Engineer's '97 Report Warned of Damage to Tiles by Foam

[oracle]

Engineer's '97 Report Warned of Damage to Tiles by Foam (http://story.news.yahoo.com/news?tmpl=story2&cid=68&ncid=68&e=2&u=/nyt/20030204/ts_nyt/engineer_s__97_report_warned_of_damage_to_tiles_by _foam)
<font size=1>Tue Feb 4, 9:03 AM ET</font>

By JAMES GLANZ and EDWARD WONG The New York Times

As early as 1997, a senior NASA engineer warned that hardened foam popping off the external fuel tank on the Columbia shuttle had caused significant damage to the ceramic tiles protecting the vehicle from re-entry temperatures.

The warning was sure to receive new scrutiny after NASA said yesterday that its investigation into the cause of the destruction of the space shuttle on Saturday was focusing on damage to tiles that may have been caused by foam or ice or a combination of the two. NASA officials also acknowledged that they might have underestimated the potential seriousness of damage sustained by the tiles when the shuttle lifted off.

Gregory N. Katnik, a NASA engineer at Cape Canaveral, said in a report dated Dec. 23, 1997, that the Columbia had sustained damage to more than 300 tiles on a recent flight. The inspection after a Columbia mission in 1997 showed that the tiles had sustained damage that was "not normal," Mr. Katnik said.

In a number of other shuttle flights, tile damage from falling foam also caused smaller amounts of damage, but NASA decided that over all, the problem did not threaten the survival of its spacecraft.

Now the agency is re-examining that assumption as it struggles to explain the mystery of how the Columbia broke up as it soared back into the atmosphere.

Ron D. Dittemore, the shuttle program manager, told a news conference yesterday that damage to the tiles was the leading focus of the investigation, but he cautioned that what appeared to be the most likely solution might prove illusory as the complex inquiry moved ahead.

"There's some other event; there's some other missing link that we don't have yet that is contributing to this temperature increase," Mr. Dittemore said. "It's a mystery to us."

But new evidence that surfaced yesterday suggested that damage to the tiles may have been more severe and covered a wider area than first estimated.

A videotape made by a team of NASA scientists at the Jan. 16 liftoff appeared to show a bushel-basket-sized chunk of debris breaking away from the external fuel tank and striking the fragile protective tiles on the underside of the left wing. A NASA analysis suggested the impact could have damaged a swath of tile as large as 7 inches wide and 32 inches long, according to an agency memorandum made public yesterday.

...


Click here to read more (http://story.news.yahoo.com/news?tmpl=story2&amp;cid=68&amp;ncid=68&amp;e=2&amp;u=/nyt/20030204/ts_nyt/engineer_s__97_report_warned_of_damage_to_tiles_by _foam)

[oracle]

Foam Has Plagued NASA For 5 Years (http://www.bayarea.com/mld/mercurynews/news/5100794.htm)
<font size=1>By Curtis Morgan, Manny Garcia and Ronnie Greene
Knight Ridder</font>

MIAMI - NASA engineers have known for at least five years that insulating foam could peel off the space shuttle's external fuel tanks and damage the vital heat-protecting tiles that the space agency says were the likely "root cause" of Saturday's shuttle disaster.

The Jan. 16 launch wasn't the first time that Columbia's fragile tiles were pummeled by chunks of foam. It happened on the spacecraft's first launch, and again, more severely, in 1997.

NASA and other researchers have been studying the problem of foam ``shedding'' from the shuttle's giant external fuel tanks for years, but the space agency's managers never considered the problem a serious threat to flight safety before Saturday's catastrophe.

The shuttle's towering tanks are covered with sprayed-on insulation that's designed to keep their super-cooled nitrogen and oxygen fuels at the necessary temperature.

Engineers typically find some damage to the orbiter's 24,000 ceramic tiles after missions, averaging about 40 "hits." The tiles lining the craft's belly can withstand searing 2,300-degree heat during re-entry, but they are relatively fragile and easily damaged by flying debris or by ice chunks that form on the fuel tanks.

...


Click here to read more (http://www.bayarea.com/mld/mercurynews/news/5100794.htm)

[DesertFox]

They might wanna look at any Muslims sweeping the floors.

Oh, that's right, that would be profiling.

[SunnyBrook]

Hey, hey, hey...Take a look at this!

[ QUOTE ]
He said on the 1997 mission the shuttle sustained a significant amount of damage to its heat tiles. In a normal mission, a shuttle will sustain damage to up to 40 tiles because of ice dropping from the external tank and hitting the tiles, Mr. Katnik reported. But on that mission, he said, "the pattern of hits did not follow aerodynamic expectations, and the number, size and severity of the hits were abnormal."

Inspectors counted 308 hits. Of those, 132 were "greater than one inch," Mr. Katnik said. Some of the hits measured up to 15 inches long with depths of up to one-and-a-half inches. The tiles were only two inches deep, so the largest hits penetrated three-quarters of the way into the tiles, he noted.

The damaged tiles were mostly around the shuttle's nose. After the mission, more than 100 tiles were taken off because "they were irreparable," Mr. Katnik said.

The report went on to speculate as to why the foam dropped off. As it turned out, to be environmentally friendly, NASA had eliminated the use of Freon in foam production, Mr. Katnik reported. The Marshall Space Flight Center in Huntsville, Ala., later concluded that the absence of Freon led to the detachment of the foam.



[/ QUOTE ]

Hmmm... /ubbthreads/images/graemlins/icon127.gif

[DesertFox]

Time to jail the Greens who instigated the anti-freon movement, on charges of murder!

[2nd_Amendment]

Yep, one geek with a hammer and one innattentive inspector. That's all it would take. I swear, initially I dismissed terrorism as a possibility but now, the more I think on it, it would be so damn easy. Bust something up a little and let gravity, motion and heat do the rest.

