Light objects travelling at high velocity


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4v50 Gary
July 8, 2003, 04:33 PM
Well, the verdict is in regarding the Columbia. A piece of foam that came off the shuttle struck the leading edge of the wing at high spead, creating a 16" x 16" gap in the tile insulation. That was to prove fatal upon reentry.

Now, didn't wildcatter P. O. Ackley prove the feasibility of fast light bullets many years ago? Turning to the 9mm v. 45, clearly the 9 mm isn't going fast enough.

Hmmm, does this post have a point?:confused:

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benEzra
July 8, 2003, 10:21 PM
Although I am firmly in the "light and fast" camp, I have to point out that the foam that hit Columbia's wing was only going about 530 mph, which is pretty close to the speed of a .45 ACP out of a 4" barrel, IRRC.

Still, goes to show that even something light and soft going 530 mph is dangerous, particularly to a brittle substance like RCC.

George Hill
July 9, 2003, 01:50 AM
I was going to joke about the grains of the foam...
But considering the loss of the ship and crew?
:(
At least we know now.

Damn.

Steel
July 9, 2003, 10:43 AM
Someone please educate me on what this "foam" is. I suspect it is not foam, to which most of us are accustomed.

Nathaniel Firethorn
July 9, 2003, 11:11 AM
It's polyurethane. Similar to the "Great Stuff" you can buy at Home Depot.

It covers the External Tank and is used to keep the liquid hydrogen and liquid oxygen cold.

Some years ago, NASA actually had problems with red-bellied woodpeckers, who thought that the external tank was a great place to build a nest. (They were right, but NASA didn't appreciate their tenancy.)

http://www.orlandosentinel.com/news/custom/space/orl-asec-tankgraphic020303,0,7321813.graphic

- pdmoderator

TallPine
July 9, 2003, 11:13 AM
Do you have a link to an article announcing this?

Nathaniel Firethorn
July 9, 2003, 11:15 AM
Shuttle "smoking gun" found (http://www.cnn.com/2003/TECH/space/07/07/sprj.colu.shuttle.investigation/index.html)

- pdmoderator

Mike Irwin
July 9, 2003, 01:40 PM
A piece of straw, at the proper velocity, can penetrate concrete block or a steel shell door.

JPM63US
July 9, 2003, 01:45 PM
The foam used on the space shuttle is not exatly "soft and squishy" and the tiles are not extremely strong either.

That said, I remember seing pictures of straw embedded into wooden structures after a tornado.

Keith
July 9, 2003, 02:45 PM
The foam in question was frozen solid and sheathed in ice from the liquid nitrogen or CO2, or super whacked-out fuel (or whatever the hell it is) being pumped through all of those hoses.

You can see that ice falling away on any launch. In this case, the foam itself broke away and carried a larger amount of weight than would normally be the case.

The damage was due to kinetic energy rather than mere velocity...

Keith

Mal H
July 9, 2003, 02:59 PM
One thing that puzzles me about the experiment is how accurately their estimate is of the velocity of the foam piece when it struck the wing. When it broke off, it was going at the same vel as the shuttle/ET system. The only force to cause deceleration would be air resistance. At the altitude it had already achieved, air resistance is somewhat lower. So achieving a -550 MPH vel in the distance from where it broke off the ET to the wing is quite spectacular. Would we have even been able to see the foam piece if it was going that fast relative to the shuttle when it hit? Recalling the experiment where the foam was shot from the cannon, anyone see the foam piece before it hit the wing or after it hit? Nope, you're looking at the wing and suddenly a hole appears.

I think the NASA folks know what they're doing, in fact I know they do, so I'm not all that worried about the problem. But, it is something to think about.


Keith - Are you thinking about other launches other than shuttle launches when you mention the ice buildup? I didn't think the ET gathered much ice from the stored LOX as does, say, the Saturn. The foam is supposed to prevent that.

Keith
July 9, 2003, 03:08 PM
Mal,

Watch a tape of ANY launch and as the engines roar to life, a veritable avalanche of ice falls away.

MrAcheson
July 9, 2003, 03:10 PM
Keith,

Air resistance and gravity. Gravity is a big part of it since it fell a significant distance. Still a deltav of 530mph seems really high to me.

bountyhunter
July 9, 2003, 03:18 PM
At least we know now.

