Does anyone know why it take two days before SpaceX can make another
launch attempt after having filled the tanks? Just pumping the fuel out
of the tank shouldn't be much longer than pumping it in, a few hours
should do. I don't think it is much surprising that there would be
something that delays the operations. I just don't know what it is.

Alain Fournier

Thus spake Alain Fournier:
> Does anyone know why it take two days before SpaceX can make another launch
> attempt after having filled the tanks? Just pumping the fuel out of the tank
> shouldn't be much longer than pumping it in, a few hours should do. I don't
> think it is much surprising that there would be something that delays the
> operations. I just don't know what it is.
>
>
> Alain Fournier

Topping off the tank farm is part of the delay. The boiloff and other
losses during tanking and detanking mean that what they recover is less
than what they pumped in. And at this point, the tank farm is filled
by tanker trucks.

There is probably a lot more inspection going on with these prototypes
than there would be with production rockets.

/dps

--
"I am not given to exaggeration, and when I say a thing I mean it"
_Roughing It_, Mark Twain

Snidely <snidely.too@gmail.com> wrote:
>Thus spake Alain Fournier:
>> Does anyone know why it take two days before SpaceX can make
>> another launch attempt after having filled the tanks? Just pumping
>> the fuel out of the tank shouldn't be much longer than pumping it
>> in, a few hours should do. I don't think it is much surprising that
>> there would be something that delays the operations. I just don't
>> know what it is.
>
>Topping off the tank farm is part of the delay. The boiloff and other
>losses during tanking and detanking mean that what they recover is less
>than what they pumped in. And at this point, the tank farm is filled
>by tanker trucks.

Yeah, I expect that for an operational launches they would have a farm
that has enough extra stored to just absorb it and recycle quickly
several times - thus moving it out of the critical path for recycling.

But there's likely relatively little benefits for them to spend that
money at this stage (and it might not be this farm anyway), just going
over all the data they collected likely ruled out Tuesday anyway so at
most it could have saved a day.

It IS slightly suspicious that the next attempt is now scheduled for
4-20 given, well, Musk [1], and given that he even hinted that he
though 420 was "likely" before 17 April was announced.

But that can just be that he knew fully well that at least one scrub
was relatively likely, second or third attempt is pretty much standard
to "new" rockets, and knowing how long it takes to recycle.

>There is probably a lot more inspection going on with these prototypes
>than there would be with production rockets.

They continued to run it past the scrub to get more data, effectively
converting it to a full Wet Dress Rehearsal to get as much information
out of it as possible.

So they got LOADS of data from all leading up to the scrub and they
definitely is going to go through it all before trying to light up the
candle again.

1. https://futurism.com/the-byte/elon-musk-coincidence-starship-stack-420

On Apr/19/2023 at 08:01, Torbjorn Lindgren wrote :

> It IS slightly suspicious that the next attempt is now scheduled for
> 4-20 given, well, Musk [1], and given that he even hinted that he
> though 420 was "likely" before 17 April was announced.

> 1. https://futurism.com/the-byte/elon-musk-coincidence-starship-stack-420

I disagree with you. I don't think that the next attempt schedule is
slightly suspicious. It is very suspicious. Musk is Musk. :-)

Alain Fournier

Torbjorn Lindgren <tl@none.invalid> wrote:

> It IS slightly suspicious that the next attempt is now scheduled for
> 4-20 given, well, Musk [1], and given that he even hinted that he
> though 420 was "likely" before 17 April was announced.
....
> 1. https://futurism.com/the-byte/elon-musk-coincidence-starship-stack-420

And whose birthday is that too?
--
/* * * Otto J. Makela <om@iki.fi> * * * * * * * * * */
/* Phone: +358 40 765 5772, ICBM: N 60 10' E 24 55' */
/* Mail: Mechelininkatu 26 B 27, FI-00100 Helsinki */
/* * * Computers Rule 01001111 01001011 * * * * * * */

On Apr/20/2023 at 03:23, Otto J. Makela wrote :
> Torbjorn Lindgren <tl@none.invalid> wrote:
>
>> It IS slightly suspicious that the next attempt is now scheduled for
>> 4-20 given, well, Musk [1], and given that he even hinted that he
>> though 420 was "likely" before 17 April was announced.
> ...
>> 1. https://futurism.com/the-byte/elon-musk-coincidence-starship-stack-420
>
> And whose birthday is that too?

