Author Topic: Wayne Hale sets up his own blog site  (Read 331486 times)

Offline Hog

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Re: Wayne Hale sets up his own blog site
« Reply #420 on: 10/27/2014 03:26 pm »
All the while with 50,224 pounds of Chandra and it's Inertial Upper Stage in the payload bay.

Its amazing what was occuring from the moment the SRB's lit.

One issue ended up helping to avoid the consequences of another.  Simply fascinating, and a great display of teamwork by all.
« Last Edit: 10/27/2014 03:28 pm by Hog »
Paul

Offline Chris Bergin

Re: Wayne Hale sets up his own blog site
« Reply #421 on: 10/27/2014 03:36 pm »
I really wanted to refer to the L2 integrated video of the MCC calls during the STS-93 ascent, but it is still behind the NSF paywall . . .  any chance you could put that on the free part of the site?

Sure. I'll upload it to youtube in 10 minutes.

PS It's not a paywall, it's a place where supporters of the site gain access to access to all our database (which would bankrupt us if everyone could use it).

And here it is. One of my favorite videos of all time as it shows the team work so well. I've locked the L2 thread, although it has some amazingly technical posts in there about this.

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Offline Ben the Space Brit

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Re: Wayne Hale sets up his own blog site
« Reply #422 on: 10/27/2014 03:46 pm »
Wow! I'm thinking that, in that first sixty seconds, with the shuttle in what we now know to be more-or-less a black zone and data on two of the SSMEs that suggested that they were... well, gone... must have been like that MCC team's worst nightmare happening right in front of them! It's to their credit that they didn't panic but kept working the problem rather than commit Columbia to a risky and untried RTLS abort as soon after launch as possible.
« Last Edit: 10/27/2014 03:49 pm by Chris Bergin »
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Offline Wayne Hale

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Re: Wayne Hale sets up his own blog site
« Reply #423 on: 10/27/2014 03:51 pm »
Thanks Chris!

Offline mtakala24

Re: Wayne Hale sets up his own blog site
« Reply #424 on: 10/28/2014 12:57 am »
Well written. Closure on the STS-93 story you started.

Can't wait for next engineering stories!

Offline Jester

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Re: Wayne Hale sets up his own blog site
« Reply #425 on: 10/29/2014 08:58 am »
to add to the STS-93 story by Mr. Hale:

"The bullet shaped LOX post pin hit the side of the right engine nozzle extension about two thirds of the way to the end with great force. Just by sheer luck, three nozzle tubes were breached. Three adjacent nozzle tubes lost cooling and started leaking hydrogen into the hot stream of gas coming out of the engine. Three tubes, not five. The adjacent cooling tubes kept the nozzle from failing during the eight and a half minutes the engines operated."

Here are 2 images taken after landing showing the 3 damaged tubes.
« Last Edit: 10/29/2014 09:04 am by Jester »

Offline elmarko

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Re: Wayne Hale sets up his own blog site
« Reply #426 on: 10/29/2014 10:33 am »
Hey Wayne, really glad you got around to posting about this in more detail finally, it's much appreciated, if a little over my head at times!

Offline Wayne Hale

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Re: Wayne Hale sets up his own blog site
« Reply #427 on: 10/29/2014 03:32 pm »
Aaron Cohen who, among other things, was the JSC center director and before that Director of Engineering at JSC told a story about the early days of shuttle development when the SSMEs were having real problems:

"I thought, if someone would just develop an anti-gravity machine we could bypass all the difficulties that come with rocket engines.  Then I realized that any anti-gravity machine that we would make would likely have braze welds and EEE parts and then we would still have headaches from those sorts of things"


Offline psloss

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Re: Wayne Hale sets up his own blog site
« Reply #428 on: 10/29/2014 11:16 pm »
Thanks for these last several posts, Wayne -- they helped shorten a couple of cross-country flights this past week.