Yeah, but what pissed me off was that they knew exactly what happened about 30 seconds after it burned up. They showed the video from flight control at the time of the "incident" and the temp sensors were lighting up in the wheel well and wing as the thing was burning up. The sensors were telling the story before the crew even knew there was a problem. Amatuer video shooters saw the breakup and it was relayed to flight control almost immediately, and they went into damage control mode.

They should have been straight with the public from the outset. The only reason it has been made public now is because there was video in the public domain showing the foam breakoff and the shuttle burning up into pieces. I think they behaved like a bunch of lawyers, and that's about the worst insult I can think of.

bountyhunter
July 9, 2003, 03:25 PM
One thing that puzzles me about the experiment is how accurately their estimate is of the velocity of the foam piece when it struck the wing. When it broke off, it was going at the same vel as the shuttle/ET system. The only force to cause deceleration would be air resistance. At the altitude it had already achieved, air resistance is somewhat lower. So achieving a -550 MPH vel in the distance from where it broke off the ET to the wing is quite spectacular. Would we have even been able to see the foam piece if it was going that fast relative to the shuttle when it hit? Recalling the experiment where the foam was shot from the cannon, anyone see the foam piece before it hit the wing or after it hit? Nope, you're looking at the wing and suddenly a hole appears.

You are correct. They are being deceptive about the velocity of the foam relative to the wing to try and not admit just how fragile the leading edge of the wing is. If they admit that, they are admitting how prone the spacecraft is to another incident of this type and that would require them to spend money and fix it.

Back when the first major shuttle disaster occurred, NASA had actually published data on the probability of a major accident at something like one in ten million. That was disputed by engineers who are familiar with MTBF (mean time before failure) analyses of such systems. The numbers offered by such folks were more like one in one hundred. In retrospect, even that value seems to be optimistic.

Mal H
July 9, 2003, 03:55 PM
Keith,
Seriously, I don't think the ice buildup and subsequent avalanche happens with shuttle launches like it does with Saturns and Titans. I have watched many launch tapes and just watched a few more just to help jog my memory. There was no evidence of an ice cascade at launch or after.

Think about this aspect of it, if a great deal of ice built up and remained on the ET, I can assure you the engineers would have devised a way for it to be removed prior to or just at launch. Wasting the fuel required to launch any extra weight is something they would definitely strive to prevent. With Saturns and Titans and Soyuz (oh my!), the ice comes off in sheets seconds after main ignition from the initial engine vibrations.

Nathaniel Firethorn
July 9, 2003, 04:03 PM
The ice cascade at T=0 does happen. But the ice has relative velocity of zero to the vehicle. Apparently the foam got decelerated by drag to 500-umpty mph relative. Big difference.

Some enterprising person could check the velocity of the foam themselves from the videos. It's impossible to be deceptive about it.

- pdmoderator

RVSinOK
July 9, 2003, 05:00 PM
Just out of curiosity, do we know how fast the shuttle was going at the time the insulation came off? I don't remember how far into the flight it was when it happened, but I do know that the shuttles accelerate pretty dang quickly! If the shuttle was moving at 1500 mph or something, a delta of 500 might be a little more believable. I know I wouldn't want to stick my arm out the window at those kind of speeds!

Just a thought......

Bainx
July 9, 2003, 05:24 PM
bountyhunter......what really pisses me off is the fact that NASA saw the foam do its damage real-time as it happened and did not abort.

280PLUS
July 9, 2003, 05:34 PM
once they light the fuse on that thing, theres no turning back, you can't just shut it off...

ive always thought nasa should spend the time and money to develop a capsule that totally protects the crew in all failures, regardless of how catastrophic, and can return them to earth if need be

and then design a spacecraft around it.

now lets get this straight,,,

we take our best and brightest

put them on a great big bomb

light it, and once we do if one, just one tiny flaw turns up somewhere

theres no way to save them?

hello, what brilliant aerospace engineers dreamed this up?

:rolleyes:

MrAcheson
July 9, 2003, 05:38 PM
HAHAHA Abort? Once the shuttle is off the pad on liftoff? Because a wing was hit with some ice, which always happens on liftoff? Please. I understand NASA's decision. Abort of a shuttle launch at that point is probably as, if not more, dangerous than re-entry with unknown damage to the heat shielding.

