Shuttle RTLS abort contradiction

On Dec 15, 6:52*pm, 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.
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?

Pat

nasa knew it was a flying catch and was just a look good feel good
abort that probably wouldnt work...

it wouldnt of looked good to fly a manned spacecraft with no real
launch abort ability.

like the escape pole its a appearance thing

On Dec 15, 2:17*pm, " wrote:
On Dec 15, 6:52*pm, 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.
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?

Pat

nasa knew it was a flying catch and was just a look good feel good
abort that probably wouldnt work...

it wouldnt of looked good to fly a manned spacecraft with no real
launch abort ability.

like the escape pole its a appearance thing

Exactly, as in all show and no blow.

The solid rocket destruction and it supersonic shockwave would have
been a lethal outcome, but none the less a good show of faith by those
idiots we over-pay and can't seem to ever get rid of without it
costing us even more than keeping them.

LH2 and LOx or even H2O2 plus whatever hydrocarbon fuel would have
been a relatively slow burn compared to a full blown solid rocket
failure.

~ BG

On Wed, 15 Dec 2010 15:52:27 -0800, 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.
Fine and dandy till you consider what would lead to it abort its ascent.

Loss of one SSME in first minute.
Loss of cabin pressurization.

Brian

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?

Pat

In sci.space.history Pat Flannery wrote:
On 12/15/2010 3:47 PM, Brian Thorn wrote:
Loss of one SSME in first minute.
Loss of cabin pressurization.

I can see the first one occurring, I assume they have single or dual
SSME failures programmed into the RTLS braking maneuver scenario?
Number two seems to suggest such severe damage (like something
coming through the forward cockpit windows) that the Shuttle may not
survive it in a aerodynamically controllable form, and it might be a
lot smarter to use the parachutes and descend into the sea rather
than try to land the orbiter.

Perhaps it is vanishingly small, but is there a chance of a Soyuz 11
style valve failure?

rick jones

--
I don't interest myself in "why." I think more often in terms of
"when," sometimes "where;" always "how much." - Joubert
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...

On 12/15/2010 05:58 PM, Rick Jones wrote:
In sci.space.history Pat wrote:
On 12/15/2010 3:47 PM, Brian Thorn wrote:
Loss of one SSME in first minute.
Loss of cabin pressurization.

I can see the first one occurring, I assume they have single or dual
SSME failures programmed into the RTLS braking maneuver scenario?

Yes (the 2-out control mode is called SERC). But an RTLS would not be
declared in a 2-out scenario. That calls for a contingency abort (ECAL
for high-inclination flights).

Number two seems to suggest such severe damage (like something
coming through the forward cockpit windows) that the Shuttle may not
survive it in a aerodynamically controllable form, and it might be a
lot smarter to use the parachutes and descend into the sea rather
than try to land the orbiter.

It doesn't have to be a full loss of the window; loss of the thermal
pane alone, or a cabin leak with dP/dt -0.15 psia/min, is cause to
abort RTLS.

There are other system failures that could cause an RTLS to be declared:

Impending loss of all APU/hydraulic systems capability.
Impending loss of all O2 or H2 cryo.
Loss of both Freon coolant loops.
Loss of any two main electrical buses.

On 12/15/2010 3:47 PM, Brian Thorn 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.
Fine and dandy till you consider what would lead to it abort its ascent.

Loss of one SSME in first minute.
Loss of cabin pressurization.

I can see the first one occurring, I assume they have single or dual
SSME failures programmed into the RTLS braking maneuver scenario?
Number two seems to suggest such severe damage (like something coming
through the forward cockpit windows) that the Shuttle may not survive it
in a aerodynamically controllable form, and it might be a lot smarter to
use the parachutes and descend into the sea rather than try to land the
orbiter.

Pat

On 12/15/2010 3:58 PM, Rick Jones wrote:


I can see the first one occurring, I assume they have single or dual
SSME failures programmed into the RTLS braking maneuver scenario?
Number two seems to suggest such severe damage (like something
coming through the forward cockpit windows) that the Shuttle may not
survive it in a aerodynamically controllable form, and it might be a
lot smarter to use the parachutes and descend into the sea rather
than try to land the orbiter.

Perhaps it is vanishingly small, but is there a chance of a Soyuz 11
style valve failure?

I don't think we use an automatic pressure equalization valve like that
on the Shuttle, do we?
Since liftoff and landing (ideally)both are at KSC, is there any need to
equalize air pressure on the way back down? Or does the Shuttle use
lower air pressure while on-orbit?

Pat

On 12/15/2010 6:05 PM, Jorge R. Frank wrote:

It doesn't have to be a full loss of the window; loss of the thermal
pane alone, or a cabin leak with dP/dt -0.15 psia/min, is cause to
abort RTLS.

There are other system failures that could cause an RTLS to be declared:

Impending loss of all APU/hydraulic systems capability.
Impending loss of all O2 or H2 cryo.
Loss of both Freon coolant loops.
Loss of any two main electrical buses.

I remember reading about the RTLS abort mode when they were first
getting ready for the Shuttle flights and NASA saying that although this
all worked in computer simulations, they sure never wanted to put it to
the test to see if it worked in real life.

Pat

I remember reading about the RTLS abort mode when they were first
getting ready for the Shuttle flights and NASA saying that although this
all worked in computer simulations, they sure never wanted to put it to
the test to see if it worked in real life.

Pat


Its like TSA at the airport, looks awesome matters little.

If highjackers attempt to take over another airliner the passengers
will attack the highjackers

the big risk is bombs, bomb sniffing dogs would be far better than
groping all passengers/

the biggest risk to airliners today is a SAM taking out a aircraft
from the ground, and TSA cant do a thing about that.....