OMG it's the SpaceX Party Thread!

[corrodedNut]

These times are between half and one hour behind the more detailed NASA schedule Bill Harwood posted on May 21:
http://www.cbsnews.com/network/news/space/home/spacenews/files/spacex_cots2_timeline.html

Yes, and during this morning's status briefing they said today's one hour delay/change would not "propagate through" to tomorrow. Then SpaceX comes out with this revised schedule, which is still an hour behind the original flight plan. I don't plan on missing anything, so I'm going to start watching at about 6:00 AM ET.

[sojourner]

It's funny. I'm actually more worried about separation of the trunk before re-entry at this point than I am about tomorrow's berthing.

[corrodedNut]

It's funny. I'm actually more worried about separation of the trunk before re-entry at this point than I am about tomorrow's berthing.

Don't worry, Dragon/trunk sep was demonstrated on the last mission. "Dragon claw", however...

[Lars_J]

It's funny. I'm actually more worried about separation of the trunk before re-entry at this point than I am about tomorrow's berthing.

Don't worry, Dragon/trunk sep was demonstrated on the last mission. "Dragon claw", however...

True, that's how the C1 Dragon separated from the 2nd stage. The "claw" will indeed be the new part - but so far SpaceX has done a great job with their separation mechanisms. I don't think one (of their MANY types) has failed yet. (knock on wood)

Speaking of separation mechanisms - I find it interesting how SpaceX seems to favor non-pyro separations in many cases, when most of the industry seems to use some variant of pyro bolts.

[Robotbeat]

It's funny. I'm actually more worried about separation of the trunk before re-entry at this point than I am about tomorrow's berthing.

Don't worry, Dragon/trunk sep was demonstrated on the last mission. "Dragon claw", however...

True, that's how the C1 Dragon separated from the 2nd stage. The "claw" will indeed be the new part - but so far SpaceX has done a great job with their separation mechanisms. I don't think one (of their MANY types) has failed yet. (knock on wood)

Speaking of separation mechanisms - I find it interesting how SpaceX seems to favor non-pyro separations in many cases, when most of the industry seems to use some variant of pyro bolts.

Non-pyro separations can be tested before hand extensively. /The same/ hardware, not just the same design. Pyros, as reliable as they can be, are use-once devices that can never actually be tested non-destructively. (Also, SpaceX has this sort of obsession with reusability, and pyros can't be reused.)

SpaceX has this big jig for testing stage separations at McGregor. The whole suite of testing that goes on at McGregor is really impressive, IMHO, and shows how it's no accident that the first three flights of Falcon 9 were successful (kind of a rarity in this business). SpaceX must have learned the hard way from the first three flights of Falcon 1 (which were, in stark contrast, all failures) that ground-testing the heck out of your hardware is a really, really good idea:




They do component testing on almost EVERYTHING, from gas generators, to individual engines to full-duration testing of integrated stages... Individual thruster testing in vacuum to testing the integrated quads, etc. And they do many stage separation tests as well... I don't know if this much integrated testing is standard in the industry, but it's really impressive to me.

(About the only thing they weren't able to test before the first Falcon 9 flight was the second stage in vacuum... Which almost killed them for Falcon 9 flight 1, but they still do full-duration integrated testing of the upper stage at sea level pressure without the nozzle extension.... The moral of the story is pretty strong, here... Integrated ground testing as much as possible will save you from embarrassing failures.)

[rickl]

What's "Dragon claw"?  I must have missed that one.

A couple of Soyuz missions managed to re-enter with another module still partially attached.  It burns away eventually but it's not something you want to do.  They didn't lose any vehicles or crews because of that, but came close on Soyuz 5.

FWIW, the thing I was most worried about before launch was the pontoons tearing away during ascent.

[Lars_J]

What's "Dragon claw"?  I must have missed that one.

It is the umbilical connection between the trunk and the capsule. It carries power and coolant lines for the radiators.

EDIT, here is a pic where the "claw" is highlighted:

[Jason1701]

(About the only thing they weren't able to test before the first Falcon 9 flight was the second stage in vacuum... Which almost killed them for Falcon 9 flight 1, but they still do full-duration integrated testing of the upper stage at sea level pressure without the nozzle extension.... The moral of the story is pretty strong, here... Integrated ground testing as much as possible will save you from embarrassing failures.)

