-
#1620
by
8900
on 03 Mar, 2009 10:48
-
Hello everyone
I have got a question about shuttle TPS
the leading wing edge and nosecone TPS of shuttle is made of something called RCC (Reinforced Carbon Carbon) panels
I look for description about this material and I found this
http://en.wikipedia.org/wiki/Reinforced_carbon-carbonIt describes RCC as:
"a composite material consisting of carbon fibre reinforcement in a matrix of graphite"
I wanna ask, since one important component is large, pure graphite crystal, why this graphite-based material won't burn with oxygen present in Earth's atmosphere? Since the Earth's atmosphere is rich with O2, and reentry temperature is very high, it should be easy to assume that graphite TPS will simply burn and be converted to CO2 easily.
In fact what protects the graphite of RCC from being destroyed by oxygen in atmosphere?
-
#1621
by
eeergo
on 03 Mar, 2009 12:30
-
I think the RCC is only in the "inside" of the panel, as it's coated with silicon carbide (SiC)... there was some concern a while ago about this coating's spalling and leading to the burning you suggest.
Not precisely an expert on this, however, surely someone more knowledgeable will clarify.
-
#1622
by
charlieb
on 03 Mar, 2009 13:03
-
THis is a 3D image of part of an SSME, anyone know what it is?
To see the 3D effect, cross your eyes until the images converge.
The Main Engine Computer and a great deal of wiring and main engine plumbing........
-
#1623
by
SiameseCat
on 07 Mar, 2009 22:59
-
Question about the GPCs: what conditions cause a GPC to be considered failed? As far as I can tell, a GPC receives fail votes from other GPCs if it misses sychroniztion points with the other GPCs. Is any checking of the GPC outputs done?
-
#1624
by
ArthurGoBoom
on 10 Mar, 2009 02:07
-
I guess we just throw questions in here haphazardly and hope for answers
I have been doing a lot of reading about Ares vs Direct and I'm curious about the thrust oscillation issue. I've seen mention of "several measures" used on the shuttle to mitigate the TO effects, but I haven't been able to find any more information on that. What systems/techniques are used on the SS to mitigate TO?
-
#1625
by
arachnitect
on 10 Mar, 2009 03:27
-
I guess we just throw questions in here haphazardly and hope for answers I have been doing a lot of reading about Ares vs Direct and I'm curious about the thrust oscillation issue. I've seen mention of "several measures" used on the shuttle to mitigate the TO effects, but I haven't been able to find any more information on that. What systems/techniques are used on the SS to mitigate TO?
search the forum for "thrust beam"
-
#1626
by
ArthurGoBoom
on 10 Mar, 2009 04:58
-
Found it, thanks
-
#1627
by
mkirk
on 10 Mar, 2009 22:27
-
Question about the GPCs: what conditions cause a GPC to be considered failed? As far as I can tell, a GPC receives fail votes from other GPCs if it misses sychroniztion points with the other GPCs. Is any checking of the GPC outputs done?
This is a better question for Jorge to answer but I will offer up these resources since they will be more usefull than me actually trying to explain how GPC failures are defined.
I have attached a chart and I will also point you to this public link (I think it is about 5 megs in size) to an older set of Shuttle Flight Rules. The chart image is self explanatory, as for the Flight Rules I would recommend you read over the first few pages of section 7 (particularly rule A7-3 which is located around pdf page 1293) to see how the shuttle program defines GPC failures.
www.jsc.nasa.gov/news/columbia/fr_generic.pdfMark Kirkman
-
#1628
by
Jorge
on 10 Mar, 2009 22:58
-
Question about the GPCs: what conditions cause a GPC to be considered failed? As far as I can tell, a GPC receives fail votes from other GPCs if it misses sychroniztion points with the other GPCs. Is any checking of the GPC outputs done?
This is a better question for Jorge to answer but I will offer up these resources since they will be more usefull than me actually trying to explain how GPC failures are defined.
I have attached a chart and I will also point you to this public link (I think it is about 5 megs in size) to an older set of Shuttle Flight Rules. The chart image is self explanatory, as for the Flight Rules I would recommend you read over the first few pages of section 7 (particularly rule A7-3 which is located around pdf page 1293) to see how the shuttle program defines GPC failures.
www.jsc.nasa.gov/news/columbia/fr_generic.pdf
Mark Kirkman
Not much I can add to the chart.
