Updates SpaceX Falcon 9 F5 CRS SpX-2 through CRS SpX-12 Updates

[GLS]

Just calculated some numbers in Excel to be sure:

Would the IDA have dropped a distance of 1.8 meters at 5g, this would be equal to it dropped from 4.5 meters at normal gravity. With 500 kg mass, quite an impact.

I think even a 0.5m fall would generate forces in the range of tons. But even if the force was low, if it "landed" with a small area, that could be enough to puncture the dome.

 

[Urwumpe]

But say if it was the second stage engine chilldown prior to its ignition that was the cause.

Highly doubtful. I don't have the blue prints or schematics of a Merlin engine to perform any competent analysis, but I doubt that SpaceX uses a large diameter line to perform chill-down.

The plume was caused by multiple tons of liquid oxygen getting released and vaporized in a few milliseconds. Such a chill-down line on the other hand, is usually only large enough to vent a few kg per second, would it rupture completely.

 

[garyw]

Highly doubtful. I don't have the blue prints or schematics of a Merlin engine to perform any competent analysis, but I doubt that SpaceX uses a large diameter line to perform chill-down.

The plume was caused by multiple tons of liquid oxygen getting released and vaporized in a few milliseconds. Such a chill-down line on the other hand, is usually only large enough to vent a few kg per second, would it rupture completely.

It would make sense, have a look at this screengrab:

https://www.dropbox.com/s/axvt9kj9x1r4q33/space-x-fail.PNG?dl=0

The first stage can be seen still firing. What ever happened didn't happen to the first stage but further up the length of the rocket.

 

[Urwumpe]

I think even a 0.5m fall would generate forces in the range of tons. But even if the force was low, if it "landed" with a small area, that could be enough to puncture the dome.

Depends on how flexible the tank dome is, and how resistant to piercing forces.

On the top of the tank dome, there are also many valves and pipes usually, which could also get damaged, usually before the tank has any chance to fail itself.

But if SpaceX used bubble tanks (like Atlas or Centaur), any sudden loss of pressurization could also lead to tank failure.

 

[GLS]

In the Spaceflightnow video, approximately at 3:04

https://www.youtube.com/watch?v=u5Nk3b42NkY#t=195

you can see a bigger and longer object tumbling after the big explosion.

There's some glinting in the 2º stage prior to "the event"... not sure if was an frost/ice reflection or something venting already.

 

[Urwumpe]

It would make sense, have a look at this screengrab:

https://www.dropbox.com/s/axvt9kj9x1r4q33/space-x-fail.PNG?dl=0

The first stage can be seen still firing. What ever happened didn't happen to the first stage but further up the length of the rocket.

Yes, but that amount of oxygen in the cloud means that up to multiple tons per second left the tank - you would need a large pipe to transmit that much. The cloud is similar to the cloud that formed during STS-51L (and it was at similar altitude).

Also, the large tumbling object in the cloud could a short time later could also speak for a massive structural failure at the second stage tank.

 

[garyw]

In the Spaceflightnow video, approximately at 3:04

https://www.youtube.com/watch?v=u5Nk3b42NkY#t=195

you can see a bigger and longer object tumbling after the big explosion.

Very interesting video. At 2:54 something can clearly be seen falling away from the vehicle. No idea what though.

 

[Donamy]

Maybe a drogue chute bringing a part of the capsule down.

 

[garyw]

I think it is part of the capsule, the break up starts at 2:50

 

[Urwumpe]

There's some glinting in the 2º stage prior to "the event"... not sure if was an frost/ice reflection or something venting already.

I see nothing unusual at the second stage until the very onset of the event. But when I simulated an object breaking off the rocket at constant acceleration with my mouse cursor, the cursor arrived nearly spot on to the tumbling object in the cloud and follows it.

I am sure, a much better analysis of the video in reverse would show the object having its temporal origin in the event of the first cloud around the second stage.

 

[dave1705]

It's very possible, that's Dragon.(or hope so)

 

[MattBaker]

ISS Consumable Status from April:

Since SpX-6 didn't happen now only the left columns are relevant.

Looks like KTO (waste containers) and food are the most limited. A Progress is scheduled for July 3rd and the Japanese Kounotori 5 is scheduled for mid-August.

This will definitely mean the next crew isn't going up for a while and an unmanned ISS for the first time in over 14 years seems possible, ironically right during the time of a year-long mission...

Let's all hope the Progress return to flight next week is going smoothly.

 

[DaveS]

Elon Musk:

There was an overpressure event in the upper stage liquid oxygen tank. Data suggests counterintuitive cause: https://twitter.com/elonmusk/status/615185689999765504

 

[Urwumpe]

There was an overpressure event in the upper stage liquid oxygen tank. Data suggests counterintuitive cause.

So, we are right to poke at the second stage LOX tank.

:ninja: by DaveS

 

[DaveS]

ISS Consumable Status from April:

Since SpX-6 didn't happen now only the left columns are relevant.

Looks like KTO (waste containers) and food are the most limited. A Progress is scheduled for July 3rd and the Japanese Kounotori 5 is scheduled for mid-August.

This will definitely mean the next crew isn't going up for a while and an unmanned ISS for the first time in over 14 years seems possible, ironically right during the time of a year-long mission...

Let's all hope the Progress return to flight next week is going smoothly.

SPX-6 did happen. This was SPX-7.

 

[Donamy]

So, we are right to poke at the second stage LOX tank.

:ninja: by DaveS

Just need to know what caused it.

 

[Quick_Nick]

Elon Musk:

There was an overpressure event in the upper stage liquid oxygen tank. Data suggests counterintuitive cause: https://twitter.com/elonmusk/status/615185689999765504

I was fully betting on Elon's Twitter to be the first source of news.

 

[GLS]

I see nothing unusual at the second stage until the very onset of the event. But when I simulated an object breaking off the rocket at constant acceleration with my mouse cursor, the cursor arrived nearly spot on to the tumbling object in the cloud and follows it.

I am sure, a much better analysis of the video in reverse would show the object having its temporal origin in the event of the first cloud around the second stage.

It really looks like some venting (not a lot) at the bottom of the 2º stage. It makes sense it's (more) visible from the Playalinda Beach DOAMS (the "north view") than from the Patrick AFB DOAMS (the "south view") due to backlighting.
Something in the 2º stage pre-start could have caused a rupture of a pipe, and the tank venting caused it to loose structural integrity and the rest we know.

Bah: now it looks like it was too much pressure instead of not enough pressure.

 

[MattBaker]

SPX-6 did happen. This was SPX-7.

Oh damn, thanks!:thumbup:

Then it looks like Progress and Kounotori might keep it on track over the summer, that's fantastic.

 

[Urwumpe]

It really looks like some venting (not a lot) at the bottom of the 2º stage. It makes sense it's (more) visible from the Playalinda Beach DOAMS (the "north view") than from the Patrick AFB DOAMS (the "south view") due to backlighting.
Something in the 2º stage pre-start could have caused a rupture of a pipe, and the tank venting caused it to loose structural integrity and the rest we know.

You are right, there is a very tiny glow about 8 second before the anomaly, that intensifies during the final 1.5 seconds.

Its not much, just enough to reflect some sunlight on the shaded side of the second stage - but at that optical quality, it could also be caused by an antenna (or anything else protruding).