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| Fred J. McCall... |
 Posted: Tue Dec 30, 2008 4:09 pm |
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"Jeff Findley" <jeff.findley at (no spam) ugs.nojunk.com> wrote:
:
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:Furthermore, when you're talking about returning from the moon, the ability
:to land at more than two locations (KSC and Edwards) is a good thing. Also,
:resistance to bad weather during landing is more important, since you're
:committed to a landing time when you leave lunar orbit and weather has much
:more time to turn bad in that situation than after a de-orbit burn in LEO.
:
Why? Why couldn't you plan your return with an LEO insertion burn and
just sit up there until conditions were good?
--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn |
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| kT... |
| Posted: Tue Dec 30, 2008 11:38 pm |
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Leopold Stotch wrote:
[quote:68bb5f8785]kT wrote
The foam problems still remain as the fundamental engineering science
of rocket science, something America has abandoned with Michael Griffin.
The "foam problem" is only a problem when you mount the crew vehicle in
tandem with the booster the way the STS does. Put the crew vehicle on
the top and shed foam till the cows come home, who cares? So long as
there is nothing important to hit foam shedding is not an issue. Hell,
put the CV on top and forget about putting foam on the thing at all.
[/quote:68bb5f8785]
Actually, the foam problem is a universal orbital debris problem for all
upper stages and core stages that remain in orbit, or that are intended
to remain in orbit. For instance, you lose 60% - 75% of your payload
mass if you expend upper stages or in orbit, or in the case of core
stages, expend them after attaining 97% or more of orbital velocity.
The foam degrades in ultraviolet and creates a huge mess on orbit. If
you want to recycle those upper stages or core stages on orbit, the foam
problem must be solved. It's the number one problem of rocket science.
Of course, if you want to waste 60% to 75% of your payload, that's your
choice. Maybe it makes you so proud to be wasteful, and proud to neglect
the problems of rocket science as you have done these last eight years.
If you are an American, considering the state of America, it doesn't
surprise me one bit, nor does it surprise me you are unaware of the
problems or orbital debris, wasteful launch operations and other
insanity and nuttiness. The Ares I rocket immediately comes to mind. |
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| Leopold Stotch... |
| Posted: Wed Dec 31, 2008 12:35 am |
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Guest
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kT wrote:
[quote:a4379630fe]Leopold Stotch wrote:
kT wrote
The foam problems still remain as the fundamental engineering science
of rocket science, something America has abandoned with Michael Griffin.
The "foam problem" is only a problem when you mount the crew vehicle
in tandem with the booster the way the STS does. Put the crew vehicle
on the top and shed foam till the cows come home, who cares? So long
as there is nothing important to hit foam shedding is not an issue.
Hell, put the CV on top and forget about putting foam on the thing at
all.
Actually, the foam problem is a universal orbital debris problem for all
upper stages and core stages that remain in orbit, or that are intended
to remain in orbit. For instance, you lose 60% - 75% of your payload
mass if you expend upper stages or in orbit, or in the case of core
stages, expend them after attaining 97% or more of orbital velocity.
The foam degrades in ultraviolet and creates a huge mess on orbit. If
you want to recycle those upper stages or core stages on orbit, the foam
problem must be solved. It's the number one problem of rocket science.
Of course, if you want to waste 60% to 75% of your payload, that's your
choice. Maybe it makes you so proud to be wasteful, and proud to neglect
the problems of rocket science as you have done these last eight years.
If you are an American, considering the state of America, it doesn't
surprise me one bit, nor does it surprise me you are unaware of the
problems or orbital debris, wasteful launch operations and other
insanity and nuttiness. The Ares I rocket immediately comes to mind.
[/quote:a4379630fe]
I haven't seen any data that supports foam shedding being an orbital
debris issue. Frankly I doubt it. When you get into the upper
atmosphere, foam shedding should halt before you get to orbit. Even if
it didn't, foam has a low density and relatively high surface area so it
would not stay in orbit long.
That said, if you put the CV on the nose instead of tandem with the
booster I don't see the need for foam. Yes you will get some ice
loading, just as the Saturn V did. It shakes off within the first few
seconds.
Put the CV on the top and forget about the foam.