Offline Lee Jay

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Re: Wayne Hale sets up his own blog site
« Reply #429 on: 10/29/2014 11:43 pm »
"As it turns out, there was a LOX shortfall of 405 lbs. The LOX low level sensors detected depletion of the LOX, commanded main engine shutdown approximately 0.15 seconds earlier than guidance would have wanted, and the final shuttle velocity was about 15 feet per second short of what was desired; out of more than 25,500 feet per second. There was enough margin in the Orbital Maneuvering System load to make up about 300 lbs, and the flight proceeded normally."

I don't understand this point.  300fps maybe?  That seems like a lot.  Otherwise, it implies a shortfall compared to the LOX shortfall.

Offline Wayne Hale

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Re: Wayne Hale sets up his own blog site
« Reply #430 on: 10/30/2014 07:56 pm »
LOX shortfall of 405 lbs was backed out by post flight analysis.  The engines were shut down by the LOX Engine Cutoff sensors in the Orbiter MPS plumbing showing 'dry'.  The resulting underspeed (shortfall from what guidance wanted) was 15 fps.  The orbital maneuvering system uses about 20 lbs of hypergols per fps (maybe a tad more since this orbiter/payload combination was heavy), ergo my estimate that about 300 lbs of OMS propellant made up the shortfall. 

Remember the SSMEs were pushing not only the orbiter and payload but also the ET and whatever residuals (hydrogen) remained in the tank. 

Offline LaunchedIn68

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Re: Wayne Hale sets up his own blog site
« Reply #431 on: 10/31/2014 12:40 am »
So was the LOX shortfall due to more being used to compensate for the loss of H2 leaking from the nozzle tubes?

If 5 and not 3 tubes had been breached, when you refer to the nozzle failing, what would have been the outcome?  Would the vehicle have survived for an RTLS or TAL?

Thanks.
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Offline Hog

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Re: Wayne Hale sets up his own blog site
« Reply #432 on: 10/31/2014 03:02 pm »
So was the LOX shortfall due to more being used to compensate for the loss of H2 leaking from the nozzle tubes?

If 5 and not 3 tubes had been breached, when you refer to the nozzle failing, what would have been the outcome?  Would the vehicle have survived for an RTLS or TAL?

Thanks.
Basically you are correct.
Initially, both man and machine knew nothing of a hydrogen leak, only that the MCC pressures were low, this caused the SSME controller to increase Oxidizer delivery to increase MCC pressure.  The controller is "thinking" "Hmm, the engine is getting enough fuel, yet, we arent maintaining proper MCC pressure, lets increase Oxygen flow to compensate".
But in reality, the MCC was already "burning" less fuel than usual(closer to stoich), then the SSME controllers command even more Oxidizer to be introduced thus compounding the issue(by running even closer to stoich).

From Mr Hale's Understanding STS-93: the key is Mixture Ratio
we know that the closer the SSME is run to stoich the hotter the reaction becomes.  In essence, the MCC is operated fuel rich(oxidizer lean) to control MCC temps/pressures.
It wasnt until after a minute into the flight, that the Booster Officer/team realized that a nozzle leak was a possibility, the other possibility was the Oxidizer pump was losing efficiency. The SSME would continue to increase Oxidizer ratios until the turbines reached their upper temperature limit. Once the turbine temp. limit was reached, teh engine would have to be throttled down in order to prevent a shutwdown.  This throttle down occurance is called "thrust limiting". Until the SSME entered Thrust Limiting the Booster team could not tell the difference between an oxidizer turbine/pump efficiency loss and a nozzle leak. The instrumentation just wasn’t precise enough to know what was going on.
http://waynehale.wordpress.com/2014/10/08/understanding-sts-93-the-key-is-mixture-ratio/

On the Nozzle Coolant Tubes
Wayne writes:
Someone had calculated that if 5 adjacent cooling tubes split or were otherwise ruptured, there would not be enough local area cooling and a burn through would occur, causing a cascading failure of the nozzle and . . . a CRIT 1 failure.