My brother. But I suspect you had someone else in mind. I don't know who
it is.

Alain Fournier

Alain Fournier <alain245@videotron.ca> wrote:

> On Apr/20/2023 at 03:23, Otto J. Makela wrote :
>> Torbjorn Lindgren <tl@none.invalid> wrote:
>>
>>> It IS slightly suspicious that the next attempt is now scheduled for
>>> 4-20 given, well, Musk [1], and given that he even hinted that he
>>> though 420 was "likely" before 17 April was announced.
>> ...
>>> 1. https://futurism.com/the-byte/elon-musk-coincidence-starship-stack-420
>> And whose birthday is that too?
>
> My brother. But I suspect you had someone else in mind. I don't know
> who it is.

Unfortunately also Adolf's. Has been used as a dog whistle.
--
/* * * Otto J. Makela <om@iki.fi> * * * * * * * * * */
/* Phone: +358 40 765 5772, ICBM: N 60 10' E 24 55' */
/* Mail: Mechelininkatu 26 B 27, FI-00100 Helsinki */
/* * * Computers Rule 01001111 01001011 * * * * * * */

On 2023-04-18 06:50, Alain Fournier wrote:
> Does anyone know why it take two days before SpaceX can make another
> launch attempt after having filled the tanks?

Considering Melon expect to be able to launch every 20 minutes (or
whatever unrealistic number) One would think /iterative development"
would see redevelopment of the launch complex.

The good news is that 25+ Raptor engines have become great assets for
the Boring company to start digging tunnels.

I remember being told that a flame treench wasn't necessary. Considering
the force at which concrete was thrwon to large distances, I have to
wonder if the FAA has any jurisdiction on "stage 0".

on 4/21/2023, JF Mezei supposed :
> On 2023-04-18 06:50, Alain Fournier wrote:
>> Does anyone know why it take two days before SpaceX can make another
>> launch attempt after having filled the tanks?
>
>
>
> Considering Melon expect to be able to launch every 20 minutes (or
> whatever unrealistic number) One would think /iterative development"
> would see redevelopment of the launch complex.
>
> The good news is that 25+ Raptor engines have become great assets for
> the Boring company to start digging tunnels.
>
> I remember being told that a flame treench wasn't necessary. Considering
> the force at which concrete was thrwon to large distances, I have to
> wonder if the FAA has any jurisdiction on "stage 0".

They do. They will take yesterday's results in consideration when
considering the launch license for the next orbital attempt.

Note also that SpaceX had already decided to install a water deluge
system (which would have reduced the energy reaching the concrete) and
was working on a flame diverter. They may find that not delaying 4&20
to allow one or both to be completed has caused longer and serious
delays for 9&26. If it's possible to repair the existing launch site,
assessments will probably take at least a month before that work can
begin. If they have to scrap it and use the second tower site, that
will take at least a year (based on the faster progress seen at KSC).

Also note that a flame trench may not have been as easy as a diverter
structure, due to the water table issue. The crater from Thursday is
already getting wet. KSC's 39A was already built up into a small hill
before SpaceX leased it.

We don't know yet if the concrete shrapnel is the cause of the first
engine outs, but there's certainly speculation about that.

/dps

--
Yes, I have had a cucumber soda. Why do you ask?

On 2023-04-21 20:22, Snidely wrote:

> Note also that SpaceX had already decided to install a water deluge
> system (which would have reduced the energy reaching the concrete) and
> was working on a flame diverter.

I had always thought that water deluge wa to control noise. Would't the
addition of water->steam to rocket exhaust add to the mass hitting the
concrete? Or does throwing water at speed=0 into the mix result in the
exhaust slowing down as it accelerates the water? Does the boiling of
water end up cooling exhaust substantially? Or not enough to matter?

Is there any information on how well the inside of the OLM ring faired?
the anchoring mechanism and all other gizmos on the inside of ring?

The umbilical case on top of OLM was not pulverized so this is good.
But did the stuff inside survive?

From point of view of reusability, my concern is that the sheer power of
the rocket at launch might not make it possible to have undamaged OLM
after every launch.

And since lots was damaged around the OLM (in particular punctured tanks
at tank farm), the design of the launch site may have flaws if there is
no "path" for a flae trench to send exhaust to.

