SpaceX (general discussion)

jeffb

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Turns out the Russians shooting down starlink thing may be a fake site. Apols if true.

EDIT: Site is unknown/unreachable now so was fake. My bad, will delete.
 
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publiusr

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Buran.ru looks to have been hacked as well.

Putin would just put his cosmonauts in harms way again if he starts sniping.
 

Michel Van

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new problems
Dragon XL program, Seems NASA not even starte with Program, it two years overtime !
 

Michel Van

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update on Starfactory at Starbase

FQo-8a0XwAUGzEl
 

Michel Van

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on issue Russia vs Starlink

they try to jam the System but...
 

sferrin

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on issue Russia vs Starlink

they try to jam the System but...
The difference between the private sector and government. Plus it's SpaceX. Not a blind fanboy of Musk but we all know if it were Boeing they'd have demanded money from Uncle Sugar and then f--ked it up.
 

Flyaway

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NASA has picked SpaceX, Amazon and four other American companies to develop the next generation of near-Earth space communication services meant to support its future missions. The agency started looking for partners under the Communication Services Project (CSP) in mid-2021, explaining that the use of commercially provided SATCOM will reduce costs and allow it to focus its efforts on deep space exploration and science missions.
 

TomcatViP

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Leaked-Booster-7-damage-image.jpeg


 

FighterJock

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Leaked-Booster-7-damage-image.jpeg



That does not look too good for Starship, especially being the booster prototype. I wonder what caused the damage to it.
 

TomcatViP

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IMOHO It failed under pressure or imploded. But, apparently, it is not known if that was during the test or as a result of the test conditions and the abrupt stop inherent to such testing.

Notice that the strengthener (ribs) are not alternate welds but discontinued what in effect reduces their role.
 

FighterJock

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IMOHO It failed under pressure or imploded. But, apparently, it is not known if that was during the test or as a result of the test conditions and the abrupt stop inherent to such testing.

Notice that the strengthener (ribs) are not alternate welds but discontinued what in effect reduces their role.

That is truly shocking TomcatVIP, I would have thought that the metal would have been strong enough to withstand pressure and the possibility of imploding, but from the picture obviously not.
 

sferrin

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There are many possible explanations. Could have been a test to failure. The test could have been setup incorrectly (oops, we forgot to remove a cap). And so on. Without knowing the specifics it's an interesting picture and not much more. (Though you can be sure the media will try to make as much hay out of it as is humanly possible.)
 

FighterJock

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That is what happens to pipe when it can't handle a vacuum, I've seen similar collapses during my fabricating career. The stiffeners should have .been continuously welded

I am surprised that they weren't continuously welded kitnut617, is that an example of bad workmanship on the part of the SpaceX engineers or outside contractors? Let's hope that there is an investigation into what happened and who ultimately was responsible.
 

publiusr

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They can’t put spacers or something in there?

Any law that says they can’t look at the SLS vertical weld tool and have the two teams compare notes?

Each group might have a solution to the other group’s woes.

Not every blasted thing has to be a zero sum game guys.
 
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TomcatViP

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those are routinely discontinued welds to save for man-hours and costs or other factors. However weld joint strength is affected and the choice of solution is to be done according to design constraints.

Notice that the presumed function of those ribs might be else. For example, given their thin sections and low span, they could also be turbulators to generate a rapid thermal exchange zone around the riser/downcomer immersed inside the tank to minimize thermal induced stress.
So far we don't know much.
 

sferrin

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We still don't know if what caused it was outside design requirements. Second guessing why it wasn't continuously welded is pointless. We have no evidence it needed to be. It's extremely unlikely that it went through manufacture, inspection, shipping, and installation without an incorrect weld style being detected.
 
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sferrin

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That is what happens to pipe when it can't handle a vacuum, I've seen similar collapses during my fabricating career. The stiffeners should have .been continuously welded
We don't know that it was required to hold a vacuum. All we know is there was a failure.
 

kitnut617

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That is what happens to pipe when it can't handle a vacuum, I've seen similar collapses during my fabricating career. The stiffeners should have .been continuously welded
We don't know that it was required to hold a vacuum. All we know is there was a failure.
It probably wasn't supposed to counter a vacuum, but a vacuum must have happened for the pipe to collapse like that.
Anyone remember the old science experiment kids did with a metal can, where you boiled some water in it, took it off the burner and then screwed the top back on and then watch it collapse as it cooled down ----
 

Archibald

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Iterative testing, folks. SpaceX is building a lot of ground and flight test prototypes that are bound to explode, crack, fail, and consequently consigned to the trash heap, steel recycling factory - or to the rocket garden nearby.

