NASA Encounters Possible Problems With Crew Launch Vehicle Design

"John Doe" wrote in message
...

NASA may have had great ideas and concepts, but
when push comes to shove, the time constraints will
force it to focus only on the fastest solution, not
necessarily the best solution.

In the current circumstance the fastest solution probably actually is
the best solution.

Much shorter payback periods are required and the development process is
currently far too slow. In addition to a lack of timely results, this
leads to a ballooning of bureaucracy and costs. A design that can not be
developed quickly is probably a wrong design. Small steps help prevent
big mistakes - something NASA is not noted for.

Low cost, high performance and high reliability requires evolutionary
competition - a race. Design and build rate is every bit as critical as
flight rate. Once every thirty years is almost going backwards.

Pete.

Maybe this is a good thing. There's not a chance in Hell that a brand
new launcher will be ready by 2010, so if Congress is serious about the
date this will compel the use of an existing launcher (read: EELV).
NASA will be doing all it can just to have a crew capsule ready by then.

richard schumacher wrote:
Maybe this is a good thing. There's not a chance in Hell that a brand
new launcher will be ready by 2010, so if Congress is serious about the
date this will compel the use of an existing launcher (read: EELV).
NASA will be doing all it can just to have a crew capsule ready by then.

I agree with your position on using the EELV as the launch vehicle for
the CLV. I'm curious as to your opinion as to the scope of work to man
rate the EELV.

In article AWCzf.499940$084.50286@attbi_s22,
John Crichton wrote:
...I'm curious as to your opinion as to the scope of work to man
rate the EELV.

It depends greatly, nay overwhelmingly, on whether NASA has decided that
it *wants* to use an EELV.

Back in the pre-Griffin days when that was actually the plan, it was
thought to be no big deal. (And there is no reason why it *should* be,
given that NASA man-rated Titan II for Gemini with no great difficulty.)

But when upper management decided that a shuttle derivative was preferred,
man-rating an EELV quite suddenly became a difficult and costly task -- so
daunting that a mostly-new shuttle-derived launcher seemed preferable.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

In article uYzzf.499021$084.16084@attbi_s22,
George wrote:
The most devastating lethal accident with a SRB would be a SRB or SRB
segment going off during ground handling... But nobody seems to care.

Really? No one cares, eh? Do you know of even one such incident occurring
regarding SRBs in the U.S. space program? No?

Yes -- there was a spectacular accident at Edwards some years ago when a
Titan SRB segment was accidentally dropped, during stacking operations on
a test stand I think. Fortunately, it fell on the ground rather than on
the stand, and there was nobody nearby.

The consequences of a similar accident inside the VAB don't bear thinking
about.

The fact is that SRBs are orders of magnitude safer than a liquid-propelled
craft.

Somebody's been drinking too much of the ATK kool-aid. :-)

One look at the sad history of Titan IV should dispel that illusion.

You can argue about relative failure rates, but they most certainly
*aren't* different by orders of magnitude... and solid failures are almost
always catastrophic, while liquid failures are usually benign -- the thing
refuses to light, or stops early, but it doesn't go BOOM. Solids mostly
go BOOM when they go bad.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

In article ,
Jeff Findley wrote:
Sources report problems have been encountered in designing an
expendable version (RS 25) of the current SSME...

Not a big surprise. The SSME was never designed to be air started, so and
air startable SSME is really an engine development program in and of itself,
partly due to the complex startup procedure...

Interestingly enough, when Rocketdyne looked at this some years ago, they
concluded that an air start for the SSME wasn't a big deal, requiring only
minor changes.

I wonder whether they were just over-optimistic back then, or whether the
RS-25 effort was quietly trying to bundle in other changes -- perhaps cost
reduction, the SSME not being exactly a cheap engine to throw away -- and
got snagged by that.

In other words, a brand new upper stage, powered by an engine NASA hasn't
used for decades, sitting on top of a new 5 segment SRB, which NASA has
never flown. The "off the shelf" components are getting less and less "off
the shelf". EELV's are sounding better every day, except for people who
would be laid off if the shuttle isn't replaced by a shuttle derived
vehicle.

Indeed so.

And if they can't build even the Porklauncher IB in a straightforward
fashion, the mind boggles at what the Porklauncher V is going to require.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

John Crichton wrote:

richard schumacher wrote:
Maybe this is a good thing. There's not a chance in Hell that a brand
new launcher will be ready by 2010, so if Congress is serious about the
date this will compel the use of an existing launcher (read: EELV).
NASA will be doing all it can just to have a crew capsule ready by then.

I agree with your position on using the EELV as the launch vehicle for
the CLV. I'm curious as to your opinion as to the scope of work to man
rate the EELV.

