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"Heavy lift: examining the requirements"



 
 
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  #1  
Old March 7th 05, 02:29 PM
Jon S. Berndt
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Default "Heavy lift: examining the requirements"

Taylor Dinerman's article in "The Space Review" this morning raised some
questions for me.

1) It did not appear that the question of infrastructure support was
addressed in the article - only the need for heavy lift. A shuttle derived
heavy lift vehicle keeps getting mentioned, but the part that seems to be
ignored is the cost of the supporting workforce, maintaining productions
lines, etc. I haven't yet seen any plausible situation requiring an HLV to
be launched at regular and frequent intervals that might justify the need
for an HLV. Am I missing something?

2) The idea of using an SRB for a CEV launcher was gently dismissed in the
article with the argument that the SRBs are inherently less safe than liquid
boosters. Having fired successfully 225 out of 226 times, and with the
single failure (SRB burnthrough) being an abortable failure in the CEV
(possibly even an ATO?), I'd suggest that the SRB has earned some respect.
Regardless, the heavy lift forms of the Delta and Atlas that were mentioned
also use SRBs, no? Multiple ones? Now, which launcher might be more
reliable?

Jon



  #2  
Old March 7th 05, 03:32 PM
Jon S. Berndt
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"Rand Simberg" wrote in message

The issue with solids on a manned vehicle isn't the reliability so
much as the ability to shut them down in an abort.


Yes, but that's the case with all of the strap-ons used by Atlas and Delta,
isn't it? That is, none of them can be shut down. So, what makes a Heavy
Atlas or Delta better than an SRB on that account?

Jon


  #3  
Old March 7th 05, 05:22 PM
Jon S. Berndt
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Rand Simberg wrote:

Heavy Delta doesn't use solids.


According to AvWeek (2/21) (_not_ referring to the Delta IV Heavy,
here):

"Any Medium launcher options for CEV would, however, have to be
equipped with more solid rocket boosters than have been flight tested
on either the new Atlas or Delta vehicles. For example, the Atlas V
551/552 medium vehicle with five solids or the Delta IV Medium with six
would be needed to satisfy the minimum performance required to launch
the 20-metric-ton CEV."

Also, the graphic accompanying the AvWeek article, and copied in
Dinerman's TSR article, the heaviest lift versions of the Delta IV
heavy _appear_ to feature strap-on solid boosters.

The point I was trying to make addressed this paragraph in his article:

"While the SRBs have had a pretty good safety record since the
Challenger disaster, they are still inherently less safe than a
liquid-fueled, and thus controllable, rocket. It has been proposed for
both the Delta 4 Medium and for the SRB-derived CEV launch systems that
they have an escape tower similar to the ones used on the Mercury,
Gemini, and Apollo capsules. Such a tower will, in any case, be a part
of any baseline CEV design. A manned system deserves a more robust,
multilayered set of safeguards."

I'm not quite sure I agree with his initial statement above that the
SRBs have (merely) a "pretty good safety record since" Challenger -
they have _all_ achieved mission targets. [I also wonder if there are
ways to effectively terminate thrust in an appropriate way should the
need arise in an abort.] Considering that (according to the original
article in TSR about SRBs used for a CEV launcher) the concept has the
support of some in the astronaut office, and that strap-on SRBs would
be used anyway to supplement an Atlas or Delta Medium launcher for CEV
(according to AvWeek, above), I feel that Dinerman shouldn't have blown
off the concept so casually. Again: which one is safer, a single STS
SRB as a first stage, or a Delta IV or Atlas Medium with several
strap-on SRBs?

Jon

  #4  
Old March 7th 05, 05:25 PM
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March 7, 2005

Another laughable op-ed from Space Review.

There is only one credible heavy lift launch vehicle
architecture : seven SSMEs on a straight stack,
with the cryogenic tank going to orbit with
a second stage, and the engine module
returning to the vicinity of the
launch site in once around
near SSTO.

Anything else is folly.

Thomas Lee Elifritz
http://elifritz.members.atlantic.net

  #5  
Old March 7th 05, 05:54 PM
Rand Simberg
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On Mon, 7 Mar 2005 07:29:16 -0600, in a place far, far away, "Jon S.
Berndt" jsb.at.hal-pc-dot.org made the phosphor on my monitor glow
in such a way as to indicate that:

2) The idea of using an SRB for a CEV launcher was gently dismissed in the
article with the argument that the SRBs are inherently less safe than liquid
boosters. Having fired successfully 225 out of 226 times, and with the
single failure (SRB burnthrough) being an abortable failure in the CEV
(possibly even an ATO?), I'd suggest that the SRB has earned some respect.
Regardless, the heavy lift forms of the Delta and Atlas that were mentioned
also use SRBs, no? Multiple ones? Now, which launcher might be more
reliable?


Atlas yes, Delta no. I don't believe that the Atlas solids are
multi-segment, but I'm not sure.

