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

[woods170]

Launch-escape systems are not designed to save the crew in all cases -- that just isn't realistic.

How did that old grim joke go, "Attempting suicide to avoid certain death"?

Yessir. And back in the days of Mercury and Apollo it was no joke; it was reality.

[Comga]

We really wander when we get bored.
It doesn’t matter what ANY of us THINK would be best for the IFA.
SpaceX is satisfying themselves and their customer NASA with what they choose to do.
The best we can do is ask and/or try to figure out why.
And wait for SpaceX to roll out the rocket so we can see if it does have legs and grid fins.

[strawwalker]

I see the logic behind an abort under thrust being the "worst case" scenario, but as long as we are all just speculating, my guess is that "worst case" on as many factors as possible just isn't the point here. The primary goal of this test at max-Q is likely to validate their model of how the actual capsule and trunk behave through an abort in such an extreme aerodynamic environment. If they verify that, then it's known how fast it would pull away from a thrusting booster in any of a variety of possible booster outcomes, so testing it with the engines running doesn't tell them a whole lot.

[CorvusCorax]

The abort maneuver for Crew Dragon involves shutting down the main engines, so a proper test of the abort during flight MUST involve the shutdown of the engines so they can verify they actually do what they are supposed to do. Wether you think this makes more sense or not it's up to you.

IMHO this isn't sufficiently justified.
SpaceX doesn't have to proof to anyone that their engines can shut down safely when commanded to shut down. They do that at
- every stage separation
- every static fire
- every time they are on the test stand in Mc Gregor
multiple times for every single engine they ever fly.

What they should demonstrate is that the "abort" signal reached the engine computers at the bottom of the 1st stage and shows up in telemetry. It is necessary to verify the timings of that, and make sure it is detected correctly. Its not needed to actually shut the engines down under those very exact conditions, that doesn't lead to any new data. (In fact it would lead to less data if this maneuver is what effectively makes the difference between getting a booster back to look at or having telemetry only among lots of tiny debris sunk in the drink)

[Roy_H]

The abort maneuver for Crew Dragon involves shutting down the main engines, so a proper test of the abort during flight MUST involve the shutdown of the engines so they can verify they actually do what they are supposed to do. Wether you think this makes more sense or not it's up to you.

IMHO this isn't sufficiently justified.
SpaceX doesn't have to proof to anyone that their engines can shut down safely when commanded to shut down. They do that at
- every stage separation
- every static fire
- every time they are on the test stand in Mc Gregor
multiple times for every single engine they ever fly.

What they should demonstrate is that the "abort" signal reached the engine computers at the bottom of the 1st stage and shows up in telemetry. It is necessary to verify the timings of that, and make sure it is detected correctly. Its not needed to actually shut the engines down under those very exact conditions, that doesn't lead to any new data. (In fact it would lead to less data if this maneuver is what effectively makes the difference between getting a booster back to look at or having telemetry only among lots of tiny debris sunk in the drink)

I would be willing to bet almost anything that there are several modes to shut down the booster engines including loss of communication with the Dragon. No abort signal required.

[CorvusCorax]

...
What they should demonstrate is that the "abort" signal reached the engine computers at the bottom of the 1st stage and shows up in telemetry. It is necessary to verify the timings of that, and make sure it is detected correctly. Its not needed to actually shut the engines down under those very exact conditions, that doesn't lead to any new data. (In fact it would lead to less data if this maneuver is what effectively makes the difference between getting a booster back to look at or having telemetry only among lots of tiny debris sunk in the drink)

I would be willing to bet almost anything that there are several modes to shut down the booster engines including loss of communication with the Dragon. No abort signal required.

Exactly. And they will want to know which of these "conditions" were met, when, in which order (not the least to see if they need to finetune things)
A "I just activated abort mode" message from Dragon would certainly be preferred over the triggering of a breakwire or two, or the worst case, lack of any communication for a timeout of x-hundred milliseconds.

Detecting the abort by lack of communication would be the worst case. You don't know whats the matter. Is it the wires? Is it the computers in the capsule? If its the com channel, is it one way or two way? Is the capsule still there? What do the accelerometers say, do I have evidence of an abort, or is acceleration matching "capsule/payload still present"? whats the status of the upper stage?

