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

[ZachS09]

I need to find where, but I remember SpaceX (I think Elon) mentioning that they want to try to land the in-flight abort mission.

Where exactly? On the drone ship or LZ-1?

[EspenU]

Why in the world would they use a Block 5 booster? This is not a "test as you fly" issue.

If I recall correctly, there were some GSE changes done to 39A for block 5. This means that launching the abort test using a block 4 could only be done from SLC-40. In addition, it would mean not being able to move SLC-40 to block 5 (assuming GSE changes also have to made there) until after the abort test.
Or modifying to block 5, then back to block 4, then back to block 5, which makes no sense at all.

So using the 3. flight of a block 5 instead of a 4 has two benefits:
- It lets them convert SLC-40 to block 5 as soon as CRS-15 has launched (again assuming that SLC-40 requires modifications).
- It increases customer trust in block 5 after multiple flights (as others have mentioned)

[Jim]

Dragon 2 is only flying from 39 so why would the abort test  use any other pad?

[Nomadd]

Dragon 2 is only flying from 39 so why would the abort test  use any other pad?

Why wouldn't they? It's not like they'll need a crew access arm.

[UKobserver]

I know it's not out of the question that they will risk expending a Block 5, but I agree with the posters who think SpaceX would be reluctant to do so. Were it to be launched on a prior block booster, losing the core on this abort test would represent an opportunity cost of at most one additional launch (if expended on it's primary mission), but we are potentially talking a much bigger opportunity cost for Block 5 if they end up meeting their target number of re-uses per core. They might be throwing away the opportunity to use that core for free for upwards of 7 Starlink flights..

That raises the valid questions as to whether the GSE at their east coast pads would still be able to support a prior block by Nov/Dec this year, and whether NASA would consider it a valid demonstration if it is done with a prior block. Unless someone has insider knowledge on that I guess we have to wait for more info, but a couple of thoughts;

1) Further to the sources that say the abort test will be on the third flight of a booster; we already know from Elon that prior blocks are internally certified for more than 2 flights (Was it 3? I don't have the reference to hand to remember how many), it's just that they are a) choosing to be conservative, b) don't want a mixed fleet any longer than they can help it, and c) refurbishing prior blocks takes a lot of time and effort. But note that it can be done, so the third flight comment could still be valid if they were planning to use a block 4 or earlier.

2) I'm sure I saw a comment from someone that one of the block 4 boosters had been built with the new block 5 thrust structure/heat shielding. I don't think it said why they had done this or which booster it was, but if accurate it might mean that they are confident flying whichever booster this is an additional time. Depending on the GSE differences required for Block 5, and whether they are backwards compatible, it may also mean that this is a block "4" booster that is able to launch from a pad both before and after it has been modified for Block 5, ie able to interface with both block 4 and 5 GSE interchangeably. Those of you with general GSE/specific GSE knowledge for block 4/5 may be able to say whether that possibility stands up to scrutiny?

Assuming it's true, which booster was it? An argument in favour of 1042 would be that this gave them an opportunity to test the new heat shielding on a real launch and recovery while they still have all the block 5 cores in build and available to be modified if an issue is identified after the test mission. 1042 also hasn't yet flown a second time, which could be evidence that they took it apart for close examination and/or that they are holding it in reserve for the abort test. Arguments against would be that it got super toasty and may in fact be beyond repair.

Another possibility might be 1045. An argument for that could be that the new thrust structure/heat shielding/cooling was ready early so they went ahead and fitted it to the last block 4. Maybe they always had an eye on the abort test and reasoned that this one change to a block 4 would give them enough confidence to launch it a third time and save wasting a block 5. It would also give them an early look/practice at refurbishing the most critical part of a block 5, and it might explain why they were so confident that they could turn 1045 around so quickly after TESS when previous boosters have had 5+ months between flights. Presumably they think they would be able to turn it around again equally quickly after CRS-15 so as not to delay the abort test. Finally, it's perhaps the least convincing reason to postulate, but there would also be a certain poetry in the one booster being used to support 3 NASA missions. A bit of history to be made there potentially as the first booster to fly 3 times, and all for the same "customer", albeit different parts of NASA. Having closely monitored it's preparations on both of it's previous flights (and also it's first refurbishment) might also give NASA more confidence to fly on it again.

