Space X successful landing of boosters

[Perd Hapley]

The above is a live feed.

https://www.youtube.com/watch?v=DPfHHls50-w

The side boosters landed near-simultaneously.

[Fly320s]

The above is a live feed.

From April 11.

Still cool, though.

[lee n. field]

always neat to watch

[Brad Johnson]

From April 11.

Still cool, though.

Some channels have gotten really bad about their Live Feed etiquette. Yes, it's a live feed, but not of the event in question. They are essentially playing TV station, putting out a broadcast feed. Yes, the original launch is live, but they they go into a continuous replay loop without benefit of calling it such.

Brad

[WLJ]

Whoops
They lost the center booster on the way back to Port Canaveral

SpaceX's Center Core Booster for Falcon Heavy Rocket Is Lost at Sea
https://www.space.com/spacex-loses-falcon-heavy-core-booster-at-sea.html

[Perd Hapley]

Curse you, YouTube. You make me look like fool! Cause fistful lose fistful of face! I keel you!

[Fly320s]

Whoops
They lost the center booster on the way back to Port Canaveral

SpaceX's Center Core Booster for Falcon Heavy Rocket Is Lost at Sea
https://www.space.com/spacex-loses-falcon-heavy-core-booster-at-sea.html

I wondered if they had some way to strap it down.  I guess the answer is no.

[AZRedhawk44]

For a standard F9 core, they have a robotic "roomba" like device that comes out of a shielded garage on the drone ship after the rocket lands, centers under the booster's engines, and extends 4 claws that latch onto hardpoints on the thrust floor of the rocket.  I think they call it "Octagrabber" if I recall right.  It's heavily weighted so that when attached, it dramatically lowers the center of gravity of the rocket.  I wouldn't be surprised if it has additional functionality, like a selectively activated electromagnet, since the landing deck is steel on the droneship.  

But it isn't compatible with the Falcon Heavy center core, because that core has a different thrust floor design since at 90 and 270 degrees there are interfaces for two F9 side boosters to latch onto the center core's thrust floor.  

[AZRedhawk44]

Kinda surprised you guys aren't talking about the Asplodey Kaboom that happened this weekend, with the SpaceX Crew Dragon capsule.

This exact capsule was up at the ISS a few weeks back, and splashed down in the Atlantic after this test launch and docking (unmanned).  SpaceX retrieved it and were initially very pleased with the lack of penetration of salt water on the design.  So much so that Musk tweeted about it.  In their pursuit of reuse of as many components as possible, they put this recovered prototype capsule on a test stand and fired up the various hypergolic engines on the craft.  There are Draco engines which provide orbital maneuvering and fine tuning during docking procedures, and there are SuperDraco engines which are the launch escape system for the craft in the event of a rocket malfunction, and they were intended to also serve as propulsive landing engines rather than parachutes.

We still don't have the full story, but the capsule was completely destroyed during one of the engine ignitions.  Don't know if it was the Dracos, or the SuperDracos.

But both use hypergolic fuel, and both use the culprits from the previous SpaceX rocket explosions:  COPV's.  Carbon Overwrap Pressure Vessels.  The most recent rocket explosion (AMOS-6) is thought to be due to fine gaps in the COPV mesh allowing liquid oxygen to creep inside the gaps between the carbon mesh and the aluminum pressure bottle inside it, and then any thermal stress/shift/flex results in a very energetic reaction with that oxygen.  Boom.  But the COPV's in the Crew Dragon aren't sitting in a bath of liquid O2.

This exact capsule was docked to the ISS less than 2 months ago, and its Draco and SuperDraco systems were fueled and operational.  That same kaboom could have happened a few weeks earlier, killing all ISS inhabitants and possibly causing irreparable harm to the station (if NASA and Roskosmos even had the drive to rebuild it in the face of such a loss).

I'm hoping that this was a controlled edge-case test with unexpected results; they had noticed that the SuperDraco fuel lines would ice up during certain phases of its mission, perhaps they were testing the results of this edge case and got a result outside of what they were expecting, in a catastrophic way, but it would still be a known failure mode they were just confirming.

[Fly320s]

I had not heard about the capsule explosion, but I'm not a SpaceX news junkie.

[WLJ]

I had not heard about the capsule explosion, but I'm not a SpaceX news junkie.

This gets into it
Only 06:04 long

SpaceX's Crew Dragon Capsule Destroyed In Engine Test
https://www.youtube.com/watch?v=Fl3Jcczz5PY&t=11s

[AJ Dual]

COPV failure is most likely. Or something energetic enough going Bang next to one to to unzip it really fast. (Composite over-wrapped pressure vessel)

If one of the superdracos had a RUD (rapid unscheduled disassembly) it would have been asplodey, but not all at once like that. Smaller side-splodey, fire from places it shouldn't,  then all asplodey with a few seconds of "gee, that's not right..." to warn you.

Although I think this is SpaceX's strength. Pushing the envelope. Blowing their stuff up in tests, figuring out invaluable data on failure modes, addressing them quickly and pragmatically... instead of tons of paperwork, PowerPoint, and subsystem testing for "failure is not an option culture" (analysis paralysis), and then having it blow up anyway, after a honeymoon period of luck, but with astronauts on board.

[AZRedhawk44]

One of the most well thought points I've seen on this particular incident, I read over on Reddit's SpaceX sub.  I can't find it now so I can't attribute it, but one guy over there suggested this could be due to an order of operations issue, a variance between real world operations and test operations.

In real use, the SuperDracos would only be fired while the COPV is 100% full and the hypergolic tanks are 100% full.  It's a launch escape system.  They're never used at any other phase of the flight.

In this particular test scenario, the SuperDracos were the last element on the test, and several Draco OMS tests happened prior.  This depletes the COPV and the hypergolic tanks.  It's possible that the SuperDraco LES software is only written to take into account 100% helium and hypergolic tanks (which is the only way they would be used).  With less pressure in the COPV due to other operations, and parts of the Draco fuel feed plumbing having been opened and closed several times, it's possible that pressure wasn't high enough to prevent cross contamination of the isolated fuel/oxidizer supplies at some location in the system.

Something that would never happen in real life, but did happen in this particular test due to order of operations of the test.

[cordex]

I thought they were planning on using those thrusters in the landing of the capsule as well.

[Firethorn]

Note guys, when AZ talks about "hypergolic" fuels, he's talking about fuels where you don't need to ignite it for it to burn.  Mix part A and part B together as you chuck it out the engine and it'll burn.  

Mix, for example, H2 and O2 and nothing will happen without a spark.  Mix ClF3 and test engineers, and you'll have immediate ignition.

Yes, I'm paraphrasing John Clark from Ignition!

Most hypergolic fuels are "interesting" even individually.

[RoadKingLarry]

I always get a chuckle when I read stories about "failed" tests. The semantics almost always indicate a "failure" during testing is an indication that the testers just wasted a lot of time and money because something didn't go quite right.
So long as lessons were learned with out loss of life it's not really a "failure".
A failure is what happens when arrogance and incompetence override common sense and space shuttles blow up.

[AZRedhawk44]

I thought they were planning on using those thrusters in the landing of the capsule as well.

That was the original design of the craft, but NASA nixed the propulsive landing development routine and insisted on parachute landing.  So now the SuperDracos only serve as a LES.