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CEV PDQ



 
 
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  #41  
Old May 9th 05, 10:57 PM
Rand Simberg
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On Mon, 09 May 2005 13:17:46 -0500, in a place far, far away, Pat
Flannery made the phosphor on my monitor glow in
such a way as to indicate that:

Also if we go over to a unmanned system, we don't have to meet the
stringent requirements for SRB safety, so we can probably reuse more SRB
segments.


So we don't care if we lose a billion-dollar payload? Or the price of
relaunching?

This notion of reliability being of no relevance for unmanned systems
gets tiresome.
  #42  
Old May 10th 05, 12:20 AM
Rand Simberg
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On Mon, 09 May 2005 14:49:40 -0500, in a place far, far away, Pat
Flannery made the phosphor on my monitor glow in
such a way as to indicate that:

Or subcool the propellants and insulate the tanks properly...


Still, how long would one have to get it all stuck together? Days or weeks?


Months, by some analyses.

The Soviet's did a stage (Block D) that used an insulation sunshade for
it LOX/Kerosene propellant on Proton-Zond and N-1:
http://www.myspacemuseum.com/l1s_2.jpg
But do we have any experience with this sort of thing?


Not that I'm aware of, at least operationally, but there's been a lot
of technology development in this area.

The closest we
came was the canceled Shuttle boosted Centaur stage.


Which wasn't designed for long-duration storage.
  #43  
Old May 10th 05, 12:21 AM
Rand Simberg
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On Mon, 09 May 2005 15:09:50 -0500, in a place far, far away, Pat
Flannery made the phosphor on my monitor glow in
such a way as to indicate that:


If we actually intend to do a manned Mars mission we are going to need
a heavy lift vehicle of some sort,


Many believe this. That doesn't render it a fact.
  #44  
Old May 10th 05, 12:23 AM
Rand Simberg
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On Mon, 09 May 2005 15:00:31 -0500, in a place far, far away, Pat
Flannery made the phosphor on my monitor glow in
such a way as to indicate that:



Rand Simberg wrote:

So we don't care if we lose a billion-dollar payload? Or the price of
relaunching?

This notion of reliability being of no relevance for unmanned systems
gets tiresome.



Not to the same degree... for a manned launch you want around 99+%
reliability if at all possible; for unmanned you can settle for 95%-97%
(like most operational expendable rockets have) and realize that the
loss of a couple in 100 launches will be more than offset by the money
you save in not having to design and build to quite the high standards
required to get to 99+%. It's where those last few percentage points
start coming into play that you run into lots of added dollars- and
extra equipment weight to overbuild things to make critical things
redundant. Which cuts into your payload weight, and therefore ups your
launch price per pound for large numbers of launches.


That's an interesting theoretical argument, but in practice, what do
you think that Thiokol would do differently in manufacturing a motor
for an unmanned launch that they do for a manned one?
  #45  
Old May 10th 05, 12:24 AM
Rand Simberg
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On Mon, 9 May 2005 11:41:59 -0400, in a place far, far away, "Scott
Hedrick" made the phosphor on my monitor glow in
such a way as to indicate that:


"Henry Spencer" wrote in message
...
Generally speaking, you cannot get a truly low-cost process by paring bits
off a high-cost one.


It ought to be a good way to use any leftover tanks and SRBs, rather than
using them as museum pieces.


Only if the development costs don't swamp any potential cost
savings...

I don't see how spending the money to develop a new vehicle that can
only be flown a few times because it's using up a finite amount of
leftover parts can make any kind of sense.
  #46  
Old May 10th 05, 01:56 AM
Ed Kyle
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Pat Flannery wrote:
Ed Kyle wrote:

(An aside - I once watched a hydrogen fire
burning on Pad 39A after an abort. The flames
licked right up the side of the orbiter (Discovery
I think it was - with crew on board and ET fueled)
discoloring the exterior. It burned for awhile and
was more than a little uncomfortable to watch).

Does anyone have more info on this incident?


It was STS-41D (first flight of Discovery) on June 26, 1984,
after an "RSLS" abort. Crew was:

Henry W. Hartsfield, Jr., Commander
Michael L. Coats, Pilot
Judith A. Resnik, Mission Specialist 1
Steven A. Hawley, Mission Specialist 2
Richard M. Mullane, Mission Specialist 3
Charles D. Walker, Payload Specialist 1

Discovery didn't get off the ground until September.
Here is a link with a description. The fire burned for
20 minutes!

"http://yarchive.net/space/shuttle/launch_abort.html"

- Ed Kyle

  #47  
Old May 10th 05, 02:04 AM
Ed Kyle
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Phil Fraering wrote:
On Mon, 09 May 2005 11:53:20 -0700, Ed Kyle wrote:

...Both Delta IV and Atlas V have the same problems
when it comes to CEV adaptation. Neither can handle
a projected 20 ton CEV without core booster
augmentation, (solid or liquid strap-on boosters).
But NASA is either going to have to live with
this or go shuttle-derived. I don't see the U.S.
government (at least not the current one) coming up
with the billions it will take to develop a new,
more powerful core rocket just to launch CEV a few
times a year.

- Ed Kyle


This is my second try at posting this.

To me this brings to mind another question: Does the CEV
need to be twenty tons?

Soyuz was designed in the 60's and weighs seven metric
tons.


Kliper, proposed as a Soyuz replacement, but able to carry
up to six, is projected to weigh 13-15 tons, but its
propulsion system will not be recovered (Lockheed has
proposed to make the CEV hardware recoverable). NASA has
listed the maximum liftoff mass of CEV, including escape
systems and fairings that would not go into orbit, to
be 20 tons. CEV doesn't have to weigh that much, of
course.

- Ed Kyle

  #48  
Old May 10th 05, 02:19 AM
Neil Gerace
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" wrote in
message ups.com...

the DIV has to fly an odd trajectory (due to structural
concerns) that means that there are points in the ascent when abort is
*not* survivable.


Is that bad? Seems to me that it happens to STS as well.


  #49  
Old May 10th 05, 02:22 AM
Herb Schaltegger
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On Mon, 9 May 2005 16:55:21 -0500, Phil Fraering wrote
(in article ):

I think at one point in the mid-90's we were discussing this here, and it
came up that over the decade previous to then, the space insurance
industry had gone bankrupt.

TWICE.


Before you start feeling too bad for any segment of the insurance
industry, realize that there's something called "reinsurance" and it's
there for just such an eventuality. If the "space insurance industry"
(*) has "gone bankrupt" (**) it's because they weren't charging high
enough premiums to cover their losses and couldn't make up the
shortfall in the financial markets.

(*) There's no such animal; they major world insurers are all arms,
tentacles and pseudopods of a handfull of multinational conglomerates.

(**) "Bankrupt" is not the right term for the financial services
industry, at least not how it's commonly used in everyday speech.
Typically, insurance concerns which have liabilities exceeding assets
go into "receivership."

--
Herb Schaltegger, GPG Key ID: BBF6FC1C
"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety." - Benjamin Franklin, 1759
http://www.individual-i.com/

  #50  
Old May 10th 05, 02:38 AM
Mary Pegg
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Pat Flannery wrote:
The problem here is that you need a minimum of four EELV launches to
land a man on the Moon if the LockMart design is chosen:


If they put people on the moon again, I'll bet some of them will be women.

cue debate about extra costs involved in providing more privacy
than was available to Apollo crew

--
Semper in faecibus sumus, sole profunditas quae variat.
 




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