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  Photo of the week 505 (June 28, 2014)

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Author Topic:   Photo of the week 505 (June 28, 2014)
heng44
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Posts: 3596
From: Netherlands
Registered: Nov 2001

posted 06-28-2014 01:55 AM     Click Here to See the Profile for heng44   Click Here to Email heng44     Edit/Delete Message   Reply w/Quote

Liftoff of STS-41D was scheduled for 8:43 a.m. EST on June 26, 1984, but Discovery's computers halted the ignition sequence at T-4 seconds after a fuel valve in engine no.3 failed to open properly. The no.2 engine had ignited and had already built up to 20% thrust when it was ordered to shut down after burning for approximately 1.7 seconds.

MCroft04
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Posts: 1782
From: Smithfield, Me, USA
Registered: Mar 2005

posted 06-28-2014 06:47 AM     Click Here to See the Profile for MCroft04   Click Here to Email MCroft04     Edit/Delete Message   Reply w/Quote
Prompting one of the best quotes from the shuttle program by Steve Hawley just after engine shutdown; "I thought we'd be a lot higher at MECO!" or something close to that according the Hank Hartsfield.

GoesTo11
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Posts: 1355
From: Denver, CO
Registered: Jun 2004

posted 06-28-2014 11:05 AM     Click Here to See the Profile for GoesTo11   Click Here to Email GoesTo11     Edit/Delete Message   Reply w/Quote
Yes... Steve Hawley and Mike Mullane were seated next to each other on the flight deck for launch, and in Riding Rockets Mullane recalls Hawley turning to him a moment after the abort and deadpanning, "I thought we'd be higher when the engines quit."

Colonel Mullane, who by his admission therein didn't see much humor in the situation at the time, recalls that as one of the moments when he began to suspect that the TFNG "geeks" had more steel in them than Mullane and many of his fellow military jet jocks in the astronaut corps had been inclined to credit them with.

MCroft04
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Posts: 1782
From: Smithfield, Me, USA
Registered: Mar 2005

posted 06-28-2014 11:26 AM     Click Here to See the Profile for MCroft04   Click Here to Email MCroft04     Edit/Delete Message   Reply w/Quote
I forgot about that story being in Mullane's book. When Hank told us the story he clearly said "MECO." Not sure whose memory is correct.

Michael Davis
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Posts: 549
From: Houston, Texas
Registered: Aug 2002

posted 06-28-2014 12:15 PM     Click Here to See the Profile for Michael Davis   Click Here to Email Michael Davis     Edit/Delete Message   Reply w/Quote
What would the consequences have been if the engine shutdown occurred just after SRB ignition?

GoesTo11
Member

Posts: 1355
From: Denver, CO
Registered: Jun 2004

posted 06-28-2014 01:03 PM     Click Here to See the Profile for GoesTo11   Click Here to Email GoesTo11     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Michael Davis:
What would the consequences have been if the engine shutdown occurred just after SRB ignition?

Given that the vehicle was committed to flight with SRB ignition, the subsequent detection of a fault in one of the SSMEs would have prompted a shutdown of that single engine only, with the other two continuing to burn and possibly throttled up to compensate for the lost engine depending on whatever in-flight abort protocol was executed. That's my layman's understanding anyway; I'm sure others here can add more specific details.

Related: One of the most interesting revelations I found in Colonel Mullane's book was that prior to Challenger, the likeliest possible cause of a loss of vehicle and crew during ascent was generally thought to be a catastrophic SSME failure. The integrity of the SRBs wasn't a subject of much concern among the astronauts at the time.

cspg
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Posts: 6312
From: Geneva, Switzerland
Registered: May 2006

posted 06-28-2014 04:58 PM     Click Here to See the Profile for cspg   Click Here to Email cspg     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Michael Davis:
What would the consequences have been if the engine shutdown occurred just after SRB ignition?

Destruction of vehicle and loss of crew mainly due to water impact (and if there's a ditching with the cargo bay with a payload, same result). The vehicle wouldn't have reached enough speed after SRB separation. Also, the orbiter would have to go into a "fast separation" from the ET for the orbiter to attain a reentry attitude quickly-all studies concluded the result into a water impact (post Challenger, the escape pole was installed but that works under very specific conditions, namely controlled gliding flight). See Dennis Jenkins' book on the shuttle for more details. Also I can't remember when in the launch phase it was considerate "safe" if an engine quit (about 3.5 minutes into the flight?).

A year later, on July 29, 1985, mission 51-F, the #1 SSME engine quit 5 minutes 45 seconds into the flight, which led to the Abort To Orbit (ATO) trajectory mode. The same mission also suffered from a main engine shutdown at T-3 seconds due to a coolant valve on SSME #2.

All times are CT (US)

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