Thrust Oscillation Issue Threatens Ares I Design, Aviation Week

Michael Gallagher wrote:

On the other hand, the guys at NASA were the ones who found the
problem in the first place.

That's ridiculous, the entire physics community knew about this problem
from day 1. We didn't think anybody was dumb enough to actually try it.

After late September of 2005, I ran a blog which clearly pointed out
these problems, surely you must remember it. You did read it, right?

http://cosmic.lifeform.org (offline)

I guess you didn't read it.

bob haller safety advocate wrote:
On Feb 2, 1:12�pm, kT wrote:
Michael Gallagher wrote:
On the other hand, the guys at NASA were the ones who found the
problem in the first place.
That's ridiculous, the entire physics community knew about this problem
from day 1. We didn't think anybody was dumb enough to actually try it.

After late September of 2005, I ran a blog which clearly pointed out
these problems, surely you must remember it. You did read it, right?

http://cosmic.lifeform.org (offline)

I guess you didn't read it.

is it possible nasa intentially chose a design they knew wouldnt work?

It's well known that they are hostile to civilian space flight.

You figure it out.

The real reason for not being too bothered if it worked or not was that the
President will be different well before any flight and nobody wants to waste
too much money.

Contrast the dodgy way the design was chosen with the efforts being put
into the Shuttle and station fixes. I think they know that these quests for
knowledge and their outcomes will be worth more for whatever comes next in
the new administration.

Kind of generic reliability concerns etc.

Brian

--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email:
__________________________________________________ __________________________________________________ __________


"bob haller safety advocate" wrote in message
...
On Feb 2, 1:12?pm, kT wrote:
Michael Gallagher wrote:
On the other hand, the guys at NASA were the ones who found the
problem in the first place.

That's ridiculous, the entire physics community knew about this problem
from day 1. We didn't think anybody was dumb enough to actually try it.

After late September of 2005, I ran a blog which clearly pointed out
these problems, surely you must remember it. You did read it, right?

http://cosmic.lifeform.org(offline)

I guess you didn't read it.

is it possible nasa intentially chose a design they knew wouldnt work?
just to keep the shuttle flying longer..........

On the other hand, the guys at NASA were the ones who found the
problem in the first place.



Is this similar to the pogo problem the early Saturn rockets had?

In any event, the best time to find big problems is early, before time
and effort and money is spent.

"robert casey" wrote in message
...


On the other hand, the guys at NASA were the ones who found the
problem in the first place.



Is this similar to the pogo problem the early Saturn rockets had?

Not really. Saturns had liquid fueled engines so the pogo problem could be
solved relatively easily. The thrust oscillation issue with large solid
rocket boosters is an entirely different problem.

In any event, the best time to find big problems is early, before time and
effort and money is spent.

While true, some problems can't be solved. One thing that Ares I doesn't
have is a lot of margin to throw mass at a problem like this. Orion is
pretty much at the limits of what Ares I can launch, so any changes needed
to solve this problem had better have little impact to the mass of Ares I.
With large vibration type problems, quite a bit of mass is sometimes what
you need to throw at the problem.

Jeff
--
A clever person solves a problem.
A wise person avoids it. -- Einstein

"Jeff Findley" wrote in message
...

"robert casey" wrote in message
...


On the other hand, the guys at NASA were the ones who found the
problem in the first place.



Is this similar to the pogo problem the early Saturn rockets had?

Not really. Saturns had liquid fueled engines so the pogo problem could
be solved relatively easily. The thrust oscillation issue with large
solid rocket boosters is an entirely different problem.

In any event, the best time to find big problems is early, before time
and effort and money is spent.

While true, some problems can't be solved. One thing that Ares I doesn't
have is a lot of margin to throw mass at a problem like this. Orion is
pretty much at the limits of what Ares I can launch, so any changes
needed to solve this problem had better have little impact to the mass of
Ares I. With large vibration type problems, quite a bit of mass is
sometimes what you need to throw at the problem.

