SpaceX Falcon 9 v1.1 - CASSIOPE - September, 2013 - GENERAL DISCUSSION THREAD

[smoliarm]

...  They must also have a tug waiting.

OK, let's say the first stage performs perfect reentry, stable tail-first descent and perfect final burn to zero V, and then splashes in the ocean with almost no splash.
A few details to consider before tugging:

1. The stage will float in close-to-horizontal position, with the thrust structure submerged and with the nose part above the water. As I understand, the stage is not designed for this kind of loads, it does not have proper ribs (spanthouts?) - and it may be structurally not-very-robust on waves.

2. The stage still has some redundant TEA-TEB charges in three of its main engines. As a chemist I can tell that TEB reacts violently not only with air but with water as well. Yes, these charges were all in air-tight capsules -- initially. But how good is their encapsulation now, after splashdown - I don't know.

3. The stage still has some liquid O2 in its tank, may be few tons. If the tank cracks, well, LOX plus ocean water -- it will be very violent interaction (and spectacular -- IF viewed from a distance).

4. Finally, there should be some kind of RCS, still loaded, somewhere on the interstage presumably. I do not know if it uses toxic/pyrophoric  MMH/NTO or just compressed He, but anyway it is sitting on top of unstable structure...

Conclusion: Quite a few things I do not know. Here is one more: If I were a captain of this tug I'm not sure if I take the job...
I just do not know

[smoliarm]

If SpaceX doesn't have a tug out there, China might.  Hmmm, eyetar anyone?

Well, for a China tug -- does F9 have a self-destruction charges for launch abort?

dictionary.com says:
No results found for 'eyetar'
Could you define it?

[Kabloona]

If SpaceX doesn't have a tug out there, China might.  Hmmm, eyetar anyone?

Well, for a China tug -- does F9 have a self-destruction charges for launch abort?

dictionary.com says:
No results found for 'eyetar'
Could you define it?

"eyetar"  = how to say  "ITAR"

http://www.pmddtc.state.gov/regulations_laws/itar_official.html

[meekGee]

As for eye-in-the-sky...  If you had a private jet, where would YOU be?

If the stage is known to be slanted nose up, venting the O2 should be relatively simple.

Any start-up charges can be commanded to fire as it is touching down, no?  How long would that take?

The stage itself, even if full of water, does not weigh more than its empty weight.  They will have some structural attach points ready for a hook up, and then it's not much for a tug to grapple with.

But if it does get submerged, it could be problematic to haul out.  They might tow it to where they can get a heavier barge to lift it out.



It takes a very small line to ensure it doesn't sink. 

[RDoc]

I'll be looking for a good intial reduction burn and a controled flight down. The last second burn may not happen as planned on this first flight. Controling the first stage down seems to have been overlooked by some here. I think keeping the stage intact on the way down will be a challenge.

Not just keeping it intact, but correctly oriented.

The CG is pretty high up, something like 12-15m when empty, so it's not clear that it wouldn't tumble without some kind of control. Perhaps something as simple as drogue chutes? They might also keep the velocity down to something reasonable in the upper atmosphere.

[smoliarm]

"eyetar"  = how to say  "ITAR"

http://www.pmddtc.state.gov/regulations_laws/itar_official.html

Thanks!
Could not guess it

[Jim]

As for eye-in-the-sky...  If you had a private jet, where would YOU be?

Watching the Delta IV

[meekGee]

Heh, honestly?

You've seen launches before...  Not two are the same and all, but still - a re-entry and a relight - not curious one bit?

[smoliarm]

As for eye-in-the-sky...  If you had a private jet, where would YOU be?

If the stage is known to be slanted nose up, venting the O2 should be relatively simple.

Any start-up charges can be commanded to fire as it is touching down, no?  How long would that take?

The stage itself, even if full of water, does not weigh more than its empty weight.  They will have some structural attach points ready for a hook up, and then it's not much for a tug to grapple with.

But if it does get submerged, it could be problematic to haul out.  They might tow it to where they can get a heavier barge to lift it out.



It takes a very small line to ensure it doesn't sink. 

>>Any start-up charges can be commanded to fire as it is touching down, no?  How long would that take?
Good point, they can program it to fire all the remaining charges as they achieve final hovering. It would take seconds.

>>If the stage is known to be slanted nose up, venting the O2 should be relatively simple.
Not sure. This is a LOX tank sitting in the water, ice in the vent could be a problem. The pressure build-up will be very fast.

>>The stage itself, even if full of water, does not weigh more than its empty weight.
No. If you have to tug it, you have to move its own 25 tons PLUS some 450 tons of water inside. Quite a big "plus".

>>They will have some structural attach points ready for a hook up...
... with a STRONGBACK - to ALL of these points. Are you sure that tugging with a LINE attached to ONE point will not rip the stage apart? Remember, it's not a ship, it does not have ribs.

>>If you had a private jet, where would YOU be?
Out of NOTAM, perhaps? But - we live in days of hexacopters

Finally -- I'm not saying it is impossible to salvage the stage from ocean landing.
My point: it's not that simple. It seems to me that it takes much more than simple tug with a line.
But - SpaceX has brilliant engineers, they could find a way. I'd love to see it

[Jim]

Heh, honestly?

