vegita1220
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He had big pecs? That's what i always just kinda assumed...
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Navy Trivia
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Since we've gotten into prime numbers, I guess I can ask my question. (physics question I guess) The shuttle Colombia: the foam that hit it from all the tests they did afterward they said it was going at some ungodly speed when it hit, and that provided the force necessary to break though the carbon. I don't see how it could be going that fast. If it broke off it would fall with gravity. Take 100 feet to be the distance for example. (plus it's foam, not very dense) Now the shuttle is accelerating, but how much acceleration can it do in that 100 feet? At the time of break off the foam and shuttle are going at the same speed, so the speed that the foam hit could only be the difference in velocity gained by the acceleration in that 100 feet span.
Whew, my question in summary is A) how could foam puncture (because of it's lack of density compared to the carbon carbon (which is very strong [at least carbon composites are]) and B) how could it acquire that crazy velocity that is claimed?
Whew, my question in summary is A) how could foam puncture (because of it's lack of density compared to the carbon carbon (which is very strong [at least carbon composites are]) and B) how could it acquire that crazy velocity that is claimed?
Well in most of those disclosures of speed that the news media is reporting they aren't talking relative velocity compared to the shuttle. They are giving the speed as it's velocity relative to the ground.
The second part about why the foam was so hard. The shuttle has the foam put on as an insulator to keep the fuel cold while sitting on the launch pad. Columbia sat on the launch pad for 2 days in the rain. That rain froze onto the foam (since it is so cold). So that foam that hit the wing was a combination of foam and ice which can puncture a small hole in the wing. The problem is that on re-entry the friction is rediculously intense so a small hole, if in the wrong spot, can quickly melt a bigger hole. In the case of where the ice hit, it was right on the left wheel well. so the superheated gas quickly went thru the aluminum and then caused the tire to explode causing a huge hole to be created. And well the heat just kept building up and melting more until it lost structural integrity.
As a side note, if you haven't read the NASA report (and you are interested in this type of thing), I would highly suggest it. It discusses possible things they could have done to try and repair it/get the astronauts back safely.
Kobyra
The second part about why the foam was so hard. The shuttle has the foam put on as an insulator to keep the fuel cold while sitting on the launch pad. Columbia sat on the launch pad for 2 days in the rain. That rain froze onto the foam (since it is so cold). So that foam that hit the wing was a combination of foam and ice which can puncture a small hole in the wing. The problem is that on re-entry the friction is rediculously intense so a small hole, if in the wrong spot, can quickly melt a bigger hole. In the case of where the ice hit, it was right on the left wheel well. so the superheated gas quickly went thru the aluminum and then caused the tire to explode causing a huge hole to be created. And well the heat just kept building up and melting more until it lost structural integrity.
As a side note, if you haven't read the NASA report (and you are interested in this type of thing), I would highly suggest it. It discusses possible things they could have done to try and repair it/get the astronauts back safely.
Kobyra
DairyCreamer
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You need to consider the immense dynamic pressure being caused by the velocity of the air hitting the shuttle.
At the time the foam broke off, surely the shuttle was travelling well in excess of Mach 5 as it blasted its way to orbit.
Once the piece of foam breaks off, it is no longer being accelerated upward by the thrust provided by the shuttle. By this, yes, the piece begins to fall toward earth with the force of gravity, but, as the atmosphere now has its free reign on the fairly sizeable chunk of dense foam, the dynamic pressure of air hitting something at Mach 5 provides huge amounts of form and surface friction on an object (same reason the shuttle glows so hot when it reenters).
Anyway, in the fractions of a second between the chunk breaking off and when it hit the shuttle, the piece was accellerated to speeds quite possibly exceeding the speed of a freshly fired bullet (relative to the movement and accelleration of the shuttle itself).
It's all about relativity. I havn't bothered to do any research for this post or calculations involving exactly how much the foam would have accellerated, however, it is definite that dynamic atmospheric pressure was the primary physical culprit in ripping off the foam
~Nate
At the time the foam broke off, surely the shuttle was travelling well in excess of Mach 5 as it blasted its way to orbit.
