SpaceX Falcon 9 v1.1 - SES-8 - DISCUSSION THREAD

[simonbp]

A few Shuttle aborts:







And Gemini 6:

[Greg906]

I head the comment on the line that the spacecraft owners were willing to extend the launch window, if necessary.

What kind of penalty in fuel/performance would the satellite/rocket suffer by launching later than the original window?

[Jarnis]

By the way, if you have been watching the webcast for an hour, you may want to refresh browser - the video tends to start to lag a bit behind real time - mine was off by almost 30s...

[Jim]

It could  be an electrical power trade off

[AJA]

And Gemini 6:

PAO: ...is putting in a call to 7 to advise them that we will not have a liftoff. Frank Borman says 'Roger, we saw it. We saw it light up, we saw it shutdown.'
Cronkite: By golly, Gemini 7 up there above the Cape saw, what we saw here, close to a 185 miles distance..

Now, THAT is a rocket engine. Holy Wow.

[Lars_J]

So what is T-0 for falcon? Liftoff or ignition?

ignition

No, it isn't. Liftoff is T-0. Here is what the SpaceX mission press kit says about the mission timeline:

- 0:00:03 Engine controller commands engine ignition sequence to start
 0:00 Falcon 9 liftoff

I've attached the press kit in PDF form as reference...

[veblen]

When I watch ULA launches for NASA, if they are working serious "issues", I am used to seeing a hold while they sort things out.

It was weird today to see the clock count down when the PAO said the issues were still being worked on. I almost felt sorry for the poor bird, although I actually feel sorry for all the workers who worked straight thru Thanksgiving in an unsuccessful attempt to launch some companies comm-sat.

[QuantumG]

SpaceX does it differently.

I almost felt sorry for the poor bird, although I actually feel sorry for all the workers who worked straight thru Thanksgiving in an unsuccessful attempt to launch some companies comm-sat.

Both equally sensible feelings.. thanks for "sharing".

[RocketmanUS]

For this Thursdays launch attempt, how many personnel were needed from out of town ( not Florida residents )?

[AJA]

Moving this over here from the Updates thread.

Case of go fever.
 Shouldn't have started the terminal count if their data review wasn't complete.
Who's watching the rocket? And who is reviewing data?

I can reconcile both the second terminal count proceeding nominally, and PROP reviewing the data from the earlier launch attempt -- even without assuming that there are redundant flight controllers (which would increase costs etc. etc.) -- IF you assume that the computer can pull the plug, as effectively as all flight controllers put together, albeit later in the count.


But this raises a question: how essential is it to have a human man each console in the first place then - from an abort call perspective? Does the ability of a human to take those fuzzy decisions before a computer, save you as much time and expense as employing someone for that purpose? Then again, could it be a SpaceX prop design/manufacture engineer who's doubling as flight controller?

[Antares]

Also, does the first stage have GOX bleed valves at the BOTTOM of the stage (as well)? There seemed to be atleast five streams venting during nominal countdown. I looked closely, and it wasn't coming out of the engine bells, but from the rim of the stage. Any explanations? How does Merlin chilldown happen - is it very cold GOX that cools the bells from the outside? I would think you'd have to slowly chill the entire propellant flow path and not just the engine bells?

Most of the engine is above the rim of the stage, so the flows could still be coming off the engines. Why would SpaceX chill the bells? The only part of an engine that needs to be chilled in is what will see cryo temps anyway (that way those parts' heat aren't vaporizing the cryos during startup). Engines are cooled during operation with fuel not LOX, so Merlin combustion chambers wouldn't need to be chilled. RP likes to be at room temp or warmer.

[Chris Bergin]

When I watch ULA launches for NASA, if they are working serious "issues", I am used to seeing a hold while they sort things out.

It was weird today to see the clock count down when the PAO said the issues were still being worked on. I almost felt sorry for the poor bird, although I actually feel sorry for all the workers who worked straight thru Thanksgiving in an unsuccessful attempt to launch some companies comm-sat.

Personally - and I'm no expert - I imagined the F9 with a big grin on her face saying "come on then! At least give me a chance!"

Rocket's safe. They'll try again. Team continues to gain experience. No harm done.

I don't see it as a negative.

[jabe]

curious,
will they demate the Satellite and take it vertical?  or is it fine to stay horizontal?
jb

[Antares]

I think it makes perfect sense to start term count while data review is going on. Listening to a SpaceX count you've got LC, VC, GC, Prop, AVI, as the key players in the systems involved. I think with 3000 people at SpaceX you've got a few key Prop folks looking at the data that caused the scrub and the usual console operators. Start the count and see if you have a Eureka back in Hawthorne. If not, it's the same result as calling the scrub without trying.

I wouldn't feel sorry for SpaceXers. Everyone chooses their jobs. If they didn't want to work hard and a lot, they should have gone to work somewhere else.

[beancounter]

When I watch ULA launches for NASA, if they are working serious "issues", I am used to seeing a hold while they sort things out.

It was weird today to see the clock count down when the PAO said the issues were still being worked on. I almost felt sorry for the poor bird, although I actually feel sorry for all the workers who worked straight thru Thanksgiving in an unsuccessful attempt to launch some companies comm-sat.

Personally - and I'm no expert - I imagined the F9 with a big grin on her face saying "come on then! At least give me a chance!"

Rocket's safe. They'll try again. Team continues to gain experience. No harm done.

I don't see it as a negative.

Nope, I don't either.  Rather safe than sorry and a day here or there is nothing in the scheme of things.

Go SpaceX for the next attempt.

[veblen]

SpaceX still shooting for one hour roll-out to pad from 6.5? They can practice with the "Mayflower".

[Lars_J]

SpaceX still shooting for one hour roll-out to pad from 6.5? They can practice with the "Mayflower".

6.5? Mayflower?

[Jim]

Moving this over here from the Updates thread.
 flight controllers

This is a launch, there are no flight controllers.  They are either  launch controllers/ system engineers.  They have no role in the vehicle after T-0, when it is in flight

[Jim]

SpaceX still shooting for one hour roll-out to pad from 6.5? They can practice with the "Mayflower".

Spacecraft take longer to power up and checkout than than, so it is not going to happen for a very long time

[edkyle99]

PS: For all the space history buffs: What other vehicles have had (safe, or otherwise) pad aborts post ignition? This is my first live one.

Happened to Shuttle a bunch, especially after the post-Columbia return to flight made everyone super cautious.

Shuttle? Really? Surprised, because that sounds like something I'd remember. Which one d'you recall?

5 shuttles, a few Delta IIs, Atlas goes way back

Titan II too I think, recalling Gemini 7 in particular.  Redstone with an early unmanned Mercury.  Ariane 5 a year or two ago.  Just about every rocket except for the all-solid first stagers like Titan III/IV, Scout, Pegasus, Minotaur, etc.  Also, none of the Saturn rockets ever aborted after ignition on a launch pad, but did during static tests.

Makes me wonder if solid rockets have shorter launch campaigns on average than liquid rockets - at least the part of the campaign that begins with the actual first countdown attempt.

 - Ed Kyle