starship? but ........ROTFL ! :-)

SpaceX's new Starship prototype appeared to burst during a pressure test late Friday (Feb. 28), rupturing under the glare of flood lights and mist at the company's south Texas facility.

The Starship SN1 prototype, which SpaceX moved to a launchpad near its Boca Chica, Texas, assembly site earlier this week, blew apart during a liquid nitrogen pressure test according to a video captured by SPadre.com.

A separate video posted by NASASpaceflight.com member BocaChicaGal clearly shows the Starship SN1's midsection buckle during the test, then shoot upward before crashing back to the ground.

Space.com has reached out to SpaceX for details of Friday's test. This story will be updated as more information is available.


https://www.space.com/spacex-starshi...e=notification



www.asps.it/patportions.htm

In article ,
says...
Out of curiosity, have cryo tanks of that size ever been built? if so,
what materials and welding technique ?


You're kidding, right? Obviously the space shuttle external tank and
the Saturn V's cryogenic tanks are in the ballpark. Saturn V's first
stage LOX and 2nd stage LOX/LH2 tanks were all larger in diameter than
Starship.

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.

On 3/1/20 8:08 PM, wrote:


SpaceX's new Starship prototype appeared to burst during a pressure test late Friday (Feb. 28), rupturing under the glare of flood lights and mist at the company's south Texas facility.

The Starship SN1 prototype, which SpaceX moved to a launchpad near its Boca Chica, Texas, assembly site earlier this week, blew apart during a liquid nitrogen pressure test according to a video captured by SPadre.com.

A separate video posted by NASASpaceflight.com member BocaChicaGal clearly shows the Starship SN1's midsection buckle during the test, then shoot upward before crashing back to the ground.

Space.com has reached out to SpaceX for details of Friday's test. This story will be updated as more information is available.


https://www.space.com/spacex-starshi...e=notification



www.asps.it/patportions.htm


Those starships are just big suppositories for their big asses.

On 2020-03-02 12:10 AM, JF Mezei wrote:
Watching the BocaChicaGal video.

The flaw happens on the left of rocket and then spreads till rocket
starts to lift off.

The first evidence I see of an anomaly is on the right side as I see it.

However, as it lifts off, the body cavitates onto itself.

Assuming the bottom weld unzipped itself, allowing the nitrogen to push
down and lift the rocket, what principles are involved in the nitregen
wanting to go down so much it created a vaccum above it which caused
tank/rocket to cavitate onto itself?

The nitrogen under pressure has found an outlet and expands outwards
creating a partial vacuum at the top of the tank where it is still
sealed. I am presuming that a RUD was unplanned for in this case because
a pressure relief valve was not opened that could have equalized
pressure in the tank to outside pressure.


I can understand the principle of a bottle made of paper which when you
flip to let the liquid escape would cause paper wlls to cavitate instead
of letting as much liquid out as air bubbles can get in t o maintain
1ATm inside.

Is this a case where the steel walls are designed solely for positive
pressure and have 0 capability of negative pressure? Would all rockets
be designed with similar behaviour?

Or can withstand only so much negative pressure before collapsing. I
know Elon was planning on design changes to make the tank more of a
structural member of the rocket to improve efficiency. Normally I
believe a purge gas is introduced into the tank to compensate for loss
of propellant. I presume for Starlink that will be nitrogen. Probably
not set up that way for this test, which wasn't supposed to unravel
presumably.

I can't speak for all rockets, but due to a discussion I had back on the
arocket mailing list some time ago I know the bi-propellant tanks of the
first stage of the Titan II ICBM had to be fueled in order to maintain
structural integrity of the rocket before the second stage was fueled
and to maintain it afterwards once the rocket was stacked in the silo.
This discussion came about because I had a question about the Damascus
AK incident and how that happened.

https://en.wikipedia.org/wiki/1980_D...sile_explosion

One of the reasons the Air Force got rid of silo based liquid fueled
rockets.

I assume they are all designed to maintain at least the same pressure
inside as there is outside at all times to prevent cavitation? Or would
most rockets have enough strength to support a fair emount of negative
pressure to maintain structural integrity?


I believe the Starship is intended to use a purge gas to maintain tank
integrity. I'm assuming that is nitrogen. I don't know that as a fact.


Secondly, considering the rocket didn't get shot up high, and
cavicvation happened early, would it be fair to state that the pressure
wasn't very high in the tank at time of failure?

Seems like a pretty good lift to me given that nitrogen is largely inert
and did not "ignite". I would not make that assumption.

Aftermath video the next morning:
https://youtu.be/U4C0wfRSUNQ


Dave

On 2020-03-02 9:15, David Spain wrote:
On 2020-03-02 12:10 AM, JF Mezei wrote:

[snip]

I assume they are all designed to maintain at least the same
pressure inside as there is outside at all times to prevent
cavitation? Or would most rockets have enough strength to support
a fair emount of negative pressure to maintain structural
integrity?

I believe the Starship is intended to use a purge gas to maintain
tank integrity. I'm assuming that is nitrogen. I don't know that as
a fact.

AIUI the Starship (and probably also the SH booster) are designed to use
"autogenous pressurisation", that is, returning a fraction of the
gasified propellants back from the engine pumps to the tanks to maintain
pressure in the tanks.

