Comparison of Delta IV, Aries 1 and Atlas V

"M" wrote in message
...
On Dec 15, 1:33 pm, "Jeff Findley"
wrote:
"M" wrote in message

...

Where can I go for a web page that has a direct comparison of the
Aries 1 payload capability versus the Delta iV Heavy and the Altas V?

It's hard to compare the two since they have completely different
missions.
That said, I think NASA's ESAS report looked at them. But people have
been
complaining that this report lacks some of the detils which are
contained in
(missing) appendices:

http://www.nasa.gov/directorates/esm...AS_report.html

I think you want:

Part 6: Launch Vehicles and Earth Departure Stages (6.5 Mb PDF)

Thanks, that is perfect. Just what I was looking for.

Please be aware that this is the "bait" Ares I of the "bait and switch"
which Griffin pulled on all of us. For Ares I, ESAS assumed a four segment
SRB topped with an air started SSME powered upper stage. This has been
replaced with a five segment SRB topped with a much less efficient J-2X
powered upper stage. Performance of Ares I has suffered as its development
has progressed.

Also, I would not trust all of the EELV information in there. It's dated,
at the least.

Jeff
--
"Many things that were acceptable in 1958 are no longer acceptable today.
My own standards have changed too." -- Freeman Dyson

On Dec 16, 9:32*am, "Jeff Findley"
wrote:
"M" wrote in message

...
On Dec 15, 1:33 pm, "Jeff Findley"
wrote:



"M" wrote in message

....

Where can I go for a web page that has a direct comparison of the
Aries 1 payload capability versus the Delta iV Heavy and the Altas V?

It's hard to compare the two since they have completely different
missions.
That said, I think NASA's ESAS report looked at them. But people have
been
complaining that this report lacks some of the detils which are
contained in
(missing) appendices:

http://www.nasa.gov/directorates/esm...AS_report.html

I think you want:

Part 6: Launch Vehicles and Earth Departure Stages (6.5 Mb PDF)

Thanks, that is perfect. Just what I was looking for.

Please be aware that this is the "bait" Ares I of the "bait and switch"
which Griffin pulled on all of us. *For Ares I, ESAS assumed a four segment
SRB topped with an air started SSME powered upper stage. *This has been
replaced with a five segment SRB topped with a much less efficient J-2X
powered upper stage. *Performance of Ares I has suffered as its development
has progressed.

Also, I would not trust all of the EELV information in there. *It's dated,
at the least.

Jeff
--
"Many things that were acceptable in 1958 are no longer acceptable today.
My own standards have changed too." *-- Freeman Dyson

What piqued my interest in that document was the reliability ratings
for manned spaceflight. I have no idea how they figured tehat the Ares
designs were safer than the Delta or Atlas.

"M" wrote in message
...

What piqued my interest in that document was the reliability ratings
for manned spaceflight. I have no idea how they figured tehat the Ares
designs were safer than the Delta or Atlas.



Oh that's easy. It's called wishful thinking.

Seriously, they do a lot of stuff like fault-tree analysis. The problem is
that's only as good as your fault-tree.

For example, ice puncturing the RCC on the shuttle wasn't considered
possible, so wasn't in any fault-tree (as far as I know).

The reality is while you can do a lot of good analysis, until you've flown
any craft a few hundred times, it's still a lot of guess work.

So, we're going to take the shuttle, with a database of 100+ flights (and
200+ successful SRB flights) and replace it with a "safer" vehicle with an
all new SRB design. Somehow a brand new vehicle will be safer on day one.

"Greg D. Moore (Strider)" wrote in message
...
So, we're going to take the shuttle, with a database of 100+ flights (and
200+ successful SRB flights) and replace it with a "safer" vehicle with an
all new SRB design. Somehow a brand new vehicle will be safer on day one.

And existing EELV designs aren't considered as safe because they had
teething problems early on in their flight history. Heck, Ares I is having
more than teething problems and there hasn't been a single test flight! All
of the problems are being hand-waved away by NASA's PR machine as normal
problems to be solved during the development cycle.

