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

[gongora]

You can't test every combination of circumstances in one flight.  The vehicle will have the aerodynamic forces acting on it regardless of whether the engines stop firing.  If the vehicle is programmed to shut down the engines when an emergency is detected (unlike what happened during the CRS-7 flight) then this may still be testing a common failure mode.  The point of the test isn't just to try aborting in the most extreme possible conditions, but to gather data on how everything performs in flight and use that to validate their analysis models.

[whitelancer64]

Over on SFN they mention that the plan is to shut the 9 Merlins off before separation.  Isn't the whole point of doing the test at max Q is to verify it will work in an actual flight?  That is to say with the engines firing as they normally would.

AIUI, they will command all the engines to shut down from the ground - the abort system will automatically detect the loss of thrust, and initiate the abort. To our human eyes this should look simultaneous.

[mn]

Will the weather constraints be the same for this launch, or can they ignore certain constraints because they are not applicable to a planned abort?

(just wondering about the 60-70% violation probability in case of a 24 hr delay)

[gongora]

The mission still goes through the part of the flight that is affected by weather.  This flight should use the same weather criteria as a crewed flight.

[mn]

Over on SFN they mention that the plan is to shut the 9 Merlins off before separation.  Isn't the whole point of doing the test at max Q is to verify it will work in an actual flight?  That is to say with the engines firing as they normally would.

AIUI, they will command all the engines to shut down from the ground - the abort system will automatically detect the loss of thrust, and initiate the abort. To our human eyes this should look simultaneous.

I had also thought it would be as you describe, but the NASA statement seems to say that the abort will trigger the engine shutdown "Once the launch escape sequence begins, Falcon 9’s first stage Merlin engines will shut down".

Not really sure and I see that you can interpret their statement differently.

I expect we'll find out definitively in a few days.

[Tomness]

Over on SFN they mention that the plan is to shut the 9 Merlins off before separation.  Isn't the whole point of doing the test at max Q is to verify it will work in an actual flight?  That is to say with the engines firing as they normally would.

Watch CRS-7 again.  The engines "zip up" (don't know what that means) & shut down & vent the pressure and fuel before it chain reaction or it detonate its self. Elon has eluded that the SiperDracos will fire & destroy the stack long begore this hince them saying if humans where on CRS-7 they would have lived and the Cargo Dragon could have saved it's self with a autautomated command to open its parachutes.

[whitelancer64]

Over on SFN they mention that the plan is to shut the 9 Merlins off before separation.  Isn't the whole point of doing the test at max Q is to verify it will work in an actual flight?  That is to say with the engines firing as they normally would.

AIUI, they will command all the engines to shut down from the ground - the abort system will automatically detect the loss of thrust, and initiate the abort. To our human eyes this should look simultaneous.

I had also thought it would be as you describe, but the NASA statement seems to say that the abort will trigger the engine shutdown "Once the launch escape sequence begins, Falcon 9’s first stage Merlin engines will shut down".

Not really sure and I see that you can interpret their statement differently.

I expect we'll find out definitively in a few days.

From the FAA's Draft EA for the abort test:

"The Falcon 9 would be configured to shut down and terminate thrust, targeting the abort test shutdown condition (simulating a loss of thrust scenario). Dragon would then autonomously detect and issue an abort command, which would initiate the nominal startup sequence of Dragon’s SuperDraco engine system. Concurrently, Falcon 9 would receive a command from Dragon to terminate thrust on the nine first stage Merlin 1D (M1D) engines. Dragon would then separate from Falcon 9 at the interface between the trunk and the second stage, with a frangible nut system. Under these conditions, the Falcon 9 vehicle would become uncontrollable and would break apart."

[mn]

Over on SFN they mention that the plan is to shut the 9 Merlins off before separation.  Isn't the whole point of doing the test at max Q is to verify it will work in an actual flight?  That is to say with the engines firing as they normally would.

AIUI, they will command all the engines to shut down from the ground - the abort system will automatically detect the loss of thrust, and initiate the abort. To our human eyes this should look simultaneous.

I had also thought it would be as you describe, but the NASA statement seems to say that the abort will trigger the engine shutdown "Once the launch escape sequence begins, Falcon 9’s first stage Merlin engines will shut down".

Not really sure and I see that you can interpret their statement differently.

I expect we'll find out definitively in a few days.

