SpaceX F9 : Crew Dragon In-Flight Abort Test : Jan. 19, 2020 : Discussion

[lonestriker]

Apologies if this has been asked...

In this test ALL of the Merlins shutdown, and then the abort initiated...

I imagine there is a constantly evolving algorithm that would evaluate all the variables, and then relative to one, two, four engines out when to proceed to abort.

Thinking of the Falcon9 & CRS flight that lost one engine on the climb would not merit pulling the lever and aborting...

Thoughts and or informed opinions, maybe even facts about abort criteria parameters?

In the press conference, Elon seemed to say that they deliberately tightened the parameters for an automatic abort so that they would trigger at a certain part of the flight.  Once the Dragon decided an abort was necessary, it commanded the Merlins to shut down.  Without waiting for confirmation that that had happened, it then released itself from the Falcon second stage, armed and fired the super-Dracos.  All in the space of less than a second.

So the trigger for the abort was not any malfunction of the Falcon, but rather the Falcon behaving normally and the Dragon being overly picky about that behavior.  On purpose.  For the sake of the test.

Now they simply have to return the definition of "normal" back to the real normal.

I don't think this is correct.  From the SpaceX webcast, John said that they would command the F9 S1 engines to shutdown to start the sequence of events.  D2 would have detected the off-nominal condition and initiated the abort.  Elon mentioned that they did tighten up the parameters, but I think that just meant that instead of aborting at x% thrust out of band, they aborted at (x - delta)% thrust loss.  So a just make it abort more easily.

But, the abort is all in the hands of D2 itself. It wouldn't be much of an abort test if they also commanded D2 to abort.  That decision has to be made by the computers themselves, not humans.  The confusion comes from the fact that as D2 aborts, it ALSO commands the F9 S1 to cut thrust (but that was already done since that was what triggered everything to start with.)

[woods170]

Just talked to a source. Can confirm that intact S2 and attached interstage is what impacted ocean and caused boom on surface. Was not quite expected that such large part of F9 would make it to the ocean intact.

[winkhomewinkhome]

Apologies if this has been asked...

In this test ALL of the Merlins shutdown, and then the abort initiated...

I imagine there is a constantly evolving algorithm that would evaluate all the variables, and then relative to one, two, four engines out when to proceed to abort.

Thinking of the Falcon9 & CRS flight that lost one engine on the climb would not merit pulling the lever and aborting...

Thoughts and or informed opinions, maybe even facts about abort criteria parameters?

In the press conference, Elon seemed to say that they deliberately tightened the parameters for an automatic abort so that they would trigger at a certain part of the flight.  Once the Dragon decided an abort was necessary, it commanded the Merlins to shut down.  Without waiting for confirmation that that had happened, it then released itself from the Falcon second stage, armed and fired the super-Dracos.  All in the space of less than a second.

So the trigger for the abort was not any malfunction of the Falcon, but rather the Falcon behaving normally and the Dragon being overly picky about that behavior.  On purpose.  For the sake of the test.

Now they simply have to return the definition of "normal" back to the real normal.

I think you have that backwards -  Falcon was commanded to shutdown Merlins, Dragon system monitoring detected a fall-off in thrust/acceleration - abort initiated...

[Barley]

But, the abort is all in the hands of D2 itself. It wouldn't be much of an abort test if they also commanded D2 to abort. 

It would still test the hardware.

There are better ways of testing software.  At worst connect the abort outputs to a chart recorder instead of actual hardware, recover the hardware, repeat.  If something like the IFA test finds a software problem, it has not found a software problem, it's found a software process problem.

[meekGee]

Just talked to a source. Can confirm that intact S2 and attached interstage is what impacted ocean and caused boom on surface. Was not quite expected that such large part of F9 would make it to the ocean intact.

If S2 was intact, wouldn't a functioning S1 been able to continue pushing S2, release it, and come back alive?

[daveglo]

Just talked to a source. Can confirm that intact S2 and attached interstage is what impacted ocean and caused boom on surface. Was not quite expected that such large part of F9 would make it to the ocean intact.