Once the piece of foam breaks off, it is no longer being accelerated upward by the thrust provided by the shuttle. By this, yes, the piece begins to fall toward earth with the force of gravity, but, as the atmosphere now has its free reign on the fairly sizeable chunk of dense foam, the dynamic pressure of air hitting something at Mach 5 provides huge amounts of form and surface friction on an object (same reason the shuttle glows so hot when it reenters).
Anyway, in the fractions of a second between the chunk breaking off and when it hit the shuttle, the piece was accellerated to speeds quite possibly exceeding the speed of a freshly fired bullet (relative to the movement and accelleration of the shuttle itself).
It's all about relativity. I havn't bothered to do any research for this post or calculations involving exactly how much the foam would have accellerated, however, it is definite that dynamic atmospheric pressure was the primary physical culprit in ripping off the foam
~Nate
Thanks guys, I realize what even a little hole can do with the re-entry (plasma jets) and all around friction especially at the leading edge. I guess a combination between the added ice and the re entry would definitely do it, but I was more confused by the ground tests NASA did with a duplicate piece (gotten from enterprise actually I think) where they shot the foam without the ice and what a huge gaping hole there was. (One of the NASA tests shows the foam not disintegrating on impact but going straight through the leading edge) and the launch video shows the foam shattering (because of the ice probably).
In addition when does NASM at Dulles open? They say both monday and next sat? Which one is it, is one for the public and the other for benefactors?
Trivia space related: What large and unintuitive material makes up a lot of the white part of the shuttle?
Also: What technology and material did the capsules use as their heat shield? And why do we not use that if it worked so well?
Why was the original fuel tank painted white, and then changed?
Which is the lightest shuttle?
What shuttle was made of spare parts?
In addition when does NASM at Dulles open? They say both monday and next sat? Which one is it, is one for the public and the other for benefactors?
Trivia space related: What large and unintuitive material makes up a lot of the white part of the shuttle?
Also: What technology and material did the capsules use as their heat shield? And why do we not use that if it worked so well?
Why was the original fuel tank painted white, and then changed?
Which is the lightest shuttle?
What shuttle was made of spare parts?
vegita1220
User
I'm pretty sure the basic heat shield concept is basically still the same, large surface area coated with some sort of insulator(anything with low heat conducting properties). Not entirely sure though.
DairyCreamer
Registered User
Comments / Answers interspersed:
http://www.nasm.si.edu/museum/udvarhazy/
Pre-shuttle re-entry heat protection was provided by ablative heat shields. They were designed to essentially melt away as the heat of reentry melted the material. The melted material would remove itself from the craft due to the aerodynamic forces associated with reentry, and instead carry the heat away from the craft, rather than allowing it to penetrate into the capsule. Citing this document (http://www-pao.ksc.nasa.gov/kscpao/nasafact/pdf/tps.pdf), the ablative material was a "phenolic epoxy resin within a nickel-allow honeycomb matrix."
I think the white paint was just to look nice, and possibly provide reduced aerodynamic drag on launch as paint does on an aircraft. The weight was huge though, something on the order of 500 to 700 lbs I believe, even for a thin coat. The decrease in weight and subsequent increase in payload capability was much preferred, and hence the paint was discontinued.
I really dont know either of these answers off the top of my head.
~Nate
Understand, even a chunk of foam like a nerf ball (which is, as I'm aware, significantly less dense than the insulating foam on the fuel tank itself) that's going Mach 1 is going to do a lot of damage. The fact that the chunk shattered actually absorbed more damage in its own destruction than if it had penetrated the wing as a solid chunk.
Information appears here it seems:
http://www.nasm.si.edu/museum/udvarhazy/
It's known as Low-Temperature Reusable Surface Insulation (LRSI). Designed to withstand temperatures ranging from 400 to 650 C, it is primarily composed of high purity silica fibers. Layers of the silica material are packed together losely to create a highly porous structure. This attributes to its lightness, as well as extremely low thermal conductivity. The surface is coated with Borosilicate glass which is highly reflective of solar radiation, preventing the temperature of the orbiter from heating too much while in orbit. (While I've studied this material before, I credit my Materials Science text for some of the information provided here).
