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Tommy wrote:
a better question is why didn't they make the shuttle out of titanium rather than aluminium. Paul Hovnanian P.E. wrote: Because the ceramic tiles also provide excellent insulation to protect the interior systems and structures of the shuttle. While titanium might withstand the temperatures of reentry, it would still conduct a significant amount of heat. Some sort of insulation layer would still be required. The ceramic tiles are very lightweight and very efficient insulators, but they are extremely brittle. I believe that the best solution is regenerative cooling (plumbing circulating cold water) in the leading edges of the shuttle. There are probably structural pipes in the leading edges already, so using the existing pipes would not add much weight. The regenerative cooling would be a backup system -- when a spot in the leading edge becomes too hot, a safety valve melts down and water begins to circulate to cool down the hot spot. |
#42
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On Wed, 22 Dec 2004 18:08:17 -1000
Michael J Wise wrote: When oh When oh WHEN are they going to make a movie of that?! When somebody starts saying "Hey, lets make a movie of that". Of course in the 35 years since the book was released so many of the ideas it contains will have been ripped off by other movies (That Kzinti looks a bit like a Wookie!) that it would be accused of being derivative. Peter Jackson dug LOTR out of this hole by spending a lot of money. Perhaps he could do the same for RW. -- Michael Smith Network Applications www.netapps.com.au | +61 (0) 416 062 898 Web Hosting | Internet Services |
#43
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In article ,
Andrew Nowicki wrote: ...I believe that the best solution is regenerative cooling (plumbing circulating cold water) in the leading edges of the shuttle. There are probably structural pipes in the leading edges already... No, there aren't. Plumbing would have to be added. Plus, there is the problem that leading-edge damage is all too likely to break the plumbing as well, especially if there's no water flow in it until something decides that it's necessary. Active cooling (which is the generic term for schemes that circulate fluid) is a promising idea, but it works best if it's your primary system, relied on for normal reentry rather than just as a fallback. -- "Think outside the box -- the box isn't our friend." | Henry Spencer -- George Herbert | |
#44
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"Michael Smith" wrote in message ... Of course in the 35 years since the book was released so many of the ideas it contains will have been ripped off by other movies (That Kzinti looks a bit like a Wookie!) that it would be accused of being derivative. Oh I don't know. I can't imagine the two looknig at all alike. Peter Jackson dug LOTR out of this hole by spending a lot of money. Perhaps he could do the same for RW. -- Michael Smith Network Applications www.netapps.com.au | +61 (0) 416 062 898 Web Hosting | Internet Services |
#45
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Maybe if they squirted halon between the tiles it would eliminate the O2 and
extinquish the friction fire. "Andrew Nowicki" wrote in message ... Tommy wrote: a better question is why didn't they make the shuttle out of titanium rather than aluminium. Paul Hovnanian P.E. wrote: Because the ceramic tiles also provide excellent insulation to protect the interior systems and structures of the shuttle. While titanium might withstand the temperatures of reentry, it would still conduct a significant amount of heat. Some sort of insulation layer would still be required. The ceramic tiles are very lightweight and very efficient insulators, but they are extremely brittle. I believe that the best solution is regenerative cooling (plumbing circulating cold water) in the leading edges of the shuttle. There are probably structural pipes in the leading edges already, so using the existing pipes would not add much weight. The regenerative cooling would be a backup system -- when a spot in the leading edge becomes too hot, a safety valve melts down and water begins to circulate to cool down the hot spot. |
#46
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"Rodney Kelp" wrote in message ... Maybe if they squirted halon between the tiles it would eliminate the O2 and extinquish the friction fire. Umm, what friction fire? "Andrew Nowicki" wrote in message ... Tommy wrote: a better question is why didn't they make the shuttle out of titanium rather than aluminium. Paul Hovnanian P.E. wrote: Because the ceramic tiles also provide excellent insulation to protect the interior systems and structures of the shuttle. While titanium might withstand the temperatures of reentry, it would still conduct a significant amount of heat. Some sort of insulation layer would still be required. The ceramic tiles are very lightweight and very efficient insulators, but they are extremely brittle. I believe that the best solution is regenerative cooling (plumbing circulating cold water) in the leading edges of the shuttle. There are probably structural pipes in the leading edges already, so using the existing pipes would not add much weight. The regenerative cooling would be a backup system -- when a spot in the leading edge becomes too hot, a safety valve melts down and water begins to circulate to cool down the hot spot. |
#47
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What ever the hell lights up the tiles.