Ares I's thrust oscillation problems sure seem to be unique to the
convoluted Ares I design. As far as I know, this will be the first time one
big SRB has been used as a first stage with a liquid fueled second stage in
a (almost) two stage to orbit launch vehicle. Now add to that the first
time such a vehicle has been used to launch astronauts and it's no wonder
why there are so many people who are a bit worried that Ares I may not live
up to its promises.

Also add to that the underperformance of Ares I which has forced Orion's
requirements to be constantly changing, and this thing is now driving
Orion's design. It's unbelievable.

This is not how Apollo/Saturn went. Apollo/Saturn was successful only
because von Braun did *not* believe the mass estimates of the spacecraft
people and he put a pretty huge performance margin into the design of Saturn
V. This time around, it's the inadequacies of the launch vehicle that are
driving the spacecraft design. To me, that's a recipe for "Epic Fail!" as
they say on the Internets. ;-)

Jeff
--
"Many things that were acceptable in 1958 are no longer acceptable today.
My own standards have changed too." -- Freeman Dyson

*From:* "Greg D. Moore \(Strider\)"
*Date:* Tue, 16 Dec 2008 23:50:54 -0500

"M" wrote in message

m...

What piqued my interest in that document was the reliability ratings
for manned spaceflight. I have no idea how they figured tehat the
Ares
designs were safer than the Delta or Atlas.



Oh that's easy. It's called wishful thinking.

Seriously, they do a lot of stuff like fault-tree analysis. The
problem is that's only as good as your fault-tree.

For example, ice puncturing the RCC on the shuttle wasn't
considered possible, so wasn't in any fault-tree (as far as I know).

The reality is while you can do a lot of good analysis, until
you've flown any craft a few hundred times, it's still a lot of
guess work.

So, we're going to take the shuttle, with a database of 100+
flights (and 200+ successful SRB flights) and replace it with a
"safer" vehicle with an all new SRB design. Somehow a brand new
vehicle will be safer on day one.

With the shuttle, loss of the mission also almost always means loss of the
crew. At least Ares has a launch escape system worthy of the name.

wrote in message
...

With the shuttle, loss of the mission also almost always means loss of the
crew. At least Ares has a launch escape system worthy of the name.

Is it?

There's at least one scenario as I recall where if the SRB detonates, the
escape system ain't worth it's weight in gold.

And note, the next most flown manned system has used its launch escape
system, but its two fatal flights (which match the Shuttle's record)
occurred well after it would have been useful. And the most recent
ballistic landings are not a good sign for Soyuz either.

The fact is, all manned launch vehicles are very low down on the learning
due to low launch rates. That means we're only making guesses (granted,
some of them more educated than others), but they are still guesses.


And Ares I seems to have taken the worst components from STS and used those.


--
Greg Moore
Ask me about lily, an RPI based CMC.

*From:* "Greg D. Moore \(Strider\)"
*Date:* Wed, 17 Dec 2008 16:59:24 -0500

wrote in message
...

With the shuttle, loss of the mission also almost always means
loss of the
crew. At least Ares has a launch escape system worthy of the name.

Is it?

There's at least one scenario as I recall where if the SRB
detonates, the escape system ain't worth it's weight in gold.

What's that? Can the SRB actually explode rather than just develop a leak
followed by a wild course divergence?


And note, the next most flown manned system has used its launch
escape system, but its two fatal flights (which match the Shuttle's
record) occurred well after it would have been useful. And the
most recent ballistic landings are not a good sign for Soyuz either.

The one fatal Apollo accident couldn't be prevented by the launch escape
system either, but surely a simple capsule can be in principle a lot safer
than the immensely complex shuttle.



The fact is, all manned launch vehicles are very low down on the
learning due to low launch rates. That means we're only making
guesses (granted, some of them more educated than others), but they
are still guesses.

That's all you can do at the end of it. However Ares I does tend to be
much more at the KISS end of the spectrum. OK, there is less redundancy
but that means there's less to go wrong too.



And Ares I seems to have taken the worst components from STS and
used those.

