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Latest candidate for SpaceX pad explosion

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  Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-17 21:23 -0700
    Re: Latest candidate for SpaceX pad explosion Sylvia Else <sylvia@not.at.this.address> - 2016-10-18 17:06 +1100
      Re: Latest candidate for SpaceX pad explosion Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-10-18 08:31 -0400
        Re: Latest candidate for SpaceX pad explosion Sylvia Else <sylvia@not.at.this.address> - 2016-10-19 11:57 +1100
          Re: Latest candidate for SpaceX pad explosion Rob <nomail@example.com> - 2016-10-19 13:48 +0000
    Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-18 03:46 -0400
      Re: Latest candidate for SpaceX pad explosion Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-10-18 08:36 -0400
        Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-19 01:29 -0400
          Re: Latest candidate for SpaceX pad explosion Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-10-19 06:23 -0400
            Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-19 13:08 -0400
              Re: Latest candidate for SpaceX pad explosion Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-10-19 16:24 -0400
                Re: Latest candidate for SpaceX pad explosion Alain Fournier <alain245@videotron.ca> - 2016-10-19 19:25 -0400
                Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-20 04:04 -0400
                  Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-20 09:17 -0700
                    Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-21 18:01 -0400
                      Re: Latest candidate for SpaceX pad explosion Rick Jones <rick.jones2@hpe.com> - 2016-10-21 22:34 +0000
                        Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-21 18:55 -0400
                      Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-21 20:57 -0700
              Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-19 18:29 -0700
          Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-19 06:30 -0700
            Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-19 13:14 -0400
              Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-19 18:35 -0700
                Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-20 04:07 -0400
                  Re: Latest candidate for SpaceX pad explosion Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-10-20 06:09 -0400
                    Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-21 17:43 -0400
                      Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-21 20:48 -0700
                        Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-22 00:31 -0400
                          Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-21 23:13 -0700
                          Re: Latest candidate for SpaceX pad explosion Dr J R Stockton <reply1600@merlyn.demon.co.uk.invalid> - 2016-10-24 15:46 +0100
                      Re: Latest candidate for SpaceX pad explosion Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-10-23 09:50 -0400
                        Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-23 07:26 -0700
                        Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-23 14:08 -0400
                          Re: Latest candidate for SpaceX pad explosion Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-10-24 06:13 -0400
                            Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-24 04:13 -0700
                            Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-24 13:25 -0400
                              Re: Latest candidate for SpaceX pad explosion Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-10-24 17:50 -0400
                                Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-24 18:17 -0400
                                  Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-24 19:26 -0700
                                    Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-25 04:26 -0400
                                      Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-25 04:24 -0700
                                        Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-25 14:48 -0400
                                          Re: Latest candidate for SpaceX pad explosion Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-10-25 21:29 -0400
                                            Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-26 01:21 -0400
                                              Re: Latest candidate for SpaceX pad explosion Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-10-26 06:15 -0400
                                                Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-26 14:19 -0400
                                                  Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-26 11:54 -0700
                                              Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-26 12:59 -0700
                                                Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-26 16:46 -0400
                                                  Re: Latest candidate for SpaceX pad explosion Rick Jones <rick.jones2@hpe.com> - 2016-10-26 21:01 +0000
                                                    Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-26 17:36 -0700
                                                  Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-26 17:29 -0700
                                                    Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-27 14:47 -0400
                                                      Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-27 12:37 -0700
                                                        Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-28 00:33 -0400
                                                          Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-27 22:54 -0700
                                          Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-26 12:48 -0700
                                Re: Latest candidate for SpaceX pad explosion Rick Jones <rick.jones2@hpe.com> - 2016-10-24 22:42 +0000
                              Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-24 19:21 -0700
                  Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-20 09:18 -0700
      Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-18 08:11 -0700
        Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-19 01:35 -0400
          Re: Latest candidate for SpaceX pad explosion Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-10-19 06:29 -0400
          Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-19 06:46 -0700
    Re: Latest candidate for SpaceX pad explosion Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-10-18 08:23 -0400
    Re: Latest candidate for SpaceX pad explosion nj_kruse@me.com (Niels Jørgen Kruse) - 2016-10-18 20:04 +0200
      Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-18 20:27 -0700
        Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-19 01:38 -0400
          Re: Latest candidate for SpaceX pad explosion Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-10-19 07:13 -0400
          Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-19 07:07 -0700
            Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-19 13:18 -0400
              Re: Latest candidate for SpaceX pad explosion Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-10-19 16:11 -0400
              Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-19 18:43 -0700
                Re: Latest candidate for SpaceX pad explosion JF Mezei <jfmezei.spamnot@vaxination.ca> - 2016-10-20 04:13 -0400
                  Re: Latest candidate for SpaceX pad explosion Jeff Findley <jfindley@cinci.nospam.rr.com> - 2016-10-20 06:18 -0400
                  Re: Latest candidate for SpaceX pad explosion Fred J. McCall <fjmccall@gmail.com> - 2016-10-20 09:23 -0700

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#58494 — Latest candidate for SpaceX pad explosion

While they haven't confirmed it as the cause yet, the current leading
candidate for the cause of the explosion is SOLID oxygen forming in
the composite overwrapped pressure vessel that helium is stored in.  

