Testing of quick disconnects

[JF Mezei]

Not sure if there is anoyone left in the group, but just in case.

Consideirng SLS has been in development for over 10 years, considering
they already had quick disconnect experience for H2 refueling on
Shuttle, I am curous on what constraints would have prevented them from
developping a reliable H2 fill line quick disconnect for SLS ?

I take it that they can't test it at VAB because they don't have LH2
lines there. (and leaking H2 indoors, not a great idea).

But when this quick disconnect was designed, wouldn't it have had some
real testing with LH2 to ensure it works well and that any limitations
and maintenance requiremenmts (eg: change rubber seals every X refills)
would be well known.


And considering the number of tests they did of this rocket, how come
this quick disconnect problem didn't get noticed before ?

[Alain Fournier]

It's normal on a new system to have some bugs.

The real question, in my opinion, is why didn't they disconnect the
whole programme years ago. Why not buy rides from SpaceX and Blue Origin
to go to the moon. It would be much cheaper than the SLS boondoggle.


Alain Fournier

[Snidely]

On Saturday, Alain Fournier exclaimed wildly:

> On Sep/10/2022 at 12:21, JF Mezei wrote :
>> Not sure if there is anoyone left in the group, but just in case.
>>
>> Consideirng SLS has been in development for over 10 years, considering
>> they already had quick disconnect experience for H2 refueling on
>> Shuttle, I am curous on what constraints would have prevented them from
>> developping a reliable H2 fill line quick disconnect for SLS ?
>>
>> I take it that they can't test it at VAB because they don't have LH2
>> lines there. (and leaking H2 indoors, not a great idea).
>>
>> But when this quick disconnect was designed, wouldn't it have had some
>> real testing with LH2 to ensure it works well and that any limitations
>> and maintenance requiremenmts (eg: change rubber seals every X refills)
>> would be well known.

AIUI, the GSE (which is a whole separate set of contractors) wasn't
done much sooner than the Green Run, which used different GSE.

But a nice little test tank would have been handy, wouldn't it?
Something like the 7.1 test tank, except validating the GSE in stead of
tank welds.

>> And considering the number of tests they did of this rocket, how come
>> this quick disconnect problem didn't get noticed before ?

It came up in the WDRs, and they thought they had it fixed. The first
launch attempt actually got past this point.

> It's normal on a new system to have some bugs.

Yeah, like the Shuttle ... it only had at least 1 scrub for every
launch thanks to how easy it is to work with LH2.

> The real question, in my opinion, is why didn't they disconnect the whole
> programme years ago. Why not buy rides from SpaceX and Blue Origin to go to
> the moon. It would be much cheaper than the SLS boondoggle.

Well, of course you know the answer is political, and that SLS is a
giant jobs program.

/dps

--
The presence of this syntax results from the fact that SQLite is really
a Tcl extension that has escaped into the wild.
<http://www.sqlite.org/lang_expr.html>

[Alain Fournier]

On Sep/11/2022 at 03:20, Snidely wrote:
> On Saturday, Alain Fournier exclaimed wildly:

>> The real question, in my opinion, is why didn't they disconnect the
>> whole programme years ago. Why not buy rides from SpaceX and Blue
>> Origin to go to the moon. It would be much cheaper than the SLS
>> boondoggle.
>
> Well, of course you know the answer is political, and that SLS is a
> giant jobs program.

Yes, you are right.

But even for that it is no longer clear that it is a win for politicians
to create jobs that way. I’m not sure about the areas where SLS jobs are
located. Here in Quebec, we are in an electoral campaign. Some
politicians are promising jobs, because they are used to doing that. But
the unemployment rate is so low, that they are mostly met with employers
complaining that the government shouldn’t unfairly compete with them
over the few available workers. I’m not sure if it makes sense for
politicians to promise jobs in this day of labour shortage.


Alain Fournier

[pnn calmagorod]

Nothing will never colonized by roketry
It is a physical law,
Continue till to the disaster

[Dean Markley]

I am pretty sure those are American flags on the moon, not Italian.

[Doctor Who]

nothing colonized yet.

[Alain Fournier]

There is no physical law that prohibits space colonisation by rocketry.
On the other hand there is a physical law that prohibits space
colonisation using PNN. If you don't know what physical law that is let
me give you a hint. PNN stands for propulsione non newtoniana.


Alain Fournier

[JF Mezei]

On 2022-09-11 03:20, Snidely wrote:

> AIUI, the GSE (which is a whole separate set of contractors) wasn't
> done much sooner than the Green Run, which used different GSE.
>
> But a nice little test tank would have been handy, wouldn't it?
> Something like the 7.1 test tank, except validating the GSE in stead of
> tank welds.

