From NASA engineering film: Sequential pix of debris hitting Columbia's wing

NASA via CNN Online & Yahoo News ^ | 2/3/03 | Wolfstar

[Mad_Tom_Rackham]

your dad? your dad? i'm disappointed... no, i'm downright deflated.

Sure hope you are all talking about Dolly Parton, and not the "other" Dolly. :O)

[Cold Heat]

I just cannot see this foam at velocity, penetrating the tiles to any degree, especially with regard to the angle of attack. It is a paper cuts steel kind of argument.

On the other hand, all this data I have read leads me to believe that they really had not nailed this problem down and were guessing at the cause.

I have taken many courses in an art called systematic troubleshooting, and I do not believe that enough data is there to determine a insulation strike cause and effect.

Wind tunnel data might prove this theory and other tests can be performed to verify it, but I think it is something else entirely. I think it may be just as likely that they hit some space debris, and have been hitting the stuff all along. Micrometeorites, bolts, nuts and metal objects that are way too small to track reliably.

[sd-joe]

"Anything hitting a brittle ceramic material at speed is bad news."

True, but did you see the report on the inspection after flight STS-87, posted by Jael. Note the small part quoted below.
They also stated that when that occured, there was a relative wind of Mach 2 to Mach 4 (Wow).

THE MAIN THING TO REMEMBER IS THAT WITH THIS MUCH DAMAGE TO THE TILES, THE FLIGHT STILL RETURNED SUCCESSFULLY.

"Three hundred and eight hits were counted during the inspection, one-hundred and thirty two (132) were greater than one inch. Some of the hits measured fifteen (15) inches long with depths measuring up to one and one-half (1 1/2) inches. Considering that the depth of the tile is two (2) inches, a 75% penetration depth had been reached."

[southland]

Regarding to speed at impact: A wet noodle would break a windshield very badly if speed were very high in the subject vehicle.

[Howlin]

Don't start making things up.

Now I remember where I have seen you before.

[glock rocks]

you're baaaaaaad.

[Luis Gonzalez]

"And why are there 398 thousand rocket scientists suddenly degreed and astute to everything NASA?"

BINGO!!!!

[Cold Heat]

Sorry, but you do not understand engineer speak. They are running a hypothesis to see if it will work. They did not confirm a damn thing.

[Jael]

"The tiles do a fantastic job of repelling heat, however they are very fragile and susceptible to impact damage."

"During the STS-87 mission, there was a change made on the external tank. Because of NASA's goal to use environmentally friendly products, a new method of "foaming" the external tank had been used for this mission and the STS-86 mission. It is suspected that large amounts of foam separated from the external tank and impacted the orbiter. This caused significant damage to the protective tiles of the orbiter. Foam cause damage to a ceramic tile?! That seems unlikely, however when that foam is combined with a flight velocity between speeds of MACH two to MACH four, it becomes a projectile with incredible damage potential."

The attention was now focused on the crew cabin cameras. These cameras gave more of a side view of the external tank as it tumbled back to Earth. These photographs revealed massive material loss on a side of the external tank that could not be viewed by the umbilical cameras!

"Where are we now? One of the questions had now been answered. The ascent phase of flight was when the damage occurred. With the information provided by the photography and the mapped flow of damage, a logical reason could be established as to "what" happened. It was determined that during the ascent, the foam separation from the external tank was carried by the aerodynamic flow and pelted the nose of the orbiter and cascaded aft from that point. Once again, this foam was carried in a relative air-stream between MACH two and MACH 4!"


http://216.239.33.100/search?q=cache:ryqlvTHKXEgC:ltp.arc.nasa.gov/space/team/journals/katnik/sts87-12-23.html+greg+katnik+tile+damage&hl=en&ie=UTF-8

[Jael]

My advice to you stands. Heed it. And stop lying about Mr. Confetti.

[Jael]

These are Mr. Confetti's post to me. I don't have a problem with him and I hope you are not trying to make one where none exist.


To: Jael

They are watching it when it happens. They know when it happens.

Duh. No sh*t, Sherlock. We're not idiots. Uuuuuuuuuuggggggggghhhhh!!!!!!!! I need my medication.

Here's a link to your article: http://spaceflightnow.com/shuttle/sts107/030203analysis/


102 posted on 02/03/2003 2:07 PM CST by MrConfettiMan (One Year+ Low Grade Brain Tumor Survivor - http://www.mcmprod.com/jj)
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NASA Could have aborted the flight before it reached orbit! ^

Posted by MrConfettiMan to Jael
On News/Activism ^ 02/03/2003 2:50 PM CST #118 of 134 ^

Sorry for the derogatory reply. It's been an aggravating day.

[Cold Heat]

I read every bit of that, and I do not concur that this is what brought the shuttle down.

The main reason for this assumption is that this tank and this insulation has been flown time and time again since STS-87. No unusual tile damage was reported from this effect. I cannot draw a conclusion on this data alone. I would like to see wind tunnel tests which we are quite capable of doing and I am sure it is in the works. That is why they wanted to try the insulation hypothesis and test it for voracity.

[Howlin]

Do you happen to be under the impression that DUH means he's agreeing with your previous post?

[Clean_Sweep]

"I don't think NASA's beyond reproach. I just think that guilt must be proven,"

The one thing we can be certain about is the fact that someone made the wrong decision, or didn't identify and assess a problem correctly. I don't think anyone wants to face the reality of making this horrible error. However an error was made without question.