If S2 was intact, wouldn't a functioning S1 been able to continue pushing S2, release it, and come back alive?

This would confirm this image from @Erdayastronaut feed:

[Okie_Steve]

Interesting, previously when S2 went blooie S1 not only held together and kept firing but Dragon separated and was potentially survivable. This time Dragon separated and survives while S1 went blooie, but S2 hung together with the interstage all the way to the surface. These thing are tougher than I thought,  probably lots of other people too!

[bulkmail]

Just talked to a source. Can confirm that intact S2 and attached interstage is what impacted ocean and caused boom on surface. Was not quite expected that such large part of F9 would make it to the ocean intact.

If S2 was intact, wouldn't a functioning S1 been able to continue pushing S2, release it, and come back alive?

I wonder the same. Also, what Okie_Steve mentions below - what's the explanation for what happened? Is it that the stage1 was destroyed by FTS (automatically after going off-course due to lack of thrust? manually after it became obvious aerodynamic forces are not enough to disintegrate S2/S1?)?

[meekGee]

Just talked to a source. Can confirm that intact S2 and attached interstage is what impacted ocean and caused boom on surface. Was not quite expected that such large part of F9 would make it to the ocean intact.

If S2 was intact, wouldn't a functioning S1 been able to continue pushing S2, release it, and come back alive?

I wonder the same. Also, what Okie_Steve mentions below - what's the explanation for what happened? Is it that the stage1 was destroyed by FTS (automatically after going off-course due to lack of thrust? manually after it became obvious aerodynamic forces are not enough to disintegrate S2/S1?)?

Once the engines are off, the stack will accrue an angle of attack, and something will break.

S1 is the longer piece, so probably failed first, separating from S2/interstage in the process...

The much shorter S2 survived just fine.

Had S1 retained control authority, it could have kept flying straight, pushed the somewhat damaged S2 to a point where it can separate, and flew back home.

Or, S2 would have disintegrated and taken S1 out with it, shades of CRS7.

Would have should have could have.    Onward!

[Herb Schaltegger]

Have we yet seen any recovery photos yet? A little surprised Elon hasn't yet posted pics of the capsule bobbing in the water or even up the deck of the recovery vessel.

[Comga]

Wow, John Kraus got a photo of the part that hit the water.

The actual part before impact:
https://twitter.com/thejackbeyer/status/1218927117443969025/

Looks like S2+Interstage.

To me it looks like the first stage and interstage, like Jarnis said.

Edit:Or not!
Seems conclusive it IS the second stage.

[joek]

Apologies if this has been asked...

In this test ALL of the Merlins shutdown, and then the abort initiated...

I imagine there is a constantly evolving algorithm that would evaluate all the variables, and then relative to one, two, four engines out when to proceed to abort.

Thinking of the Falcon9 & CRS flight that lost one engine on the climb would not merit pulling the lever and aborting...

Thoughts and or informed opinions, maybe even facts about abort criteria parameters?

In the press conference, Elon seemed to say that they deliberately tightened the parameters for an automatic abort so that they would trigger at a certain part of the flight.  Once the Dragon decided an abort was necessary, it commanded the Merlins to shut down.  Without waiting for confirmation that that had happened, it then released itself from the Falcon second stage, armed and fired the super-Dracos.  All in the space of less than a second.

So the trigger for the abort was not any malfunction of the Falcon, but rather the Falcon behaving normally and the Dragon being overly picky about that behavior.  On purpose.  For the sake of the test.

Now they simply have to return the definition of "normal" back to the real normal.

I think you have that backwards -  Falcon was commanded to shutdown Merlins, Dragon system monitoring detected a fall-off in thrust/acceleration - abort initiated...

This was addressed during Q&A near the end of the press conference during an exchange with Everyday Astronaut which helped clarify.  Dragon detected a condition; Elon mentioned only "tightened parameters" which subsequently initiated abort, part of which was the F9 shutdown command.  The F9 shutdown was not the initiating-causal event.