Earlier in the same piece of writing Wayne defines a CRIT-1 failure.
a CRIT 1 failure – loss of vehicle and crew ‘promptly’.

« Last Edit: 10/31/2014 03:12 pm by Hog »
Paul

Offline Lee Jay

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Re: Wayne Hale sets up his own blog site
« Reply #433 on: 10/31/2014 03:25 pm »
LOX shortfall of 405 lbs was backed out by post flight analysis.  The engines were shut down by the LOX Engine Cutoff sensors in the Orbiter MPS plumbing showing 'dry'.  The resulting underspeed (shortfall from what guidance wanted) was 15 fps.  The orbital maneuvering system uses about 20 lbs of hypergols per fps (maybe a tad more since this orbiter/payload combination was heavy), ergo my estimate that about 300 lbs of OMS propellant made up the shortfall. 

Remember the SSMEs were pushing not only the orbiter and payload but also the ET and whatever residuals (hydrogen) remained in the tank. 

Ah...300lbs of OMS propellant.  Somehow, I missed that.  Makes sense.

Thanks for the great posts!

Offline Lee Jay

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Re: Wayne Hale sets up his own blog site
« Reply #434 on: 10/31/2014 03:29 pm »
In essence, the MCC is operated fuel rich(oxidizer lean) to control MCC temps/pressures.

Isn't that also done to increase ISP?

Quote
It wasnt until after a minute into the flight, that the Booster Officer/team realized that a nozzle leak was a possibility, ...

Was I the only one that was amazed when Booster figured that out and said so on the loop audio posted above?  I thought that was pretty amazing.

Offline Hog

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Re: Wayne Hale sets up his own blog site
« Reply #435 on: 11/01/2014 11:39 pm »
In essence, the MCC is operated fuel rich(oxidizer lean) to control MCC temps/pressures.

Isn't that also done to increase ISP?

Quote
It wasnt until after a minute into the flight, that the Booster Officer/team realized that a nozzle leak was a possibility, ...

Was I the only one that was amazed when Booster figured that out and said so on the loop audio posted above?  I thought that was pretty amazing.
ISP could be a side benefit, but in my common opine, the SSME guys would take a small ISP hit to keep the machinery and MCC in 1 piece.

No you were not the only person impressed when the Booster team came up with that call.(Although now retrospective of me typing out some of the calls on the loop, it APPEARS that MAIN ENGINES didnt relay their possible diagnoses of a nozzle leak until almost 3:30 MET. Regardless, thats damn speedy work considering the issues that began seconds after liftoff!

Video Elapsed Time/Mission Elapsed Time(VET vs MET gets a bit screwy at the end as the video displays the MET counter and it "floats" along with the VET)

