Lunar Lander in a 5.2m faring?

"Rüdiger Klaehn" wrote:

:Fred J. McCall wrote:
:
:[snip]
: :The Russians have been transferring storable hypergolic fuel and oxidizer
: :from Progress tankers to their stations (including ISS) for years. No EVA
: r clumsy pressure fittings seem to be required for this to work.
:
: Now you might want to look at the thrust developed and burn durations.
: I don't see any of those vehicles going to the Moon, landing, and then
: taking back off.
:
:So let me get this straight:

This is almost a sure sign that someone is about to run down into the
ditch by making claims that aren't in evidence.

:scaling up from the several hundred kgs the russian progress routinely
:transfers to the ISS http://www.russianspaceweb.com/progress.html to
:the tens of tons required for a lunar mission is so complex that it
:can't be possibly be finished until 2018.

Not quite sure where I said that. I said it was not simple. If you
think just increasing the size of everything solves the problem you
are being QUITE simplistic in your analysis.

:But building a huge heavy lift vehicle out of shuttle components has
:negible technological risk?

Don't know where you think I said that, either. See what I mean about
running off into the ditch?

:Orbital propellant transfer of storable propellants and even mild
:cryogens such as liquid oxygen and liquid methane is not that hard.

For some rather large and variable value of 'that hard'.

:There are even materials which remain flexible at liquid oxygen
:temperatures, so you could use a simple bladder system. It is just that
:nobody has ever seriously tried to do it.

And usually if it's something nobody has ever tried that seems like an
'obvious' idea, there is a good reason they've never tried it.

--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw

Anthony Frost wrote:

:In message
: Fred J. McCall wrote:
:
: "Jeff Findley" wrote:
:
: Why do the feed lines have to be high pressure?
:
: How does the fuel get into the engine? Little tiny men with buckets?
:
:Pumps that come /after/ the connectors?

And just what makes the fuel want to go to them, again?

--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn

"Fred J. McCall" wrote in message
...
Anthony Frost wrote:

:In message
: Fred J. McCall wrote:
:
: "Jeff Findley" wrote:
:
: Why do the feed lines have to be high pressure?
:
: How does the fuel get into the engine? Little tiny men with buckets?
:
:Pumps that come /after/ the connectors?

And just what makes the fuel want to go to them, again?

Moderate pressure, like what you find in the ET. From the (admittedly old)
NSTS 1988 News Reference Manual, it's pressures are 20-22 psi in the O2 tank
and 32-34 psi in the H2 tank. That would seem to be enough pressure to get
LOX and LH2 moving through the 17 inch diameter feed lines.

Jeff
--
Remove icky phrase from email address to get a valid address.

In message
Fred J. McCall wrote:

Anthony Frost wrote:

In message
Fred J. McCall wrote:

"Jeff Findley" wrote:

Why do the feed lines have to be high pressure?

How does the fuel get into the engine? Little tiny men with buckets?

Pumps that come /after/ the connectors?

And just what makes the fuel want to go to them, again?

Exactly the same process as is used in every other space restartable
engine maybe? Where do you suppose the pumps for the S-IV-B J2 engine
were? You have low pressure lines for as much of the distance between
tank and combustion chamber as possible, and try and arrange the pump
output to feed almost directly into the chamber. OK, it is rocket
science, but it's pretty obvious.

Anthony

In article ,
Fred J. McCall wrote:
:The Russians made it work quite routinely -- untouched by human hands --
:for refueling Mir (and, I believe, ISS) from Progress tankers. There's
:nothing that hard about it.

Depends on what your fuels are and how you get them to the engines.
So what you're proposing are gas-pressurized hypergolic fuel engines
with (relatively) low thrust?

Not necessarily.

Making the pipe bigger, to feed higher-thrust engines, poses no
fundamental problems, especially since (unlike ISS/Mir) there is no
particular need to be able to break the connection again once it's made.

As others have noted, essentially all rockets are gas-pressurized for the
feed from the tank to the engine, and not at high pressures either. The
Saturn V first stage, with engines devouring over 13 tons of fuel per
second, ran its fuel tank at about 25psi and its LOX tank at about 20psi.
All the high-pressure stuff is on the engine.

And there's no particular reason why hypergolics are magic in this
connection -- if anything, it's easier with non-hypergolics, because
they aren't as corrosive.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

Henry Spencer wrote:
In article ,
Fred J. McCall wrote:
:The Russians made it work quite routinely -- untouched by human hands --
:for refueling Mir (and, I believe, ISS) from Progress tankers. There's
:nothing that hard about it.

Depends on what your fuels are and how you get them to the engines.
So what you're proposing are gas-pressurized hypergolic fuel engines
with (relatively) low thrust?