Discussions on nasaspaceflight.com speculate that the recently destroyed
Starship SN1 was intended to go on to test autogenous pressuration, and
that this explains why it had engine mounts for only one Raptor engine
although one engine would not be enough for a significant test flight
and a static-firing test with only one engine would be unrealistic.

--
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
. @ .

In article ,
says...

On 2020-03-01 18:20, Jeff Findley wrote:

You're kidding, right? Obviously the space shuttle external tank and
the Saturn V's cryogenic tanks are in the ballpark.

Sorry brain fart. I was thinking about what is now called Super Heavy
(but not yet built). Starship itself has a scale well within what has
been built before. So building something that size is not beyond
hiumankind's experience.

Super Booster (first stage for Starship) is the same diameter as
Starship. Still on the same order of magnitude (i.e. Saturn V first two
stages were larger in diameter).

The tricky bits are the tank domes and how they attach to the
cylindrical sections. I believe I saw an Elon Musk Tweet this morning
that said they're going to double check that area on SN2 (an area
already built), so presumably that's what failed on SN1's tanking test.

The length of the tanks do not matter much since the barrel sections
would all be the same and attach to each other in the same manner.

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.

In article ,
says...

Watching the BocaChicaGal video.

https://youtu.be/sYeVnGL7fgw

Going frame by frame (pause, and use the "," and "." to step back or
forward respectively frame by frame).

The flaw happens on the left of rocket and then spreads till rocket
starts to lift off.

However, as it lifts off, the body cavitates onto itself.

Assuming the bottom weld unzipped itself, allowing the nitrogen to push
down and lift the rocket, what principles are involved in the nitregen
wanting to go down so much it created a vaccum above it which caused
tank/rocket to cavitate onto itself?

It's *liquid* nitrogen. A huge leak at the bottom of a closed liquid
tank creates a vacuum inside the top of the tank. This is *exactly* how
a mercury (or water) barometer works.

A launch vehicle tank isn't designed to handle any external pressure
(why would it be?), so it literally buckles and crushes when it
encounters an external pressure greater than the internal pressure.

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.

In article , says...
I assume they are all designed to maintain at least the same pressure
inside as there is outside at all times to prevent cavitation? Or would
most rockets have enough strength to support a fair emount of negative
pressure to maintain structural integrity?


I believe the Starship is intended to use a purge gas to maintain tank
integrity. I'm assuming that is nitrogen. I don't know that as a fact.

Actually it will pressurize the liquid methane tank with gaseous methane
and the LOX tank with gaseous oxygen. The hot gases will come from the
Raptor engines. Note that the space shuttle's external tank was
pressurized in much the same way (the SSME's were designed to send hot
gases back to the ET for pressurization). This saves mass since you
don't need separate pressurant tanks (typically helium, which is lighter
than nitrogen).

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.

Il giorno martedì 3 marzo 2020 00:14:16 UTC+1, JF Mezei ha scritto:
On 2020-03-02 12:29, wrote:

I think Musk is crazy because:
1) is trying to do something better than Saturn 5
2) Saturn 5 was scrapped about 50 years ago by NASA


Technology has advanced a bit since the 1960s.
What is being "displayed in public" at BocaChica doesn't represent the
real developmenht in my opinion.

Consider that the Raptor engines are being developped in a serious and
private environment and are being tested with no hystericals.

The glorified beer kegs build publicly at Boca Chica gives SpaceX wants
to test very inexpensively some construction techniques with steel that
it has no experience with. So the failure of "SN1" teach SpaceX more
about how to weld steel. Maybe they will find a way to do steel, maybe
they will conslude it can't be done and switch back to more modern
materials.

Note that when working with composites, small flaws in laying up the
fibre that leave air bubbles can be "fatal" to the structure. So I
suspect that SpaceX is at the same stage with learning to do flawless
welds. If you have seen close up pictures, you will see welds havce a
lot of arrows and markings along the welds.

Good luck to Mr. Musk and his starships.
We asps go in the PNN path

quo fata ferunt

E.Laureti

On 2020-03-02 6:14 PM, JF Mezei wrote:

Consider that the Raptor engines are being developped in a serious and
private environment and are being tested with no hystericals.

I suspect that isn't really correct. I'd have to double check but AFAIK
there isn't tons of security around the McGregor test site. I've seen
plenty of test stand photos taken there. Esp. back in the Grasshopper
days of Falcon 9. There isn't much hysteria because, well frankly the
Raptor has been pretty much thoroughly tested these days. That isn't the
same as saying there won't be Raptor failures in the future, but it
isn't exactly new tech for SpaceX either.

The glorified beer kegs build publicly at Boca Chica gives SpaceX wants
to test very inexpensively some construction techniques with steel that
it has no experience with. So the failure of "SN1" teach SpaceX more
about how to weld steel. Maybe they will find a way to do steel, maybe
they will conslude it can't be done and switch back to more modern
materials.

Way too soon to think that.

Note that when working with composites, small flaws in laying up the
fibre that leave air bubbles can be "fatal" to the structure. So I
suspect that SpaceX is at the same stage with learning to do flawless
welds. If you have seen close up pictures, you will see welds havce a
lot of arrows and markings along the welds.

I think you are confusing failure with progress and are too skeptical.
With each "failure" you learn an incredible amount of information that
can be put to practical use almost immediately. Instead of crying
"fail!" after each RUD I say "progress!".

Wasn't it Edison who said something to the effect that they'd learned
first about 10,000 ways NOT to build a light bulb?

Dave