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

[Robotbeat]

Yup, helium is still too cheap, but if it were 10x the price and they were launching >100 times a year and landing at the same spot, it'd probably be worth looking into.

[OxCartMark]

Nice thing about recovering the rocket stage is you ALSO can recover the helium that's pressurizing it. The helium fills the ullage volume, it's not expended!

  Yea, that's what I said at the beginning of this.

Nice thing about recovering the rocket stage is you ALSO can recover the helium that's pressurizing it. The helium fills the ullage volume, it's not expended!

Yes, but it looks like the remaining LOX is vented after landing, so that would also vent the helium.

No.  You've thinking of venting the gas above the LOX which is a mix of oxygen and helium.  If you were to do that you'd still have nearly all of the LOX and would have to wait for it to boil into gas then vent that gas, a long process.  What needs to happen is to vent the LOX from the bottom of the tank and stop that venting process once the liquid is out of the tank.  ...Which leaves all of the helium in the tank for re-use (after cleaning it up).  And don't forget about the He on top of the fuel as well.

You do know every other launcher expends the helium if it's used to pressurize nice to even be discussing reuse of helium from the copv bottles

Yes, but the others don't have the goal / vision / ambition of daily launches to consider.

[avollhar]

At the time this was explained as needing to have a constant thermal emissivity so that IR imaging could obtain correct temperatures for every surface point.  Otherwise you have to calibrate for the emissivity of every different surface separately.

I don't think it's related to soot.

With the right paint (higher IR emissivity), you can effectively cool via radiation. One reason why electronic heatsinks are black anodized rather than polished aluminum.

If your semiconductor heatsink is cooling appreciably via radiation compared to convection then you
are having a very bad day.

Most heavy duty heatsinks I see are strip or extruded aluminum, albeit matte rather than polished.

In this forum I am obviously talking about near-space/vacuum conditions. And then surface coating makes a huge difference as you are purely radiative. The emissivity for aluminum varies from 0.05 (polished) over 0.21(sandblasted) to 0.77 (anodized) (source http://www.infrared-thermography.com/material.htm) which does make a difference in vacuum.

That said, the Merlin engine bell is made from some niobium alloy and the game might change.

[acsawdey]

In this forum I am obviously talking about near-space/vacuum conditions. And then surface coating makes a huge difference as you are purely radiative. The emissivity for aluminum varies from 0.05 (polished) over 0.21(sandblasted) to 0.77 (anodized) (source http://www.infrared-thermography.com/material.htm) which does make a difference in vacuum.

That said, the Merlin engine bell is made from some niobium alloy and the game might change.

Maybe this is what you meant, but only the nozzle extension used on the M1D-vac is niobium alloy. And it is pretty clear from watching the onboard video from the second stage that it is radiatively cooled ...

[Jim]

No.  You've thinking of venting the gas above the LOX which is a mix of oxygen and helium.  If you were to do that you'd still have nearly all of the LOX and would have to wait for it to boil into gas then vent that gas, a long process.  What needs to happen is to vent the LOX from the bottom of the tank and stop that venting process once the liquid is out of the tank.  ...Which leaves all of the helium in the tank for re-use (after cleaning it up).  And don't forget about the He on top of the fuel as well.

There is no such thing as "venting" from the bottom of a tank.  And still if you remove the LOX, the remaining gas is a mixture of O2 and He.  To recover the He, the gas mixture will be need to be sucked/displaced out of the prop tank.  It would need to be compressed for transportability.  The gas mixture will need to be take to a gas liquidification plant to distill out the He.

You do know every other launcher expends the helium if it's used to pressurize nice to even be discussing reuse of helium from the copv bottles

Yes, but the others don't have the goal / vision / ambition of daily launches to consider.

The removal ops would not fit in with Spacex turnaround times,  since it would be time consuming.
Just remove the RP-1 and open the all the vents.

Spacex is just going vent the He.  Quicker and cheaper.

[saliva_sweet]

The removal ops would not fit in with Spacex turnaround times,  since it would be time consuming.
Just remove the RP-1 and open the all the vents.

Spacex is just going vent the He.  Quicker and cheaper.

