes prior to Entry Interface (EI).

And you have to transfer to it correctly, and follow the checklists. Also, you need to start the APU´s if you want to land.