The issue with solids on a manned vehicle isn't the reliability so
much as the ability to shut them down in an abort.
  #6  
Old March 7th 05, 06:55 PM
Rand Simberg
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On Mon, 7 Mar 2005 08:32:08 -0600, in a place far, far away, "Jon S.
Berndt" jsb.at.hal-pc-dot.org made the phosphor on my monitor glow
in such a way as to indicate that:

"Rand Simberg" wrote in message

The issue with solids on a manned vehicle isn't the reliability so
much as the ability to shut them down in an abort.


Yes, but that's the case with all of the strap-ons used by Atlas and Delta,
isn't it? That is, none of them can be shut down. So, what makes a Heavy
Atlas or Delta better than an SRB on that account?


Heavy Delta doesn't use solids. As to Atlas, that's going to become
an issue if it's to be used as a CEV launcher.
  #7  
Old March 7th 05, 08:50 PM
Rand Simberg
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On 7 Mar 2005 08:22:38 -0800, in a place far, far away, "Jon S.
Berndt" made the phosphor on my monitor glow in such
a way as to indicate that:

Again: which one is safer, a single STS
SRB as a first stage, or a Delta IV or Atlas Medium with several
strap-on SRBs?


Probably the former, though they're both terrible launchers for
putting people into orbit.
  #8  
Old March 7th 05, 11:50 PM
Ed Kyle
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Jon S. Berndt wrote:
... Considering that (according to the original
article in TSR about SRBs used for a CEV launcher) the concept has

the
support of some in the astronaut office, and that strap-on SRBs would
be used anyway to supplement an Atlas or Delta Medium launcher for

CEV
(according to AvWeek, above), I feel that Dinerman shouldn't have

blown
off the concept so casually.


The overall reliability record is good for solid
boosters, but when they've gone, they've gone
nasty in a hurry. I'm thinking of the Titan 34D
in 1986, of a Titan 4 in the early 90s, and of
the Delta II during the late 90s and a Delta
during the late 70s. These all ended in big
detonations. That is why incorporating them into
manned launchers is so difficult.

Again: which one is safer, a single STS
SRB as a first stage, or a Delta IV or Atlas Medium with several
strap-on SRBs?


Single SRB is statistically more reliable. But is
it safer? Probably. On the other hand, an argument
can be made that neither SRB or EELV with solids
would be safer than an all-liquid system.

The problem with this editorial is that it starts out
arguing for a new heavy-lifter, but ends up talking
about whether solid boosters should be used for
manned launches. It would have been better to keep
the two topics separate.

Few will argue that solids shouldn't be used for
unmanned, heavy-lift launchers. That discussion is
about how big heavy-lifters should be - or whether
they're needed at all.

The solids-for-humans question is an entirely different
problem. The astronaut office is going to have a say
in this one. Right now, if sounds like the majority is
saying "no". It could be that we already have the heavy
launcher (EELV Heavy - just augmenting a little can get
it up to 30 tons to LEO) but that a new or derived
all-liquid Medium is needed to boost the 20 ton-ish CEV.
It could be a matter of adding a second RS-68 or RD-180
to the EELV boosters.

- Ed Kyle

  #9  
Old March 8th 05, 12:08 AM
Ed Kyle
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Jon S. Berndt wrote:
Taylor Dinerman's article in "The Space Review" this morning raised

some
questions for me.

... I'd suggest that the SRB has earned some respect.
Regardless, the heavy lift forms of the Delta and Atlas that were

mentioned
also use SRBs, no? Multiple ones? Now, which launcher might be more
reliable?


In addition to the flight safety issues that make
solids a bigger challenge for human launches, there
is a perhaps more important ground safety issue.
Accidents on the ground have killed far more people
than have died in space missions. The presence of
"live" SRBs in the VAB has added cost to the shuttle
program due to safety limitations, for example. A
worst-case fear has long been the unlikely-but-not-
impossible case of an SRB lighting up within the
VAB during processing.

- Ed Kyle

  #10  
Old March 8th 05, 03:12 AM
Murray Anderson
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"Rand Simberg" wrote in message
.. .
On Mon, 7 Mar 2005 07:29:16 -0600, in a place far, far away, "Jon S.
Berndt" jsb.at.hal-pc-dot.org made the phosphor on my monitor glow
in such a way as to indicate that:

2) The idea of using an SRB for a CEV launcher was gently dismissed in

the
article with the argument that the SRBs are inherently less safe than

liquid
boosters. Having fired successfully 225 out of 226 times, and with the
single failure (SRB burnthrough) being an abortable failure in the CEV
(possibly even an ATO?), I'd suggest that the SRB has earned some

respect.
Regardless, the heavy lift forms of the Delta and Atlas that were

mentioned
also use SRBs, no? Multiple ones? Now, which launcher might be more
reliable?


Atlas yes, Delta no. I don't believe that the Atlas solids are
multi-segment, but I'm not sure.

The issue with solids on a manned vehicle isn't the reliability so
much as the ability to shut them down in an abort.


Atlas V SRB's are not segmented and have fixed nozzles.

Murray Anderson


 




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