-
#1629
by
C5C6
on 12 Mar, 2009 13:07
-
Hi, I don't understand why there is this tower with a flame near the shuttle.....is that GH2??? where does it come from and why??
-
#1630
by
DMeader
on 12 Mar, 2009 13:24
-
This is the vent system connection that there is an issue with right at the moment, no?
-
#1631
by
C5C6
on 12 Mar, 2009 13:39
-
Hi, I don't understand why there is this tower with a flame near the shuttle.....is that GH2??? where does it come from and why??
It's a hydrogen flame stack.
When the tank is filled the hydrogen is a lot colder than the outside temperature and even with the foam insulation some of the hydrogen will evaporate to it's gaseous state. So, additional liquid hydrogen has to be pumped into the tank. This increases the pressure in the tank.
The hydrogen gas must be vented somewhere otherwise it will over pressure the tank.
At certain points (I believe when the pressure in the tank reaches a predetermined level) some of the Hydrogen gas is vented down to the flame stack and burnt off.
thanks!! now I understand why the shuttle vents GO2 too.....so I assume that there is a continuous flow of LH2 and LO2 to the tank after tanking is complete to compensate for the evaporation.....
the gas I see near the beanie cap is GO2 venting, and the gas venting through the SSME is also GO2?? where does that GO2 come from???
After tank pressurization minutes before launch, the beanie cap stops venting GO2.....but the gas venting through the SSMEs continue flowing....why??
-
#1632
by
DaveS
on 12 Mar, 2009 15:30
-
The gas seen coming from the SSME's is (I believe) Liquid Hydrogen. It's used to super cool the SSME's so that they don't suffer from cryogenic shock when the engines are ignited at T-6.
It's GOX. You never, ever vent hydrogen freely into the atmosphere due to the flammability and explosion risk. You burn it off under controlled conditions.
-
#1633
by
psloss
on 12 Mar, 2009 15:34
-
The gas seen coming from the SSME's is (I believe) Liquid Hydrogen. It's used to super cool the SSME's so that they don't suffer from cryogenic shock when the engines are ignited at T-6.
It's GOX. You never, ever vent hydrogen freely into the atmosphere due to the flammability and explosion risk. You burn it off under controlled conditions.
Yes -- exactly why they scrubbed yesterday: the gaseous hydrogen venting from the leak.
-
#1634
by
DerekL
on 12 Mar, 2009 15:39
-
Hi, I don't understand why there is this tower with a flame near the shuttle.....is that GH2??? where does it come from and why??
It's GH2 that has boiled off, it boils off because it is impossible to keep it liquid throughout the entire system. (The insulation required would be unwieldy.)
-
#1635
by
kch
on 12 Mar, 2009 18:11
-
The gas seen coming from the SSME's is (I believe) Liquid Hydrogen. It's used to super cool the SSME's so that they don't suffer from cryogenic shock when the engines are ignited at T-6.
It's GOX. You never, ever vent hydrogen freely into the atmosphere due to the flammability and explosion risk. You burn it off under controlled conditions.
....unless you're a Delta IV approaching T-0......
... which is when (and how) you get the typical Delta IV BAF (Big-@$$ Fireball) ...
-
#1636
by
Austin
on 14 Mar, 2009 14:10
-
About 1:30 seconds into their ascent on STS 5, capcom Bob Steward advised Vance Brand and his crew of a "slightly depressed trajectory" as a result of the headwinds. I know that the GPCs are configured for higher or lower engine throttles (72 or 67 percent, for example) to compensate for higher or lesser winds during certain times of the year, but this call on STS 5 occurred well past MAX Q. I am estimating that 1:30 into flight they would be roughly 15 miles in altitude, or about 78,000 feet. Would this not be too high in the atmosphere for headwinds to be an issue? Perhaps the trajectory had already been affected and Stewart was just letting them know (a kind of heads-up?)
Also, I don't remember this issue arising on any subsequent flight (at least not hearing this call). Can anyone comment?
