Author Topic: The all-eventful STS-93 launch (Read 67513 times)

DaveS · « **Reply #20 on:** 12/07/2005 03:59 pm »

The leak off H2 wasn't gaseous H2. It was LH2. So what was that Columbia's onboard computerss sensed the LH2 leak and compensated by using more LOX.

So a few seconds prior to planned MECO, the ECO sensors sensed that the LOX had gotten to that level where the ECO sensors is indicating "dry" instead of "wet".
So the computers automatically shut down the SSMEs prior to planned MECO leaving Columbia with a slight underspeed. This was well within the capabilities of the OMS.

psloss · « **Reply #21 on:** 12/08/2005 01:10 pm »

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DaveS - 16/11/2005 12:33 PM
RTLS on an single engine? They were in the danger of losing two engines. I don't think that's possible since you have zero bank control on the vehicle after SRB seperation. I think that for the crew's own safety, ditching the orbiter would have preferred. Sure, it would have total loss of vehicle and payload but crew would still have been alive. Ditching the orbiter would have been much safer than trying a totally untested abort in the least optimal conditions.

But I could be wrong on the true capabilities of the shuttle system.

There are several failures that could force an RTLS; obviously, main engine performance is a primary issue. But there are other systems that could fail that would necessitate returning as soon as possible -- for example, a high crew-cabin leak rate or imminent loss of cooling capabilities.

For the 93 ascent, the problem was electrical/wiring; the way the main engine controllers are connected to the electrical busses (six controllers, three busses) provides for a good deal of redundancy. Each engine has two redundant controllers; they are connected to different busses such that if a single bus fails, each engine still has an operating controller. If an additional bus had failed, only one engine would have shutdown, but there would be no further redundancy. (Of course, you're already down to a single bus at that point.)

For general background, this is THE public site for shuttle abort information (in my opinion):
http://www.theandyzone.com/launchzone/launchzone.htm

The RTLS reference:
http://www.theandyzone.com/launchzone/rtlsp1.htm

Philip Sloss

psloss · « **Reply #22 on:** 12/09/2005 11:17 am »

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psloss - 8/12/2005 9:10 AM
For the 93 ascent, the problem was electrical/wiring; the way the main engine controllers are connected to the electrical busses (six controllers, three busses) provides for a good deal of redundancy. Each engine has two redundant controllers; they are connected to different busses such that if a single bus fails, each engine still has an operating controller. If an additional bus had failed, only one engine would have shutdown, but there would be no further redundancy. (Of course, you're already down to a single bus at that point.)

Clarification on this: on the 93 launch, the short was on one phase of one bus (each bus has three phases); the bus was still functional, but the transient did knock the two MECs tied to it offline.

I still remember being out on the causeway for that launch (the first night launch I attended), which I've posted about elsewhere:
http://www.lupwa.org/Wanderings/July1999/19990723.asp

Philip Sloss

Rocket Guy · « **Reply #23 on:** 12/09/2005 03:42 pm »

Let's clarify one thing here for those that may be be aware:

There were two, separate problems on STS-93 during ascent. There was an electrical short due to frayed wiring coming in contact with metal. And there was a a hydrogen leak, unrelated to the short. The leak was caused when a pin broke inside the oxygen injector and was shot out of the engine, impacted the side of the nozzle and caused a rupture in the hydrogen line there which leaked the rest of the way up.

Launch Fan · « **Reply #24 on:** 12/09/2005 03:43 pm »

Cool site Philip! Personal launch experiences are very well recieved around these parts

Andy L · « **Reply #25 on:** 12/09/2005 05:41 pm »

Enjoyed the description of the sound you get from a launch. A few of the personal videos of launches on here give a good impression, but apparently it's a lot more than even we can imagine.

psloss · « **Reply #26 on:** 12/09/2005 10:44 pm »

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Ben - 9/12/2005 11:42 AM

Let's clarify one thing here for those that may be be aware:

There were two, separate problems on STS-93 during ascent. There was an electrical short due to frayed wiring coming in contact with metal. And there was a a hydrogen leak, unrelated to the short. The leak was caused when a pin broke inside the oxygen injector and was shot out of the engine, impacted the side of the nozzle and caused a rupture in the hydrogen line there which leaked the rest of the way up.

Good point; here's a link to a transcript of Bill Readdy's testimony in the short term after the flight:
http://www.house.gov/science/readdy_092399.htm

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(Excerpt from the transcript regarding the post pin ejection)

Post-landing inspection and detailed analyses revealed that the leak resulted from impact damage to the interior nozzle coolant tubes. The impact occurred when a main injector liquid oxygen post pin contacted 3 of the 1080 tubes (Figures 2, 3, 4). This engine’s main injector had 2 of the over 500 lox posts deactivated by a gold plated pin. STS-93 was the last planned flight of the older Phase II engines. The new and greatly improved Block II-A engines eliminate this failure mode.