With all the back and forth on this I have yet to see a post with a reasonable explanation for failure that is unrelated to the loose foam. If it wasn't the foam, then it was a defective problem that should have been identified prior to launch.

[Jael]

Thought this might interest you.

NEWS RELEASE
United States Air Force
Air Force Materiel Command

Office of Public Affairs
Arnold Engineering Development Center
100 Kindel Drive
Arnold AFB, TN 37389-2213
(931) 454-5586
http://www.arnold.af.mil

Writer:  Danette Duncan
Date: March 19, 1999
Release # 99-041
Photo # none

AEDC Performs Shuttle Materials Test for NASA/Lockheed Martin

ARNOLD AFB, Tenn.—Arnold Engineering Development Center is assisting the National Aeronautics Space Administration with improvements in existing Space Shuttle materials.

According to NASA, during several previous Space Shuttle flights, including the shuttle launched Nov. 29, 1998, the shuttle external tank experienced a significant loss of foam from the intertank. The material lost caused damage to the thermal protection high-temperature tiles on the lower surface of the shuttle orbiter. The loss of external tank foam material and subsequent damage to reentry tiles is a concern because it causes tile replacement costs to significantly increase, however, it is not a flight safety issue. As a result, NASA-Marshall Space Flight Center selected AEDC to perform flight hardware materials tests on the shuttle’s external tank panels in the center’s von Karman Facility Supersonic Tunnel A. The purpose was to establish the cause of failure for the tank thermal protection materials at specified simulated flight conditions. "NASA chose AEDC due to its technical expertise and historical program successes," Steve Holmes, a NASA-MSFC technical coordinator, said.

The Lockheed Martin-manufactured non-reusable external tank, the largest element of the Space Shuttle, fuels the shuttle orbiter during powered flight and is comprised of three components—a liquid oxygen tank, a liquid hydrogen tank and an intertank assembly that connects the two propellant tanks. At the full capacity of 528,600 gallons of propellant, the external tank weighs 1.6 million pounds. The tank is covered with a multi-layered, spray-on foam insulation that provides thermal insulation for the tank against the extreme internal and external temperatures generated during prelaunch, launch and flight.

Wayne Hawkins, Sverdrup project engineer, explained the foam system is exposed to multiple forces, causing difficulty in determining the actual failure of the thermal protection system. "Multiple forces act on the foam system," Hawkins said. "The environmental factors include thermal protection system cell expansion, aerodynamic loading, highly variable local flow conditions, oscillating shocks, vibration, temperature and main external tank substrate flexure."

Although NASA and other facilities have performed a number of tests in an attempt to define the underlying root cause of this foam loss, they were not successful. At one time, the center’s 4-foot and 16-foot transonic aerodynamic wind tunnels were possibilities for the test, but Tunnel A’s ability to closely duplicate flight conditions and control both ambient pressure and test sample immersion time made it the facility of choice. Tunnel A is a continuous flow-variable density wind tunnel with an automatically driven flexible-plate nozzle and a 40- by 40-inch test section and can cover the Mach number range of 1.5 to 5.5.

"The ideal success for the test is the generation of foam loss on a consistent basis with simulated flight conditions," Hawkins said.

Although the AEDC Tunnel A tests did not replicate the in-flight failures, they did provide detailed measurements to better understand the flight environment and fundamental failure mode. From these tests, NASA determined the failure is caused principally by foam cell expansion due to external heating at approximately Mach 4 combined with pressure change and aerodynamic shear. Specialized miniature shear gages and other instrumentation were installed during the test to measure these forces. The customer and sponsor were pleased with the AEDC test results. "No other facility can test with articles/models as large as AEDC with conditions that can match flight," Holmes said.

[spunkets]

The extremely low thermal conductivity of those tiles is due entirely to the low density silica coating over the Nomex. In leading edge areas, the tiles have higher melting insulaters, but they too have a very high void density. All of that stuff has a very thin outer skin, but the essential part of the tiles has little compressive stength. Remember it's mostly empty space by design, so the heat causing the very high temps isn't conducted to the underlying aluminum.

They actually have(and did have) enough data now to analyze what happened during that strike as I outlined in #295. They also have enough data to know what would happen if the silica is removed from the Nomex. The Nomex burns right off followed by whatever is underneath. Once there's a hole, it grows until the process driving it's growth ceases, or the hole results in a catastrophic failure. A catestrophic failure happened here and the only big driving force for it was the frictional and momentum forces occuring during the deceleration of reentry.

[Jael]

There was nothing to agree with in the post, except for the fact that NASA monitored the lift off as it happened. And yes, he was not arguing that.

Do you have a problem with that? You have said he corrected me twice about something. I have proven to you that he did not. Now, I will stop short of calling you a lair, but your trolling people is out of order.

I am posting on this thread because it is something that deeply interest me. If you have some kind of desire to disrupt threads about a very serious issue, find someone else to do it with.

[Jael]

You don't have to concur that this is what brought the shuttle down. None of us can know for sure right now anyway. But Greg Katnik said several things that directly disprove what your post said. I just thought you would be interested in hearing what the guy has to say that's in charge of that aspect of the shuttle.

[Cold Heat]

Could have tried to reprogram the re-entry sequences so the impacted area took less heat.

According to NASA, they do that anyway on every flight.

[Fred Mertz]

Try ignoring howlin. I know it's not easy, but you can do it if you try.