This is how it would work.  For this flight SpaceX was apparently
trying to increase the degree of super-cryo chilling on the liquid
oxygen, so they were pumping it even colder than normal (close to
freezing point).  Some of the super-chilled LOX could have gotten into
the COPV and then frozen.  As tank pressure went up, the solid oxygen
could not be squeezed back out of the overwrap and detonated with the
carbon composite wrapping.  This breeched the helium pressurization
tank, overpressuring the LOX tank and things go up from there.

SpaceX has not confirmed that this is their leading theory (or even a
theory).  It is being reported as something that came out of a private
conversation with Musk and SpaceX says they have a policy of not
commenting on private conversations by Musk.

If that's really the problem, it makes a return to flight easier. Just
revert to the 'normal' amount of chilling that they used on previous
flights.


-- 
"Insisting on perfect safety is for people who don't have the balls to 
    live in the real world."   
                      -- Mary Shafer, NASA Dryden

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#58495

On 18/10/2016 3:23 PM, Fred J. McCall wrote:
> While they haven't confirmed it as the cause yet, the current leading
> candidate for the cause of the explosion is SOLID oxygen forming in
> the composite overwrapped pressure vessel that helium is stored in.
>
> This is how it would work.  For this flight SpaceX was apparently
> trying to increase the degree of super-cryo chilling on the liquid
> oxygen, so they were pumping it even colder than normal (close to
> freezing point).  Some of the super-chilled LOX could have gotten into
> the COPV and then frozen.  As tank pressure went up, the solid oxygen
> could not be squeezed back out of the overwrap and detonated with the
> carbon composite wrapping.  This breeched the helium pressurization
> tank, overpressuring the LOX tank and things go up from there.
>
> SpaceX has not confirmed that this is their leading theory (or even a
> theory).  It is being reported as something that came out of a private
> conversation with Musk and SpaceX says they have a policy of not
> commenting on private conversations by Musk.
>
> If that's really the problem, it makes a return to flight easier. Just
> revert to the 'normal' amount of chilling that they used on previous
> flights.
>
>

Customers might be less than happy with the idea that their production 
launch vehicle is being experimented on, though the contract may allow 
for that.

Sylvia.

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#58499

In article <e6lsg2F944hU1@mid.individual.net>, 
sylvia@not.at.this.address says...
> 
> On 18/10/2016 3:23 PM, Fred J. McCall wrote:
> > While they haven't confirmed it as the cause yet, the current leading
> > candidate for the cause of the explosion is SOLID oxygen forming in
> > the composite overwrapped pressure vessel that helium is stored in.
> >
> > This is how it would work.  For this flight SpaceX was apparently
> > trying to increase the degree of super-cryo chilling on the liquid
> > oxygen, so they were pumping it even colder than normal (close to
> > freezing point).  Some of the super-chilled LOX could have gotten into
> > the COPV and then frozen.  As tank pressure went up, the solid oxygen
> > could not be squeezed back out of the overwrap and detonated with the
> > carbon composite wrapping.  This breeched the helium pressurization
> > tank, overpressuring the LOX tank and things go up from there.
> >
> > SpaceX has not confirmed that this is their leading theory (or even a
> > theory).  It is being reported as something that came out of a private
> > conversation with Musk and SpaceX says they have a policy of not
> > commenting on private conversations by Musk.
> >
> > If that's really the problem, it makes a return to flight easier. Just
> > revert to the 'normal' amount of chilling that they used on previous
> > flights.
> >
> >
> 
> Customers might be less than happy with the idea that their production 
> launch vehicle is being experimented on, though the contract may allow 
> for that.

Sylvia, this quite often the case with SpaceX.  It's still a young 
company and is still optimizing Falcon 9.  Unfortunately, when you push 
the envelope like this, sometimes an "unknown unknown" bites you in the 
ass.

But, look at the usual suspects.  ULA has done very little in the way of 
innovation related to the EELV's and costs still went up!  Why is that?  
You'd think if everything was "standardized", costs would come down, but 
they didn't.  

