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resid. hypergolics



 
 
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  #1  
Old June 26th 07, 06:11 PM posted to sci.space.shuttle
John H[_2_]
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Posts: 14
Default resid. hypergolics

I was watching a repeat of the post landing briefing and Mike Linebaugh was
talking about purging residual hypergolics from the orbiter after landing...
are those LH2 and LO2 and I assume its whats left over from liftoff in parts
of the pumps, pipes? whatever... wouldnt they just evaporate or sublime or
whatever they do out in space? or if they are in a closed system they might
still be present? Or is he talking about whats left over in the re-entry
engines.


  #2  
Old June 26th 07, 06:48 PM posted to sci.space.shuttle
Danny Deger
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Posts: 530
Default resid. hypergolics


"John H" wrote in message
...
I was watching a repeat of the post landing briefing and Mike Linebaugh was
talking about purging residual hypergolics from the orbiter after
landing... are those LH2 and LO2 and I assume its whats left over from
liftoff in parts of the pumps, pipes? whatever... wouldnt they just
evaporate or sublime or whatever they do out in space? or if they are in a
closed system they might still be present? Or is he talking about whats
left over in the re-entry engines.


It is what is left over in the "re-entry" engines -- called the Orbital
Maneuvering System. The small jets that control attitude -- called the
Reaction Control System -- are also hypergolic.

Danny Deger

  #3  
Old June 26th 07, 07:54 PM posted to sci.space.shuttle
[email protected]
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Posts: 22
Default resid. hypergolics

On Jun 26, 10:11 am, "John H" wrote:
I was watching a repeat of the post landing briefing and Mike Linebaugh was
talking about purging residual hypergolics from the orbiter after landing...
are those LH2 and LO2 and I assume its whats left over from liftoff in parts
of the pumps, pipes? whatever... wouldnt they just evaporate or sublime or
whatever they do out in space? or if they are in a closed system they might
still be present? Or is he talking about whats left over in the re-entry
engines.



LH2 and LO2 are not considered hypergolics. And they're not
terribly dangerous, at least compared to hypergolics. You can
breathe some of their vapors with no ill effects (in fact, you NEED
to breathe some O2).

The shuttle uses MMH and nitrogen tetroxide as hypergolic
propellants for the RCS and OMS engines. Those are what
have to be purged, as they're extremely hazardous to come
in contact with, even in low concentrations.

http://en.wikipedia.org/wiki/Hypergolic

  #4  
Old June 27th 07, 01:50 AM posted to sci.space.shuttle
Danny Deger
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Posts: 530
Default resid. hypergolics


"Clark" wrote in message
...
snip

Add to that hydrazine for the APUs and there are some nasty chemicals on
board...


Good point. The APU fuel is pretty nasty stuff.

Danny Deger

NASA offered me $15,000 to take down my web site. Take a look and see why.
www.dannydeger.net

  #5  
Old June 27th 07, 02:37 AM posted to sci.space.shuttle
John H[_2_]
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Posts: 14
Default resid. hypergolics


wrote in message
ups.com...
On Jun 26, 10:11 am, "John H" wrote:
I was watching a repeat of the post landing briefing and Mike Linebaugh
was
talking about purging residual hypergolics from the orbiter after
landing...
are those LH2 and LO2 and I assume its whats left over from liftoff in
parts
of the pumps, pipes? whatever... wouldnt they just evaporate or sublime
or
whatever they do out in space? or if they are in a closed system they
might
still be present? Or is he talking about whats left over in the re-entry
engines.



LH2 and LO2 are not considered hypergolics. And they're not
terribly dangerous, at least compared to hypergolics.


I was reading that there is a "spark plug"
in the main combustion chamber that ignites the gasses... then
what are those sparks that shoot outside the SSME just before liftoff?




  #6  
Old June 27th 07, 04:49 AM posted to sci.space.shuttle
Greg D. Moore \(Strider\)
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Posts: 2,865
Default resid. hypergolics



"John H" wrote in message
...


LH2 and LO2 are not considered hypergolics. And they're not
terribly dangerous, at least compared to hypergolics.


I was reading that there is a "spark plug"
in the main combustion chamber that ignites the gasses... then
what are those sparks that shoot outside the SSME just before liftoff?