The specifics of the condition which Dragon detected and then initiated abort was not addressed but it seemed clear that the initiating event was not an F9 shutdown command.  Those "tightened parameters" could refer to any number of possibilities.
 E.g., flight profile tightened from nominal 3% to 0.1% variance after T+n; injecting an intentional variance which exceeded that "tightened parameter" into one Merlin's thrust profile; a simple timer coupled to a some other input(s); or ...

In short, think lonestriker and rpapo have it right.

[mme]

Apologies if this has been asked...

In this test ALL of the Merlins shutdown, and then the abort initiated...

I imagine there is a constantly evolving algorithm that would evaluate all the variables, and then relative to one, two, four engines out when to proceed to abort.

Thinking of the Falcon9 & CRS flight that lost one engine on the climb would not merit pulling the lever and aborting...

Thoughts and or informed opinions, maybe even facts about abort criteria parameters?

In the press conference, Elon seemed to say that they deliberately tightened the parameters for an automatic abort so that they would trigger at a certain part of the flight.  Once the Dragon decided an abort was necessary, it commanded the Merlins to shut down.  Without waiting for confirmation that that had happened, it then released itself from the Falcon second stage, armed and fired the super-Dracos.  All in the space of less than a second.

So the trigger for the abort was not any malfunction of the Falcon, but rather the Falcon behaving normally and the Dragon being overly picky about that behavior.  On purpose.  For the sake of the test.

Now they simply have to return the definition of "normal" back to the real normal.

I don't think this is correct.  From the SpaceX webcast, John said that they would command the F9 S1 engines to shutdown to start the sequence of events.  D2 would have detected the off-nominal condition and initiated the abort.  Elon mentioned that they did tighten up the parameters, but I think that just meant that instead of aborting at x% thrust out of band, they aborted at (x - delta)% thrust loss.  So a just make it abort more easily.

But, the abort is all in the hands of D2 itself. It wouldn't be much of an abort test if they also commanded D2 to abort.  That decision has to be made by the computers themselves, not humans.  The confusion comes from the fact that as D2 aborts, it ALSO commands the F9 S1 to cut thrust (but that was already done since that was what triggered everything to start with.)

I'm team Elon on this one. Tim Dodd asked for clarification in the presser and Musk stated that the *abort* was triggered by F9 reaching a specific velocity. He stated that the engines were shutdown by the abort itself rather than the abort being triggered by the loss of thrust. I know there have been a lot of conflicting statements on this but until I hear from someone else from SpaceX responding to the specific question (as Elon did), I'm taking that as the most explicit, knowledgeable statement.

[Hog]

Has anyone compared the Orion AA2 to the Dragon-2 IFA?

Boeing Orion Ascent Abort


Comments on the apparent booster to capsule separation speeds between the 2?

[edkyle99]

This so called friendly “return the flag” challenge, while I’m sure intended to be a motivator, has IMHO, turned out to be the opposite...my sense is that there is a lot more at play here...political games, etc...my opinion only but  seems that SpaceX has gone above and beyond NASA requirements for Commercial Crew and yet the reins are pulled back on them to allow Boeing and Starliner to catch up...

Reined in?  That exploding Crew Dragon last year had something to do with the schedule, no?  That pushed back IFA, and surely DM-2 itself, by many months.

 - Ed Kyle

[meekGee]

This so called friendly “return the flag” challenge, while I’m sure intended to be a motivator, has IMHO, turned out to be the opposite...my sense is that there is a lot more at play here...political games, etc...my opinion only but  seems that SpaceX has gone above and beyond NASA requirements for Commercial Crew and yet the reins are pulled back on them to allow Boeing and Starliner to catch up...

Reined in?  That exploding Crew Dragon last year had something to do with the schedule, no?  That pushed back IFA, and surely DM-2 itself, by many months.

 - Ed Kyle

Of course it did.  But as of today, SpaceX completed all their requirements.  Boeing is investigating their craft and their processes following an anomaly.

