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Author Topic:   Shuttle SRB 's

Posts: 1488
From: Brimfield, MA
Registered: Mar 2002

posted 10-09-2005 03:07 PM     Click Here to See the Profile for ejectr   Click Here to Email ejectr     Edit/Delete Message   Reply w/Quote
What would happen if the 3 main engines fired up and then only 1 SRB ignited?

I'm assuming the computers would sense this, shut down the mains and the SRB that ignited would just burn out on the pad.

Anyone know for sure?

[This message has been edited by ejectr (edited October 09, 2005).]


Posts: 72
From: Oak Hill, VA, USA
Registered: Jun 2005

posted 10-09-2005 03:29 PM     Click Here to See the Profile for katabatic   Click Here to Email katabatic     Edit/Delete Message   Reply w/Quote
My understanding is that would be a non-survivable event, with loss of the vehicle and severe damage to the pad.


Posts: 868
From: Shady Side, Md
Registered: Sep 2004

posted 10-09-2005 05:03 PM     Click Here to See the Profile for Apollo-Soyuz   Click Here to Email Apollo-Soyuz     Edit/Delete Message   Reply w/Quote
Once the signal is given to ignite the SRB's, they cannot be shut down. If only one ignites, I think the vehicle will begin to tumble due to imbalance of thrust and is not survivable.

John Macco
Vice President
Space Unit
Shady Side, Md.

[This message has been edited by Apollo-Soyuz (edited October 09, 2005).]


Posts: 3593
From: Midwest, USA
Registered: Jul 2005

posted 10-09-2005 06:37 PM     Click Here to See the Profile for mjanovec   Click Here to Email mjanovec     Edit/Delete Message   Reply w/Quote
Originally posted by ejectr:
I'm assuming the computers would sense this, shut down the mains and the SRB that ignited would just burn out on the pad.

If I remember correctly, the signal for the release of the hold down arms is sent at roughly the same time as the SRB ignition signal is sent. So there really is no opportunity to hold the vehical in place in the event only one SRB ignites.


Posts: 1843
From: Daytona Beach, FL
Registered: May 2000

posted 10-09-2005 11:14 PM     Click Here to See the Profile for Ben   Click Here to Email Ben     Edit/Delete Message   Reply w/Quote
Fortunately, the chance of an SRB not igniting when the command is sent is smaller than you can imagine. It has never happened on any SRB ever so far as I am aware. It's one of the disaster scenarios that is not even considered.

When NASA describes the frangible bolts breaking away they usually phrase it as, "we are *so* certain about the SRBs igniting that we fire the bolts 1/1000 second before they light."


Posts: 93
From: Saginaw, MI USA
Registered: Feb 2004

posted 10-10-2005 09:05 AM     Click Here to See the Profile for sfurtaw   Click Here to Email sfurtaw     Edit/Delete Message   Reply w/Quote
I could be wrong, but I thought that I heard at Space Camp (which was some time ago!) that there are four igniters at the top of each SRB, each one acting like a flame-thrower shooting a flame down the booster. Can anyone confirm this?

Scott Furtaw
In Memoriam: The Astronaut/Cosmonaut Memorial Web Site

spacecraft films

Posts: 802
From: Columbus, OH USA
Registered: Jun 2002

posted 10-10-2005 12:07 PM     Click Here to See the Profile for spacecraft films   Click Here to Email spacecraft films     Edit/Delete Message   Reply w/Quote
I heard a discussion of this scenario once. Generally, it isn't a survivable event, but the response to such an event is described as throwing all three SSMEs and the one functioning SRB to the limit of their gimbals to correct the trajectory and try and ride it out.

Remember that with the loss of an SRB the accelleration off the pad would be slow... with the thrust not that much more than the weight of the vehicle. And dragging along a fully-loaded SRB would really be a strain.

Somehow I remember John Young being in this discussion and he ended it by saying something to the effect of "It would be a sporty ride."

At least that is my recollection.


[This message has been edited by spacecraft films (edited October 10, 2005).]


Posts: 1181
From: Huntsville, AL, USA
Registered: Jun 2003

posted 10-11-2005 12:57 PM     Click Here to See the Profile for DavidH   Click Here to Email DavidH     Edit/Delete Message   Reply w/Quote
So could you go ahead and fire the exploding bolts to release the SRBs?
If so, what happens?

"America's challenge of today has forged man's destiny of tomorrow." - Commander Eugene Cernan, Apollo 17 Mission, 11 December 1972


Posts: 589
From: Ridgecrest, CA USA
Registered: Sep 2000

posted 10-11-2005 10:43 PM     Click Here to See the Profile for OV-105   Click Here to Email OV-105     Edit/Delete Message   Reply w/Quote
I think if only one SRB did light, I would hate to the RSO on that day.

New Member


posted 10-12-2005 08:40 PM     Click Here to See the Profile for CJC   Click Here to Email CJC     Edit/Delete Message   Reply w/Quote
If the starboard SRB fails to ignite then the vehicle will hit the launch tower as it lifts off. If the port SRB fails then the stack might stand a chance of clearing the tower but the strain imposed on the stack would ultimatly tear it apart.


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