Correct.

The "sparklers" you see are there to burn off residual hydrogen that may
leak out before launch or during a launch abort so there's no chance of a
fire or explosion.






--
Greg Moore
SQL Server DBA Consulting Remote and Onsite available!
Email: sql (at) greenms.com http://www.greenms.com/sqlserver.html


  #7  
Old June 27th 07, 05:14 PM posted to sci.space.shuttle
Danny Deger
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Posts: 530
Default resid. hypergolics

"Greg D. Moore (Strider)" wrote in message
nk.net...


"John H" wrote in message
...


LH2 and LO2 are not considered hypergolics. And they're not
terribly dangerous, at least compared to hypergolics.


I was reading that there is a "spark plug"
in the main combustion chamber that ignites the gasses... then
what are those sparks that shoot outside the SSME just before liftoff?



Correct.

The "sparklers" you see are there to burn off residual hydrogen that may
leak out before launch or during a launch abort so there's no chance of a
fire or explosion.



Did anyone see the Delta Heavy launch? It had/has lots of unburned hydrogen
around the booster that ignites at lift off. It looks like the darn thing
is going to blow up.

--
Danny Deger

NASA offered me $15,000 to take down my web site. Take a look and see why.
www.dannydeger.net

  #8  
Old June 27th 07, 07:31 PM posted to sci.space.shuttle
Damon Hill[_4_]
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Posts: 566
Default resid. hypergolics

"Danny Deger" wrote in
:

Did anyone see the Delta Heavy launch? It had/has lots of unburned
hydrogen around the booster that ignites at lift off. It looks like
the darn thing is going to blow up.


That seems to be part of the RS-68s design, using lots of hydrogen
to chill down the engines just prior to ignition. It was anticipated
and allowed for with insulating blankets and inert gas purges, but
it sure looks like a Bad Moment In Launch History until it lifts off.
I've heard a hint that Boeing/Rocketdyne is working on the problem.

--Damon

  #9  
Old June 27th 07, 09:41 PM posted to sci.space.shuttle
Danny Deger
external usenet poster
 
Posts: 530
Default resid. hypergolics

"Damon Hill" wrote in message
31...
"Danny Deger" wrote in
:

Did anyone see the Delta Heavy launch? It had/has lots of unburned
hydrogen around the booster that ignites at lift off. It looks like
the darn thing is going to blow up.


That seems to be part of the RS-68s design, using lots of hydrogen
to chill down the engines just prior to ignition. It was anticipated
and allowed for with insulating blankets and inert gas purges, but
it sure looks like a Bad Moment In Launch History until it lifts off.
I've heard a hint that Boeing/Rocketdyne is working on the problem.

--Damon


I have recently "retired" (see my web site) from NASA and the word on the
street at NASA was the first thing Boeing would have to do to man rate the
Delta Heavy is to have it NOT look like it is going the blow up at lift off.

--
Danny Deger

NASA offered me $15,000 to take down my web site. Take a look and see why.
www.dannydeger.net

  #10  
Old June 28th 07, 03:14 PM posted to sci.space.shuttle
Jeff Findley
external usenet poster
 
Posts: 5,012
Default resid. hypergolics


"Danny Deger" wrote in message
...

I have recently "retired" (see my web site) from NASA and the word on the
street at NASA was the first thing Boeing would have to do to man rate the
Delta Heavy is to have it NOT look like it is going the blow up at lift
off.


Everyone knows that management is concerned first with appearances. It's
true in *every* organization, not just NASA. It prevents a lot of
confrontations with upper management, who usually don't have a clue about
the *real* day to day processes in the organizations they manage, if you get
rid of *anything* that may look out of place to them, even if you know what
you're "fixing" isn't *really* a problem. It's similar to what you have to
go through to get ISO certified. ;-)

In the case of the Delta IV Heavy, the fireball at liftoff isn't supposed to
be a problem, but it does have the effect of getting your customer's
management worked up, so it will almost certainly be fixed. Even if NASA
never flies anyone on a Delta IV Heavy, Boeing's other customers will almost
certainly be happier if they don't see a fireball on the pad every time they
launch a payload with Delta.

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)


 




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