Orbital ATK is "innovating" a bit, but mostly by seeking out the lowest 
bidders for the bits of their liquid fueled stage(es).  The rest is 
solid stages made in house.  I *really* hate solids for launch.  Too 
much vibration, extremely violent failure modes, can't be economically 
reused, and little chance that costs will ever drop by orders of 
magnitude.  So, on the "solids" side of the house, Orbital ATK isn't 
innovating in a way that would ever reduce costs.

The other way to look at this is that if we never innovate, costs will 
not come down by the orders of magnitude that is needed for the US to 
become a truly space-fairing nation.  That's really Musk's long term 
goal, to send a truly huge number of people to Mars.  This vision is in 
stark contrast to NASA's "vision" of sending a handful of NASA 
astronauts to Mars (citizens can apply, but will have a snowball's 
chance in hell of becoming a NASA astronaut).

Jeff
-- 
All opinions posted by me on Usenet News are mine, and mine alone.  
These posts do not reflect the opinions of my family, friends, 
employer, or any organization that I am a member of.

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#58521

On 18/10/2016 11:31 PM, Jeff Findley wrote:
> In article <e6lsg2F944hU1@mid.individual.net>,
> sylvia@not.at.this.address says...
>>
>> On 18/10/2016 3:23 PM, Fred J. McCall wrote:
>>> While they haven't confirmed it as the cause yet, the current leading
>>> candidate for the cause of the explosion is SOLID oxygen forming in
>>> the composite overwrapped pressure vessel that helium is stored in.
>>>
>>> This is how it would work.  For this flight SpaceX was apparently
>>> trying to increase the degree of super-cryo chilling on the liquid
>>> oxygen, so they were pumping it even colder than normal (close to
>>> freezing point).  Some of the super-chilled LOX could have gotten into
>>> the COPV and then frozen.  As tank pressure went up, the solid oxygen
>>> could not be squeezed back out of the overwrap and detonated with the
>>> carbon composite wrapping.  This breeched the helium pressurization
>>> tank, overpressuring the LOX tank and things go up from there.
>>>
>>> SpaceX has not confirmed that this is their leading theory (or even a
>>> theory).  It is being reported as something that came out of a private
>>> conversation with Musk and SpaceX says they have a policy of not
>>> commenting on private conversations by Musk.
>>>
>>> If that's really the problem, it makes a return to flight easier. Just
>>> revert to the 'normal' amount of chilling that they used on previous
>>> flights.
>>>
>>>
>>
>> Customers might be less than happy with the idea that their production
>> launch vehicle is being experimented on, though the contract may allow
>> for that.
>
> Sylvia, this quite often the case with SpaceX.  It's still a young
> company and is still optimizing Falcon 9.  Unfortunately, when you push
> the envelope like this, sometimes an "unknown unknown" bites you in the
> ass.
>

Still, its customers might reasonably expect their satellites to be 
launched on proven hardware, operated in the proven way, with 
experiments involved with innovation done on hardware that isn't 
launching an expensive satellite.

But we don't know what the contract says.

Sylvia.

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#58535

Sylvia Else <sylvia@not.at.this.address> wrote:
> Still, its customers might reasonably expect their satellites to be 
> launched on proven hardware, operated in the proven way, with 
> experiments involved with innovation done on hardware that isn't 
> launching an expensive satellite.

In some cases, rockets have been qualified by launching dummy satellites
(just a block of concrete or lead of the proper mass), but of course then
some people consider this a waste of resources and a pollution of space.

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#58496

On 2016-10-18 00:23, Fred J. McCall wrote:

> freezing point).  Some of the super-chilled LOX could have gotten into
> the COPV and then frozen.  As tank pressure went up, the solid oxygen
> could not be squeezed back out of the overwrap and detonated with the
> carbon composite wrapping.  This breeched the helium pressurization
> tank, overpressuring the LOX tank and things go up from there.

Is there a diagram somewhere ?

What is "COPV" ?

If something is solid, does it care that pressure around it is
increasing?  And while I am at it, are any liquids compressible ?

H2O is at its densest at 4°C. So when its temprarture drops further it
expands.  Does LOX behave the same near its freezing temperature ?

If, when solidifying, LOX expands, I could see this causing structural
strain that could lead to a tank rupturing if it can't take the load.

What if Helium ruptured, and evaporating helium cooled the LOX into
solid and then the solid expands, breaks the tank ?

