Falcon 9 +SRB

Pat Flannery wrote:
On 6/8/2010 6:25 AM, Jeff Findley wrote:

The scary thing about those Aerojet SRB's is the amount of vibration
they produced. I'm not sure you'd ever be able to safely put people
on top of such a beast. These SRB's make the shuttle SRB's look
like toys.

Wasn't this the test where the exhaust products took all the paint off
of the cars they settled on?

Pat

Don't know about that, but I recall something like that happening after a
shuttle launch to cars in the VAB parking lot.

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

On Jun 9, 3:24�pm, Pat Flannery wrote:
On 6/9/2010 2:23 AM, Alan Erskine wrote:

However, look at all the vibration-absorbing systems needed by Orion.
That was because of the SRB problems.

They should have spotted that problem right at the time the booster was
first suggested; it wasn't like they didn't have any vibration data on
the SRBs after all those Shuttle flights.

Pat

In a big rush tm payoff existing contractors maybe they didnt care?

Or a conspiracy theory

Pick solids knowing its a bad idea, in the hopes when the vibration
cant be fixed, the shuttle program will continue, either long or short
term.

either way it may have been a upper level nasa attempt to retain jobs

In article ,
says...

On 9/06/2010 12:38 AM, Jeff Findley wrote:
In articleA9qdneQHMJFxKpDRnZ2dnUVZ_hKdnZ2d@giganews. com, jrfrank@ibm-
pc.borg says...

On 06/07/2010 09:54 PM, Alan Erskine wrote:
On 8/06/2010 1:57 AM, Frogwatch wrote:
SpaceX shows a falcon 9 heavy consisting of three identical falcon 9
segments. Of course, this is 27 engines. Would it be more reliable
to use the falcon 9 as a core and shuttle SRB strap ons?
Next, what are the plans for the payload of this falcon 9 that is in
orbit? Do they plan to de-orbit it to test the landing?

No, it would be less reliable as the SRB is a very (VERY) bad thing.
It's said that 50% of all shuttle crews can't read the instrument panel
whilst the SRB's are burning. That's due to vibration and that's
potentially fatal.

It's also said that 84.5% of all statistics are made up on the spot.

It would be interesting to find out if Alan's assertion has any truth
behind it. How about it Alan, care to back up your assertion with a
cite?

Jeff

Well.... it wasn't an assertion; it's "been said" - I don't remember who
said it.

Ok..... I personally can't remember this "being said", let alone who
would have said it.

However, look at all the vibration-absorbing systems needed by Orion.
That was because of the SRB problems.

True. As the SRB's get bigger, the vibrations get bigger in amplitude
and the frequencies get lower. Both of these are a bad thing,
especially when the frequencies get low enough to approach a natural
frequency of the launch vehicle structure.

Plus there is the issue of the propellant and casing being segmented,
which does introduce failure modes into the design (compared to a single
segment design). Joints introduce more potential locations for
propellant burn through as well as the potential for pressure leaks or
other structural problems.

Having multiple large SRB's in a launch vehicle design introduces the
headache of potentially different thrust profiles between the two SRB's.
From what I understand, ATK pours the propellant grain for the segments
in pairs, so they can be as closely matched as possible.

Bigger isn't better when it comes to solid rocket boosters.

Jeff
--
The only decision you'll have to make is
Who goes in after the snake in the morning?

On 6/9/2010 2:23 AM, Alan Erskine wrote:

However, look at all the vibration-absorbing systems needed by Orion.
That was because of the SRB problems.

They should have spotted that problem right at the time the booster was
first suggested; it wasn't like they didn't have any vibration data on
the SRBs after all those Shuttle flights.

Pat

Jeff Findley wrote:

True. As the SRB's get bigger, the vibrations get bigger in amplitude
and the frequencies get lower. Both of these are a bad thing,
especially when the frequencies get low enough to approach a natural
frequency of the launch vehicle structure.

But as the SRB's get bigger, one can expect the launch vehicle to also
get bigger and the natural frequencies of the launch vehicle to get lower.
So, I agree with you that as the SRB's get bigger the bigger amplitude
of their vibrations make the problem grow, but the lower frequencies
are not necessarily more problematic.

This is not to say that I think large SRB's are a good thing, far from
it. Just that it is good to know the real reasons why they are a bad
thing.


Alain Fournier

On Wed, 09 Jun 2010 10:25:39 GMT, Alan Erskine
wrote:
On 9/06/2010 12:38 AM, Jeff Findley wrote:

It would be interesting to find out if Alan's assertion has any
truth
behind it. How about it Alan, care to back up your assertion
with a
cite?


There's a more practical reason for not using the SRB - it's
40-year-old
technology.


Uh, how old are YOU, Jeff? She we all have not listened to von Braun
because he was over 40 ?

Old technology doesn't mean bad technology. There are lots of good
reasons why solids are a bad idea (vibe, abrupt and violent failure
modes, etc), and the were just as bad an idea when tbey were new as
they are now.

--
Done By Droid.

In article ,
says...

On Wed, 09 Jun 2010 10:25:39 GMT, Alan Erskine
wrote:
On 9/06/2010 12:38 AM, Jeff Findley wrote:

It would be interesting to find out if Alan's assertion has any
truth
behind it. How about it Alan, care to back up your assertion
with a
cite?


There's a more practical reason for not using the SRB - it's
40-year-old
technology.


Uh, how old are YOU, Jeff? She we all have not listened to von Braun
because he was over 40 ?

Old technology doesn't mean bad technology. There are lots of good
reasons why solids are a bad idea (vibe, abrupt and violent failure
modes, etc), and the were just as bad an idea when tbey were new as
they are now.

Alan wrote that, not me.

My objections to large segmented solids have to do with their high
operational cost, large vibrations, and the rapid onset and severity of
some of their failure modes.

Jeff
--
The only decision you'll have to make is
Who goes in after the snake in the morning?