Not necessarily.

Making the pipe bigger, to feed higher-thrust engines, poses no
fundamental problems, especially since (unlike ISS/Mir) there is no
particular need to be able to break the connection again once it's made.

As others have noted, essentially all rockets are gas-pressurized for the
feed from the tank to the engine, and not at high pressures either. The
Saturn V first stage, with engines devouring over 13 tons of fuel per
second, ran its fuel tank at about 25psi and its LOX tank at about 20psi.
All the high-pressure stuff is on the engine.

This is about 1.5 bar. Surely the height of the rocket is more
significant than this. The Shuttle ET oxygen tank is 30m up. Oxygen has
a density of of about 1.14. If the launch acceleration (including
gravity) is 3g, then this adds up to about 10 bar.

OK - it doesn't really help in zero g at start.

On 23 Oct 2005 03:56:21 -0700, "Alex Terrell"
wrote, in part:

But how can you get a descent lunar lander, capable of landing ~10 tons
on the lunar surface, into the 5.2m dimater faring offered by SpaceX
(or Boeing, LM, or the Stick)?

A lunar lander with 8,650 pounds empty weight and 32,500 pounds weight
of crew and propellant (that is, pounds of mass, or weight in Earth's
gravity) or a mass of 10,149 kilograms in the descent stage, and 4,547
kilograms in the ascent stage...

is alleged to have been sent to the Moon within a fairing 21 feet and 8
inches in diameter.

Ah, but that is 6.6 meters, so indeed a narrower fairing is being
proposed. And the mission is proposed to put four astronauts on the
lunar surface, so something bigger than the Apollo Lunar Module is
required - and the pictures being presented do show something which is
clearly quite a bit larger than the LM.

I don't see this as an insuperable obstacle, since a spaceship can be
made tall and narrow; it doesn't have to look like the Lunar Module,
having a round crew module, and a short base.

John Savard
http://home.ecn.ab.ca/~jsavard/index.html
http://www.quadibloc.com/index.html
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In article .com,
Alex Terrell wrote:
Saturn V first stage, with engines devouring over 13 tons of fuel per
second, ran its fuel tank at about 25psi and its LOX tank at about 20psi.
All the high-pressure stuff is on the engine.

This is about 1.5 bar. Surely the height of the rocket is more
significant than this.

Depends on which tank you're thinking of. For the LOX tank it was
significant, especially at high G near the end of the burn. For the
kerosene tank it mattered much less, since that was right above the
engines. But yes, in a big rocket or for a tank that's well above the
engines, hydrostatic pressure can add quite significantly to the tank
pressurization.

The Shuttle ET oxygen tank is 30m up. Oxygen has
a density of of about 1.14. If the launch acceleration (including
gravity) is 3g, then this adds up to about 10 bar.

Launch acceleration is under half that; shuttle acceleration peaks at
3G late in ascent.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

Again, as based upon what hard-science that any such fly-by-rocket
technology has yet to have safely functioned on behalf of a soft moon
landing?

Conditional laws of physics, soft-science and the perpetrated cold-war
of cloak and dagger spookology of continual evidence exclusion doesn't
cut the mustard, now does it?

The new and improved do-everything lander, along with all the necessary
smoke and mirrors is likely to tip the scales at 30 tonnes (5 tonnes
lunar - a rather considerable fuel burn-off by the time it's parked
underneath an extremely dusty lunar deck).
~

Kurt Vonnegut would have to agree; WAR is WAR, thus "in war there are
no rules" - In fact, war has been the very reason of having to deal
with the likes of others that haven't been playing by whatever rules,
such as GW Bush.
Life upon Venus, a township w/Bridge & ET/UFO Park-n-Ride Tarmac:
http://guthvenus.tripod.com/gv-town.htm
The Russian/China LSE-CM/ISS (Lunar Space Elevator)
http://guthvenus.tripod.com/lunar-space-elevator.htm
Venus ETs, plus the updated sub-topics; Brad Guth / GASA-IEIS
http://guthvenus.tripod.com/gv-topics.htm

I'm still not clear what can be done in a 5.2m faring.

T-Space proposal to NASA was for a tall (16.45m) thin (6.7m) lander
with two small floors for habitation, and LH2 and LOX tanks above. This
would have weighed some 35 tons overall. So some 50% bigger than
Falcon, Delta etc.

Are there control problems in landing such a tall craft?

I also raised the dual engine concpet, with the payload in the middle.
However, both engines must work. Can the concept work?

I've seen very little disucssion about "man-rating" lunar landers. This
is probably the riskiest part of the mission, since no escape system
can save the crew from an engine failure after launch or just before
landing. Should NASA use a Spacex "engine-out" capable design, with
five or more engines?