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#58500

In article <5805d34d$0$24472$b1db1813$7968482@news.astraweb.com>, 
jfmezei.spamnot@vaxination.ca says...
> 
> On 2016-10-18 00:23, Fred J. McCall wrote:
> 
> > freezing point).  Some of the super-chilled LOX could have gotten into
> > the COPV and then frozen.  As tank pressure went up, the solid oxygen
> > could not be squeezed back out of the overwrap and detonated with the
> > carbon composite wrapping.  This breeched the helium pressurization
> > tank, overpressuring the LOX tank and things go up from there.
> 
> Is there a diagram somewhere ?
> 
> What is "COPV" ?

Composite overwrapped pressure vessel.  Essentially a very thin metal 
tank overwrapped by carbon fiber composite to make the tank strong and 
light.  The carbon fiber gives the tank its strength.

https://en.wikipedia.org/wiki/Composite_overwrapped_pressure_vessel

> If something is solid, does it care that pressure around it is
> increasing?  And while I am at it, are any liquids compressible ?

It does when it's an energetic solid oxidizer (can't get much more 
energetic than solid oxygen) right next to a solid fuel (carbon fiber).  
You do that and you have what is called a "contact explosive".  The 
increase in pressure would cause it to literally explode.
 
Jeff
-- 
All opinions posted by me on Usenet News are mine, and mine alone.  
These posts do not reflect the opinions of my family, friends, 
employer, or any organization that I am a member of.

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#58525

On 2016-10-18 08:36, Jeff Findley wrote:

> It does when it's an energetic solid oxidizer (can't get much more 
> energetic than solid oxygen) right next to a solid fuel (carbon fiber). 

Ahh. I remember asking early one what could be combusting in the rocket
with LOX leaking and gotten no answer.

I takle it that carbon fibre even when encased in resin is highly
combustible ? is the resin/epoxy also combustible in contact with LOX ?

(reminder to self: make sure not to spill any LOX on my bicycle :-(

Would fibre glass be less explosive or would the resin still provide the
combustible material that would yield the same result ?

> You do that and you have what is called a "contact explosive".  The 
> increase in pressure would cause it to literally explode.


Would it be fair to assume that a breach in the metal coating inside the
tank would have exposed LOX to carbon ?

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#58528

In article <580704ac$0$57488$b1db1813$145976f0@news.astraweb.com>, 
jfmezei.spamnot@vaxination.ca says...
> 
> On 2016-10-18 08:36, Jeff Findley wrote:
> 
> > It does when it's an energetic solid oxidizer (can't get much more 
> > energetic than solid oxygen) right next to a solid fuel (carbon fiber). 
> 
> Ahh. I remember asking early one what could be combusting in the rocket
> with LOX leaking and gotten no answer.
> 
> I takle it that carbon fibre even when encased in resin is highly
> combustible ? is the resin/epoxy also combustible in contact with LOX ?

LOX makes just about anything combustible, but you still need an 
ignition source.  In this case, the solid oxygen being compressed (with 
nowhere to go) inside the composite overwrap is suspected to be the 
source of ignition.  If it had stayed liquid (i.e. LOX) like on every 
other Falcon 9 test firing and flight, it would not have ignited. 
 
> (reminder to self: make sure not to spill any LOX on my bicycle :-(

LOX spilled on anything combustible is bad.  LOX on clothes will catch 
fire.  LOX soaked in asphalt is a contact explosive (make your launch 
facilities out of concrete!).

> Would fibre glass be less explosive or would the resin still provide the
> combustible material that would yield the same result ?

Possibly, but fiberglass would be much weaker, and much heavier.  

> > You do that and you have what is called a "contact explosive".  The 
> > increase in pressure would cause it to literally explode.
> 
> 
> Would it be fair to assume that a breach in the metal coating inside the
> tank would have exposed LOX to carbon ?

You're thinking about this all wrong.  The helium tank is the COPV.  So 
the metal bit is containing the helium (else it would leak out of the 
composite).  The composite overwrap is in contact with the LOX *at all 
times*, because the helium tanks are inside the LOX tank.  This is 
because if your helium tank is inside the LOX tank, it's colder, and can 
therefore hold much more helium at its rated pressure than a tank that 
is exposed to ambient temperatures (i.e. outside the LOX tank).  

Jeff
-- 
All opinions posted by me on Usenet News are mine, and mine alone.  
These posts do not reflect the opinions of my family, friends, 
employer, or any organization that I am a member of.

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#58538

On 2016-10-19 06:23, Jeff Findley wrote:

> LOX spilled on anything combustible is bad. 

Would it be fair to state that the helium filled COPV has some sort of
coating on the outer surface to normally prevent LOX from igniting the
carbon fibre ?


> composite).  The composite overwrap is in contact with the LOX *at all 
> times*, because the helium tanks are inside the LOX tank. 

So how come the carbon on the outside of helium tank does not combust as
it sits in a pool of LOX ? (see question above).