Apollo 12 had a funny case of undefined capsule state once after the rocket was hit by lightning during accent. The panel was blank, but the astronauts could tell the booster was still "there" because they still felt the thrust.

These things can make the decision shutdown engines or keep thrusting surprisingly difficult. On one hand, considering Merlin has a noticeable thrust transient on shutdown, it'd be important not to take too long. But just as with the LAS you can't be toooo trigger happy either. If in doubt, it might be better if the engines remain running, cause if you shut them down, you have a LOM for sure.

SpaceX would want to have all that data, along with the decision what their software as flying on DM2 *would* have done with the signals they are getting. They are also going to look into hypotheticals. "OK, Assuming we have an abort, but the engines didn't receive that signal... what would have happened" - possibly deductable from the rest of the data.

But none of that requires actually shutting down the engines. Its a test flight without astronauts, you do whatever gives you the most valuable data overall.

Maybe that IS the case with engines shut down. Maybe they'd be interested to know how exactly their booster tumbles after a complete loss of thrust. Maybe getting the booster back in more or less one piece would be more valuable... only SpaceX knows, and I bet even within SpaceX there's some people who'd be more interested in some kind of data than the other, having to come to a consensus

At this point the "coolness-factor" of trying to save the booster against all odds possibly also comes into play
I don't think this would (or should) be the driving factor, but it could be a tie-breaker.

[lonestriker]

Can we just take SpaceX's word for what they're doing and not second guess what's not in the documents they've filed?  They are going to shutdown the engines to trigger the abort (they are simulating a loss of thrust scenario).  They are not going to unzip the rocket or blow up S2 to trigger the abort (though the FTS may still do that job depending on how the components react.)  There will be no legs or fins (and no mention of a landing attempt at all or ASDS), so even if the booster survives the initial separation, there's no way to get it back intact.

[CorvusCorax]

Can we just take SpaceX's word for what they're doing and not second guess what's not in the documents they've filed?  They are going to shutdown the engines to trigger the abort (they are simulating a loss of thrust scenario).  They are not going to unzip the rocket or blow up S2 to trigger the abort (though the FTS may still do that job depending on how the components react.)  There will be no legs or fins (and no mention of a landing attempt at all or ASDS), so even if the booster survives the initial separation, there's no way to get it back intact.

No

If this was about anyone else but SpaceX, I'd agree.
But SpaceX in particular has a history of changing plans short notice and getting new FAA licenses issued as close as 2 days before flight. The document linked
(original here: https://www.faa.gov/about/office_org/headquarters_offices/ast/environmental/nepa_docs/review/launch/ ) is only Draft, not the final license, and its half a year old. We have no clue what changes have been made to the application since.

Why, usually not much happens with Spaceflight plans in just half a year. Even someone fast moving as SpaceX could barely change their plans from a carbon fibre vehicle to stainless steel hull and get a first prototype built

OK, that was Spaceship. F9 is a lot more mature, human rating certification and all, but still. Claiming that SpaceX does something a specific way because they said so N months ago only tells you what their plans where back then. We had countless cases where stuff was dismissed here on the forum because it contradicted months-old Elon tweets, only for a new Elon tweet proving it right a day later.

SpaceX has mentioned they'd like to get the hardware back if possible - during the pre-DM1 social media press conference and in the context of In-Flight-Abort - which is not a definite statement, but its much more recent than the FAA draft. I think this is enough to justify putting the older FAA draft into question and assuming everything's possible right now.

Of course, until the day the In Flight Abort launches, this remains being the case. Even if Elon would tweet today they were going to try and save the booster after all - that could ossibly change again by the time they actually launch.

Which makes things more interesting.

[Vettedrmr]

Have we heard any kind of schedule for IFA other than Q2?

Thanks, and have a good one,
Mike

[Comga]

Have we heard any kind of schedule for IFA other than Q2?

Thanks, and have a good one,
Mike

The “latest and greatest” info, outside of L2, is almost always the Manifest thread which still says “Q2”.
You never have to worry that something is known and allowed to be posted but has not been posted.

[scr00chy]

Have we heard any kind of schedule for IFA other than Q2?

Thanks, and have a good one,
Mike

Ben Cooper says "NET Late June".