-
#1637
by
Jim
on 14 Mar, 2009 14:38
-
About 1:30 seconds into their ascent on STS 5, capcom Bob Steward advised Vance Brand and his crew of a "slightly depressed trajectory" as a result of the headwinds. I know that the GPCs are configured for higher or lower engine throttles (72 or 67 percent, for example) to compensate for higher or lesser winds during certain times of the year, but this call on STS 5 occurred well past MAX Q. I am estimating that 1:30 into flight they would be roughly 15 miles in altitude, or about 78,000 feet. Would this not be too high in the atmosphere for headwinds to be an issue? Perhaps the trajectory had already been affected and Stewart was just letting them know (a kind of heads-up?)
Also, I don't remember this issue arising on any subsequent flight (at least not hearing this call). Can anyone comment?
Max Q and head winds are not really related in this case.
"result of the headwinds" meaning they already encountered them and the reaction is a depressed trajectory
-
#1638
by
Austin
on 14 Mar, 2009 16:17
-
About 1:30 seconds into their ascent on STS 5, capcom Bob Steward advised Vance Brand and his crew of a "slightly depressed trajectory" as a result of the headwinds. I know that the GPCs are configured for higher or lower engine throttles (72 or 67 percent, for example) to compensate for higher or lesser winds during certain times of the year, but this call on STS 5 occurred well past MAX Q. I am estimating that 1:30 into flight they would be roughly 15 miles in altitude, or about 78,000 feet. Would this not be too high in the atmosphere for headwinds to be an issue? Perhaps the trajectory had already been affected and Stewart was just letting them know (a kind of heads-up?)
Also, I don't remember this issue arising on any subsequent flight (at least not hearing this call). Can anyone comment?
Max Q and head winds are not really related in this case.
"result of the headwinds" meaning they already encountered them and the reaction is a depressed trajectory
Okay, so my suspicions were correct -- the call was after the fact to make sure the crew as aware of the depressed trajectory. Thought it was too high in the atmosphere for headwinds to be an issue.
Didn't mean to suggest a correlation between headwinds and Max Q, but I was thinking out loud about how the computers regulate the engine throttles in other circumstances.
Thanks for your response, which was accurate and concise as always!
-
#1639
by
mkirk
on 14 Mar, 2009 16:43
-
Hi, I don't understand why there is this tower with a flame near the shuttle.....is that GH2??? where does it come from and why??
It's a hydrogen flame stack.
When the tank is filled the hydrogen is a lot colder than the outside temperature and even with the foam insulation some of the hydrogen will evaporate to it's gaseous state. So, additional liquid hydrogen has to be pumped into the tank. This increases the pressure in the tank.
The hydrogen gas must be vented somewhere otherwise it will over pressure the tank.
At certain points (I believe when the pressure in the tank reaches a predetermined level) some of the Hydrogen gas is vented down to the flame stack and burnt off.
thanks!! now I understand why the shuttle vents GO2 too.....so I assume that there is a continuous flow of LH2 and LO2 to the tank after tanking is complete to compensate for the evaporation.....
the gas I see near the beanie cap is GO2 venting, and the gas venting through the SSME is also GO2?? where does that GO2 come from???
After tank pressurization minutes before launch, the beanie cap stops venting GO2.....but the gas venting through the SSMEs continue flowing....why??
I’m not sure it was clear from all of the responses so I would like to add a point of clarification.
Both Hydrogen and Oxygen are circulating through the SSMEs for thermal conditioning.
The hydrogen leaves the engine through a bleed valve into the LH2 recirculation line and is ultimately directed back to the ET. With the oxygen, a portion is directed form the turbo pump drains and out the drain line at the bottom of the nozzle (this is the white vapor you see coming out of the SSMEs up until start time). Most of the oxygen however, flows out the overboard bleed valve and thought the T-0 umbilical (tail service mast) which directs it back to the ground facility.
Mark Kirkman
I have been doing a lot of reading about Ares vs Direct and I'm curious about the thrust oscillation issue. I've seen mention of "several measures" used on the shuttle to mitigate the TO effects, but I haven't been able to find any more information on that. What systems/techniques are used on the SS to mitigate TO?