Thoughts?

[cscott]

I suspect they have improvements to block 5 that make them think they can recover the booster successfully after the abort test.  If so, then the GSE changes to the pads make doing the test on a block 5 from LC39A logistically convenient.

[Jim]

Dragon 2 is only flying from 39 so why would the abort test  use any other pad?

Why wouldn't they? It's not like they'll need a crew access arm.

You don't know that.  There might be a need for access to the cabin before the test.

Also, the umbilicals for the Dragon2 are not needed for other pads.  So why modify on TEL and pad cabling for one test?

Everything needed will be at 39

[wannamoonbase]

I suspect they have improvements to block 5 that make them think they can recover the booster successfully after the abort test.  If so, then the GSE changes to the pads make doing the test on a block 5 from LC39A logistically convenient.

Although no one will want to see a Block 5 booster lost at this time.  I have to think the milestone payment from NASA for completing this test will be more profitable than most of SpaceX’s other launches.

So fly that thing and get on with it.

[Coastal Ron]

If this will be a Block 5, and they do want to recover the 1st stage, is this the sequence?

1. Launch from Pad 39A

2. Dragon aborts during Max Q, and lands at sea

3. Falcon 9 2nd stage, fully fueled, is ejected?

4. Falcon 9 1st stage, with more fuel than planned for landing, flies around to burn off excess fuel and position for landing?

5. Falcon 9 1st Stage lands at LZ-1/2?

Obviously ejecting the 2nd stage while the Dragon is nearby would be a safety concern. But then again if the Dragon is aborting it could be because it's Falcon 9 is going through a rapid unplanned disassembly, so debris avoidance is assumed.

Thoughts?

[rpapo]

2. Dragon aborts during Max Q, and lands at sea

3. Falcon 9 2nd stage, fully fueled, is ejected?

Between (2) and (3), and happening at max-Q, you have a serious problem with the aerodynamics of the top of the second stage, if indeed they launch this with a fully fueled second stage present.  I can easily imagine the second stage doing a CRS-7 from the stress.  You have a similar problem with the first stage if the launch is conducted without a second stage.

I seriously doubt they'd try this without a second stage present, both because the weight and acceleration would be way off normal, and because the mounting hardware for Dragon is at the top of the second stage.  Mounting Dragon on a bare first stage would require whole new hardware.  Or at least I think it would.

[gongora]

I suspect they have improvements to block 5 that make them think they can recover the booster successfully after the abort test.  If so, then the GSE changes to the pads make doing the test on a block 5 from LC39A logistically convenient.

Although no one will want to see a Block 5 booster lost at this time.  I have to think the milestone payment from NASA for completing this test will be more profitable than most of SpaceX’s other launches.

So fly that thing and get on with it.

The milestone payment isn't that much ($30M).  http://www.parabolicarc.com/2015/03/04/spacex-cctcap-milestones/

[Nomadd]

Dragon 2 is only flying from 39 so why would the abort test  use any other pad?

Why wouldn't they? It's not like they'll need a crew access arm.

You don't know that.  There might be a need for access to the cabin before the test.

Also, the umbilicals for the Dragon2 are not needed for other pads.  So why modify on TEL and pad cabling for one test?

Everything needed will be at 39

I didn't think of the Dragon umbilicals. But I thought they weren't using a 2nd stage, so the access arm wouldn't be any good if that was the case.

[LouScheffer]

I seriously doubt they'd try this without a second stage present, both because the weight and acceleration would be way off normal, and because the mounting hardware for Dragon is at the top of the second stage.  Mounting Dragon on a bare first stage would require whole new hardware.  Or at least I think it would.

Without knowing anything about what SpaceX is planning, I'd think the opposite - no second stage.   It adds expense and complexity without improving the test.

The first stage has its own avionics and INS, since it can land.   It should be straightforward to program it to have the exact same velocity/altitude profile as a normal flight (the second stage is something like 20% of the total mass, so the engines have plenty of range to throttle down to compensate).  The aerodynamics are the same from the point of view of the dragon - in either case there is a long cylinder behind, same diameter.