Note though, I am not saying the CV must be a capsule. You could do
a lifting body ( a la X-24 or HL-10 or the like) or some sort of winged
airframe. If you are not building a large cargo carrying vehicle I
don't that a nose mounted CV is incompatible with non-capsule
configurations. |
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| kT... |
| Posted: Wed Dec 31, 2008 1:26 am |
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Leopold Stotch wrote:
[quote:86ae0193f7]kT wrote:
Leopold Stotch wrote:
kT wrote
The foam problems still remain as the fundamental engineering
science of rocket science, something America has abandoned with
Michael Griffin.
The "foam problem" is only a problem when you mount the crew vehicle
in tandem with the booster the way the STS does. Put the crew
vehicle on the top and shed foam till the cows come home, who cares?
So long as there is nothing important to hit foam shedding is not an
issue. Hell, put the CV on top and forget about putting foam on the
thing at all.
Actually, the foam problem is a universal orbital debris problem for
all upper stages and core stages that remain in orbit, or that are
intended to remain in orbit. For instance, you lose 60% - 75% of your
payload mass if you expend upper stages or in orbit, or in the case of
core stages, expend them after attaining 97% or more of orbital velocity.
The foam degrades in ultraviolet and creates a huge mess on orbit. If
you want to recycle those upper stages or core stages on orbit, the
foam problem must be solved. It's the number one problem of rocket
science.
Of course, if you want to waste 60% to 75% of your payload, that's
your choice. Maybe it makes you so proud to be wasteful, and proud to
neglect the problems of rocket science as you have done these last
eight years. If you are an American, considering the state of America,
it doesn't surprise me one bit, nor does it surprise me you are
unaware of the problems or orbital debris, wasteful launch operations
and other insanity and nuttiness. The Ares I rocket immediately comes
to mind.
I haven't seen any data that supports foam shedding being an orbital
debris issue.
[/quote:86ae0193f7]
It's a first principles result.
[quote:86ae0193f7]Frankly I doubt it.
[/quote:86ae0193f7]
You can doubt all you want, it's a first principles result well backed
up by simple physics and chemistry.
[quote:86ae0193f7]When you get into the upper
atmosphere, foam shedding should halt before you get to orbit.
[/quote:86ae0193f7]
I'm not talking about big chunks of foam, I'm talking about ordinary uv
catalyzed hydrocarbon polymer chain degradation. I guess you never heard
of it, or never experienced it in real life. Ever been in the tropics?
[quote:86ae0193f7]Even if
it didn't, foam has a low density and relatively high surface area so it
would not stay in orbit long.
[/quote:86ae0193f7]
Sure, uh-huh. It's almost as stupid as painting spacecraft.
[quote:86ae0193f7]That said
[/quote:86ae0193f7]
You haven't said anything.
if you put the CV on the nose instead of tandem with the
[quote:86ae0193f7]booster I don't see the need for foam. Yes you will get some ice
loading, just as the Saturn V did. It shakes off within the first few
seconds.
[/quote:86ae0193f7]
That's what I'm talking about, we can use creative methods to eliminate
the foam entirely and that opens up an entire new regime of spaceflight.
In other words, on orbit recovery of engines and retrofitting of tanks.
[quote:86ae0193f7]Put the CV on the top and forget about the foam.
[/quote:86ae0193f7]
You still need to insulate the hydrogen tank while it sits on the
ground, and develop a method to recycle the boiloff during launch.
This is a non-trivial but eminently solvable problem of rocket science.
[quote:86ae0193f7]Note though, I am not saying the CV must be a capsule. You could do a
lifting body ( a la X-24 or HL-10 or the like) or some sort of winged
airframe. If you are not building a large cargo carrying vehicle I
don't that a nose mounted CV is incompatible with non-capsule
configurations.
[/quote:86ae0193f7]
Whatever. The real problem remains the foam on the tankage. |
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| Ian Parker... |
| Posted: Wed Dec 31, 2008 2:14 am |
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On 30 Dec, 19:56, Fred J. McCall <fjmcc... at (no spam) gmail.com> wrote:
[quote:3e389a37ad]
You seem to think the tiles on the Shuttle are ablative protection.
They're not. Hence, by your own implication, the shuttle must be
"potentially a solution".
If the tiles are non ablative it rather surprises me that no research[/quote:3e389a37ad]
has been done on making a strong ceramic material. This is perfectly
possible to do. There are when all is said and done ceramic and carbon
fiber reinforced materials.