Jeff
--
A clever person solves a problem.
A wise person avoids it. -- Einstein

I'm certainly not a rocket scientist by any stretch, but it would appear
that some type of dampening needs to occur between the solid rocket motors
and the Orion. Can this be accomplished by placing the Orion in some kind
of dampening skid, possiibly made of vulcanized rubber? It might even
solve the problem of what to do with all those defective Firestone tires.
:-)

George

George wrote:
I'm certainly not a rocket scientist by any stretch, but it would appear
that some type of dampening needs to occur between the solid rocket motors
and the Orion. Can this be accomplished by placing the Orion in some kind
of dampening skid, possiibly made of vulcanized rubber? It might even
solve the problem of what to do with all those defective Firestone tires.
:-)

It would be best if the dampening occurred between the SRB stage and the
LOX/LH2 upper stage.
If these were hooked together by warren truss girders the way the
Russians attach the upper stage of the Soyuz booster to the basic R-7
lower stage, it might be possible to incorporate some sort of shock
absorbers into that support structure and isolate the vibrations created
by the SRB from the whole upper part of the vehicle... this would be
ideal, as you don't want high frequency vibrations going through the
lightly built cryogenic upper stage either.

Pat

"Pat Flannery" wrote in message
...


George wrote:
I'm certainly not a rocket scientist by any stretch, but it would appear
that some type of dampening needs to occur between the solid rocket
motors and the Orion. Can this be accomplished by placing the Orion in
some kind of dampening skid, possiibly made of vulcanized rubber? It
might even solve the problem of what to do with all those defective
Firestone tires. :-)

It would be best if the dampening occurred between the SRB stage and the
LOX/LH2 upper stage.
If these were hooked together by warren truss girders the way the
Russians attach the upper stage of the Soyuz booster to the basic R-7
lower stage, it might be possible to incorporate some sort of shock
absorbers into that support structure and isolate the vibrations created
by the SRB from the whole upper part of the vehicle... this would be
ideal, as you don't want high frequency vibrations going through the
lightly built cryogenic upper stage either.

Pat

Good points. I wasn't sure where exactly the isolation should occur, but
isolating the SRBs from the rest of the stack altogether seems to me to be
the best remedy. Good idea. I like the truss girder idea. Probably
cheaper and less impact on mass as well. Possibly they could be
constructed from vibration-absorbing composite materials. I think the
second vehicle from the left in the drawing at the link below may be
something like what you are describing:

http://www.friends-partners.org/part...l/lktksles.jpg

Or possibly something like this:

http://www.friends-partners.org/part...r/r7ur5cut.gif

I believe the Soviet N-1 also used such trusses.

George

George wrote:
"Pat Flannery" wrote in message
...

George wrote:

I'm certainly not a rocket scientist by any stretch, but it would appear
that some type of dampening needs to occur between the solid rocket
motors and the Orion. Can this be accomplished by placing the Orion in
some kind of dampening skid, possiibly made of vulcanized rubber? It
might even solve the problem of what to do with all those defective
Firestone tires. :-)

It would be best if the dampening occurred between the SRB stage and the
LOX/LH2 upper stage.
If these were hooked together by warren truss girders the way the
Russians attach the upper stage of the Soyuz booster to the basic R-7
lower stage, it might be possible to incorporate some sort of shock
absorbers into that support structure and isolate the vibrations created
by the SRB from the whole upper part of the vehicle... this would be
ideal, as you don't want high frequency vibrations going through the
lightly built cryogenic upper stage either.

Pat


Good points. I wasn't sure where exactly the isolation should occur, but
isolating the SRBs from the rest of the stack altogether seems to me to be
the best remedy.