The SRBs have worked 199 times out of 200. IMO the escape system takes
away a good portion of the risk of sitting on top of a rocket that can't
be shut down once started, although obviously the escape system has to
work...

wrote:
What's that? Can the SRB actually explode rather than just develop a leak
followed by a wild course divergence?


It's never happened on any Shuttle launch or SRB test firing, but it's
possible for it to blow off its top dome with fatal results to the Orion.
To make that happen would require that the pressure inside the casing
went way too high; either by cracking of the propellant grain causing
too much burning area, or something plugging the central bore of the
grain or the engine nozzle.

Pat

wrote in message
...
*From:* "Greg D. Moore \(Strider\)"
*Date:* Wed, 17 Dec 2008 16:59:24 -0500


There's at least one scenario as I recall where if the SRB
detonates, the escape system ain't worth it's weight in gold.

What's that? Can the SRB actually explode rather than just develop a leak
followed by a wild course divergence?

Correct. See Pat's response.




And note, the next most flown manned system has used its launch
escape system, but its two fatal flights (which match the Shuttle's
record) occurred well after it would have been useful. And the
most recent ballistic landings are not a good sign for Soyuz either.

The one fatal Apollo accident couldn't be prevented by the launch escape
system either, but surely a simple capsule can be in principle a lot safer
than the immensely complex shuttle.

Why? You still need life support? You still need RCS.

People often point to the difference between wings and parachutes. Yet
there the record is about the same. One failure of a parachute system and
one of a winged system.

In addition though, we've had what, 3 now ballastic entries of the most
recent Soyuz design. One of them looks like it was damn close to a fatal
landing. All of them landing hundreds of miles off course.





The fact is, all manned launch vehicles are very low down on the
learning due to low launch rates. That means we're only making
guesses (granted, some of them more educated than others), but they
are still guesses.

That's all you can do at the end of it.

Wrong. The Boeing 787 design has already had more flights than the space
shuttle. The way to safety is to get your way deep into that learning
curve. And by the time you step foot on a 787, that particular airframe has
probably made more flights than any orbitor. And definitely more flights
than any single Soyuz.

However Ares I does tend to be
much more at the KISS end of the spectrum. OK, there is less redundancy
but that means there's less to go wrong too.

KISS? Active dampening to absorb the thrust oscillations? Doesn't sound
very KISS to me. Adding a whole new roll control system, etc? Hardly KISS.




And Ares I seems to have taken the worst components from STS and
used those.

The SRBs have worked 199 times out of 200.

Right, and the SRB design for Ares I is fairly different. 5 segments
instead of 4. Different grain. Different pour pattern.

So on flight 1 we're back to "0" on the learning curve.


IMO the escape system takes
away a good portion of the risk of sitting on top of a rocket that can't
be shut down once started, although obviously the escape system has to
work...

Right, you've taken the worst aspect of the SRB design and now make it
require a way around it.





--
Greg Moore
Ask me about lily, an RPI based CMC.

"M" wrote in message
...
What piqued my interest in that document was the reliability ratings
for manned spaceflight. I have no idea how they figured tehat the Ares
designs were safer than the Delta or Atlas.

It was, and still is, a "paper" vehicle, so the predicted reliability does
not have to have any relationship to actual demonstrated reality. For Ares
I, this is especially true when the heritage four segment SRB (only slightly
modified from the shuttle SRB) was later replaced with a new five segment
SRB. On top of that, for Ares V, they're exploring things like changing the
propellant formula and changing the SRB casings from steel (heritage shuttle
design) to composites (never flown on the shuttle). Ares V will be an all
new design using all new hardware. Others have commented, partly in jest,
that only the ET's spray on foam insulation will be the same.

This is a bait and switch of the highest order. The shuttle derived parts
of Ares have been thrown out the window. Even much of the shuttle ground
infrastructure will have to be upgraded or replaced due to the sweeping
changes made to Ares V (e.g. the size of the core is larger in diameter than
the shuttle ET).

I sincerely hope the Obama administration puts the floundering Ares program
out of its misery and demands that Orion be launched on EELV's, just as OSP
was supposed to be launched.

Jeff
--
"Many things that were acceptable in 1958 are no longer acceptable today.
My own standards have changed too." -- Freeman Dyson