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

[MattMason]

Lots of reposts of photos and content created by others today. It's always nice to reference/credit the sources.

On a different subject, what are all the streaks flying around before and for a short while after S2 ignition? Looks to me like pulsed streams of liquid from a bunch of different outlets? I don't recall seeing anything like that in previous flights.

I cannot recall if Falcon 9 uses pyrotechnic bolts, commonly used to hold stages together on modern launch vehicles. If Falcon 9 uses such bolts, the sparks you see are these bolts detonating to separate the first and second stages. If SpaceX doesn't use such bolts, you're seeing an equivalent separator activating, which is no cause for alarm.

[DigitalMan]

From my house I couldn't see the launch from my driveway due to clouds but a while back I recall seeing 1st stage return enveloped in flames the whole length of the rocket for a couple minutes before getting lower in the atmosphere.

[notsorandom]

Lots of reposts of photos and content created by others today. It's always nice to reference/credit the sources.

On a different subject, what are all the streaks flying around before and for a short while after S2 ignition? Looks to me like pulsed streams of liquid from a bunch of different outlets? I don't recall seeing anything like that in previous flights.

I cannot recall if Falcon 9 uses pyrotechnic bolts, commonly used to hold stages together on modern launch vehicles. If Falcon 9 uses such bolts, the sparks you see are these bolts detonating to separate the first and second stages. If SpaceX doesn't use such bolts, you're seeing an equivalent separator activating, which is no cause for alarm.

They are still using pushers and not explosive bolts. Elon mentioned a long time ago that he didn't like that explosive bolts couldn't be tested before use.

[MattMason]

i have a question so please help. What is that S shaped thing on the big screen in the control room? Its at exactly 34:23 please take a look

I am looking at it and going what view is that, what is it?

We're rarely given a look at the flight controller's main screens, be it at their control center at KSC during a NASA-contracted CRS mission or with private launches such this one. The view there is too blurry to make anything out.

But given that the SpaceX team is shown totally losing their minds, everyone there likely gets to see a company-only internal feed of LZ-1, other data displays, as well as the feed from the 2nd stage camera that's shown publicly.

[cscott]

Wrt to the soot (and I've posted this theory in other threads as well) my bet is that the lower soot is from launch (LOX icing plus flow recirculation), and the upper soot is from S2 ignition.  In particular, you can see shadows in the upper soot caused by protuberances on the core which make it clear that the source of the upper soot is from above.

Wrt S2 "sparks" I believe what you're seeing is small bits of ice catching the light as they shake free.  There's a powerful light beside the camera; the freeze frames posted on the update thread show how bright it is when reflected specularly from the departing first stage; bits of ice would catch the light in the same way.

[abaddon]

I get that this forum is obsessed with every little detail.  (As am I... I wouldn't be here if I wasn't).  I also get that the soot is a very obvious sign of use, and the pattern looks odd, and it's interesting to speculate why it looks like it does.

That all said... is it really important?  Does anyone think that the soot will do anything, other than make them spend a little more effort cleaning the stage?  (Honest question here).  It seems likely to me that this will be waaaaay down on a list of things that might make it hard to refurbish a once-used first stage.

I did see some speculation from someone that the dark color near the octaweb is ablative coating, not soot, and that's a little more interesting if it is on the nose.  If it is ablative than there is going to be a plan to replace it in place already, I'd imagine.

[Ben the Space Brit]

That all said... is it really important?  Does anyone think that the soot will do anything, other than make them spend a little more effort cleaning the stage?  (Honest question here).

That's a good question.

To me, the significance of the soot is the implication that something unexpected (to us) was happening on or around the stage during its decent through the atmosphere. Depending on what is the root cause, it could have implications for performance or reliability. For example - is it (as some have speculated) a chilling effect from the LOX? Therefore does it indicate a flaw in the tank insulation or an indication of ice build-up during flight? Build up of frost could lead to issues like changes in the centre of gravity or asymmetric drag during the free-fall descent phase in between MECO3 and MES4.

[DavidH]

I get that this forum is obsessed with every little detail.  (As am I... I wouldn't be here if I wasn't).  I also get that the soot is a very obvious sign of use, and the pattern looks odd, and it's interesting to speculate why it looks like it does.

That all said... is it really important?  Does anyone think that the soot will do anything, other than make them spend a little more effort cleaning the stage?  (Honest question here).  It seems likely to me that this will be waaaaay down on a list of things that might make it hard to refurbish a once-used first stage.