And if the LOX became solid, wouldn't it further enhance the
integrity/strength of the helium tank by providing even more support ?

Or does "solid" LOX really mean a slushy mixture, or an actual solid
block of LOX surrounding the helium tank.

Would the helium tank have contributed to the cooling of the LOX to form
an "ice" layer over the COPV tank ?

from a scuba dividng point of view, when you fill scuba tanks and
increase pressure, they get warm

If you pour liquid helium in an empty tank at 1ATM, I assume it will at
first evaporate big time and be endothermic. But eventually, won't it
become exithermic once pressure builds up and the liquid no longer
evaporates ?

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#58543

In article <5807a88d$0$36027$c3e8da3$76a7c58f@news.astraweb.com>, 
jfmezei.spamnot@vaxination.ca says...
> 
> On 2016-10-19 06:23, Jeff Findley wrote:
> 
> > LOX spilled on anything combustible is bad. 
> 
> Would it be fair to state that the helium filled COPV has some sort of
> coating on the outer surface to normally prevent LOX from igniting the
> carbon fibre ?

I doubt it.  What coating would be LOX compatible and not crack due to 
the expansion and contraction of the COPV during normal fills and drains 
while inside the LOX tank?

> > composite).  The composite overwrap is in contact with the LOX *at all 
> > times*, because the helium tanks are inside the LOX tank. 
> 
> So how come the carbon on the outside of helium tank does not combust as
> it sits in a pool of LOX ? (see question above).

No ignition source.

> And if the LOX became solid, wouldn't it further enhance the
> integrity/strength of the helium tank by providing even more support ?

No, the overwrap was trying to squeeze the oxygen back out, but could 
not, so the theory is the overwrap failed (I'm guessing at or near the 
location of the solid oxygen).  That failure would release a lot of 
energy, providing an ignition source.
 
> Or does "solid" LOX really mean a slushy mixture, or an actual solid
> block of LOX surrounding the helium tank.

It means solid oxygen.  Like how ice is solid water.

> Would the helium tank have contributed to the cooling of the LOX to form
> an "ice" layer over the COPV tank ?

The pressure in the LOX supply line had to be greater than the pressure 
in the tank, otherwise, how would you ever fill the tank?  As such, the 
LOX would drop in pressure as it entered the tank, resulting in a 
corresponding drop in temperature.  That could result in the outside of 
the COPV getting so cold that solid oxygen was formed.  

> from a scuba dividng point of view, when you fill scuba tanks and
> increase pressure, they get warm

Filling them from what?  Is a compressor involved?  If so, that 
compressor *increases* the pressure of the gas which increases the 
temperature of the gas.  Clearly you can't do that with LOX and expect 
it to be "sub-cooled" in the rocket.  So clearly SpaceX isn't doing it 
that way.

> If you pour liquid helium in an empty tank at 1ATM, I assume it will at
> first evaporate big time and be endothermic. But eventually, won't it
> become exithermic once pressure builds up and the liquid no longer
> evaporates ?

I don't know the details of how SpaceX does it (i.e. in what order are 
the tanks filled).  You'd have to ask them.

Jeff
-- 
All opinions posted by me on Usenet News are mine, and mine alone.  
These posts do not reflect the opinions of my family, friends, 
employer, or any organization that I am a member of.

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#58546

On Oct/19/2016 at 4:24 PM, Jeff Findley wrote :
> In article <5807a88d$0$36027$c3e8da3$76a7c58f@news.astraweb.com>,
> jfmezei.spamnot@vaxination.ca says...

>> Would the helium tank have contributed to the cooling of the LOX to form
>> an "ice" layer over the COPV tank ?
>
> The pressure in the LOX supply line had to be greater than the pressure
> in the tank, otherwise, how would you ever fill the tank?  As such, the
> LOX would drop in pressure as it entered the tank, resulting in a
> corresponding drop in temperature.  That could result in the outside of
> the COPV getting so cold that solid oxygen was formed.

I'm not sure about that. We are talking about sub-cooled LOX here. My 
understanding is that it is sub-cooled before being pumped into the 
tank. If you pump sub-cooled LOX into a tank the drop in pressure as it 
enters the tank doesn't have to be significant, and it is gases (or 
plasmas) that drop in temperature when the pressure drops. Liquids, not 
so much.


Alain Fournier

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#58556

On 2016-10-19 16:24, Jeff Findley wrote:

> I doubt it.  What coating would be LOX compatible and not crack due to 
> the expansion and contraction of the COPV during normal fills and drains 
> while inside the LOX tank?