On Ares I (the one with the vibration problem) there's only a single SRB
forming the first stage:
http://images.spaceref.com/news/2006/ares.1.chart.jpg

Good idea. I like the truss girder idea. Probably
cheaper and less impact on mass as well. Possibly they could be
constructed from vibration-absorbing composite materials. I think the
second vehicle from the left in the drawing at the link below may be
something like what you are describing:

http://www.friends-partners.org/part...l/lktksles.jpg


That's the lunar landing stage for the Chelomei UR-700 direct ascent
manned Moon mission from the 1960's USSR.
In that case the truss girders are to cut weight down rather than using
a solid cylindrical structure to join the two bottom stages to the
landing section of the spacecraft.
On the Soyuz core stage (which bears a uncanny resemblance to Ares 1
once the four strap-on boosters are jettisoned):
http://esamultimedia.esa.int/images/...2A_08182_H.jpg
The upper stage is attached by the girders so that its engines can be
ignited while still attached to the core stage, and their exhaust can
escape from the spaces between the girders prior to separation of the
upper stage. In this manner there are no ullage rockets needed to keep
the propellants in the upper stage seated during staging, as the rocket
is under trust during the whole ascent (we used the same technique on
the Titan II). Some Russian model rocket builders did a detailed metal
model of the truss frame that holds the core and upper stages of a Soyuz
boosters together, so you can see it's structural design:
http://www.rocket.aero/soyuz2big.jpg http://www.rocket.aero/soyuz4big.jpg
If you look to the right of the second photo, that's the end that hooks
to the upper stage. If you were to install some sort of vibration
dampening devices in those short cylinders that attach to the upper
stage base ring (shown detached in the first photo)
that would allow the vibrations to be isolated to the first stage.

Or possibly something like this:

http://www.friends-partners.org/part...r/r7ur5cut.gif

I believe the Soviet N-1 also used such trusses.


Yes, that shows Chelomei's Proton (UR-500), and both it and Korolev's
N-1 used the same "engine firing while stages still attached" technique
as the Soyuz Korolev designed. It was a very common feature on Soviet
space boosters and missiles.
I don't know if any had any sort of vibration dampening system
incorporated into the attachment trusses.
Its use on the RT-2 (NATO code name SS-13 Savage)
http://www.fas.org/nuke/guide/russia/icbm/rt-2.htm
Is interesting, as this was a solid-fueled ICBM... so it wouldn't need
any ullage rockets on it.
In this case one can wonder if its primary use was some sort of
vibration dampening.

Pat

George wrote:


"Pat Flannery" wrote in message
...


George wrote:
I'm certainly not a rocket scientist by any stretch, but it would appear
that some type of dampening needs to occur between the solid rocket
motors and the Orion. Can this be accomplished by placing the Orion in
some kind of dampening skid, possiibly made of vulcanized rubber? It
might even solve the problem of what to do with all those defective
Firestone tires. :-)

It would be best if the dampening occurred between the SRB stage and the
LOX/LH2 upper stage.
If these were hooked together by warren truss girders the way the
Russians attach the upper stage of the Soyuz booster to the basic R-7
lower stage, it might be possible to incorporate some sort of shock
absorbers into that support structure and isolate the vibrations created
by the SRB from the whole upper part of the vehicle... this would be
ideal, as you don't want high frequency vibrations going through the
lightly built cryogenic upper stage either.

Pat

Good points. I wasn't sure where exactly the isolation should occur, but
isolating the SRBs from the rest of the stack altogether seems to me to be
the best remedy. Good idea. I like the truss girder idea. Probably
cheaper and less impact on mass as well. Possibly they could be
constructed from vibration-absorbing composite materials. I think the
second vehicle from the left in the drawing at the link below may be
something like what you are describing:

http://www.friends-partners.org/part...l/lktksles.jpg

Or possibly something like this:

http://www.friends-partners.org/part...r/r7ur5cut.gif

I believe the Soviet N-1 also used such trusses.


Or, this. The Space Shuttle

http://www.gcs.k12.in.us/bholt/Space...%20diagram.JPG

The +X load path from the SRB to the ET is at the intertank at the top. The
+X load path from the Orbiter to the ET is at the bottom of the Hydrogen
tank. So the structure of the Hydrogen tank provides some isolates to the
Orbiter from the +X thrust vibrations.

Orbiter to ET attack points
Nose, Y and Z load paths
Tail, X, Y and Z load paths, and roll moments

SRB to ET attach points
Nose, X Y and Z load paths
Tail, Y and Z load paths, and roll moment.