I did see some speculation from someone that the dark color near the octaweb is ablative coating, not soot, and that's a little more interesting if it is on the nose.  If it is ablative than there is going to be a plan to replace it in place already, I'd imagine.

If it indicates any kind of damage or the amount of fuel/lox remaining (at some/any point in flight). If the mass of Orbcomm was less than the performance of the vehicle, indicated by lots of remaining fuel, then how does that affect future GEO/performance limited S/C launches WRT landing, etc.

I can think up reasons this would be of use. However, I agree with you. There are some strange theories being tossed about and people here tend to the absurd when it comes to chasing a rabbit down a hole.

[Robotbeat]

The first stage appears to have buckled right above the octoweb.

You can see this most clearly in the 10 second video Elon Musk tweeted as "Live video from LZ-1," but you can also see it 33:35 into the entire launch video. However, the lighting is deceptive in both video.

The buckling probably happened upon contact with the ground, the relight for landing, or max-Q upon re-entry. The landing seemed pretty gentle, but the landing relight would have had the highest structural loads from the thrust do the the reduced propellant mass. However if max-Q occurred during the re-entry burn, the re-entry loads could have exceeded the landing burn. The thrust and aerodynamic drag would be summed to produce the force the structure was subjected to.

It all depends on how high they were during the re-entry burn, how rarified the atmosphere was, and how fast they were going. I'm not sure how SpaceX have the octoweb seated in the aluminum core, but clearly the access holes they usually place at the base of the aluminum core are a weak spot (if the ocotweb supports the aluminum core that low). The buckling is why I don't think they will re-fly the stage, which violates their previously stated plans.

How could they strengthen the base of the stage? Thicken the aluminum? Add internal struts? Create vertically spread internal attachment points for the Octoweb or front bulkhead?

Can anyone make out if the buckling had occured prior to landing form the helo video?

Nope. No buckling occurred.

[AncientU]

Classic.  The "it ain't proven yet" line starts at the top.

If it were his own company, he might have worried about the possibility that it might actually work instead of clinging to the hope that it won't.

A Arianespace factory worker has less to worry about in near term from the F9 recovery than SpaceX factory worker. Every recovered booster is one less that SpaceX needs to produce and SpaceX are not known for carrying surplus workers.

There are many more things to build than Falcon boosters and Merlins.  I suspect job security isn't a problem for those that thrive on the SpaceX pace and prospects.


Edit: Deleted comment due to Kim's suggestion.

[Kim Keller]

And Arianespace workers don't worry because they are quasi-government -- same reason NASA workers don't worry.

You might want to reconsider that line. Arianespace workers are not quasi-government, they are company employees who can be hired, fired and laid off just like any other commercial employee. NASA civil servants aren't guaranteed a job for life, and NASA contractors definitely get nervous around contract expiration time.

[Robotbeat]

Half of russian space forum members are still in denial

Why would they be?  The original proposal for the flight path the Falcon stage took was a Russian one.  We don't know if Musk, or his staff, ever saw that, though.

It would be quite surprising if they hadn't. The F9 return trajectory with the 3 burns is practically identical to the Russian scheme.

Link?

[abaddon]

It would be quite surprising if they hadn't. The F9 return trajectory with the 3 burns is practically identical to the Russian scheme.

Well, let's think about this a bit...

The first burn, the boost-back burn.  If you want to RTLS it is required. 
The second burn, the entry interface burn.  They tried using parachutes and cork on earlier Falcons and gave up on that.
The third burn, the landing burn.  Yeah...

It doesn't seem impossible to me that someone could come up with this independently.

That said, given that Musk originally attempted to buy Russian rockets before founding SpaceX, and given that he's seemingly borrowed some ideas from the Russians (e.g. horizontal integration), it seems highly implausible that he didn't know about their plans at the time that they decided to go with fully propulsive return...

[Kabloona]

Half of russian space forum members are still in denial

Why would they be?  The original proposal for the flight path the Falcon stage took was a Russian one.  We don't know if Musk, or his staff, ever saw that, though.

It would be quite surprising if they hadn't. The F9 return trajectory with the 3 burns is practically identical to the Russian scheme.

Link?

Been posted here several times over the last year or so. Type "russian boostback" into the NSF search function to find previous discussions of it.