You would indeed need a custom interstage with Dragon attachments on top.  They might then add more baffling to the inside of the interstage to improve the chance of booster survival, if it's not too much work or too expensive.

[RocketLover0119]

If they do indeed attempt a booster landing, is it possible that aluminum fins could be attached instead of titanium just in case something goes awry on landing?

[Joffan]

2. Dragon aborts during Max Q, and lands at sea

3. Falcon 9 2nd stage, fully fueled, is ejected?

Between (2) and (3), and happening at max-Q, you have a serious problem with the aerodynamics of the top of the second stage, if indeed they launch this with a fully fueled second stage present.  I can easily imagine the second stage doing a CRS-7 from the stress.  You have a similar problem with the first stage if the launch is conducted without a second stage.

I seriously doubt they'd try this without a second stage present, both because the weight and acceleration would be way off normal, and because the mounting hardware for Dragon is at the top of the second stage.  Mounting Dragon on a bare first stage would require whole new hardware.  Or at least I think it would.

I don't know if the effort is worth it, but my hope is that a dummy second stage is used, perhaps with blow-out panels over a shaped nose (FH side-core-like) to cope with the  MaxQ environment. I'm thinking that at least some of the ballast would need to be loaded at the normal fuelling stage to avoid unusual stresses on the first stage.

[woods170]

Dragon 2 is only flying from 39 so why would the abort test  use any other pad?

Why wouldn't they? It's not like they'll need a crew access arm.

You don't know that.  There might be a need for access to the cabin before the test.

Also, the umbilicals for the Dragon2 are not needed for other pads.  So why modify on TEL and pad cabling for one test?

Everything needed will be at 39

In case you had failed to notice: SpaceX plans to attach the CAA AFTER their DM-1 mission.
So why should SpaceX have on-pad access to the in-flight abort Dragon, when it is NOT necessary to have on-pad access to the DM-1 Dragon?

If we follow your (IMO flawed) line of reasoning the pad-abort test should not have flown from LC-40 either. Yet, it did.

[woods170]

Dragon 2 is only flying from 39 so why would the abort test  use any other pad?

Why wouldn't they? It's not like they'll need a crew access arm.

You don't know that.  There might be a need for access to the cabin before the test.

Also, the umbilicals for the Dragon2 are not needed for other pads.  So why modify on TEL and pad cabling for one test?

Everything needed will be at 39

I didn't think of the Dragon umbilicals. But I thought they weren't using a 2nd stage, so the access arm wouldn't be any good if that was the case.

For the in-flight abort test only a data-, comms- and electrical umbilical is sufficient. Similar to the single umbilical used for the pad abort test. That can easily be added to the LC-40 TEL.
The storable propellants on-board Crew Dragon are not loaded at the pad, but at the Crew Dragon processing facility.

[kevin-rf]

I thought the brains where in the second stage (yes the first stage has a brain), so really,they would want a second stage...

Seems like to much extra work to not test as you fly.

[rpapo]

I thought the brains where in the second stage (yes the first stage has a brain), so really,they would want a second stage...

Seems like to much extra work to not test as you fly.

True, though with that said, for a contrary example we only need look at Little Joe and the Apollo abort system tests.

https://en.wikipedia.org/wiki/Little_Joe_II

So only SpaceX itself knows just what they intend to do.

[John Alan]

I'll go on the record now and predict... 

Used but nice block 5 S1
New and completely equipped block 5 S2 (even the Mvac would fire, no parts missing)
The Dragon test spacecraft planned...
FULLY fueled on all components... and flown off Pad 39 as if it's going to space...

Why?...
Because the last thing we need... is the internet and NASA arguing later it was not a legitimate worse case test... 
MAKE IT worst case... screw trying to save S1...
Blow S2 Amos style right at Max-Q (high in the stack, worst case) and watch Dragon hopefully do it's job outrunning the carnage in it's rear view mirror...

The $30 mil covers S2 and the launch costs...
S1 was used already and took one for the team... no big deal in the grand scheme...
They hopefully get Dragon back in fine shape... and they better hang it up somewhere so we can see it...
Doing it this way is actually the cheapest IMHO...
No going out of normal manned launch process...
No special parts or special programming trying to save S1...
Just blow it all to heck at Max-Q and show that it works... period... 

My 2 cents...