But doesn't the coating inside the COPV do exactly that ?
(expand/contract during normal fills) ?

It's be driven into me that the second LOX comes into contact with
combustible material, it causes very fast combustion.

So I do not understand how LOX being in contact with carbon fiber would
not cause instant combustion.


> No ignition source.

If you pour LOX onto BBQ charcoal, it instantly burns, without a match
to ignite it.  So why would it magically not do that in a tank if there
is some carbon present and in contact with LOX ?



> No, the overwrap was trying to squeeze the oxygen back out, but could 
> not, so the theory is the overwrap failed (I'm guessing at or near the 
> location of the solid oxygen). 

I see a problem with that. To be structurally strong, layers of
composites (either carbon or glass fibre) have to be very tightly
laminated against each other with resin holding them together.

If LOX was able to find its way between layers of carbon fibre, it means
delamination had already happened which means the tank's structural
strength was already compromised. So something would have happened
before to cause the delamination that would have created a gap between
composite layers for LOX to seep through.


And if the cooling happens as the LOX goes from the high pressure
loading pipe to the lower pressure LOX tank, than it isn't contact with
helium tank that would have caused it to solidify. In fact, if the
helium was warmer than the LOX, then LOX that was in contact with helium
tank would be less likely to become solid.


In my mind, it would be more likely the helium tank got so cold that the
carbon fibre became brittle and failed, releasing helium into the LOX
tank, causing that tank to rupture and then things went kablooey.


> It means solid oxygen.  Like how ice is solid water.

You've obviously never seen slush ?  water at 0° can exist both solid
and liquid. And slush has solid "flakes" of water mixed with liquid
water. (think milk shake or a "Slush" drink).

I find it unlikely that the LOX became a solid block of "solid". Far
more likely it would have been a "slush" type of mixture which is still
adaptable to shape changes.



> Filling them from what?  Is a compressor involved?  If so, that 
> compressor *increases* the pressure of the gas which increases the 
> temperature of the gas.  Clearly you can't do that with LOX and expect 
> it to be "sub-cooled" in the rocket.  So clearly SpaceX isn't doing it 
> that way.

Making any gas liquid is an exothermal reaction. (either you compress
the gas (exothermal) or you cool it (exothermal).

They can do a combo where they compress it and cool it.


However, the difference with scuba is that scuba, you are compressing
air inside the tank by adding air to it, so it is exothermal in the
scuba tank.


But for LOX, they would be compressing it off-site and cooling
itoff-site into a liquid, and when it goes into the rocket's tank, it is
just poured into 1ATM and liquid allowed to boil. So it does get colder.

You may recall in that for the shuttle, the tanks were not pressurized
during pre-flight and they closed the vent seconds before liftoff (since
the tanks couldn't support that much pressure).

IF SpaceX does it the same way, it would mean that the tanks would
remain closed to 1ATM  pre-flight letting LOX boil off and only close
valve to pressurise tank just before liftoff.

And that would obviously mean that the tanks would not have been
pressurized at the time of explosion.

However, failure of helium tank inside of LOX likely released way too
much pressure to be vented instantly so the LOX tank broke.

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#58561

JF Mezei <jfmezei.spamnot@vaxination.ca> wrote:

>On 2016-10-19 16:24, Jeff Findley wrote:
>>
>> I doubt it.  What coating would be LOX compatible and not crack due to 
>> the expansion and contraction of the COPV during normal fills and drains 
>> while inside the LOX tank?
>>
>
>But doesn't the coating inside the COPV do exactly that ?
>(expand/contract during normal fills) ?
>

What "coating inside the COPV" would that be, exactly?

>
>It's be driven into me that the second LOX comes into contact with
>combustible material, it causes very fast combustion.
>

Educate yourself.

>
>So I do not understand how LOX being in contact with carbon fiber would
>not cause instant combustion.
>

So you don't understand how any pressure fed rocket can work.
Congratulations.

>
>> No ignition source.
>
>If you pour LOX onto BBQ charcoal, it instantly burns, without a match
>to ignite it.  So why would it magically not do that in a tank if there
>is some carbon present and in contact with LOX ?
>

Because it doesn't do that with charcoal unless the charcoal is hot?

>
>> No, the overwrap was trying to squeeze the oxygen back out, but could 
>> not, so the theory is the overwrap failed (I'm guessing at or near the 
>> location of the solid oxygen). 
>
>I see a problem with that. To be structurally strong, layers of
>composites (either carbon or glass fibre) have to be very tightly
>laminated against each other with resin holding them together.
>

Bullshit.  Do you know what 'laminated' means?