The independent assessment team report made toward the end of '99 also has some more detail on both incidents:
http://www.hq.nasa.gov/osf/siat.pdf

Launch Fan · « **Reply #27 on:** 01/12/2006 05:42 pm »

One of my favourite threads, and given Rmathews has a related extra amount of info on the abort rational, I wanted to bump it.

Jackson · « **Reply #28 on:** 03/29/2006 05:29 pm »

Yikes! This could have been scary. Didn't know it was Eileen in charge. She was a pro on this.

Chris Bergin · « **Reply #29 on:** 04/03/2006 10:06 am »

A couple of very interesting videos, courtesy of Philip Sloss.

CLICK HERE FOR VIDEO DOWNLOAD - Media Conference on how they reduced the weight of Columbia for this mission.

CLICK HERE FOR VIDEO DOWNLOAD - Media Conference on the reasons for the scrub just prior to main engine start.

psloss · « **Reply #30 on:** 04/03/2006 11:36 am »

For those who don't recognize the person featured in both videos, it is Grant Cates, who was the flow director for Columbia at the time. (That's Ron Dittemore answering the first question.)

Tahii · « **Reply #31 on:** 04/04/2006 07:05 am »

Cheers for those media conference videos. Great source of information.

Hotol · « **Reply #32 on:** 04/04/2006 11:43 am »

I love it when Bill Harwood bullies Grant Cates into giving some data.

Cates tries to say he'll talk about it later and you can hear Bill and someone else saying they want to hear about it now and Bill saying "it's interesting!", to which Cates starts reading off data. Classic.

psloss · « **Reply #33 on:** 04/04/2006 12:49 pm »

The details of the weight reduction were interesting to some people, which is why I presume Mr. Harwood pressed for the details in a countdown status briefing...it's the kind background detail that one would expect in the pre-flight briefings from JSC rather than a countdown briefing. (Still, I'm glad he asked, since I missed a lot of the preflight proceedings until I got to Florida just before the first launch attempt.)

I think many of the people here would have been interested in this information at the time, but then again I don't know how many forums there were for this back in 1999. (It wasn't as cheap to publish material as it is today.) Mr. Harwood did the only story that I can recall to reference a good chunk of this information.

Pointman 7 · « **Reply #34 on:** 04/04/2006 08:26 pm »

Great additions to this excellent thread. Interesting that they had to bring the weight down, but kept all the items such as the treadmill because of the CG.

Zoomer30 · « **Reply #35 on:** 05/12/2006 05:45 pm »

The had really 2 issues on that flight. 1 was the short circuit that casued the engine controllers to go out (lucky each engine has more than one). The 2nd issue that was not known till later was that at engine start, a inector pin came out of the combustion chamber and hit the side of the nozzle. this caused a hydrogen leak from the nozzle. This casued that fuel to be "lost", so that MECO came a fraction of a sec early (you dont want to "run a SSME dry", that would casued turbopump failure).

Here is a pic from Wikipedia, shows the ship after landing, notice the ding in the nozzle wall on the lower right hand engine. Wikipedia has the very high res version of this photo, shows at least 4 tubes were effected. Just do a serch for SSME on Wikipedia.

Shuttle>CEV · « **Reply #36 on:** 06/29/2006 10:52 pm »

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Chris Bergin - 3/4/2006 4:53 AM

A couple of very interesting videos, courtesy of Philip Sloss.

CLICK HERE FOR VIDEO DOWNLOAD - Media Conference on how they reduced the weight of Columbia for this mission.

CLICK HERE FOR VIDEO DOWNLOAD - Media Conference on the reasons for the scrub just prior to main engine start.

The video won't load, how did the reduce Columbia's weight?

DaveS · « **Reply #37 on:** 06/29/2006 11:00 pm »

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Shuttle>CEV - 30/6/2006 12:39 AM

The video won't load,

Are your you have installed the DIVX(www.divx.com) codec?

RHAnthony · « **Reply #38 on:** 01/08/2007 06:46 am »

For anyone who hasn't yet, go to www.wikipedia.org and search for SSME to get that larger version of the SSME photo above. It's a great photo, with LOTS of details!

AstroRJY · « **Reply #39 on:** 04/20/2007 12:57 am »

The calls are actually " Houston-Columbia, we're in the roll.."

and also the call both ways at about T+ 65-70 seconds is Go AT throttle up, never go "with".

Not to be overly critical, great videos and liked reading the posts.