If there's 20k in there and can get back 10 they just might go for it. They're not known for leaving a penny on the ground. They did send back all the lox to the gas plant when the COPV blew on the 1st Orbcomm launch and I think it's worth about the same.

[dorkmo]

doesnt spacex bring a helium simi trailer to the landing site? i assumed they needed to pressure up the stage in order to go horizontal.

[Jim]

1.  They're not known for leaving a penny on the ground.

2.  They did send back all the lox to the gas plant when the COPV blew on the 1st Orbcomm launch and I think it's worth about the same.

1.  Yes they are.  They run into a lot of dead ends.
2.  what LOX?

[CameronD]

The removal ops would not fit in with Spacex turnaround times,  since it would be time consuming.
Just remove the RP-1 and open the all the vents.

Spacex is just going vent the He.  Quicker and cheaper.

..but if they left at least some of it in the tanks, the ops team could practice Donald Duck impressions for the after party.   

[chalz]

Funny.  But.

It belongs in a lab, in pieces, to expedite searching for any close-calls or low-margin situations with the rocket.  Destructive testing as well.
…

One question I have about all this expectation of tear-downs and forensic examinations is how much it will cost? The manpower and time for what may prove a fruitless search might be a good reason not to do it.

The better plan could be 'test as you fly' i.e. after checking for gross damage they do a static fire. It is a procedure they do a lot, does not require special expertise, tests engines and structure, and errors will be easily apparent.

Keeping the first stage returned for posterity is pretty sentimental but if that is the price for having a visionary CEO who has got the company this far and could take them much further then we should be willing to bare it.

[Jcc]

You do know every other launcher expends the helium if it's used to pressurize nice to even be discussing reuse of helium from the copv bottles

Yes. I also agree with those who say it is likely not practical to try to save the He in the ullage, but at least they can save any residual left in the COPV bottles, right?

[wannamoonbase]

Funny.  But.

It belongs in a lab, in pieces, to expedite searching for any close-calls or low-margin situations with the rocket.  Destructive testing as well.
…

One question I have about all this expectation of tear-downs and forensic examinations is how much it will cost? The manpower and time for what may prove a fruitless search might be a good reason not to do it.

The better plan could be 'test as you fly' i.e. after checking for gross damage they do a static fire. It is a procedure they do a lot, does not require special expertise, tests engines and structure, and errors will be easily apparent.

Keeping the first stage returned for posterity is pretty sentimental but if that is the price for having a visionary CEO who has got the company this far and could take them much further then we should be willing to bare it.

I agree.  Test that which has flown then refly.  Visual and non destructive will get you down the road.  It's not like they intend to fly to exhaustion.

Regarding saving the first stage.  It is serving a required function at 39A.  Further if one needs to be dissected like an alien in a SciFi movie than surely waiting 2 months from Orbcomm to SES-9 or CRS-8 shouldn't be too much to ask.  Also, the eyes of history doesn't care much about 2nd.

59 years after Sputnik what's another month or two? 🤔

Edit: remove cheekiness

[zodiacchris]

If they manage to land Jason's Falcon1.1, they can dissect that to their hearts desire as it will not fly again. It will have gone through a similar flight and stress envelope, and structurally it is very similar to the FT, so that would be a fitting role for it.
I'd like to see the first stage in a museum, in the years to come we'd be kicking ourselves if we let it go. Too have proper and relevant exhibits like this in a museum, rather than the now ever present interactive displays, should be inspiring to the younger generation, and if it is just because of the sheer size of the thing!

[Johnnyhinbos]

For me, personally, the bird I'd like to see in a museum would be the first one to fly twice...

[OxCartMark]

Just dawned on me that this stage may represent to Elon a somewhat lesser version (a step along the way) of his original vision - a terrarium on mars to inspire those sitting on the fence about space exploration and engineering. 

[meekGee]

Funny.  But.

It belongs in a lab, in pieces, to expedite searching for any close-calls or low-margin situations with the rocket.  Destructive testing as well.
…

One question I have about all this expectation of tear-downs and forensic examinations is how much it will cost? The manpower and time for what may prove a fruitless search might be a good reason not to do it.

The better plan could be 'test as you fly' i.e. after checking for gross damage they do a static fire. It is a procedure they do a lot, does not require special expertise, tests engines and structure, and errors will be easily apparent.