Are you talking about the roll control failure?

[corrodedNut]

Dragon/trunk sep system uses frangible nuts, IIRC. That and the FRGF may be the only pyros the whole stack.

BTW, we're ruining the party thread!

[Robotbeat]

(About the only thing they weren't able to test before the first Falcon 9 flight was the second stage in vacuum... Which almost killed them for Falcon 9 flight 1, but they still do full-duration integrated testing of the upper stage at sea level pressure without the nozzle extension.... The moral of the story is pretty strong, here... Integrated ground testing as much as possible will save you from embarrassing failures.)

Are you talking about the roll control failure?

Yes. That was the first time they had fired the stage in vacuum, which is why they didn't catch it.

Testing the crap out of everything on the ground is a pretty good strategy. You don't need to necessarily do infinite paper trade studies, but you really should do as much ground testing as possible. Computer simulations are still no substitute for testing your hardware (though obviously are good for testing software, especially with hardware-in-the-loop simulations). And as XCOR has found out, CFD is still no substitute for wind tunnel testing.

(And I think that non-destructive testing is a big advantage... If your hardware can be tested multiple times on the test stand without reducing its performance, then the cost-both financial and schedule--to test is a lot lower than if each test consumes your hardware, and thus you're more willing and more likely to test early and often.)

[Jason1701]

Why did the vacuum cause the roll control failure? I thought that was independent of the environment.

[robertross]

And what time is that scheduled for? *Praying for a decent time*

About 8 or 9 AM Eastern.

Yes!!!!!! 

Hopefully you can even see a flyby overhead, I hope everyone who can: can.
It was very memorable for me (not that I'm all that 'gaga' over SpaceX, but it is a unique experience), even waking up at 4:15am with 5 hours sleep.

SO worth that one unique moment, much like a rocket launch.

[Lars_J]

Why did the vacuum cause the roll control failure? I thought that was independent of the environment.

Didn't a combination of the environment and acceleration cause the cryogenic fluids to flow in a way that froze the control mechanism? That's what I recall - I could be wrong. They flew a tweaked design on the following flight.

[BrightLight]

In an earlier post I commented on the lack of regularity in the spacex launch schedule, but I have to say that the string of milestones gives me great pleasure to see go SpaceX !

[BrightLight]

In an earlier post I commented on the lack of regularity in the spacex launch schedule, but I have to say that the string of milestones gives me great pleasure to see go SpaceX !

[corrodedNut]

Why did the vacuum cause the roll control failure? I thought that was independent of the environment.

Didn't a combination of the environment and acceleration cause the cryogenic fluids to flow in a way that froze the control mechanism? That's what I recall - I could be wrong. They flew a tweaked design on the following flight.

Legend has it their computer fluid models told them they didn't need slosh baffles. The computer was wrong, so they added slosh baffles.

...aaaand we're still ruining the party thread!!

[Lars_J]

Party!!!!

[rickl]

BTW, we're ruining the party thread!

I promise not to report you for going off-topic.   

Of course I've been reading the update and discussion threads, but I've been confining most of my comments to this thread, since I don't have much knowledge or expertise to add to the others.

I think the looser structure of the party thread was a great idea.

[robertross]

BTW, we're ruining the party thread!

I promise not to report you for going off-topic.   

Of course I've been reading the update and discussion threads, but I've been confining most of my comments to this thread, since I don't have much knowledge or expertise to add to the others.

I think the looser structure of the party thread was a great idea.

I agree, Chris hit it right on the mark with thtis thread.
A good thought going forward, especially with the upcoming Cygnus launch later this year and future Commerical Crew opportunities

[Silmfeanor]

I think the looser structure of the party thread was a great idea.

I agree - although I certainly hope these threads don't get too much more " fun"  - there is a reason this forum doesn't have a " anything goes" area, and I appreciate that very much. The fear of asking a question that is stupid or already has been answered made me educate myself on the basic stuff very fast.

That said, good idea to blow off some steam. Looking forward to other " cheering" threads - as long as they are contained, and don't spill over in other threads, so we can keep up the ratio of information-per-post nice and high..