Umm, what friction fire? "Andrew Nowicki" wrote in message ... Tommy wrote: a better question is why didn't they make the shuttle out of titanium rather than aluminium. Paul Hovnanian P.E. wrote: Because the ceramic tiles also provide excellent insulation to protect the interior systems and structures of the shuttle. While titanium might withstand the temperatures of reentry, it would still conduct a significant amount of heat. Some sort of insulation layer would still be required. The ceramic tiles are very lightweight and very efficient insulators, but they are extremely brittle. I believe that the best solution is regenerative cooling (plumbing circulating cold water) in the leading edges of the shuttle. There are probably structural pipes in the leading edges already, so using the existing pipes would not add much weight. The regenerative cooling would be a backup system -- when a spot in the leading edge becomes too hot, a safety valve melts down and water begins to circulate to cool down the hot spot. |
#48
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Rodney Kelp wrote:
Maybe if they squirted halon between the tiles it would eliminate the O2 and extinquish the friction fire. There really isn't a fire on the exterior of the shuttle in the sense that combustion is occurring. The friction simply heats the outer skin (tiles) and the adjacent atmosphere to a temperature where they become incandescent. So there really isn't anything to extinguish. As far as introducing some sort of coolant into the skin, you'd have to determine the amount of heat generated. A good estimate is that all of the shuttle's kinetic energy is converted into heat at the skin interface (some is lost to shock waves, etc.). Then, given the specific heat of various coolants, calculate how many tons of coolant you'd have to haul up at launch and throughout the mission in order to cool the skin. The shuttle is cooled by transferring the heat of friction to the surrounding atmosphere which carries it away. Air is already up there so there's no need to carry it along on the flight. -- Paul Hovnanian ------------------------------------------------------------------ Have gnu, will travel. |
#49
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Rodney Kelp wrote:
What ever the hell lights up the tiles. The tiles eroded because 3000-degree oxygen got past their oxide barriers. I'm not sure you'd have much luck getting halogen to force back through those cracks against hypersonic air, and you'd probably pop the tiles off with the internal pressurization required. Mike Miller, Materials Engineer |
#50
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Paul Hovnanian wrote:
As far as introducing some sort of coolant into the skin, you'd have to determine the amount of heat generated. A good estimate is that all of the shuttle's kinetic energy is converted into heat at the skin interface (some is lost to shock waves, etc.). Then, given the specific heat of various coolants, calculate how many tons of coolant you'd have to haul up at launch and throughout the mission in order to cool the skin. When the shuttle reenters the atmosphere, the most intense heating lasts about 8 minutes. At that time the nose cone experiences temperature of 1600 K and heat flux of 380,000 W/m^2. Suppose that some ceramic tiles fell off the nose cone leaving a square hole 10x10cm = 4x4" How much water would be needed to remove the heat from the hole? The amount of heat = (heat flux)x(area)x(time)= 380,000 x 1/100 x 480 = 1,824,000 joules. Specific heat of water is 4183 J/kg/K Heat of vaporization of water is 2,256,000 J/kg. Suppose that water temperature rises from 0 degrees Celsius to 100 degrees Celsius. 1 kilogram of water (= 1 liter of water) can remove 4183x100 + 2256,000 = 2,674,300 joules of heat -- just the amount needed to remove not only the peak heat, but all the heat. This quick estimate proves that backup water cooling system would not be too heavy. The piping delivering the water would not be heavy either. If we are moving one liter of water through the piping in 8 minutes, we need to pump 2 cubic centimeters of water per second. Suppose that the water moves through the piping at 10 meters per second. What is the diameter of the piping D? PixDXDx10/4 = 2/10^6, so D = 5x10-4 m = 0.5 mm. There is commercial stainless steel tubing made of type 304 steel. Its internal diameter is 0.51 mm. External diameter is 0.82 mm. 100 meters of this tubing weighs about 256 grams. The entire backup cooling system can be as lightweight as two kilograms! Will NASA implement such a system? Never ever. |
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