Musk stated he went for Methane because he knew of difficulties working
with LH2. NASA has had decades experience with LH2 on Shuttle. So if
they knew working with LH2 was challenging, how come theyt didn't do
more extensive testing of the quick disconnects?

Surely there are still adults at NASA who would have been able to tell
the next generation engineers of the need to test and test those LH2
connections?


Also very strange that Flight Termination System and some of the stuff
on the Orion would consume batteries while on pad instead of being
powered by ground. Very interesting design decision, would have though
everything would get ground powered while on pad and only switch to
batteriues in last few minutes of countdown.

[Doctor Who]

you are an idiot who don't want to see the reality.

[David Spain]

Could have been a different set of contractor(s) than those that did the
Shuttle as well. Testing regimen should have been spelled out in the
contract, if was inadequate, well cost-plus. If NASA wants more thorough
testing they have to pay for it.

This is just but one example of why it's more difficult to do this when
a government agency is trying to accomplish something via contractors vs
doing it yourself.

David Spain

[JF Mezei]

On 2022-09-23 09:58, David Spain wrote:

> This is just but one example of why it's more difficult to do this when
> a government agency is trying to accomplish something via contractors vs
> doing it yourself.

NASA had over 25 years experience with Shuttle/hydrogen and quick
disconnects.

The whole SLS project was specced by NASA via political pressure to
maintain jobs at the contractors that did Shuttle. I would have hoped
that experience from shuttle would have been transferef especially sicne
NASA had experience with those contractors.

But there are other worrysome things like limited battery lifetime once
out of VAB for so many systems instead of powering the rocket while at
pad to not deplete batteries. Just curious why this wasn't implemented.
Weather delays and scrubs for technical issues are not something that
are unknown.

Due to IAN, the rocket is being rolled back to VAB, so I assume they
will get to change batteries at that point.

One can criticise NASA's design of the system (SRBs etc), but in the
past, NASA was very pedantic on testing and validating designs, so it is
very strange to see components arriving on pad with less than stellar
reliability especially when NASA is fully aware of difficulties of
working with LH2.

[David Spain]

On 2022-09-26 1:54 AM, JF Mezei wrote:
> On 2022-09-23 09:58, David Spain wrote:
>
>> This is just but one example of why it's more difficult to do this when
>> a government agency is trying to accomplish something via contractors vs
>> doing it yourself.
>
>
>
> NASA had over 25 years experience with Shuttle/hydrogen and quick
> disconnects.
>
> The whole SLS project was specced by NASA via political pressure to
> maintain jobs at the contractors that did Shuttle. I would have hoped
> that experience from shuttle would have been transferef especially sicne
> NASA had experience with those contractors.
>
> But there are other worrysome things like limited battery lifetime once
> out of VAB for so many systems instead of powering the rocket while at
> pad to not deplete batteries. Just curious why this wasn't implemented.
> Weather delays and scrubs for technical issues are not something that
> are unknown.

It's not a question of powering the rocket. These batteries are used as
part of the flight termination system, which operates independently of
the SRS and controlled by range safety. I'm not sure why NASA accepted
such a tight operating regime for these batteries. I believe I read it
is 20 days after roll-out. Air Force range safety can grant extension
waivers on this.

>
> Due to IAN, the rocket is being rolled back to VAB, so I assume they
> will get to change batteries at that point.
>
> One can criticise NASA's design of the system (SRBs etc), but in the
> past, NASA was very pedantic on testing and validating designs, so it is
> very strange to see components arriving on pad with less than stellar
> reliability especially when NASA is fully aware of difficulties of
> working with LH2.

As Rand Simberg points out on his blog a whole set of clocks start
ticking once the SLS rocket rolls out of the VAB. Two of those are the
SRB's themselves. They were stacked back in January of ->2021<- and have
essentially sat ever since. The contractor has already granted NASA one
extension, since originally they were only spec'd to be able to sit up
until September of 2021 IIRC. The issues (once again) are joint
integrity and propellant 'sag'. If this doesn't launch by December it's
not clear NASA will get another waiver and it'll be back to the VAB for
a restacking.

That's not actually such a bad thing. Valuable data would be had should
that be done. In fact, it would be wise to stack one vertically on a
test stand for up to two years then take it apart and see how it did.
Maybe an unused bay in the VAB.

The other big issue with SLS that was not so big for the Shuttle was the
the fact that the rotating service structure allowed a lot of work to
continue on the Shuttle even after it had been rolled out to the pad.
SLS does not have this, because why would you need to service an
*expendable* rocket?