<snip silly hypothetical>

>
>In my mind, it would be more likely the helium tank got so cold that the
>carbon fibre became brittle and failed, releasing helium into the LOX
>tank, causing that tank to rupture and then things went kablooey.
>

And your mind is precisely why you are NOT in the rocket business.

>
>> It means solid oxygen.  Like how ice is solid water.
>
>You've obviously never seen slush ?  water at 0° can exist both solid
>and liquid. And slush has solid "flakes" of water mixed with liquid
>water. (think milk shake or a "Slush" drink).
>
>I find it unlikely that the LOX became a solid block of "solid". Far
>more likely it would have been a "slush" type of mixture which is still
>adaptable to shape changes.
>

I find it unlikely that you know more than people who do this shit for
a living.

>
>> Filling them from what?  Is a compressor involved?  If so, that 
>> compressor *increases* the pressure of the gas which increases the 
>> temperature of the gas.  Clearly you can't do that with LOX and expect 
>> it to be "sub-cooled" in the rocket.  So clearly SpaceX isn't doing it 
>> that way.
>
>Making any gas liquid is an exothermal reaction. (either you compress
>the gas (exothermal) or you cool it (exothermal).
>

while you're looking up what 'laminate' means, look up 'exothermal' as
well.  But you'll have to look up 'exothermic', since 'exothermal'
isn't a word.

Hint:  There is no 'reaction'.

<snip silliness>


-- 
"Ignorance is preferable to error, and he is less remote from the
 truth who believes nothing than he who believes what is wrong."
                               -- Thomas Jefferson

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#58569

On 2016-10-20 12:17, Fred J. McCall wrote:

> What "coating inside the COPV" would that be, exactly?
> Educate yourself.

The liner.

And your insults still provide no explanation on how they prevent LOX
which is in direct contact with carbon fibre (which surrounds the
embedded helium tank) from bursting into flames.


> Because it doesn't do that with charcoal unless the charcoal is hot?

I have seen videos of LOX being poured onto cold charcoal years ago on
TV. Not pretty.

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#58570

JF Mezei <jfmezei.spamnot@vaxination.ca> wrote:
> On 2016-10-20 12:17, Fred J. McCall wrote:

> > Because it doesn't do that with charcoal unless the charcoal is
> > hot?

> I have seen videos of LOX being poured onto cold charcoal years ago
> on TV. Not pretty.

Are you quite certain it was just cold charcoal sitting there with no
flame source nearby?  Everything I've seen in an admittedly cursory
web search has involved lighting a charcoal grill where there was
already an open flame - scrap of paper on the pile, that sort of
thing.

rick jones
-- 
The computing industry isn't as much a game of "Follow The Leader" as
it is one of "Ring Around the Rosy" or perhaps "Duck Duck Goose." 
                                                    - Rick Jones
these opinions are mine, all mine; HPE might not want them anyway... :)
feel free to post, OR email to rick.jones2 in hpe.com but NOT BOTH...

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#58571

On 2016-10-21 18:34, Rick Jones wrote:

> Are you quite certain it was just cold charcoal sitting there with no
> flame source nearby?  Everything I've seen in an admittedly cursory
> web search has involved lighting a charcoal grill where there was
> already an open flame - scrap of paper on the pile, that sort of
> thing.

It was one of those "Discovery Channel" (back then it was more science
than entertainment) and they clearly stated it was cold charcoal which
would ignite as they poured LOX on it.

If that is not the case and it is perfectly safe to pour LOX onto
carbon, then obviously my worry about LOX being on contact with carbon
fibre is moot.

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#58573

JF Mezei <jfmezei.spamnot@vaxination.ca> wrote:

>On 2016-10-20 12:17, Fred J. McCall wrote:
>
>> What "coating inside the COPV" would that be, exactly?
>> Educate yourself.
>
>The liner.
>

The liner is not a 'coating', you idiot.

>
>And your insults still provide no explanation on how they prevent LOX
>which is in direct contact with carbon fibre (which surrounds the
>embedded helium tank) from bursting into flames.
>

Because no explanation is required.  I also haven't explained why
water is wet or why things don't fall up.

>
>> Because it doesn't do that with charcoal unless the charcoal is hot?
>
>I have seen videos of LOX being poured onto cold charcoal years ago on
>TV. Not pretty.
>

Given your performance here, I'd bet you didn't know what the fuck you
were looking at.  With no ignition source nothing happens and you can
happily soak charcoal in LOX until it's saturated.  Of course, once
you do that and then expose it to an ignition source it explodes quite
violently.

http://www.bkinzel.de/misc/ghg/

Now you can post your cite of LOX being poured onto cold charcoal WITH
NO IGNITION SOURCE PRESENT.


