Shuttle RTLS abort contradiction

In article
tatelephone,
says...

In the Shuttle RTLS abort, the stack continues its ascent till SRB
shutdown, then turns around till its SSMEs are facing forward and fires
them to reduce its velocity, jettisons the ET and glides back to the KSC.
Fine and dandy till you consider what would lead to it abort its ascent.
If it's a problem with the SRBs, that would probably destroy the launch
stack.
So the most likely problems after that are either a problem with the
SSMEs or the guidance system.
But you are counting on both the SSMEs and guidance system to position
you correctly and slow you down so you can return to KSC.
So how exactly is this supposed to work?

RTLS is in the books, but some people think it's not a very realistic
option. When asked about testing the RTLS abort mode, John Young
reportedly answered, "We don't need to practice bleeding."

Jeff
--
42

On Dec 16, 10:33*am, Jeff Findley wrote:
In article
tatelephone,
says...



In the Shuttle RTLS abort, the stack continues its ascent till SRB
shutdown, then turns around till its SSMEs are facing forward and fires
them to reduce its velocity, jettisons the ET and glides back to the KSC.
Fine and dandy till you consider what would lead to it abort its ascent..
If it's a problem with the SRBs, that would probably destroy the launch
stack.
So the most likely problems after that are either a problem with the
SSMEs or the guidance system.
But you are counting on both the SSMEs and guidance system to position
you correctly and slow you down so you can return to KSC.
So how exactly is this supposed to work?

RTLS is in the books, but some people think it's not a very realistic
option. *When asked about testing the RTLS abort mode, John Young
reportedly answered, "We don't need to practice bleeding."

Jeff
--
42

kinda like testing a suicide machine to make certain its safe and
effective?

In sci.space.policy David Spain wrote:
Jorge R. Frank wrote:
Impending loss of all APU/hydraulic systems capability.

How impending? Seem like this is a good candidate for an ocean
ditching not RTLS. Loss of a shuttle is bad, loss of the shuttle
infrastructure is much worse.

Call it "Return Towards Launch Site" then?-)

rick jones
--
The glass is neither half-empty nor half-full. The glass has a leak.
The real question is "Can it be patched?"
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

Pat Flannery wrote:
In the Shuttle RTLS abort, the stack continues its ascent till SRB
shutdown, then turns around till its SSMEs are facing forward and fires
them to reduce its velocity, jettisons the ET and glides back to the KSC.

You means keeps firing them. There ain't no restart on SSMEs. From what I
recall I think the maneuver can best be described as a shallow powered dive
from upside down until right side up. But forward velocity must be maintained
to retain aerodynamic stability. I'm not sure there is any 'slowing' relative
to air speed, ground speed yes. After all it is returning...

But I agree, this abort procedure can best be labeled... dicey...

However it was simulated zillions of times. Jorge can you enlighten us on
the RTLS abort criterion? When was RTLS abort forced? I seem to remember at
somewhere around T+130s we have single engine 'TAO' (sp?), which adds
transatlantic abort option but not 'negative return' which happens sometime
later. So there is some overlap correct? But there is no RTLS option until
SRBs are done? SRBs can't be separated early? There would need to be some
delay before the case destruct charges are fired to allow shuttle to clear the
SRBs. But the SRBs can't be steered away from the stack on an abort?

(I agree, any massive SRB failure/explosion while still attached to the stack
seems to be, the best I know, unrecoverable).

Dave

[PS: I'm sure this info in on-line somewhere. I'm also doubly sure I don't
have the time to go searching for it right now, but links always appreciated.]

David Spain wrote:
But I agree, this abort procedure can best be labeled... dicey...

etc. Notice Jorge has already responded. Failure to scroll in newsreader.

Sorry. Ignore....

Dave

Jorge R. Frank wrote:
Impending loss of all APU/hydraulic systems capability.

How impending? Seem like this is a good candidate for an ocean ditching not
RTLS. Loss of a shuttle is bad, loss of the shuttle infrastructure is much worse.

Dave

On Dec 16, 9:37*pm, Pat Flannery wrote:
On 12/16/2010 3:20 PM, David Spain wrote:

Pat Flannery wrote:
In the Shuttle RTLS abort, the stack continues its ascent till SRB
shutdown, then turns around till its SSMEs are facing forward and
fires them to reduce its velocity, jettisons the ET and glides back to
the KSC.

You means keeps firing them. There ain't no restart on SSMEs.

I forgot that it does indeed fly under SSME power back towards KSC
before dropping the ET.

[PS: I'm sure this info in on-line somewhere. I'm also doubly sure I
don't have the time to go searching for it right now, but links always
appreciated.]

There is info on the abort modes hehttp://www.aerospaceweb.org/question...ft/q0278.shtml

Pat

theres no abort till the solids are thru firing and seperated from the
orbiter.

so if only one solid fires or one has a problem its a very bad
day......

On Thu, 16 Dec 2010 18:32:05 -0500, David Spain
wrote:

Jorge R. Frank wrote:
Impending loss of all APU/hydraulic systems capability.

How impending? Seem like this is a good candidate for an ocean ditching not
RTLS. Loss of a shuttle is bad, loss of the shuttle infrastructure is much worse.

Well, even if they won't make it back to the Shuttle Landing Facility,
getting back closer to the SRB recovery ships would certainly improve
the chances of crew survival after bailout.

Brian

On Thu, 16 Dec 2010 10:33:49 -0500, Jeff Findley
wrote:


RTLS is in the books, but some people think it's not a very realistic
option. When asked about testing the RTLS abort mode, John Young
reportedly answered, "We don't need to practice bleeding."

Yes, but I think we all agree that when it comes down to, most of us
will choose "slim chance" over "no chance".

Brian

On 12/16/2010 3:20 PM, David Spain wrote:
Pat Flannery wrote:
In the Shuttle RTLS abort, the stack continues its ascent till SRB
shutdown, then turns around till its SSMEs are facing forward and
fires them to reduce its velocity, jettisons the ET and glides back to
the KSC.

You means keeps firing them. There ain't no restart on SSMEs.

I forgot that it does indeed fly under SSME power back towards KSC
before dropping the ET.

[PS: I'm sure this info in on-line somewhere. I'm also doubly sure I
don't have the time to go searching for it right now, but links always
appreciated.]

There is info on the abort modes he
http://www.aerospaceweb.org/question...ft/q0278.shtml

Pat