- Ian Parker |
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| bob haller safety advocate... |
| Posted: Wed Dec 31, 2008 3:35 am |
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I am fascinated with the idea of taking all these main engines to
orbit for reuse?
now consider theres no easy way to fuel them, the launch environment
is very different than in orbit use after months or longer of sitting
around, and whats big enough to send into interplanetary space?
whats the payload? |
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| Scott Stevenson... |
| Posted: Wed Dec 31, 2008 3:48 am |
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On Wed, 31 Dec 2008 07:03:33 GMT, Leopold Stotch
<butters at (no spam) southpark.org> wrote:
[quote:7b9ae208ea]
Sorry, I don't understand your hangup on the foam. We have several
perfectly good boosters that are sans external foam. The external foam
on the STS ET is purely an artifact of the tandem mounting of the CV
(with its fragile TPS) next to the ET. If you put the CV on top of the
booster stack you don't need the external foam. Saturn V didn't have
it, Delta IV doesn't have it, Atlas V doesn't have it. Neither do any
of the large Soviet/Russian boosters currently in service.
CV on top = no external foam
CV in tandem = external foam
External Foam + Tandem CV = Inherent danger to CV
Yes, we could probably put a lot of effort into materials research
to find a better (perhaps even much better) external foam which would
mitigate some of the danger inherent in a tandem CV/booster arrangement.
Or, you could pick an inherently safer arrangement and put the CV on
top of the booster stack and forget about external foam insulation
altogether. Second option sounds like better engineering to me.
[/quote:7b9ae208ea]
OK, I know that if this were an actual idea, somebody smarter than I
would have had it already...
Why would the foam have to go on the outside of the tank at all? If
you put the foam on the inside of the tank walls, you don't have a
shedding problem. I know it's easier to build the tank, then spray
the foam on the outside of the completed unit, but still...
Does the tank get hot enough at launch (air friction/heat from the
engines) that it would weaken it if it weren't covered in foam?
take care,
Scott |
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| Ian Parker... |
| Posted: Wed Dec 31, 2008 6:21 am |
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On 31 Dec, 14:23, "Jeff Findley" <jeff.find... at (no spam) ugs.nojunk.com> wrote:
[quote:ab1ab44e1d]If the tiles are non ablative it rather surprises me that no research
has been done on making a strong ceramic material. This is perfectly
possible to do. There are when all is said and done ceramic and carbon
fiber reinforced materials.
There has been research in this area, but the shuttle design does not lend
itself to retrofitting tougher tiles to the design. The added weight of
tougher tiles reduces payload by an equal amount.
Yes, accepted for the Shuttle. If you were to design a new winged[/quote:ab1ab44e1d]
vehicle this would not be the case as refractory material would be an
integral part of the fusilage, not just an add on. It would seem that
the powers that be have decreed that there will be no second bite of
the cherry.
I feel BTW that the main problem of a hypersonic plane is materials.
The methods of propulsion are fairly well known.
- Ian Parker |
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| Jeff Findley... |
| Posted: Wed Dec 31, 2008 10:21 am |
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"Fred J. McCall" <fjmccall at (no spam) gmail.com> wrote in message
news:mrvkl45n6k5utnvqphlc36amedvfrljn7d at (no spam) 4ax.com...
[quote:30bba43e31]"Jeff Findley" <jeff.findley at (no spam) ugs.nojunk.com> wrote:
:
:
:Furthermore, when you're talking about returning from the moon, the
ability
:to land at more than two locations (KSC and Edwards) is a good thing.
Also,
:resistance to bad weather during landing is more important, since you're
:committed to a landing time when you leave lunar orbit and weather has
much
:more time to turn bad in that situation than after a de-orbit burn in
LEO.
:
Why? Why couldn't you plan your return with an LEO insertion burn and
just sit up there until conditions were good?
[/quote:30bba43e31]
Because of the huge delta-V requirements to do so. The Orion design
decision to discard the service module makes aerocapture, and subsequent
loitering in LEO and de-orbit burn, very difficult without a service module
attached.
If the Orion design did not throw away the service module, but instead
incorporated it into the capsule design, aerocapture and loitering in LEO
would at least be theoretically possible without a huge change to the
design. Such a capsule design would be a good candidate to make completely
reusable since you're not throwing away huge portions of your spacecraft to
destructively reenter.
Jeff
--
"Many things that were acceptable in 1958 are no longer acceptable today.