> Also note that a flame trench may not have been as easy as a diverter
> structure, due to the water table issue.

Apparently, the OLM is already fairly high off the ground, but the beams
that support it all around make it difficult to make an above ground
flame diverter/trench. I am not all that concerned about a below ground
flame trench that is filled with water. Wouldn't the exhaust very
quickly push that water out to sea with said water providing some
protection to the flame trench floor?

> We don't know yet if the concrete shrapnel is the cause of the first
> engine outs, but there's certainly speculation about that.

Am more concerned about engine shutdowns well after launch. The engine
tests we've seen in last 2 years have actually been engine start tests,
not engine runs, except for 1 engine and 6 engine tests where engine ran
for a number of seconds after spin-up And the 6 engine test causing much
concrete damage).

Melon Husk claims that he welcomes dissenting opinions and when backed
with fact is willing to change his mind. I a quite curious on whether
staff at SpaceX are affraid to speak up against his "aspirations" to
provide reality check so Husk's aspirational goal of simple OLM without
flame trench was never challenged, whether there were challenges but
Husm overturned them, or whether the engineers really thought the pad
would survive.

(I use Melon Husk because last december, my twitter account was
suspended because they found a post I had made in June 2022 quoting a
public SEC letter send to him and I was forced to delete it to
re-instate account, so now, I no longer mention his name so their
algorithms won't find what I say about him). (and deleted all tweets I
made about hium back to 2017).

JF Mezei was thinking very hard :

Skipping a bit:

> Am more concerned about engine shutdowns well after launch. The engine
> tests we've seen in last 2 years have actually been engine start tests,
> not engine runs, except for 1 engine and 6 engine tests where engine ran
> for a number of seconds after spin-up And the 6 engine test causing much
> concrete damage).

The primary engine testing, like that of Merlins, happens at a Texas
site up nearer the horn of Texas. Engine runs of a couple minutes
happen there. Of course, that location tests engines one at a time, so
the vibration environment is different.

/dps

--
And the Raiders and the Broncos have life now in the West. I thought
they were both nearly dead if not quite really most sincerely dead. --
Mike Salfino, fivethirtyeight.com

On Saturday, JF Mezei yelped out that:

> And since lots was damaged around the OLM (in particular punctured tanks
> at tank farm), the design of the launch site may have flaws if there is
> no "path" for a flae trench to send exhaust to.

I have seen no evidence of punctured tanks. There are two tanks in the
tank farm where the outer shells have been dented; AIUI these are water
tanks. Perhaps you have more information, though.

/dps

--
As a colleague once told me about an incoming manager,
"He does very well in a suck-up, kick-down culture."
Bill in Vancouver

On Saturday or thereabouts, JF Mezei declared ...

> Apparently, the OLM is already fairly high off the ground, but the beams
> that support it all around make it difficult to make an above ground
> flame diverter/trench. I am not all that concerned about a below ground
> flame trench that is filled with water. Wouldn't the exhaust very
> quickly push that water out to sea with said water providing some
> protection to the flame trench floor?

I'm sure you can provide us with a model that shows the expected
results. Just a bit finite element code.

/dps "or ask a civil engineer"

--
Yes, I have had a cucumber soda. Why do you ask?

On Apr/22/2023 at 20:59, Snidely wrote :
> On Saturday or thereabouts, JF Mezei declared ...
>
>> Apparently, the OLM is already fairly high off the ground, but the beams
>> that support it all around make it difficult to make an above ground
>> flame diverter/trench.  I am not all that concerned about a below ground
>> flame trench that is filled with water. Wouldn't the exhaust very
>> quickly push that water out to sea with said water providing some
>> protection to the flame trench floor?
>
> I'm sure you can provide us with a model that shows the expected
> results.  Just a bit finite element code.
>
> /dps "or ask a civil engineer"

In a case Mr Mezei didn't understand what Mr Snidely was saying:

The exhaust from the rocket is a complex super-sonic flow. There will be
a bounce back of the shock-wave towards the rocket. The shape and timing
of such a bounce back is not a simple thing and can have some
counter-intuitive effects. A flame trench is not just a simple thing
that you ask a guy with a shovel to dig according to some sketch on a
napkin. You need to optimise the shape (that is where the finite element
code comes in).

Alain Fournier