Effective, too. What's worse to an ego than being attacked by cowards? Appearing to have failed all on your own...

[DesertFox]

All they'd had to have done would be to chisel out a few tiles and reglue 'em with Elmer's.

[Keith J]

Its not used as glue...the Freon (trademark, capitalized) was used to "foam" the unpolymerized urethane. The urethane foam would then cure to a hard, closed cell foam. Since the ether-based urethane is very resistant to moisture, it formed an in-situ vapor barrier. Remember that word, vapor barrier.

Enter the greens and the "ban CFC's at any cost" crowd. Freon is verboten and the urethane system is changed to an ester based monomer using in situ generated carbon dioxide as the foaming agent. The result was a foam with some open cells and less moisture tolerance thanks to the ester base. Furthermore, this system was heavier than the Freon-foamed insulation and guess what was deleted to save weight. Yes, the paint. There is the explaination of the orange fuel tanks. But the real problem was this new insulation has poor vapor barrier properties and as such, ice formed when the cryogenic LOX and liquified H2 were loaded. This ice reduced the flexibility of the insulation, increasing the likelyhood of fracture and poor adhesion of the insulation to the tank.

BTW, the glue used to hold the TPS tile in place is a silicone rubber room-temperature vulcanizing (RTV) like the kind Dow Corning sells.

[Warlady]

I hope NASA and the Congressional investigators point this out because the econazis are to blame.

[SunnyBrook]

Funny how in their rush to fill the hours with shuttle coverage and speculation, the networks have yet to address this little theory!

[Lopeover]

Tuesday, Feb. 4, 2003
Clinton Environmental Policy Sabotaged the Shuttle

Thank fussy "environmentalists" from the Clinton administration for the substandard but politically correct foam that NASA thinks caused the Columbia disaster.

"NASA engineers have known for at least five years that insulating foam could peel off the space shuttle's external fuel tanks and damage the vital heat-protecting tiles that the space agency says were the likely 'root cause' of Saturday's shuttle disaster," the left-of-center Philadelphia Inquirer noted today in an article by Knight Ridder News Service.


http://www.newsmax.com/showinsidecover.shtml?a=2003/2/4/174925

[Keith J]

The NewsMax article has some errors...first of all, it was the Montreal Protocol which banned the use of the CFC's, not the Clinton admin.

The aluminum skin loses most of its strength at 350 F but it doesn't burn per se until it melts, something that happens at ~1100 F.

I do not doubt the switch in material was at fault for the shedding problem.

[DesertFox]

I KNEW they shoulda used gorilla glue.

[Keith J]

[ QUOTE ]
DesertFox said:
I KNEW they shoulda used gorilla glue.

[/ QUOTE ]

Ummm, that is a single-component polyurethane of I think a ester base...just like the tank insulation! The tiles don't fall off until they are broken.

Gorilla Glue foams as the isocynate reaction with the hydroxyls releases carbon dioxide.

[DesertFox]

I knew that. *snicker*

[SunnyBrook]

Keith, where've you been?

BTW, are you an engineer?

Inquiring minds and all...

[DesertFox]

Yes, SunnyBrook, he is, and one of the smartest and best-educated people on the planet. I'm not kidding and not being sarcastic.

LP's better-lookin', though.

[DesertFox]

And I'm older and oracle's suaver.

[Keith J]

I be a engineer...I'm spotty on the board...my current job has me running some finite element analysis on a slow system so I get the problem set up and wait...two hours...for results.

I did some dabbling in polyurethanes at the last job. Neat stuff.

No DF, there arequite a few sharper than me...but they are trying to fool people. I just want things right.

[DesertFox]

Honesty is the sine qua non in science, Keither. You know and I know it. An honest man with your talents seems to be a rare commodity these days. I claim you for us.

[Keith J]

My views are AUTOMATICALLY SUSPECT! Nevermind the opposing side is funded by Earthfirst feminazis on dope for abortion against energy hate the US...

[DesertFox]

You gotta point. They are disinterested ditzes, and everybody knows you can always trust a disinterested ditz.

[SunnyBrook]

So Keith, what's your take on probable cause here? Did you see the article I linked on the other thread about the astronauts taking pictures of the wing? There was some tech jargon in there about the things going wrong between 8:52 a.m. and @ 9:00 when the shuttle destructed.

[Keith J]

The felt pad to which the tiles are bonded prevents damage from spreading. None of the 7 would have seen the damage unless they were in front of a huge mirror, had a satellite photograph the underside or somehow taken a good look through other remote means.
[just a theory]
The intital temperature spike readings sound about right for a wheel well leak. If this was the case, the hydraulic actuators of the well flap and gear might have had a partial uncommanded extend as the fluid temperatures rose and expanded. This would represent the degraded trim response. As the flap opened more, temperatures rose to the point of rupturing the tire. At this time, the craft is now uncontrollable and soon disintegrates.
[/just a theory]

Supporting facts:

The hydraulic door flap and gear mechanisms are one-way hydraulic pistons. This is logical since there is never a commanded retraction, just extension of the gear. The gear are retracted in the reassembly/turn around.

The hydraulic fluid used has a considerably higher expansion coefficient than mineral oils/PAO's etc. Its a special fire-retardant fluid.

The gear door was in the immediate area of the foam damage.

Evidence of the left tire air pressure rising, then nulling and temperature rise is noted. Rate of temperature rise is consistent with a slow leak.

Supposition:

Uncompensated hydraulic system in the retracted position. This could have been the case of exceeding the temperature limits and the compensator stroked to its limit. Once at the limit, the system pressure would then rise.

[SunnyBrook]

Keith:

Thanks for taking the time to explain. I think I copy that.
/ubbthreads/images/graemlins/biggrin.gif