You've seen launches before...  Not two are the same and all, but still - a re-entry and a relight - not curious one bit?

Not from an airplane.   

[meekGee]

As for eye-in-the-sky...  If you had a private jet, where would YOU be?

If the stage is known to be slanted nose up, venting the O2 should be relatively simple.

Any start-up charges can be commanded to fire as it is touching down, no?  How long would that take?

The stage itself, even if full of water, does not weigh more than its empty weight.  They will have some structural attach points ready for a hook up, and then it's not much for a tug to grapple with.

But if it does get submerged, it could be problematic to haul out.  They might tow it to where they can get a heavier barge to lift it out.



It takes a very small line to ensure it doesn't sink. 

>>Any start-up charges can be commanded to fire as it is touching down, no?  How long would that take?
Good point, they can program it to fire all the remaining charges as they achieve final hovering. It would take seconds.

>>If the stage is known to be slanted nose up, venting the O2 should be relatively simple.
Not sure. This is a LOX tank sitting in the water, ice in the vent could be a problem. The pressure build-up will be very fast.

>>The stage itself, even if full of water, does not weigh more than its empty weight.
No. If you have to tug it, you have to move its own 25 tons PLUS some 450 tons of water inside. Quite a big "plus".

>>They will have some structural attach points ready for a hook up...
... with a STRONGBACK - to ALL of these points. Are you sure that tugging with a LINE attached to ONE point will not rip the stage apart? Remember, it's not a ship, it does not have ribs.

>>If you had a private jet, where would YOU be?
Out of NOTAM, perhaps? But - we live in days of hexacopters

Finally -- I'm not saying it is impossible to salvage the stage from ocean landing.
My point: it's not that simple. It seems to me that it takes much more than simple tug with a line.
But - SpaceX has brilliant engineers, they could find a way. I'd love to see it

NOTAM is just a Notice to Airmen...  You don't want non-cognizant airplanes wondering around there.   But if you're on the lookout for it?  You're in international waters, there's nobody to close an airspace... 

Safety wise, it's not homing in on you - you will not get hit accidentally.


True about the O2 vent, but that's mostly true if you weren't planning for it.  This vent never has to re-close.


You need a strongback only if you are very intent on preserving the tanks in pristine conditions.  I can't see the thrust structure losing integrity.  It sees a lot of side forces during launch, it's not a flimsy thing.

And besides, your first goal is to prevent sinking, and you do that by latching on to any anchor point.  Then later you can sling up the tank and attach buoys.

You are right about the tow mass, but good deck winches will keep your line from breaking.  These guys make good marine winches:  http://www.markeymachinery.com/

[aero]

Just a thought. The tanks are pressurized, or vented, aren't they? That is, on reaching the surface after the landing burn, the internal pressures of the tanks are at least atmospheric pressure, I hope. I wouldn't want to see them buckle because the fuel had been all pumped out.

[yg1968]

This isn't news for L2 members but it's now public information:

Sources say the first launch of SpaceX's Falcon 9 v1.1 from Vandenberg is NET Sept. 10. That's a five-day slip from the previous target.

https://twitter.com/StephenClark1/status/372505876713590784

[Downix]

I'll be honest guys, this flight has me the most concerned out of all of SpaceX's so far.

1) Commercial payload, not government, which means insurance riders will rate themselves on it.

2) first launch of a new main engine. Like it or not, the Merlin-1D is untried, lots of risks for a first launch with a new engine.

3) first launch of a new first stage. The 1.1 stage is new, sharing very little with the 1.0. Or at least it shouldn't. Behavior for a longer stage is different, as the Extra-Long Tank Thor can attest to.

4) first launch of a fairing system. We've lost multiple launches due to fairing failure in the past decade.

5) new launch pad. Like it or not, means different personnel, different experiences, training is a big unknown.

This all adds up to nervous-nellie for me. I hope they pull it off, but there are a lot more factors here than in any previous launch they've had. This fails, their hopes for commercial success will dwindle fast.

[Prober]

As for eye-in-the-sky...  If you had a private jet, where would YOU be?

Watching the Delta IV

a given 

[Downix]

As for eye-in-the-sky...  If you had a private jet, where would YOU be?

Watching the Delta IV

::thumbsup::

[AndyX]

This isn't news for L2 members but it's now public information:

Days old for L2, which is continuing to be brilliant for this mission. Love L2.

[edkyle99]

5) new launch pad. Like it or not, means different personnel, different experiences, training is a big unknown.

Clearing the pad will be vital, to avoid a Baikonur 45/2, still in ruins 23 years on.

 - Ed Kyle

[Downix]

5) new launch pad. Like it or not, means different personnel, different experiences, training is a big unknown.

Clearing the pad will be vital, to avoid a Baikonur 45/2, still in ruins 23 years on.

 - Ed Kyle

Thank you Ed.

(egads, we agree on something, this is a bad omen for SpaceX)

[Robotbeat]

Remember before the previous SpaceX launch(es)? Everyone scared? Well, they got to orbit each of 5 times and survived the (significant) hiccups, pretty good for a new launch vehicle.