[Vettedrmr]

The “latest and greatest” info, outside of L2, is almost always the Manifest thread which still says “Q2”.
You never have to worry that something is known and allowed to be posted but has not been posted.

From a newbie, thanks for the reference! 

Ben Cooper says "NET Late June".

Thanks, and y'all have a good one,
Mike

[vt_hokie]

I would assume anything less than nominal on the upcoming launch abort test would require a second such test prior to DM-2.  Here's to that test going as smoothly as DM-1 went!

[smoliarm]

I would assume anything less than nominal on the upcoming launch abort test would require a second such test prior to DM-2.  Here's to that test going as smoothly as DM-1 went!

- If I remember correctly, the In-Flight Abort Test WAS NOT on CCiCap schedule of milestones. Originally, NASA did not want and require such test. And NASA did not plan to pay for it, it was SpaceX's initiative planned to perform on their own expense. If I'm wrong, please, correct.
But if I'm right - then it is hard for me to see WHY this - *anything less than nominal on the upcoming launch abort test would require a second such test prior to DM-2* - would be the case.

[rpapo]

But if I'm right - then it is hard for me to see WHY this - *anything less than nominal on the upcoming launch abort test would require a second such test prior to DM-2* - would be the case.

I find it hard to imagine that if anything went wrong, they wouldn't take some time to investigate.

[Vettedrmr]

But if I'm right - then it is hard for me to see WHY this - *anything less than nominal on the upcoming launch abort test would require a second such test prior to DM-2* - would be the case.

It becomes one of "well, we didn't require it, but now that we've seen <insert whatever problem here>, we need to make sure that doesn't happen again."

It may, or may not, require a 2nd test, depending on what the problem is.

Have a good one,
Mike

[gongora]

I would assume anything less than nominal on the upcoming launch abort test would require a second such test prior to DM-2.  Here's to that test going as smoothly as DM-1 went!

- If I remember correctly, the In-Flight Abort Test WAS NOT on CCiCap schedule of milestones. Originally, NASA did not want and require such test. And NASA did not plan to pay for it, it was SpaceX's initiative planned to perform on their own expense. If I'm wrong, please, correct.
But if I'm right - then it is hard for me to see WHY this - *anything less than nominal on the upcoming launch abort test would require a second such test prior to DM-2* - would be the case.

In-flight abort test is a CCiCap milestone that kept getting delayed, with a $30M payment for doing it (at least that was the value at the time).  It's the path SpaceX chose, so it is part of their certification now.  I really doubt a failure during the test would cause another in-flight abort test to be required.  You can analyse and fix whatever problems occurred without doing another full-up flight test (assuming they at least get to the point of triggering the abort.)

[FutureSpaceTourist]

SpaceX says still on track for June abort test:

https://twitter.com/thesheetztweetz/status/1113440866243371008

Statement from a SpaceX spokesperson: “SpaceX is on track for a test of Crew Dragon’s in-flight abort capabilities in June and hardware readiness for Crew Dragon’s second demonstration mission to the Space Station in July.”

So hopefully good sign in terms of Dragon refurbishment following DM-1.

[Roy_H]

I had really hoped that this IFA could be launched earlier. Elon's encouraging post that the Dragon suffered no damage from the dunk in the ocean led me to believe the referb process could be done quickly. Also there has to be a week or two between the IFA and STP-2 to re-configure the TEL from F9 to FH and they are both scheduled for June. Now I read on the FCC paperwork thread that IFA net is June 10.

Given recovery in almost perfect condition, what work on the Dragon would require 3 months? If the date conflicts with STP-2 will the IFA be delayed further?

Edit: If SpaceX thinks STP-2 will fly first, they will not re-configure the TEL for F9, but leave it as is. Something to watch for.

[Vettedrmr]

Looking from the outside in it's hard to tell.  But I doubt that SpX has staff that are dedicated to only working on one flight; they are more likely working on all the upcoming launches concurrently.  So, the FH launch probably took a lot of assets to get off (especially since it was the first B5 Heavy configuration, and only the 2nd flight period), which took them away from the IFA mission.

Also, they are probably doing a lot of inspections of the capsule, much more than normal.  You can't just look at the telemetry, but after the first flight they probably just about dismantled the poor thing seeing how everything stood up.

Have a good one,
Mike