NASA Encounters Problems With Ares 1 Launch Vehicle Design

Greg D. Moore (Strider) wrote:
"Rusty" wrote in message
oups.com...

At one time they could design and build the Saturn V and land on the
moon in 8-years. Now they have trouble designing a rocket that can
carry a capsule to orbit.


True, but money was no object then.



I don't think money is the thing stopping them now. They can't even
design a rocket that works on paper.

Rusty

Pat Flannery wrote:

Is the problem the second stage coming in too heavy, or is there a ISP
problem with it?

Yes and yes. The problem arose when the powerful and efficient SSME was
droipped in favor of the lower-thrust, lower-Isp J-2X. Somethign to do
about SSME's exploding when you try to air-start them (ou'd think that
would have been brought up sooner...). With the lower-performing J-2,
there is a need for more propellant for the same delta-V, and more
propellant needed to overcome greater gravity losses due to lower T/W.
So the 4-segment RSRM had to grow to 5 segments in order to put the
upper stage at roughly the same point on the launch curve.


This should have never gotten to this point, and if they have this sort
of problems with Ares I, God knows how Ares V is going to go wrong, as
that has a lot more variables in its design.

It also has a lot more margin for growth, and was meant to have J-2X's
from the get-go.

Pat Flannery wrote:

They know the thing won't meet specifications even as they propose it,

The Stick as proposed would almost certainly have worked, if the SSME
could have been made air startable. Wasn't ATK that decided to go with
a relatively weeny upper stage engine.

In article ,
Pat Flannery wrote:
This turkey is now adding an albabtross to its own body.

This one throws me.
The extended SRB should have been a easily calculated quantity based on
Shuttle experience.
Is the problem the second stage coming in too heavy, or is there a ISP
problem with it?

The fundamental problem is simply that a single SRB is a lousy first
stage. Lots of thrust, but not great Isp, so the second stage has to do a
lot of the work. Heavy but skinny, so the second stage has to be skinny
too -- a problem for a stage that needs lots of bulky LH2, and also it
limits your engine options because there's no *room* for a multi-engine
cluster in such a narrow stage.

Short of resorting to seriously unconventional configurations, I suspect
the only way to save this turkey would be to ditch the idea of getting to
orbit with two stages -- a perfectly reasonable idea, but not if the first
is a shuttle SRB -- and concede that the Porklauncher IB has to have three
stages, and the second has to be LOX/kerosene rather than LOX/LH2. But my
guess would be that the hydrogen religion is too deeply entrenched by now
for MSFC to swallow that.

I don't think they're going to make this one work without rethinking at
least one major past decision -- something they've never been good at. So
they've got a choice between using an EELV variant for crew launches, or
biting the bullet and going straight to the Porklauncher V. I'd guess
they will do the latter, just because the former smacks much too much of
admitting defeat.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

wrote in message
oups.com...
Greg D. Moore (Strider) wrote:
True, but money was no object then.

I think that it's more to the point that there was a well-defined goal
to meet, and a timescale to follow; that's about the only situation
where government ever gets anything useful done. Without such a goal
you could give them an infinite amount of money and they'd still waste
it all.

Oh, there's a well-defined goal, just no one wants to admit it. It's to
spend the pork evenly.

If NASA were serious about access to space, they'd continue to fly the
Shuttle as old and unsafe as it is and support more private efforts.

"Rusty" wrote in message
oups.com...

Greg D. Moore (Strider) wrote:
"Rusty" wrote in message
oups.com...

At one time they could design and build the Saturn V and land on the
moon in 8-years. Now they have trouble designing a rocket that can
carry a capsule to orbit.


True, but money was no object then.



I don't think money is the thing stopping them now. They can't even
design a rocket that works on paper.


Sure it is. Enough money and you can make a pig fly. :-)

As Scott points out, some of this appears to stem from the descision to not
pursue the SSME air-startable version (money doncha know).

But going back even further it goes back because they want to "save money"
and decided to go with "shuttle derived".


Rusty

Greg D. Moore (Strider) wrote:


As Scott points out, some of this appears to stem from the descision to not
pursue the SSME air-startable version (money doncha know).

But going back even further it goes back because they want to "save money"
and decided to go with "shuttle derived".



And by saving money, we have started down the Shuttle path again....you
know, it'll be so safe, that maybe it doesn't really _need_ that escape
tower.

Pat

Greg D. Moore (Strider) wrote:
"Rusty" wrote in message
oups.com...

Greg D. Moore (Strider) wrote:
"Rusty" wrote in message
oups.com...

At one time they could design and build the Saturn V and land on the
moon in 8-years. Now they have trouble designing a rocket that can
carry a capsule to orbit.


True, but money was no object then.



I don't think money is the thing stopping them now. They can't even
design a rocket that works on paper.


Sure it is. Enough money and you can make a pig fly. :-)

As Scott points out, some of this appears to stem from the descision to not
pursue the SSME air-startable version (money doncha know).

But going back even further it goes back because they want to "save money"
and decided to go with "shuttle derived".



There may be better ways to put together a launch vehicle using
"shuttle derived". Take a look at Nasaspaceflight.com, it's called the
"Direct Shuttle Derivative":

http://forum.nasaspaceflight.com/for...ts=399&start=1


Rusty

Greg D. Moore (Strider) wrote:

But going back even further it goes back because they want to "save money"
and decided to go with "shuttle derived".

People often think that if a Completely Free launch Vehicle appeared,
launched, say, from a runway, that NASA could simply shut down their
other launch ops and have cheap space flight. Not so. Closing down the
VAB, the Shuttle pads, the processing facilities and all the rest will
cost *vast* sums of money. You can't simply turn off the lights and
padlock the doors.

And further down the road, if "shuttle derived" is completely scrapped,
America's ICBM/SLBM fleet is screwed. No RSRM = no ATK-Thiokol = No
Minuteman/Trident missiles.

Henry Spencer wrote:

Heavy but skinny, so the second stage has to be skinny
too -- a problem for a stage that needs lots of bulky LH2, and also it
limits your engine options because there's no *room* for a multi-engine
cluster in such a narrow stage.

Ahem: aerospike or plug cluster. Would fit great.



they've got a choice between using an EELV variant for crew launches...


Which? The Putinsky or the Fireball?