Inferno

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.

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

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 |

"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

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.

"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.

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.

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.

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

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.