Here's the SpaceX trajectory for comparison. The graphic is not a SpaceX product and not to scale, but the concept is essentially correct.

It doesn't seem impossible to me that someone could come up with this independently.

Yes, the universal laws of physics dictate the three-burn boostback/landing as optimal, so no doubt SpaceX could have come up with it independently. But no doubt they are also smart enough to do their homework and learn from others. Also, remember the patent dispute with Blue and how that hinged on "prior art," ie knowing what others had already published.

[inventodoc]

And Arianespace workers don't worry because they are quasi-government -- same reason NASA workers don't worry.

You might want to reconsider that line. Arianespace workers are not quasi-government, they are company employees who can be hired, fired and laid off just like any other commercial employee. NASA civil servants aren't guaranteed a job for life, and NASA contractors definitely get nervous around contract expiration time.

sorry, but do you know what it takes for a company to fire an employee in France?      I concede your other points.

[macpacheco]

The critical aspect isn't coming up with that 3 burn scheme.
Its having a rocket efficient enough that it has spare DeltaV to do useful work and the 3 burns.
Its designing rocket engines that can endure this cycle at least a half a dozen times with high reliability (SpaceX still needs to prove that).
All of that while not making the rocket way more expensive than regular expendable ones.

[Kim Keller]

sorry, but do you know what it takes for a company to fire an employee in France?      I concede your other points.

No, I don't. But I do know that Arianespace isn't just a French company. There's partners in nine other countries that help make up the consortium.

[Antilope7724]

If return and reuse of the Falcon pans out, there will probably be another rev of the vehicle optimized for reuse. Maybe some parts need to be strengthened, maybe some will be found to be over-built. Maybe a different exterior coating or better paint, etc.

[vanoord]

I don't think this is genuine...

http://losangeles.craigslist.org/lac/hvo/5370563072.html

 

[CorvusCorax]

sorry, but do you know what it takes for a company to fire an employee in France?      I concede your other points.

No, I don't. But I do know that Arianespace isn't just a French company. There's partners in nine other countries that help make up the consortium.

Also it should be noted that Arianespace operates much like "old school" space in the US. Arianespace is marketing and conducting the launches and assembling the launchers but its components come from commercial subcontractors - not just in Europe but all over the world. (I think Airbus being the biggest one.)

Airbus is also the biggest shareholder of Arianespace - such mirroring the role of Boing in ULA.

If the market share of Arianespace drops, and as such less launches happen, its the sub-contractors and the sub-sub-contractors that would feel it most. That is also where any layoffs are most likely to happen.

Keep in mind SpaceX is as cost effective mostly due to their in house strategy, but that's exactly where they do things different than everyone else.

Old-school space's fat that needs to be trimmed is in this distributed infrastructure of commecial subcontractors. And the potential cost savings in this "layer" might actually be substancially higher than what could be gaines from reuseability - at least within the next 5-10 years.

After all, so far SpaceX has not re-used a single vehicle commercially (Grassopper was a self-financed internal test) SpaceX has spent massive sums on developing their rocket science and production methods basically from scratch and on top spends ****loads of money on further development of technologies of reuseability - new engine technologies (Raptor, deep cryo, ...) as well as the eventual mars colonization program ...
and still is cheaper than everyone else!

If you optimize for reuseability, the stage development and production doesn't have to be as cost optimized. It can be very expensive to produce a stage in the first place, as long as the cost for re-use and maintenance is low. Boing and Airbus are both very effective with the expensive subcontractor model for production - of airplanes! Here the market has long optimized reuse ( A boing 747 is being reflown and refurbished for several decades. Some airplanes are around and in active service since the 1930's! )


With that in mind, Arianespace has exactly two options how to possibly compete with SpaceX:

Variant 1: Stay expendable, but use an extremely highly integrated production model to make the stages dead-cheap. (This won't happen I think. The way Arianespace as well as the shareholder companies - and in fact almost ANY european conglomerate is structured, they NEED the subcontractor model to function - not at least for political reasons since every european country wants some of the cake for their industry)
This will basically cost a lot of jobs - mostly at the subcontractor level, as stuff would HAVE to be made higher up.

Variant 2: Stay expensive (in production) but go for high reuseability much like it happens for airplaines.
That would fit the european corporate model much better, so eventually I think that's whats gonna happen - once the generation ostrich management team has been replaced.