Keeping the first stage returned for posterity is pretty sentimental but if that is the price for having a visionary CEO who has got the company this far and could take them much further then we should be willing to bare it.

I agree.  Test that which has flown then refly.  Visual and non destructive will get you down the road.  It's not like they intend to fly to exhaustion.

Regarding saving the first stage.  It is serving a required function at 39A.  Further if one needs to be dissected like an alien in a SciFi movie than surely waiting 2 months from Orbcomm to SES-9 or CRS-8 shouldn't be too much to ask.  Also, the eyes of history doesn't care much about 2nd.

59 years after Sputnik what's another month or two? 🤔

Edit: remove cheekiness

NDT and museum are not mutually exclusive.  The components you'd want to test to failure are internal - like the infamous struts.  I don't think anyone wants to tear the rocket to pieces...

But this is a matter of priorities.

Reliability is priority #1, and there isn't a rocket today that had this chance of post-flight analysis.  They should take advantage of it.

And if possible, they should do re-flights to test the more holistic aspects of the rocket for reuse - that's priority #2.

Place in a museum is #?   The museums will be happy to get whatever they get, even a year later.  And nobody cares about "first".  There were four shuttles.  No museum was whining because they got #3 or #4.

[saliva_sweet]

1.  They're not known for leaving a penny on the ground.

2.  They did send back all the lox to the gas plant when the COPV blew on the 1st Orbcomm launch and I think it's worth about the same.

1.  Yes they are.  They run into a lot of dead ends.
2.  what LOX?

1) That was just my impression given they're happy to go dumpster diving to get the stuff they like for cheap.

2) When they were prepping for OG2-1 launch a COPV blew. The launch was delayed by more than a month so they had a bunch of lox left over. They shipped it back in trucks. I may recall incorrectly.

[Jet Black]

1.  They're not known for leaving a penny on the ground.

2.  They did send back all the lox to the gas plant when the COPV blew on the 1st Orbcomm launch and I think it's worth about the same.

1.  Yes they are.  They run into a lot of dead ends.
2.  what LOX?

1) That was just my impression given they're happy to go dumpster diving to get the stuff they like for cheap.

2) When they were prepping for OG2-1 launch a COPV blew. The launch was delayed by more than a month so they had a bunch of lox left over. They shipped it back in trucks. I may recall incorrectly.

(1) That looks like a non sequitur, Jim. Yes they run into a lot of dead ends in that they will try something and if it doesn't work, drop it. That's not the same as attempting to reuse what they can to save money (whether it's materials or knowhow). If anything, a willingness to drop things in the long term can be a money saving exercise in itself since it means they don't go down the same road as the concorde-type-fallacy in which they spend more and more just to justify an earlier spend and end up wasting piles of cash doing something that is inefficient (this is common in governments where ministers or the like would rather allow massive project finance bloat than drop a project, because they would be perceived as having wasted all the already spent money)

[JamesH]

Funny.  But.

It belongs in a lab, in pieces, to expedite searching for any close-calls or low-margin situations with the rocket.  Destructive testing as well.
…

One question I have about all this expectation of tear-downs and forensic examinations is how much it will cost? The manpower and time for what may prove a fruitless search might be a good reason not to do it.

Manpower/time that is only spent once/twice, and MIGHT prove to be fruitless, or MIGHT find something very important. Fruitless is still fruitful if it proves everything works.

[Jet Black]

Funny.  But.

It belongs in a lab, in pieces, to expedite searching for any close-calls or low-margin situations with the rocket.  Destructive testing as well.
…

One question I have about all this expectation of tear-downs and forensic examinations is how much it will cost? The manpower and time for what may prove a fruitless search might be a good reason not to do it.

The better plan could be 'test as you fly' i.e. after checking for gross damage they do a static fire. It is a procedure they do a lot, does not require special expertise, tests engines and structure, and errors will be easily apparent.

Keeping the first stage returned for posterity is pretty sentimental but if that is the price for having a visionary CEO who has got the company this far and could take them much further then we should be willing to bare it.

There is no such thing as a fruitless search in this case, because nobody has ever achieved this before and so nobody knows fully what will happen. We have models of course, but there will always be inaccuracies and the data they get will refine their models.