My own standards have changed too." -- Freeman Dyson |
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| Jeff Findley... |
| Posted: Wed Dec 31, 2008 10:23 am |
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"Ian Parker" <ianparker2 at (no spam) gmail.com> wrote in message
news:57be49a3-eeb2-4826-a92f-905f34c3f652 at (no spam) r36g2000prf.googlegroups.com...
[quote:0348b940d4]On 30 Dec, 19:56, Fred J. McCall <fjmcc... at (no spam) gmail.com> wrote:
You seem to think the tiles on the Shuttle are ablative protection.
They're not. Hence, by your own implication, the shuttle must be
"potentially a solution".
If the tiles are non ablative it rather surprises me that no research
has been done on making a strong ceramic material. This is perfectly
possible to do. There are when all is said and done ceramic and carbon
fiber reinforced materials.
[/quote:0348b940d4]
There has been research in this area, but the shuttle design does not lend
itself to retrofitting tougher tiles to the design. The added weight of
tougher tiles reduces payload by an equal amount.
Jeff
--
"Many things that were acceptable in 1958 are no longer acceptable today.
My own standards have changed too." -- Freeman Dyson |
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| Ian Parker... |
| Posted: Wed Dec 31, 2008 11:30 am |
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On 31 Dec, 17:58, "Jeff Findley" <jeff.find... at (no spam) ugs.nojunk.com> wrote:
[quote:cedb7288bf]"Ian Parker" <ianpark... at (no spam) gmail.com> wrote in message
news:fb67b81d-886e-4e4f-a816-433b92b01d8e at (no spam) r10g2000prf.googlegroups.com...
I feel BTW that the main problem of a hypersonic plane is materials.
The methods of propulsion are fairly well known.
False. The total duration of all hypersonic engines being run on actual
vehicles can be measured in seconds. This is still a research topic, not a
proven technology.
To a large extent this is due to the fact that that materials are not[/quote:cedb7288bf]
there. It is and it isn't. To run hypersonic engines cool is a
research topic. Yes indeed. CFD, which is now extremely accurate shows
that hypersonic engines are possible IF THE MATERIALS WERE THERE.
Engines do operate for seconds. The limiting factor for operating
longer is materials, really only materials + the fact that most
hypersonic engines have been small. Again to minimise material
stresses.
By knowing how to build a hypersionic engine if the masterials if the
materialls were there I am really refering to CFD resutls. CFD says
"Yes, hypersonic engine, but what do you build it out of?"
In a sense this is an illuminating in that it is possible to set
parameters.
I DO NOT just feel things. What I say has the backing of solid CFD.
http://www.google.co.uk/search?hl=en&q=Hypersonic+CFD&meta
- Ian Parker |
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| Ian Parker... |
| Posted: Wed Dec 31, 2008 11:33 am |
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On 31 Dec, 20:45, Bin(t) Al-kalb wrote:
[quote:575578f750]On Wed, 31 Dec 2008 10:55:29 -0700, Fred J. McCall
fjmcc... at (no spam) gmail.com> wrote:
How can you even deign to express an opinion when you're this
ignorant?
"Ebba yearbuh ibbu alwaysbuh buh samebuh. Ibba alwaysbuh playbuh
babbulh foolbuh."
[/quote:575578f750]
You mean you are working on it yourself. Pity about Aurora. Lot of
money wasted eh! I have news for you. 500GFlop machines are now
available on the consumer market. Put that in your pipe and smoke it.
- Ian Parker |
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| kT... |
| Posted: Wed Dec 31, 2008 12:00 pm |
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Scott Stevenson wrote:
[quote:cc78e3a237]On Wed, 31 Dec 2008 07:03:33 GMT, Leopold Stotch
butters at (no spam) southpark.org> wrote:
Sorry, I don't understand your hangup on the foam. We have several
perfectly good boosters that are sans external foam. The external foam
on the STS ET is purely an artifact of the tandem mounting of the CV
(with its fragile TPS) next to the ET. If you put the CV on top of the
booster stack you don't need the external foam. Saturn V didn't have
it, Delta IV doesn't have it, Atlas V doesn't have it. Neither do any
of the large Soviet/Russian boosters currently in service.
CV on top = no external foam
CV in tandem = external foam
External Foam + Tandem CV = Inherent danger to CV
Yes, we could probably put a lot of effort into materials research
to find a better (perhaps even much better) external foam which would
mitigate some of the danger inherent in a tandem CV/booster arrangement.
