SpaceX Falcon 9 FT - ORBCOMM-2 - Dec. 21, 2015 (Return To Flight) DISCUSSION

[yokem55]

Looking at the photos of F9-21 posted today and comparing them with earlier Falcon 9 v1.1 rockets, I'm coming up with 30 inch-ish stretches for both the interstage and the second stage for a total of around 60 inches.  Give or take a few inches.  The interstage stretch may slightly exceed the second stage stretch.

 - Ed Kyle

This is the first I've heard of an interstage stretch. Is the M-1d-vac's bell longer as well?

[Johnnyhinbos]

Looking at the photos of F9-21 posted today and comparing them with earlier Falcon 9 v1.1 rockets, I'm coming up with 30 inch-ish stretches for both the interstage and the second stage for a total of around 60 inches.  Give or take a few inches.  The interstage stretch may slightly exceed the second stage stretch.

 - Ed Kyle

This is the first I've heard of an interstage stretch. Is the M-1d-vac's bell longer as well?

Yes - the M1Dvac nozzle was extended. There may be a little extract in there for the second stage center pusher as well

[MarekCyzio]

If it's longer it also needs to be wider. Wonder what is clearance between interstate and the nozzle now. And how risky separation is.

[mme]

The key phrase in your post is "restricting access." ie no outside photographers going into LZ-1, period.

Why?  Isn't it just concrete?  What's in there the USAF doesn't want anyone seeing?
I don't mind rules so long as they make sense.

Safety would be my guess.     

 - Ed Kyle

That's my assumption.  They're obviously not certain the landing will be successful, even though they've been convinced it will not pose a risk to the public.  I suspect they don't want to deal with people wanting to get to their equipment in the middle of (not unlikely) accident response operations.

Admittedly speculation on my part, my reading of the rumor was that the AF would not allow civilians on to CCAFS to set up cameras.  IMO it's more a security issue than a safety issue.  Though it could be both.

I don't think unescorted civilians are allowed on CCAFS anymore, are they?  That would mean escorting people to set up the equipment, escorting them away from the pad and then escorting back to collect their equipment after.  Sounds like a major hassle to me.

[Robotbeat]

If it's longer it also needs to be wider. Wonder what is clearance between interstate and the nozzle now. And how risky separation is.

Doesn't have to be wider. They may have changed the nozzle angle. But anyway, it doesn't need to be MUCH wider.

In any case, this is no doubt part of why they added the center pusher... to reduce separation risk.

...but still makes me nervous. Not a totally new rocket (not as big of a change as from v1.0->1.1), but enough new that the risk of a failure is increased. I trust they put enough sweat and tears into this new rocket that it will be successful, but I'm nervous. I give it 90-95% chance of success.

[InfraNut2]

If it's longer it also needs to be wider. Wonder what is clearance between interstate and the nozzle now. And how risky separation is.

That is exactly why the center pusher was added: to precisely control separation so there is insignificant sideways movement, since the clearance now is significantly smaller.

[MarekCyzio]

A lot of new technology in this rocket. I keep my fingers crossed everything works the way it is designed to. I would love to see it land safely and start the new era of space flight today.

[ugordan]

A lot of new technology in this rocket. I keep my fingers crossed everything works the way it is designed to. I would love to see it land safely and start the new era of space flight today.

For starters, I would love to see the primary mission go fine given the changes they made to this thing.

[Robotbeat]

A lot of new technology in this rocket. I keep my fingers crossed everything works the way it is designed to. I would love to see it land safely and start the new era of space flight today.

For starters, I would love to see the primary mission go fine given the changes they made to this thing.

Same here! Another failure would be a body blow.

[NovaSilisko]

A lot of new technology in this rocket. I keep my fingers crossed everything works the way it is designed to. I would love to see it land safely and start the new era of space flight today.

At risk of sounding like Jim, it won't be a new era until they're both returning and reusing F9 stages regularly. Getting it back is a huge accomplishment, but only the beginning of the beginning.

[jcm]

What do we know about the second stage restart burn at this point?
My understanding was they would restart stage 2 at T+34:00 to demonstrate the ability
of the upgraded rocket to do the GTO insertion burn for SES-9. But the NOTAM for stage 2 reentry
just posted on the updates thread shows reentry at T+54 min. So I guess the burn is actually
a deorbit burn, maybe around 400 m/s just to prove it can restart, rather than matching the delta-V for SES-9 or anything.
Do we know anything more?



Apologies if I missed a discussion of this further up...

[mtakala24]

Elon Musk ‏@elonmusk  2m2 minutes ago
Just reviewed mission params w SpaceX team. Monte Carlo runs show tmrw night has a 10% higher chance of a good landing. Punting 24 hrs.



Not sure what 'punting' means...

[Robotbeat]

Elon Musk ‏@elonmusk  2m2 minutes ago
Just reviewed mission params w SpaceX team. Monte Carlo runs show tmrw night has a 10% higher chance of a good landing. Punting 24 hrs.



Not sure what 'punting' means...

It means the launch is now tomorrow night!

Very interesting. Landing is now a major consideration for them on this flight. Makes sense, as this is a low-margin flight.

[ugordan]

Scrubbing for a 10% increase in landing probability vs 10% lower chance of no weather violation for launch?

[Garrett]

Elon Musk ‏@elonmusk  2m2 minutes ago
Just reviewed mission params w SpaceX team. Monte Carlo runs show tmrw night has a 10% higher chance of a good landing. Punting 24 hrs.

Not sure what 'punting' means...

"To punt" in this case means "to kick".
So launch is off tonight, kicked over to tmw night.

[jimbowman]

So much for the "primary mission"

[Mapperuo]

Very strange decision when tomorrows launch weather is 10% worse according to forecasts?

[Norm38]

The chance for weather violation is 10% higher tomorrow but chance for landing is 10% better?  How does that work?

[ulm_atms]

I have a feeling they are still having plumbing issues with the subcooled LOX....

To punt for a 10% gain in landing but a 10% increase is weather violation (which kinda makes no sense when you think about it) is um....strange.  Makes me wonder what the actual margin is in the return to land.  if 10% makes such a big difference...that's cutting is quite close.

If the subLOX is ok...I'm surprised Orbcom is ok with a delay.  If it is a subLOX issue...i can see why they would go with this punt.

my .02

[Beast@Tanagra]

Elon just said "mission params", nothing about weather specifically. Is there something about the launch windows that might leave higher margin for tomorrow? The weather difference may be inconsequential here.