From the FAA's Draft EA for the abort test:

"The Falcon 9 would be configured to shut down and terminate thrust, targeting the abort test shutdown condition (simulating a loss of thrust scenario). Dragon would then autonomously detect and issue an abort command, which would initiate the nominal startup sequence of Dragon’s SuperDraco engine system. Concurrently, Falcon 9 would receive a command from Dragon to terminate thrust on the nine first stage Merlin 1D (M1D) engines. Dragon would then separate from Falcon 9 at the interface between the trunk and the second stage, with a frangible nut system. Under these conditions, the Falcon 9 vehicle would become uncontrollable and would break apart."

So they the first stage will terminate thrust, which will cause the dragon to initiate an abort, which will cause the dragon to send a command to the first stage to terminate thrust. (if I were excel I'd complain of a circular reference)

Or is the later statement just a description of what normally happens during an abort even though it's irrelevant in this context?

Edit: Maybe one of the test objectives is to verify that during an abort dragon commands the first stage to terminate thrust, and they will have telemetry to confirm that it did that. (even though it would not be necessary in this case, we still want to verify that dragon does what it should do in other failure scenarios)

[whitelancer64]

Over on SFN they mention that the plan is to shut the 9 Merlins off before separation.  Isn't the whole point of doing the test at max Q is to verify it will work in an actual flight?  That is to say with the engines firing as they normally would.

AIUI, they will command all the engines to shut down from the ground - the abort system will automatically detect the loss of thrust, and initiate the abort. To our human eyes this should look simultaneous.

I had also thought it would be as you describe, but the NASA statement seems to say that the abort will trigger the engine shutdown "Once the launch escape sequence begins, Falcon 9’s first stage Merlin engines will shut down".

Not really sure and I see that you can interpret their statement differently.

I expect we'll find out definitively in a few days.

From the FAA's Draft EA for the abort test:

"The Falcon 9 would be configured to shut down and terminate thrust, targeting the abort test shutdown condition (simulating a loss of thrust scenario). Dragon would then autonomously detect and issue an abort command, which would initiate the nominal startup sequence of Dragon’s SuperDraco engine system. Concurrently, Falcon 9 would receive a command from Dragon to terminate thrust on the nine first stage Merlin 1D (M1D) engines. Dragon would then separate from Falcon 9 at the interface between the trunk and the second stage, with a frangible nut system. Under these conditions, the Falcon 9 vehicle would become uncontrollable and would break apart."

So they the first stage will terminate thrust, which will cause the dragon to initiate an abort, which will cause the dragon to send a command to the first stage to terminate thrust. (if I were excel I'd complain of a circular reference)

Or is the later statement just a description of what normally happens during an abort even though it's irrelevant in this context?

Edit: Maybe one of the test objectives is to verify that during an abort dragon commands the first stage to terminate thrust, and they will have telemetry to confirm that it did that. (even though it would not be necessary in this case, we still want to verify that dragon does what it should do in other failure scenarios)

Yes, AFAIK it's part of the normal procedure. For example, if the thrust on 3 engines failed but the rest kept firing, the Dragon's command to shut down the remaining engines would actually do something.

This would give the Dragon maximum separation between the failing booster and itself, as well as preventing the booster from flying out of control somewhere else.

[FutureSpaceTourist]

twitter.com/starfleettours/status/1217525632827121664

IMPORTANT ANNOUNCEMENT 📢

Launch weather is 90% GO, but the marine forecast and consultations with the National Weather Service suggest a significant but not certain chance of a Small Craft Advisory due to high seas that would result in the boats not being able to go out safely

https://twitter.com/starfleettours/status/1217525633464569864

It is rare that the weather precludes the boats but not the launch, and a first in Star Fleet's history, but unfortunately for everyone it looks like it might happen on this most spectacular and unique of test flights.

Just wondering what the potential implications are for recovering Dragon after the abort? Presumably high seas could cause a scrub due to inability to safely recover Dragon?

[Vettedrmr]

I guess it depends on if the recovery craft are considered "small craft".  Here inland I have no idea.

[FutureSpaceTourist]

I guess it depends on if the recovery craft are considered "small craft".  Here inland I have no idea.

Even if they’re not classed as small craft, safely lifting Dragon out of the water to get it on board presumably has some limits on how rough the sea is?

[Rondaz]

Early Weather Reports Positive for SpaceX In-Flight Abort Test

James Cawley Posted on January 15, 2020

With the launch of SpaceX’s in-flight abort demonstration three days away, early weather reports are promising. According to Mike McAleenan, a launch weather officer with the U.S. Air Force 45th Space Wing, there is a 90 percent chance of favorable weather at liftoff. The primary concern is flight through precipitation, as some shallow coastal rain showers are predicted.