Pre-shuttle re-entry heat protection was provided by ablative heat shields. They were designed to essentially melt away as the heat of reentry melted the material. The melted material would remove itself from the craft due to the aerodynamic forces associated with reentry, and instead carry the heat away from the craft, rather than allowing it to penetrate into the capsule. Citing this document (http://www-pao.ksc.nasa.gov/kscpao/nasafact/pdf/tps.pdf), the ablative material was a "phenolic epoxy resin within a nickel-allow honeycomb matrix."
I think the white paint was just to look nice, and possibly provide reduced aerodynamic drag on launch as paint does on an aircraft. The weight was huge though, something on the order of 500 to 700 lbs I believe, even for a thin coat. The decrease in weight and subsequent increase in payload capability was much preferred, and hence the paint was discontinued.
I really dont know either of these answers off the top of my head.
~Nate
Dairy,
Good answers all true, what I was referring to was the FRSI "felt blankets" It's fabric that's what is so unusual about it, it's actually sewn together (saw a cool video)
The ablative material is part asbestos I believe. It was hand injected into each honeycomb cell and then radar scanned (I think its radar, just guessing) for bubbles (and replaced if any bubbles occurred)
On the paint issue you were also right on, each successive shuttle is lighter than the previous based on incremental improvements, which gives it more payload capacity (clue on last 2 questions) There is even 2 designs (if not more) of the external tank the latter of which is significantly lighter (which was a controversy with the Colombia tragedy because they still used the old design, but which NASA says is not a factor.)
Good answers all true, what I was referring to was the FRSI "felt blankets" It's fabric that's what is so unusual about it, it's actually sewn together (saw a cool video)
The ablative material is part asbestos I believe. It was hand injected into each honeycomb cell and then radar scanned (I think its radar, just guessing) for bubbles (and replaced if any bubbles occurred)
On the paint issue you were also right on, each successive shuttle is lighter than the previous based on incremental improvements, which gives it more payload capacity (clue on last 2 questions) There is even 2 designs (if not more) of the external tank the latter of which is significantly lighter (which was a controversy with the Colombia tragedy because they still used the old design, but which NASA says is not a factor.)
Endeavour was built using spare parts after the Tragic Challenger accident in 1996.
The lightest is Atlantis which weighs approximately 172,521lbs. The nest lightest is Discovery which weighs 173,152lbs., and Endeavour which weighs 173,286lbs.
Here is a link to a cool fact sheet as well. It doesn't have the above info, but it does have somm neat stats, if that sort of thing interests you.
http://spaceflight.nasa.gov/shuttle/upgrades/upgrades5.html
A better question, since this is a Navy site, would be "What percentage of NASA Pilots have come from the Navy?"
The lightest is Atlantis which weighs approximately 172,521lbs. The nest lightest is Discovery which weighs 173,152lbs., and Endeavour which weighs 173,286lbs.
Here is a link to a cool fact sheet as well. It doesn't have the above info, but it does have somm neat stats, if that sort of thing interests you.
http://spaceflight.nasa.gov/shuttle/upgrades/upgrades5.html
A better question, since this is a Navy site, would be "What percentage of NASA Pilots have come from the Navy?"
DairyCreamer
Registered User
Yah, the FRSI covers the orbiter bay doors, a good chunk of the top side of the wings, parts of the fusealage that are otherwise shielded by the wings, and the nacelles for the OMS engines (shielded by the main wing on re-entry).
My materials book states the FRSI is composed of nylon fibers coated with silicone rubber. Above 400 C is melts, but that's why it's used on the cooler parts of the shuttle. The LRSI covers 70% of the shuttle surface according to my book... another website I'm reading right now states that 50% of the shuttles "upper surfaces" are covered with the felt material.
Neat stuff... I wouldn't mind travelling at 17,000+ Miles an hour I could settle for Mach 2 in a Super Hornet though too 
~Nate
My materials book states the FRSI is composed of nylon fibers coated with silicone rubber. Above 400 C is melts, but that's why it's used on the cooler parts of the shuttle. The LRSI covers 70% of the shuttle surface according to my book... another website I'm reading right now states that 50% of the shuttles "upper surfaces" are covered with the felt material.
Neat stuff... I wouldn't mind travelling at 17,000+ Miles an hour
I could settle for Mach 2 in a Super Hornet though too ~Nate
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