TallPine
July 9, 2003, 05:42 PM
once they light the fuse on that thing, theres no turning back, you can't just shut it off...

No, they can do an RTLS (Return To Launch Site). I don't remember the time window for this, or how they separate from the boosters.

Also, there is a sub orbital abort which lands them in Dakar, West Africa. This is why they have to launch by a certain time (around noon) Eastern time so that it is still daylight in Africa at the time of a possible abort/landing.

Brat7748
July 9, 2003, 06:19 PM
NASA being PC caused the disaster, they didn't want to use the evil CFC's so they switched to something more enviro-friedly

http://www.foxnews.com/story/0,2933,77832,00.html

See this story...its other places on the web also

benewton
July 9, 2003, 06:25 PM
Brat:
I've seen that info before, and I believe it.

As noted by others before, PC can kill you.

Believe it!

benEzra
July 10, 2003, 12:03 AM
RTLS is so dangerous that some astronauts question how likely the vehicle is to actually survive it, so it's a REALLY last-ditch effort. And all the other abort modes (TAL, AOA, or ATO) all involve a high-speed reentry, so that doesn't help you much.

Also, the foam strike wasn't actually caught until the launch tapes were reviewed, I think the next day.

As far as rigidity and ice buildup, that's always a possibility, but they were able to get a really accurate estimate of the size, mass, and density from the ascent video. (Telemetry tells you how fast the vehicle was going--probably in excess of Mach 3 at that point--atmospheric tables tell you how dense the air is at that altitude, and Isaac Newton gives you the numbers.)

And if they were really trying to "cover up" how fragile the RCC leading edge panels are, blowing a hole in them on national TV isn't the way to do it. Face it, engineers make honest mistakes. In hindsight, the foam shedding SHOULD have been taken seriously, but let's not make it into a coverup.

BTW, lots of good links on www.nasawatch.com, for those interested in an inside view of the agency.

280PLUS
July 10, 2003, 09:06 AM
"No, they can do an RTLS (Return To Launch Site). I don't remember the time window for this, or how they separate from the boosters."

hmph, never heard of this before

has it ever been proven to work?

i still say they need a survivable capsule

id put crew safety first

i don't believe that was done

they rely too much on everything working as expected

now 2 relatively simple problems have cost us 2 crews

what about the more complicated technologies involved?

well gee 2 out of 200, thats only a 1% failure rate

ok, i can accept that, nothing/noone is perfect

what % of our best and brightest have we wasted now?

they don't give you that number, do they?

wait, i'm going to get my tinfoil hat...

i hear helicopters... :what:

:D

benEzra
July 10, 2003, 08:00 PM
RTLS (Return To Launch Site) involves separating from the SRB's at the normal time, then at a subsequent point turning the orbiter-ET stack around while still under thrust, and flying backward (into its own exhaust plume) as it uses the thrust to decelerate to a practical standstill. When the fuel in the ET is nearly exhausted, the shuttle cuts the engines, the stack goes into freefall, and the shuttle quickly separates from the ET and falls back into the atmosphere, hopefully gliding to a landing back at the Kennedy Space Center runway.

The tricky part is turning the shuttle around under thrust, flying backward (even though the air is extremely rarified, there may be some effect there), and separating from the ET under pressure and time constraints that usually aren't there.

The time window is also extremely short--they'd almost have had to have made the decision to abort within a minute or two of the foam strike, I'd suppose.

Mikul
July 11, 2003, 03:19 PM
The California legislature should be pressing for a ban on foam based on its proven ability to knock the Space Shuttle out of the sky. Hey, it's actually BETTER logic than what they used to ban .50 caliber rifles.

280PLUS
July 11, 2003, 05:03 PM
besides, the extra weight would cost too much more in fuel consumption...

:rolleyes:

4v50 Gary
July 11, 2003, 06:21 PM
More glory dying in the biggest firecracker on earth (or in orbit) than from being runned over by a homeless person pushing a shopping cart.

Waitone
July 11, 2003, 08:54 PM
I hope NASA doesn't say, "Well, it was the foam. Shame. We'll do better next time." and don't go any further. NASA opted to change to an enviro friendly adhesive formulation which was known at the time of conversaion to not be as effective as what was being replace.

If my life was on the line in a shuttle, I would care nothing of "enviro friendly" adhesive formulations. I would want something that would work every time.