Dave

[David Spain]

On 2022-09-26 8:34 AM, David Spain wrote:
> On 2022-09-26 1:54 AM, JF Mezei wrote:
>> On 2022-09-23 09:58, David Spain wrote:
>>
>>> This is just but one example of why it's more difficult to do this when
>>> a government agency is trying to accomplish something via contractors vs
>>> doing it yourself.
>>
>>
>>
>> NASA had over  25 years experience with Shuttle/hydrogen and quick
>> disconnects.

Some of NASA's contractors had the experience. NASA had the paperwork.
Institutional knowledge is a broad thing. It's not like NASA can fire
one set of contractors and bring in another with zero knowledge of what
was done and get them up to speed instantly. This is a major difference
between the way NASA does business and SpaceX for example. Not to
mention people move on, retire etc. both at the contractor and at NASA.
Things don't go as seamlessly as you'd expect.

Dave

[JF Mezei]

On 2022-09-26 08:34, David Spain wrote:

> As Rand Simberg points out on his blog a whole set of clocks start
> ticking once the SLS rocket rolls out of the VAB.

I can understand SRBs which have a "best before" date because
built-already fueled. I can understand limits on how many times you
can fill/empty the tanks since going from tropical to cryo temperature
cycles impacts the metals.

But to design the Orion Capsule such that it either doesn't get power
from pad or didn't bother with provisions to power experiments while at
pad is very strange for NASA. Same with the flight termination system
whose batteries should be able to be recharged while at pad.

The odds of delays at pad are the same whether rocket is reusable or
not. And the cost of providing pad power to these systems wouldn't be
that great compared to overall cost.

It is just strange that pedantic NASA wouldn't have required the rocket
to be able to stand at pad without using batteries.

> continue on the Shuttle even after it had been rolled out to the pad.
> SLS does not have this, because why would you need to service an
> *expendable* rocket?

It was decided to complete preparation at the pad, and load payloads at
the pad, hence the RSS for shuttle. But the shuttle itself was getting
pad power and the crew compartment was fully powered and experiments,
fridges etc powered by pad until a minute or two before launch.

The fact that SLS can't be maintained at pad is all the more reason to
allow it to be powered by the pad since changing AA or CR2032 batteries
spread throughout the stack requires roll back to the VAB.

[Greg (Strider) Moore]

"JF Mezei" wrote in message news:74qYK.341737$wLZ8....@fx18.iad...

>
>On 2022-09-26 08:34, David Spain wrote:
>
>> As Rand Simberg points out on his blog a whole set of clocks start
>> ticking once the SLS rocket rolls out of the VAB.
>
>I can understand SRBs which have a "best before" date because
>built-already fueled. I can understand limits on how many times you
>can fill/empty the tanks since going from tropical to cryo temperature
>cycles impacts the metals.
>
>But to design the Orion Capsule such that it either doesn't get power
>from pad or didn't bother with provisions to power experiments while at
>pad is very strange for NASA. Same with the flight termination system
>whose batteries should be able to be recharged while at pad.

Two schools of thought on something like that:
1) If we're launching only once or twice a year, why develop all the
infrastructure at the pad?
2) On the other hand, because we plan on only launching once or twice a
year, it could be we're at the pad for long periods of time, so we should
develop the need for it.

Think of it this way too. For a variety of reasons Apple started the trend
of not being able to quickly/easily swap out batteries on their iPhones. For
one, it makes it lighter. Fewer connections, etc. For another, "well folks
will upgrade before the battery dies..."

Also, rechargeable batteries are a bit more complicated, adds weight,
potential outgassing, potential over charging, etc. So you can argue it
might be safer to do all that work in a separate building, not on the rocket
itsefl.

>
>The odds of delays at pad are the same whether rocket is reusable or
>not. And the cost of providing pad power to these systems wouldn't be
>that great compared to overall cost.
>
>It is just strange that pedantic NASA wouldn't have required the rocket
>to be able to stand at pad without using batteries.
>
>> continue on the Shuttle even after it had been rolled out to the pad.
>> SLS does not have this, because why would you need to service an
>> *expendable* rocket?
>
>
>It was decided to complete preparation at the pad, and load payloads at
>the pad, hence the RSS for shuttle. But the shuttle itself was getting
>pad power and the crew compartment was fully powered and experiments,
>fridges etc powered by pad until a minute or two before launch.
>
>The fact that SLS can't be maintained at pad is all the more reason to
>allow it to be powered by the pad since changing AA or CR2032 batteries
>spread throughout the stack requires roll back to the VAB.

I would tend to agree. Shuttle, for all its problems WAS in theory designed
for quick servicing, which meant being able to do a good deal of work at the
pad.
SLS obviously wasn't.

Heck, even the Saturn V had the mobile service structure!

--
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CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net
IT Disaster Response -
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