NASA and SpaceX are targeting no earlier than Saturday, Jan. 18, for the In-Flight Abort Test from Launch Complex 39A in Florida. The four-hour test window starts at 8 a.m. EST. The test will demonstrate the escape capabilities of SpaceX’s Crew Dragon spacecraft — showing that the crew system can protect astronauts even in the unlikely event of an emergency during launch.

In-flight abort is the final, major test before astronauts fly aboard the Crew Dragon spacecraft and Falcon 9 rocket to the International Space Station as part of the agency’s Commercial Crew Program. For this test, SpaceX will configure Crew Dragon to intentionally trigger a launch escape prior to 1 minute, 30 seconds into flight to demonstrate Crew Dragon’s capability to safely separate from the Falcon 9 rocket in the unlikely event of an in-flight emergency.

https://blogs.nasa.gov/kennedy/2020/01/15/early-weather-reports-positive-for-spacex-in-flight-abort-test/

[ejb749]

Will they "configure the Crew Dragon to intentionally trigger a launch escape", or are they triggering the Falcon 9 to shutdown to cause the Dragon to detect the failure and then abort?

[joek]

Will they "configure the Crew Dragon to intentionally trigger a launch escape", or are they triggering the Falcon 9 to shutdown to cause the Dragon to detect the failure and then abort?

Would think it is more the former than the latter: Dragon initiates abort and sends shutdown to F9.  Ultimately Dragon is in control of its abort decision, and the conditions under which Dragon initiates abort may involve more than just signalling to-from F9.

Whether this test includes F9 signalling is an open question... but the more I think about it, might be that they initiate from F9... but that does not necessarily mean triggering F9 to shut down, simply that F9 signals Dragon "we have a problem"... then Dragon makes the decisions (e.g., command F9 shutdown or some-such).  Hope that makes sense.

[quagmire]

The Dragon I believe will be programmed as if it will be a live flight to test the abort criteria software. How else will they test if the programming doesn't have issues if it is programmed differently then it would for a real mission? It being programmed to trigger the abort will not be how it will be programmed for a manned launch.

So having the F9 being the triggering event makes more sense. F9 shuts down engines at Max Q-> Dragon senses loss of thrust-> initiates abort sequence as it would for DM-2 and operational flights. The test isn't just seeing if the Dragon can physically survive a Max Q abort, but it functions like it should as well.

[Smrg]

They could put a bomb in S2 and leave the S1 engines running.
That would simulate the worst case abort condition, with S1 chasing the Dragon for a short time and a blast to outrun.

[AndrewRG10]

They could put a bomb in S2 and leave the S1 engines running.
That would simulate the worst case abort condition, with S1 chasing the Dragon for a short time and a blast to outrun.

Or you know, they could do what they're actually doing. Shutting down S1 engines to simulate loss of thrust

[abaddon]

The Dragon I believe will be programmed as if it will be a live flight to test the abort criteria software. How else will they test if the programming doesn't have issues if it is programmed differently then it would for a real mission? It being programmed to trigger the abort will not be how it will be programmed for a manned launch.

The in-flight abort is designed to prove the Dragon can escape a failing F9 at the moment of maximum aerodynamic pressure.  Looking at the lens of it being designed to prove the abort system is fully operational in all ways is the wrong lens.

That doesn't mean a lot of systems won't be exercised in this live test.  In contrast, Boeing is using computer modeling to prove the Starliner can escape at Max-Q and is not even running an in-flight abort test at all.  As shown by the anomaly in the demo flight, the avionics were not properly configured (wrong clock) and might also have malfunctioned in an abort scenario.  A live abort test will cover a lot of functionality, but that's not the reason for the test, and asking why the test isn't covering (x abort scenario) is not understanding that.

[Norm38]

They could put a bomb in S2 and leave the S1 engines running.
That would simulate the worst case abort condition, with S1 chasing the Dragon for a short time and a blast to outrun.

Originally I thought something like that would be necessary, to demonstrate that a shock wave from an explosion could be outrun.  But the CRS-7 failure actually lessoned that concern.  The 2nd stage disintegrated in flight, but it did not explode.  The cargo Dragon had no abort motor and (to my knowledge), did not suffer damage from the 2nd stage.  The 1st stage did not plow into it.

So I'm good with just shutting down the 1st stage and triggering the abort off that.