Is it me or are we now discussing the number of people who die because of environmental restrictions. The space shuttle leaps to mind right behind the fire fighters who were burned to death because a helicopter pilot didn't want to risk sucking up some kind of bottom feeding endangered fish.

Waitone
July 12, 2003, 11:33 AM
http://www.newsmax.com/archives/articles/2003/7/11/121741.shtml

Cause of Two Shuttle Disasters: Enviro Dogma
Hannes Hacker
Friday, July 11, 2003


Now that a dramatic new test has confirmed that a piece of thermal insulation flaking off of space shuttle Columbia's external tank during launch was the most likely cause of its destruction during re-entry, the typical second-guessing in the press has focused on NASA engineers, asking: "What did Mission Control know, and when did they know it?"

Somehow, NASA engineers should have guessed about the damage done to Columbia's thermal tiles and pulled an Apollo 13-style rabbit out of their hat. The implication is that they should have been omniscient and omnipotent.

Having heroes like NASA's mission controllers around to quietly brave the world's criticism certainly serves to divert attention from those who have done the most to contribute to this disaster, and who regard themselves as omniscient and omnipotent enough to command the entire American economy and the lives of its citizens: the environmentalists.

Why did the shuttle's foam insulation flake off? In response to an edict from the EPA, NASA was required to change the design of the thermal insulating foam on the shuttle's external tank. They stopped using Freon, or CFC-11, to comply with the 1987 Montreal Protocol, an agreement designed to head off doubtful prognostications of an environmental disaster.

But it was the elimination of the old foam that led to a real disaster for the shuttle program.

The maiden flight with the new foam, in 1997, resulted in a 10-fold increase to foam-induced tile damage. The new foam was far more dangerous than the old foam.

But NASA, a government organization afraid of antagonizing powerful political interests, did not reject the EPA's demands and thoroughly reverse the fatal decision. Instead, they sought a compromise by applying for a waiver from the EPA that allowed them to use the old foam on some parts of the external tank.

NASA notes that it is impossible to ascertain with certainty whether it was the old or the new foam that caused the recent disaster, and environmentalists will no doubt say this means that we can't pin the disaster on them. But any unnecessary increase in risk in an enterprise so unforgiving of error, is unacceptable.

P.C. Junk 'Science' Trumps Engineering

The bottom line is that NASA took a much greater risk to comply with EPA demands. Environmentalist junk science trumped sound engineering.

This is not the first time that has happened. The cause of the 1986 Challenger explosion is officially established as hot gases burning through an O-ring joint in one of the solid-rocket boosters. NASA was roundly criticized for its decision to launch in cold weather over the objection of some engineers, but there was a deeper cause that was not as widely reported.

In 1985 NASA had switched to a new putty to seal the O-ring joints. The new putty became brittle at cold temperatures, thus allowing Dr. Richard Feynman to teach NASA a famous lesson. At the congressional hearing investigating the accident, he simply placed some of the O-ring putty in a glass of ice water and crumbled it in his fingers.

NASA had changed the sealant because its original supplier for O-ring putty stopped producing it for fear of anti-asbestos lawsuits.

No Lessons Learned From the Challenger Disaster

Had NASA not run out of the original putty, the Challenger disaster would not have happened. Indeed, when the Air Force ran out of the same putty and replaced it with the same brittle substitute, their Titan 34D heavy-lift boosters suffered two sudden launch failures, after a string of successes that had lasted as long as that of the space shuttle.

These accidents are not primarily the fault of careless engineers, nor are they merely the unintended consequences of bureaucrats blindly following federal rules. They are the result of a philosophy that hold human needs, such as the need for a safe shuttle launch or re-entry, as less important than a concern to preserve the purity of nature from the products of industrial civilization, such as CFCs and asbestos insulation.

Al Gore's Twisted Dream

Had 2000 presidential candidate Al Gore had his way, Columbia's last mission would have carried a spacecraft called Triana into space. Triana was meant to beam continuous images, via the Internet, of a very small Earth as seen from a point between Earth and the sun.

The idea was to convey the message of how small and fragile the Earth is, and consequently how small man is, compared to the vastness of space.

That's the theory: Man is small and should sacrifice for vast nature. The practice? Fourteen dead astronauts.

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