Or, you could pick an inherently safer arrangement and put the CV on
top of the booster stack and forget about external foam insulation
altogether. Second option sounds like better engineering to me.
OK, I know that if this were an actual idea, somebody smarter than I
would have had it already...
Why would the foam have to go on the outside of the tank at all? If
you put the foam on the inside of the tank walls, you don't have a
shedding problem. I know it's easier to build the tank, then spray
the foam on the outside of the completed unit, but still...
[/quote:cc78e3a237]
They did that with some of the Saturn stages I think. That's one option.
Another option we're looking at is having heat resistant insulation
plaquettes retract at launch, or otherwise be somehow discarded. This is
the preferred approach because we want to recycle or repressurize with
the boiloff gases during the launch flight phase, to keep the tank well
pressurized and to pump the residual fuel for scavenging. Like I have
previously indicated, this is cutting edge rocket science, because what
we want to end up with in orbit is a fully functional spaceflight ready
core or upper stage, completely repressurized with residual fuel safed.
[quote:cc78e3a237]Does the tank get hot enough at launch (air friction/heat from the
engines) that it would weaken it if it weren't covered in foam?
[/quote:cc78e3a237]
That's the corresponding 'rocket science' problem, integrated with the
foam problem. The thermal and the resulting structural loads resulting
from the thermal heating. Hydrogen vehicles mostly go straight up, so
the thermal load early in flight are not that great, but they really
quickly accelerate while transitioning to horizontal, so there are some
non-trivial hypersonic heating load, which have never been properly
characterized due to the finessing away of the problem with the foam.
Associated with that problem is the terminal acceleration problem
associated with hydrogen fuel, gee forces with can approach 8 gees at
main engine cutoff, unless multiple engines are used along with
sequential shutdown, or deep throttling engines are available. In order
to conserve fuel, quicker transitions to horizontal can occur, which
necessarily incur much greater structural loads. These problems are
integrated, thermal loads tied into structural load, tied into flight
profile, tied into fuel consumption. These are problems which have
existed since the beginning of space flight which simply have not been
investigated from a scientific perspective. We're 'rocket scientists'.
We want engines that can take eight gees, and tanks that can be
repressurized in flight in order to take the severe structural loads
which may occur, and materials that can take the thermal abuse and still
be flight ready immediately after launch, once the engines shut down.
That requires ZERO foam.
[quote:cc78e3a237]take care,
Scott
[/quote:cc78e3a237] |
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| Fred J. McCall... |
| Posted: Wed Dec 31, 2008 1:55 pm |
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Guest
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Ian Parker <ianparker2 at (no spam) gmail.com> wrote:
:On 30 Dec, 19:56, Fred J. McCall <fjmcc... at (no spam) gmail.com> wrote:
:>
:> You seem to think the tiles on the Shuttle are ablative protection.
:> They're not. Hence, by your own implication, the shuttle must be
:> "potentially a solution".
:>
:
:If the tiles are non ablative ...
:
*IF*???? Jesus, Ian, go look it up! The Shuttle tiles are sintered
silicon dioxide and are ***NOT*** an ablative heat shield.
How can you even deign to express an opinion when you're this
ignorant?
:
:... it rather surprises me that no research
:has been done on making a strong ceramic material. This is perfectly
:possible to do. There are when all is said and done ceramic and carbon
:fiber reinforced materials.
:
If you think it's "perfectly possible to do", I suggest you do it. It
needs to insulate as well as and be as light as the current Shuttle
TPS.
Good luck with that.
--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson |
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| Jeff Findley... |
| Posted: Wed Dec 31, 2008 1:58 pm |
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Guest
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"Ian Parker" <ianparker2 at (no spam) gmail.com> wrote in message
news:fb67b81d-886e-4e4f-a816-433b92b01d8e at (no spam) r10g2000prf.googlegroups.com...
[quote:8b5b7caa06]
I feel BTW that the main problem of a hypersonic plane is materials.
The methods of propulsion are fairly well known.
[/quote:8b5b7caa06]
False. The total duration of all hypersonic engines being run on actual
vehicles can be measured in seconds. This is still a research topic, not a
proven technology.
Jeff
--
"Many things that were acceptable in 1958 are no longer acceptable today.
My own standards have changed too." -- Freeman Dyson |
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