And since the FAA is delaying that first fully-stacked orbital flight, they are making lemons into lemonade destroying rigs and test beds and prototypes on the ground.

The more flawed birds they break and destroy on the ground, the more they refine Starship and BFR fuel fractions and mass fractions.

And with the rocket equation being such a giant PITA and female dog (to use polite accronyms) every single percent is a victory.

Take Starship, for example. 1200 mt of propellants, 150 metric tons of payload: fixed numbers.
The only weight parameter for improvement is the empty weight, presently around 100 metric tons (or so it seems)

1200+150 = 1350 mt.
100 mt of empty weight, total: 1450 mt at takeoff.

With Raptors at 330 seconds on the ground and 380 in complete vacuum, let's take an arbitrary middleground (right between ground and vacuum values) at 355 seconds...

1-(115/1450) = 0.92
1-(100/1450) = 0.93
1-(87/1450) = 0.94
1-(72/1450) = 0.95

but delta-v wise:
9.81*355*ln(1450/115)= 8826 m/s (zero payload)
9.81*355*ln(1450/100)= 9312 m/s (zero payload)
9.81*355*ln(1450/87) = 9797 m/s (zero payload)
9.81*355*ln(1450/72)= 10456 m/s (zero payload)

So 1% improvement in mass fraction makes a big difference delta-v wise, - but it is damn hard to shave that much mass out of the steel build Starship...

Guess why Musk won't fight for a SSTO Starship - not orbital at least. Now, suborbital with a big payload, that's another matter.
 
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publiusr

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Well, there’s a hell of a vacuum in space. SLS’s tank doesn’t need to withstand it for reuse in terms of landing and refilling. Starship does. I hope they sort this out. This is why I like reuse to mean wet workshop. No heat shield needed. Simpler build.
 

Archibald

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9.81*355*ln(1450/100)= 9312 m/s

Or, with some payload... 9.81*355*ln((1450+60)/(100+60)) = 7817 m/s.

This is ISS orbital velocity OR an ascent to Earth orbit without the big losses - drag + steering + gravity.

The neat thing: at 7800 m/s it is still possible to make a flight comparable to a Shuttle Abort Once Around, that is: an incomplete orbit nearly circling the globe.
So, there you go: a Starship without a BFR below it could still hurl a C-17 size payload (60 mt) to the other side of the planet in merely an hour. And that's why the US military is growing interested...
 

siegecrossbow

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They might be planning on directed energy attacks. Most of the starlink constellation is very low and thus vulnerable.
They need very power full laser to hit them 1584 times…
had Russia still one of these ?

Starlink sats are not earth observation satellites, they don’t have sensors that can be blinded to the beat of my knowledge. I don’t think any extant lasers could physically destroy satellites yet, not even ones in low earth orbit.

——————————————————————

View: https://m.youtube.com/watch?v=S2MCDgHPjQM
 

sferrin

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Well, there’s a hell of a vacuum in space. SLS’s tank doesn’t need to withstand it for reuse in terms of landing and refilling. Starship does. I hope they sort this out. This is why I like reuse to mean wet workshop. No heat shield needed. Simpler build.
It's not about "vacuum" it's about pressure differentials.
 

kitnut617

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Well, there’s a hell of a vacuum in space. SLS’s tank doesn’t need to withstand it for reuse in terms of landing and refilling. Starship does. I hope they sort this out. This is why I like reuse to mean wet workshop. No heat shield needed. Simpler build.
It's not about "vacuum" it's about pressure differentials.
You beat me to it --- :)
 

jeffb

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Well, there’s a hell of a vacuum in space. SLS’s tank doesn’t need to withstand it for reuse in terms of landing and refilling. Starship does. I hope they sort this out. This is why I like reuse to mean wet workshop. No heat shield needed. Simpler build.
It's not about "vacuum" it's about pressure differentials.
Minimum weight propellant tanks are a bit like balloons, their pressurisation helps them maintain their shape.
 

jeffb

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They might be planning on directed energy attacks. Most of the starlink constellation is very low and thus vulnerable.
They need very power full laser to hit them 1584 times…
had Russia still one of these ?

Starlink sats are not earth observation satellites, they don’t have sensors that can be blinded to the beat of my knowledge. I don’t think any extant lasers could physically destroy satellites yet, not even ones in low earth orbit.

——————————————————————

View: https://m.youtube.com/watch?v=S2MCDgHPjQM
Didn't say that starlink sats were Earth observation sats. They are high bandwidth, highly encrypted comms channels though which can be and (anecdotally) have been used for Ukrainian military comms.

The story turned out to be fake though, so issue is moot.
 

siegecrossbow

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They might be planning on directed energy attacks. Most of the starlink constellation is very low and thus vulnerable.
They need very power full laser to hit them 1584 times…
had Russia still one of these ?

