Worry over SRBs

2) With regard to 51-L: Didn't it turn out that there was enough of a
chamber pressure differential between the left and right SRB where a
problem could have been detected had that system been monitored in real
time during launch (as I recall, the chamber pressures were being
recorded, but not monitored in real time)?


doesnt matter once lit it must burn to completion. theres no way to get
away from a solid you know is going bad.

"Kim Keller" wrote in message
...

"Craig Cocca" wrote in message
oups.com...
1) Are there any examples of an expendable rocket shutting its engines
down when a failure mode is detected, or do non-human-rated vehicles
only "fly or explode"? The only recent example I could think of where
the launcher shut itself down when something had gone wrong is on the
maiden launch of Space X's Falcon 1.

Engine shutdown is a range safety option the expendable rocket builder can
use instead of destruct charges. AFAIK, only SpaceX has gone that
direction. I don't know why other builders haven't chosen it.

I was discussing this with some coworkers today. It seems that all US ELVs
execute an engine shutdown command as part of the range safety destruct
command sequence. The engine shutdown command is intended to shut down an
engine that may otherwise continue operating for a brief period after the
rocket comes apart. This was evidently a "lesson learned" from the early
days of the rocket bidness. The destruct charge is necessary to prevent the
rocket from becoming an *intact* powered projectile. SpaceX was able to fly
without a full flight termination system at Kwaj, but will have to use one
when operating out of Vandenberg or CCAFS.

"Bob Haller" wrote in message
oups.com...
doesnt matter once lit it must burn to completion. theres no way to get
away from a solid you know is going bad.

That's ridiculous. If you have time to know it's going bad, you have time to
escape. An LES-type system can extract a crew before they are overcome by
the explosion. They may be very sore from the g-loading, but they'll be
alive.

Kim Keller wrote:
"Bob Haller" wrote in message
oups.com...
doesnt matter once lit it must burn to completion. theres no way to get
away from a solid you know is going bad.

That's ridiculous. If you have time to know it's going bad, you have time to
escape. An LES-type system can extract a crew before they are overcome by
the explosion. They may be very sore from the g-loading, but they'll be
alive.

I was talking about the SHUTTLE, in that case even knowing a solid was
bad theres not a thing that could be done.

"Bob Haller" wrote in message
oups.com...
I was talking about the SHUTTLE, in that case even knowing a solid was
bad theres not a thing that could be done.

Granted. STS *should* have had an adequate escape system.

Kim Keller beweerde :
"Bob Haller" wrote in message
oups.com...
I was talking about the SHUTTLE, in that case even knowing a solid was
bad theres not a thing that could be done.

Granted. STS *should* have had an adequate escape system.

During the ascent WITH the SRB's (first 2 minutes) escaping from the
vehicle is impossible.
Reason is when you exit the orbiter, you will end up in the exhaust of
the SRB's, if your'e not struck by the leading edge of the port side
wing (where the RCC panels are). Not a pleasant thought.

When the SRB's are fired, there is no way to shut them down, this is
the major disadvantage of a solid propellant rocket.
A liquid fuel engine can easally shut down by closing the fuel lines:
no fuel, no ignition.

André

"André, PE1PQX" wrote in message
...
When the SRB's are fired, there is no way to shut them down, this is the
major disadvantage of a solid propellant rocket.
A liquid fuel engine can easally shut down by closing the fuel lines: no
fuel, no ignition.

I'm going from memory here, so hopefully I won't pull another
Columbia/Challenger style mix-up. :-)

You can install thrust termination systems on SRB's. The shuttle SRB's have
thrust termination systems that fire linear shaped charges that split the
SRB open from the bottom to the top. However, if you look at drawings for
the SRB's planned for use on the Titan III-M, you'll often note that there
are circular shaped areas on the sides of each SRB, near the top. In this
case, the plan was to have linear shaped charges blow open these circular
areas to release the pressure inside the SRB, which would stop it from
firing. Other options would include blowing the nozzle off, blowing the
nose off, or blowing both the nozzle and nose off.

However, with the shuttle, it was determined that any thrust termination
system on the SRB's would result in loads so high that the orbiter would be
destroyed anyway. So the designers went with unzippering the SRB along its
length, which insures that thrust is *completely* terminated.

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)

"André, PE1PQX" wrote in message
...
During the ascent WITH the SRB's (first 2 minutes) escaping from the
vehicle is impossible.

In its present condition that's true. But there are always engineering
solutions. Getting program mangers to relax requirements so they can be
incorporated is the tough part.

Reason is when you exit the orbiter, you will end up in the exhaust of the
SRB's, if your'e not struck by the leading edge of the port side wing
(where the RCC panels are). Not a pleasant thought.

Who said anything about exiting the orbiter as a parachutist? There are
better ways to escape. The problem is, they should be built in from the
beginning of design.

When the SRB's are fired, there is no way to shut them down, this is the
major disadvantage of a solid propellant rocket.
A liquid fuel engine can easally shut down by closing the fuel lines: no
fuel, no ignition.

I know all this. It's part of my job.

On Wed, 12 Jul 2006 03:03:22 GMT, "Kim Keller"
wrote:

When the SRB's are fired, there is no way to shut them down, this is the
major disadvantage of a solid propellant rocket.
A liquid fuel engine can easally shut down by closing the fuel lines: no
fuel, no ignition.

I know all this. It's part of my job.

By the way, Kim... congrats on getting your letter published in
AvLeak! (Mail is slow where I am...)

Brian

"Jeff Findley" wrote:


"André, PE1PQX" wrote in message
...
When the SRB's are fired, there is no way to shut them down, this is the
major disadvantage of a solid propellant rocket.
A liquid fuel engine can easally shut down by closing the fuel lines: no
fuel, no ignition.

I'm going from memory here, so hopefully I won't pull another
Columbia/Challenger style mix-up. :-)

You can install thrust termination systems on SRB's.

Correct.

However, with the shuttle, it was determined that any thrust termination
system on the SRB's would result in loads so high that the orbiter would be
destroyed anyway.

Correct.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL