SpaceX F9 - Comm Crew In Flight Abort - LC-39A

[Cosmacelf]

From the twitter video the 1st and second stages appeared to be surviving and looked quite stable. The RSD looked to me to be the result of an automated self destruct event.

Thoughts from others?

At some point Elon stated that once the engines are off and the dragon has blasted away, the booster will rapidly become unstable and an explosion/fireball was inevitable.

Everyday Astronaut will no doubt weigh in on this since he asked a question about this, but my understanding of the sequence is that the main booster engines were cut, then Dragon blasted off.

Elon explained that in a normal scenario, if Dragon's computers decided to abort, the first thing it would do would be to send the main engines shutdown command to the booster. So it wasn't clear if they sent a general "abort" command to Dragon, or whether they set really tight and slightly erroneous mission profile parameters in Dragon to cause it to automatically decide to abort. Elon did say that they had set unusually tight mission profile parameters in Dragon's abort system for this test, so maybe it was the automated system that initiated the abort (otherwise why would you have tighter than normal parameters?).

 

[Cosmacelf]

To borrow Elon's term, that "fireball" (it wasn't really an explosion) was dramatic. Was I the only one to have a Challenger flashback? If they'd only had an abort system.

Yes indeed. Was it Challenger where the astronauts were alive and communicating all the way down?

 

[SMAlset]

Last two screen grabs I’ll post (btw i try to add these on launches I catch assuming people would like to see as they read the thread). First was the fireball which was cool to see (knowing circumstances of it and pre-warned to expect) and second was the clarity of the image of the Dragon capsule from the airplane’s view (tap to zoom in).

i don’t recall from the conference how far away from the fireball the capsule was already when the abort command was received.

 

[Cosmacelf]

i don’t recall from the conference how far away from the fireball the capsule was already when the abort command was received.

Your question doesn't seem to make sense? The abort occurred when dragon was on the booster. I was under the impression they didn't send any particular command to the booster post separation, it just exploded on its own.

Elon mentioned that dragon was about 1 mile away from the booster when the booster exploded.

 

[ecarfan]

Thanks for posting that video link. I think Tim Dodd asked the only deeply interesting question regarding the details of the abort sequence and got Elon to open up about what happens. The rest of the conference was not very interesting.

If you missed the press conference I found this. Has the launch and abort as well. Conference starts at 1:46:08.

 

[EldestOyster]

The answer to Tim Dodd's question wasn't 100% clear, but the information was there. The abort system was programmed to activate as the vehicle exceeded a certain speed. Of course, they like to take the instrumentation off the screen right when it gets interesting, but I tried to count it as it went. Speed looked to have been around 1850 km/sec when the abort was triggered. Everything that happened subsequently was tied directly to the abort program sequence.

If you look on twitter, Elon posted a much better view of the event. Here, you can see the Super Dracos starting up even before the Falcon 9's engines show any hint of shutting down. In fact, since I already took a screen shot, I'll add that.

 

[Cosmacelf]

No doubt it takes a little while for the main engines to actually shut down once the shutdown command is given. Fuel in pipes etc.

 

[EldestOyster]

No doubt it takes a little while for the main engines to actually shut down once the shutdown command is given. Fuel in pipes etc.

Fuel in pipes, valves that rotate to a new position, turbines and pumps slowing down, as you say. That was part of the confusion. Elon said the whole abort sequence covers all of 700 ms, and you see MECO taking a lot longer than that. He also mentioned that Dragon could still get away even if the main engines didn't respond to the shutdown order. So I was glad to see that subsequent footage, as it told the story better.

 

[SMAlset]

Your question doesn't seem to make sense? The abort occurred when dragon was on the booster. I was under the impression they didn't send any particular command to the booster post separation, it just exploded on its own.

Elon mentioned that dragon was about 1 mile away from the booster when the booster exploded.

didn’t mean sent from ground but preprogrammed in to happen and processed as it was triggered by events/data received by the computer system. At least that’s what I came away believing.

 

[ggr]

1850 km/sec

That's about 6% lightspeed! Wow!

 

[destructure00]

From the twitter video the 1st and second stages appeared to be surviving and looked quite stable. The RSD looked to me to be the result of an automated self destruct event.

Thoughts from others?

If you watch the short clip in this tweet, it looks to me like the booster starts to pitch/yaw (not sure what the correct term is) a tiny bit after engine shutdown. Then you can see what looks like some LOX or smoke or something start to be expelled from the side that I think would be more into the "wind", and that stream is not quite parallel with the booster. So it seems to me like it wasn't stable, and at that speed it likely doesn't take much to cause a catastrophic structural failure. Once the structure fails, the tanks rupture, and BOOM.

I read in another tweet somewhere that if AFTS was triggered it would destroy both 1st and 2nd stage. You can see what looks like an intact stage 2 exiting the fireball, and later exploding when it hit the water, presumably still full of fuel.

All of that together means to me that it wasn't a triggered self-destruct event.

 

[Electroman]

Intact stage 2 hitting the water and exploding? Where did you see that?

 

[destructure00]

Intact stage 2 hitting the water and exploding? Where did you see that?

2nd stage falling:

Fireball after impact

 

[destructure00]

Here's another great video

Better pic of 2nd stage falling

 

[destructure00]

Everyday Astronaut got video of it as well. Start at 1:45:40

 

[EldestOyster]

Speed looked to have been around 1850 km/sec

That's about 6% lightspeed! Wow!

You try holding together at that speed!

ggr is right; that should be 1850 km/hr. Sadly, I'm less familiar with the metric values used for space flight. But most of it is very fast, which is why I sometimes slip and say "per second".

 

[Grendal]

From the twitter video the 1st and second stages appeared to be surviving and looked quite stable. The RSD looked to me to be the result of an automated self destruct event.

Thoughts from others?

Watch that same twitter video. Near the end you can see that the second stage is leaking propellant. The expectation is that the pressure from slamming into the atmosphere of the un-aerodynamic second stage would rupture the tanks. That apparently happened and I expect the big kaboom happened a fraction of a second after the tanks ruptured. I was surprised no one asked the question directly about whether the AFSD system was activated in the post launch conference but the pre-launch conference basically said it would not be activated since the booster would be destroyed anyway. The consensus on SpaceX Facebook group is that it was not used and that it became unstable, hit the atmosphere in a way to cause it to break apart, which then caused the conflagration we all saw.

 

[Grendal]

Question. Does NASA plan to have a mix of manned and unmanned Dragon ISS delivery flights after the first successful crewed mission? I know SpaceX won't do this for political reasons, but when cargo deliveries start being handled by Dragon 2, I wish they would land those retropulsively as designed. Let NASA fish their astronauts out of the sea for a few years, while the space mice and other equipment rotating out of ISS get a nice cushy ground landing at KSC. Just like F9 boosters for the past several years.

It's not NASA. SpaceX is unwilling to waste time and more money on a system that will only be used for the ISS or a very rare something more. SpaceX is all about development of Starship and Super Heavy. They expect that system to make F9 and FH obsolete. So spending time and money on a system they intend to make obsolete will take time and money away from Starship and Super Heavy development.

 

[Grendal]

Scott Manley gives a thorough breakdown of the events.

Amazing footage from USLaunch Report:

 

[Grendal]

Even as both parachutes are made by same manufacturer, both design are different and are proprietary ip of each company; SpX mark II /= Boeing mark II.

It's been said at various interviews that SpaceX, working with the parachute company, designed the new Mark III parachutes. During some interview, Bridenstine confronted Elon about the new parachutes and how much better they were and Elon said that since it was a safety issue that he'd be willing to let Boeing use them for Starliner. That probably hasn't happened though. Boeing would need to spend more money on more testing for Starliner with any new parachutes.