VET/MET
1:05/0:00 Liftoff
2:11/1:07 MAIN ENGINES: "3 at 104"
2:34/1:29 PROPULSION: "Right SRB hyd. pressures look "Interesting".
2:50/1:45 MAIN ENGINES: "We see higher fuel and oxidizer temps. on the right engine. Doesnt look like a perfromance case at this time, but I'm verifying."
3:10/2:05  "SRB Sep."
3:20 /2:15 FLIGHT DYNAMICS OFFICER: "Performance Nominal"
4:32/3:27 MAIN ENGINES:"Possible pre-thrust limiting nozzle leak, the fuel temps. and the HPOT temps and OPOV is open, the fuel discharge pressure is low. But we're not meeting all cues. We're not meeting the HPOT turbine temps.............
4:48/3:43 BOOSTER (steps on ME): "Ya we're not, we're only half way towards the turbine temps. on the HPOT for that.
4:55/3:50  FDO:"Negative Return"
5:04/3:59 BOOSTER: "And the OPOV hasnt moved nearly enough for that."
5:07/4:02 FDO:"Flight we took a thrust update of Plus 6.
5:10/4:05 FLIGHT:"Plus Six, copy that. Booster, how;s your engines looking?"
5:12/4:07 BOOSTER: "Engines looking good flight. The right looks like the tags are off of the right, doesn"t line up with anything."
5:44/4:39 MAIN ENGINES:"And Booster, Main Engines with sensitivities."
6:13/5:08 FDO "Press to ATO"
6:21/5:16 GUIDANCE PROCEDIRES OFFICER "Single Engine OPS-3"
6:53/5:48 FDO "Single engine Bajul 104"
7:04/5:59 FDO "Press to MECO"
8:01/6:56 FDO "Single engine Press 104"
8:32/7:32 MAIN ENGINES: "3-G throttles'
8:49/7:48 FDO:"23 K"
8:50/7:49 MPS"LOX at 5"
9:00/7:59 MPF "Fuel at 5"
9:12/8:11 MPS:"Arm."
9:16/8:15 GUIDANCE:"Fine count."
9:22/8:22 MAIN ENGINES: "MECO,MECO confirmed."
9:22/8:22 MIN PROPULSION SYSTEM: "LOX low level cut."
9:38/8:37: FDO: "15 foot per second underspeed, OMS-1 not required"
9:42/8:41 BOOSTER: "Flight it looks like it was a low LOX level cut-off."
10:12/9:11 FLIGHT: "Booster, did you see the flash on the low level sensors prior to MECO?"
10:14/9:13 BOOSTER: "Ya, we saw the low level sensors all 4 of them dry right at MECO and with teh underspeed there, it looks like it was a LOX low level cutoff".
10:21/9:20 FLIGHT: "YIKES!
10:22/9:21 MAIN ENGINES: "You bet!"
10:22/9:21 BOOSTER;"Concur."
10:23/9:22 FLIGHT:"We dont need any more of these!"
xxxxxxxxxxxxxxxxxxxxx

Very "interesting" launch to say the least!


« Last Edit: 11/01/2014 11:41 pm by Hog »
Paul

Offline Chris Bergin

Re: Wayne Hale sets up his own blog site
« Reply #436 on: 11/02/2014 11:04 pm »
If I win the Lottery, I'm going to pay Mr. Hale silly money to just talk to me about Shuttle for an afternoon. It would money well spent! ;D

Wow:
http://waynehale.wordpress.com/2014/11/02/significant-conversations/
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Offline robertross

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Re: Wayne Hale sets up his own blog site
« Reply #437 on: 11/02/2014 11:56 pm »
If I win the Lottery, I'm going to pay Mr. Hale silly money to just talk to me about Shuttle for an afternoon. It would money well spent! ;D

Wow:
http://waynehale.wordpress.com/2014/11/02/significant-conversations/

Indeed, WOW.
I don't think there's another person more qualified to make such statements.

Thanks Mr. Hale, I think we all needed that.
« Last Edit: 11/02/2014 11:58 pm by robertross »

Offline Wayne Hale

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Re: Wayne Hale sets up his own blog site
« Reply #438 on: 11/03/2014 11:32 pm »
Its a tough business and I have been really irritated at the blather from some elements of the news media  I should know better, but the speculation presented as fact and the shear ignorance are overwhelming.  Makes me wonder about the rest of the news I hear.

Keep up the good work guys.

Offline sdsds

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Re: Wayne Hale sets up his own blog site
« Reply #439 on: 11/04/2014 12:44 am »
From twitter:
Quote
@waynehale
Off to Virginia for a solid week of engineering work!

From http://www.orbital.com/NewsInfo/MissionUpdates/Orb-3/
Quote
The composition of the AIB is as follows: [...]
Members
[...]
Wayne Hale, Independent Consultant and Former NASA Space Shuttle Program Manager
— 𝐬𝐝𝐒𝐝𝐬 —

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