Delta IV Medium - a capsule, launch escape tower and a ladder.

http://cosmic.lifeform.org

Henry Spencer wrote:
But when upper management decided that a shuttle derivative was preferred,
man-rating an EELV quite suddenly became a difficult and costly task -- so
daunting that a mostly-new shuttle-derived launcher seemed preferable.

I realise that "man rated" has many implications for the pressurised
crew compartment.

What are the requirements for the launcher that are not already there by
default, even for cargo launches ?

What sort of hardware/design does Delta-4 lack ? (assuming all the
navigation/command/control would be in the CEV capsule and which would
be mad rated no matter what the launcher would be).

Or would man rating Delta 4 really be the space equivalent of ISO-9000,
a process to fully document the process to ensure quality control ?

"Henry Spencer" wrote in message
...
In article uYzzf.499021$084.16084@attbi_s22,
George wrote:
The most devastating lethal accident with a SRB would be a SRB or SRB
segment going off during ground handling... But nobody seems to care.

Really? No one cares, eh? Do you know of even one such incident
occurring
regarding SRBs in the U.S. space program? No?

Yes -- there was a spectacular accident at Edwards some years ago when a
Titan SRB segment was accidentally dropped, during stacking operations on
a test stand I think. Fortunately, it fell on the ground rather than on
the stand, and there was nobody nearby.

The consequences of a similar accident inside the VAB don't bear thinking
about.

Umm, but no one was hurt. You don't even have one dot on your curve. So
how does this apply to the argument that "The most devastating lethal
accident with a SRB would be a SRB or SRB segment going off during ground
handling"? Handling ANY fuel is a dangerous propsition. SRBs are no
exception. But they are vastly more safe than liquid fuels, expecially
liquid oxygen and liquid hydrogen. How many accidents have occurred
handling these intrinsically unsafe fuels? A lot, I will wager.

The fact is that SRBs are orders of magnitude safer than a
liquid-propelled
craft.

Somebody's been drinking too much of the ATK kool-aid. :-)

One look at the sad history of Titan IV should dispel that illusion.

http://science.ksc.nasa.gov/shuttle/...s_Bow_Wave.pdf

http://64.233.167.104/search?q=cache...failures&hl=en

http://www.globalsecurity.org/space/..._iv-20_sum.htm

Umm, none were apparently related to the solid rocket fuel, as far as I can
tell, which was my point. And as we know, the Shuttle SRBs are not the
Titan SRBs. There has been one failure related to the Shuttle SRBs (with
catastrophic consequences). That problem (a poorly designed O-ring joint
that was subjected to temperatures beyond its design tolerances prior to
launch) was fixed, and there have been no failures since. But my point is
that solid rocket fuel itself is intrisically more safe to handle than is
liquid rocket fuel, because of its low volatility and reactivity relative
to liquid fuel.

You can argue about relative failure rates, but they most certainly
*aren't* different by orders of magnitude... and solid failures are
almost
always catastrophic, while liquid failures are usually benign -- the
thing
refuses to light, or stops early, but it doesn't go BOOM. Solids mostly
go BOOM when they go bad.

Benign? As I recall, the Challenger SRB failure did not result in a "boom"
with regard to the SRBs. However, the failure of one of the SRB O-rings
DID result a burn through of the solid propelant gases, which caused the
liquid fuel to go "boom". I can also point you to the catastrophic failure
of one of the old Liquid fueled ICBMS (I believe it was the liquid stage of
a Titan) when it exploded in its silo, and threw its warhead out onto the
midwest countryside. And finally, the Soviets' own expereince with liquid
fueled rockets has been less than 'stellar', as was our own early
experiences with them.

Of course, a solid booster can not be shut down if there is a problem. But
how many times has that problem happened with the Space Shuttle (aside from
Challenger)? None, as far as I know.

George

George wrote:

Handling ANY fuel is a dangerous propsition. SRBs are no
exception. But they are vastly more safe than liquid fuels, expecially
liquid oxygen and liquid hydrogen. How many accidents have occurred
handling these intrinsically unsafe fuels? A lot, I will wager.

Another of George's scientific methods.

SRBs are vastly more inefficient, heavy, expensive, time consuming.

Somebody's been drinking too much of the ATK kool-aid. :-)

But my point is
that solid rocket fuel itself is intrisically more safe to handle than is
liquid rocket fuel, because of its low volatility and reactivity relative
to liquid fuel.

And more expensive, more time consuming, heavier, and less efficient.

Consider the reaction byproducts, the pollution. That never bothers you.

Benign? As I recall, the Challenger SRB failure did not result in a "boom"
with regard to the SRBs. However, the failure of one of the SRB O-rings
DID result a burn through of the solid propelant gases, which caused the
liquid fuel to go "boom".

Right, it was all the hydrogen's fault, the SRBs had nothing to do with it.

Let me guess, you're a GEOLOGIST, aren't you.

I really need a network

plonk

http://cosmic.lifeform.org