-- 
"Ignorance is preferable to error, and he is less remote from the
 truth who believes nothing than he who believes what is wrong."
                               -- Thomas Jefferson

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#58549

JF Mezei <jfmezei.spamnot@vaxination.ca> wrote:

You're still not getting it.

>On 2016-10-19 06:23, Jeff Findley wrote:
>
>> LOX spilled on anything combustible is bad. 
>
>Would it be fair to state that the helium filled COPV has some sort of
>coating on the outer surface to normally prevent LOX from igniting the
>carbon fibre ?
>

No.

>
>> composite).  The composite overwrap is in contact with the LOX *at all 
>> times*, because the helium tanks are inside the LOX tank. 
>
>So how come the carbon on the outside of helium tank does not combust as
>it sits in a pool of LOX ? (see question above).
>

They're at the top of the tank.  Where does the boil-off happen?

>
>And if the LOX became solid, wouldn't it further enhance the
>integrity/strength of the helium tank by providing even more support ?
>

Composite OVERWRAP.  The hypothesis is that liquid oxygen got into the
overwrap and froze solid.  It is now surrounded by carbon and since it
is solid cannot 'squeeze out' as pressure increases in the LOX tank.

>
>Or does "solid" LOX really mean a slushy mixture, or an actual solid
>block of LOX surrounding the helium tank.
>

A slushy mixture would squeeze back out.  It means solid INSIDE THE
OVERWRAP.

>
>Would the helium tank have contributed to the cooling of the LOX to form
>an "ice" layer over the COPV tank ?
>

Jesus, do you not understand what OVERWRAPPED means?  Do this.  Get an
Ace Elastic bandage.  Make a fist.  Wrap the elastic bandage around
your fist in multiple layers as tightly as you can.  Get a small ice
chip.  Force it between the layers of Ace bandage.  THAT is what we're
talking about.  Your fist is the metal He tank.  The bandage is the
composite overwrap.  The ice chip is, well, the ice chip.

>
>from a scuba dividng point of view, when you fill scuba tanks and
>increase pressure, they get warm
>

PV=nRT.

>
>If you pour liquid helium in an empty tank at 1ATM, I assume it will at
>first evaporate big time and be endothermic. But eventually, won't it
>become exithermic once pressure builds up and the liquid no longer
>evaporates ?
>

You're misusing the words 'exothermic' and 'endothermic'.  The helium
pressure isn't the issue.  OXYGEN pressure is the issue.  Oxygen
vaporizes, which increases pressure in the tank until the safety valve
lets it vent.  The tank is not being externally pressurized like a
scuba tank on a compressor.  It is being internally pressurized by
some of the LOC evaporating.


-- 
"Ignorance is preferable to error, and he is less remote from the
 truth who believes nothing than he who believes what is wrong."
                               -- Thomas Jefferson

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#58533

JF Mezei <jfmezei.spamnot@vaxination.ca> wrote:

>On 2016-10-18 08:36, Jeff Findley wrote:
>>
>> It does when it's an energetic solid oxidizer (can't get much more 
>> energetic than solid oxygen) right next to a solid fuel (carbon fiber). 
>>
>
>Ahh. I remember asking early one what could be combusting in the rocket
>with LOX leaking and gotten no answer.
>
>I takle it that carbon fibre even when encased in resin is highly
>combustible ? is the resin/epoxy also combustible in contact with LOX ?
>
>(reminder to self: make sure not to spill any LOX on my bicycle :-(
>
>Would fibre glass be less explosive or would the resin still provide the
>combustible material that would yield the same result ?
>

The overwrap is there as MECHANICAL support, not insulation.
Fiberglass exposed to LOX temperatures is going to be, well, glass and
shatter into tiny pieces.

COVPs are not uncommon in rockets.  However, supercooled LOX is.

>
>> You do that and you have what is called a "contact explosive".  The 
>> increase in pressure would cause it to literally explode.
>>
>
>Would it be fair to assume that a breach in the metal coating inside the
>tank would have exposed LOX to carbon ?
>

Uh, you seem to have this backward.  The composite is an OVERWRAP
around the helium tank to provide structural support.  Oxygen getting
inside the overwrap exposes LOX to carbon.  Normally the liquid
squeezes back out of the overwrap as the LOC tank is pressurized.
However, if it actually froze to a solid in there, it stays where it
is and gets carbon compressed into it.  The pressure on the oxygen
surrounded by the carbon is what causes the problem.


-- 
"Insisting on perfect safety is for people who don't have the balls to 
    live in the real world."   
                      -- Mary Shafer, NASA Dryden

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