From here on out, what remains is politics.

[DigitalMan]

This so called friendly “return the flag” challenge, while I’m sure intended to be a motivator, has IMHO, turned out to be the opposite...my sense is that there is a lot more at play here...political games, etc...my opinion only but  seems that SpaceX has gone above and beyond NASA requirements for Commercial Crew and yet the reins are pulled back on them to allow Boeing and Starliner to catch up...

Reined in?  That exploding Crew Dragon last year had something to do with the schedule, no?  That pushed back IFA, and surely DM-2 itself, by many months.

 - Ed Kyle

Of course it did.  But as of today, SpaceX completed all their requirements.  Boeing is investigating their craft and their processes following an anomaly.

From here on out, what remains is politics.

According to Kathy there are still some parachute tests to do.  I think she mentioned they are waiting on another set.

[joek]

...
Comments on the apparent booster to capsule separation speeds between the 2?

Hard to compare based on that video.  Also questionable apples-oranges comparison.  Too many differences in the environments, LV's and LAS systems.  For example, Orion LAS is essentially full-out once they light it up.  Have not seen information on what kind of G's that imparts.  Dragon LAS can be modulated--and apparently was during this test with 3.5G limit.

Per comments during the presser, Dragon LAS can push 6+ G's; how Dragon might determine if-when that is necessary or how it might change the SC-LV distance is unknown.  Maybe it is capable of determining effectiveness of booster shutdown command before deciding?  Maybe it has a way of knowing nominal distance from LV in the initial phase before deciding?  And if it is not sure, maybe it puts pedal-to-the-metal (which we did not see today)?

Not to mention other differences, such as Orion LAS is jettisoned relatively early in flight; whereas Dragon LAS is available all the way to orbit.  How does that change the equation?

An interesting comparison and probably worthy of its own thread (not this one).

[Jeff Lerner]

This so called friendly “return the flag” challenge, while I’m sure intended to be a motivator, has IMHO, turned out to be the opposite...my sense is that there is a lot more at play here...political games, etc...my opinion only but  seems that SpaceX has gone above and beyond NASA requirements for Commercial Crew and yet the reins are pulled back on them to allow Boeing and Starliner to catch up...

Reined in?  That exploding Crew Dragon last year had something to do with the schedule, no?  That pushed back IFA, and surely DM-2 itself, by many months.

 - Ed Kyle

Of course it did.  But as of today, SpaceX completed all their requirements.  Boeing is investigating their craft and their processes following an anomaly.

From here on out, what remains is politics.

According to Kathy there are still some parachute tests to do.  I think she mentioned they are waiting on another set.

This is exactly what I’m talking about...haven’t SpaceX successfully completed 10 consecutive Mark 3 parachute tests (11 if you include today’s)...what more does NASA want with SpaceX...??..

Again, i ask the question, after today’s test, which of the first Commercial Crews would fly on their respective spacecraft tomorrow...my bet would be with Dragon 2...

[joek]

This so called friendly “return the flag” challenge, while I’m sure intended to be a motivator, has IMHO, turned out to be the opposite...my sense is that there is a lot more at play here...political games, etc...my opinion only but  seems that SpaceX has gone above and beyond NASA requirements for Commercial Crew and yet the reins are pulled back on them to allow Boeing and Starliner to catch up...

Reined in?  That exploding Crew Dragon last year had something to do with the schedule, no?  That pushed back IFA, and surely DM-2 itself, by many months.

 - Ed Kyle

Of course it did.  But as of today, SpaceX completed all their requirements.  Boeing is investigating their craft and their processes following an anomaly.

From here on out, what remains is politics.

According to Kathy there are still some parachute tests to do.  I think she mentioned they are waiting on another set.

According to Kathy there are still some parachute tests to do.  I think she mentioned they are waiting on another set.

Yes, IIRC from the presser, two more Dragon parachute system level tests.  Also mentioned was completion of data analysis and certification from this (and presumably additional) tests.  Based on remarks during the presser, "what remains" is more than politics.