Starlink sats are not earth observation satellites, they don’t have sensors that can be blinded to the beat of my knowledge. I don’t think any extant lasers could physically destroy satellites yet, not even ones in low earth orbit.

——————————————————————

View: https://m.youtube.com/watch?v=S2MCDgHPjQM
Didn't say that starlink sats were Earth observation sats. They are high bandwidth, highly encrypted comms channels though which can be and (anecdotally) have been used for Ukrainian military comms.

The story turned out to be fake though, so issue is moot.

My point is that current ground based lasers are not powerful enough to do physical damage to anything other than optical sensors in orbit. I wasn’t addressing your post.
 

kitnut617

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Well, there’s a hell of a vacuum in space. SLS’s tank doesn’t need to withstand it for reuse in terms of landing and refilling. Starship does. I hope they sort this out. This is why I like reuse to mean wet workshop. No heat shield needed. Simpler build.
It's not about "vacuum" it's about pressure differentials.
Another scenario is when you attach a pump that is too powerful for the pipe you attach it too, the pump starts to starve itself. If the pipe wall isn't strong enough it will collapse like in the photo too. It's still vacuum related though.
 

sferrin

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Well, there’s a hell of a vacuum in space. SLS’s tank doesn’t need to withstand it for reuse in terms of landing and refilling. Starship does. I hope they sort this out. This is why I like reuse to mean wet workshop. No heat shield needed. Simpler build.
It's not about "vacuum" it's about pressure differentials.
Another scenario is when you attach a pump that is too powerful for the pipe you attach it too, the pump starts to starve itself. If the pipe wall isn't strong enough it will collapse like in the photo too. It's still vacuum related though.
You still have positive pressure, in an absolute sense, inside the pipe. (Unless your pump is so good it can pull a perfect vacuum with air still coming in at the other end. ;) ) You're just pulling air out faster than the opening at the other end can let it in. It's the difference in pressure between the inside and outside of the pipe that crushed it.
 

kitnut617

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Well, there’s a hell of a vacuum in space. SLS’s tank doesn’t need to withstand it for reuse in terms of landing and refilling. Starship does. I hope they sort this out. This is why I like reuse to mean wet workshop. No heat shield needed. Simpler build.
It's not about "vacuum" it's about pressure differentials.
Another scenario is when you attach a pump that is too powerful for the pipe you attach it too, the pump starts to starve itself. If the pipe wall isn't strong enough it will collapse like in the photo too. It's still vacuum related though.
You still have positive pressure, in an absolute sense, inside the pipe. (Unless your pump is so good it can pull a perfect vacuum with air still coming in at the other end. ;) ) You're just pulling air out faster than the opening at the other end can let it in. It's the difference in pressure between the inside and outside of the pipe that crushed it.
Agreed! But isn't it fluid that is flowing through that pipe ?

I've seen it happen on construction sites my job used to take me to. They would be pumping out a flooded excavation, water going through it was fine, but when sludge starts getting sucked in, it doesn't flow so good. End result is the pipe collapses as the pump powers up as it tries to suck it through.

The company I worked for used propane fueled trucks, in extreme cold like we get here in Alberta, liquid propane starts to turn to jelly ----- could it be the same scenario here? The fluid jellifying would be like that.
 

sferrin

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I don't know if the interior of the pipe was underpressured or the exterior was overpressured.
 

publiusr

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Now this is probably a stupid comment-but let me throw this out here. I read in phys.org about paper thin speakers. Well, could you use that and fluids to work with tanks instead of against them?
 

Michel Van

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SpaceX made it 150th launch and 116 suborbital flight of first stage
bringing Crew Dragon Freedom to ISS with 4 astronauts on board
While ULA prepare their 150th launch for 19 may 2022. (AV-096 with Boeing Starliner)

up coming in June
one Falcon Heavy launches for DoD
August
two Falcon Heavy launches
NASA with two deep space probes
the other will dropping two com sats near GEO, from here they move on ion engines into position
 
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FighterJock

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SpaceX made it 150th launch
bringing Crew Dragon Freedom to ISS with 4 astronauts on board
While ULA prepare their 150th launch for 19 may 2022. (AV-096 with Boeing Starliner)

up coming in June
one Falcon Heavy launches for DoD
August
two Falcon Heavy launches
NASA with two deep space probes
the other will dropping two com sats near GEO, from here they move on ion engines into position

I wonder what the two deep space probes are for NASA Michel Van? That would not be the often talked about Uranus probe would it? I hope that the second probe is going to Neptune because Voyager 2 left a lot of unanswered questions especially about Triton with it’s retrograde orbit and it’s geysers.
 

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