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

[oiorionsbelt]

You can see the man lift in this picture.

[MarsInMyLifetime]

Works for me. It was so small in perspective that it didn't jump out. A cable harness would be relatively easy to attach under those circumstances.

[meekGee]

I see that boom lifts can get up to 185 feet, so that does seem like a possibility. But in that case, after the worker returns to ground, why not use that same system as the support, rather than bring in a separate crane? I suppose the crane could lift a platform into place and then take over station-keeping. We missed something in the wee hours!

The crane, we think, lifts the rocket onto a ground mount that holds it "properly" by the mating features on the base, to allow leg folding/removal.

Then, two cranes are used to lay it flat on a trailer.  (Overall, a very cumbersome procedure).

Manlifts can't lift anything significant (and are not allowed to, either)

I really hope that they come up with a mobile derector soon.

[edkyle99]

For traditional "Sooting" to occur, you would need a fuel rich combustion with unburnt carbon in it to condense on the target surface (much like in diesel engines when under high load)
Is Merlin using such a fuel rich mixture?

The gas generators likely burn fuel rich, and their exhaust goes overboard after turning the turbines.

 - Ed Kyle

[Robotbeat]

Regarding the scorch marks on the F9 core - I found an extremely educative video about flame protection and its effects on the 1969 Apollo 11 Saturb V launch - and the systems applied to the launch pad hold down clamps and service structures to protect them from the exhaust



The top of the Falcon 9 1st stage would face very similar conditions on 2nd stage ignition - and so does the tail end during reentry.

For traditional "Sooting" to occur, you would need a fuel rich combustion with unburnt carbon in it to condense on the target surface (much like in diesel engines when under high load)
Is Merlin using such a fuel rich mixture?

I don't think so:
Fuel rich kerosene burns yellow. That can be seen for example after stage landing. The first stage exhaust however has an extremely blue white tint to it, much brighter I think than in previous falcon 9 launches -  maybe attributed to the denser, super cooled oxygen. That would indicate a balanced or even oxygen rich combustion, and that would hardly leave any sooting.

Unless the burnt surface had a protective paint like these Saturn V structures, that would char them black

Merlin 1D is DEFINITELY fuel-rich. An oxygen-rich engine requires advanced metallurgy. Only the Russians have done this operationally (though perhaps SpaceX will develop that sort of tech for parts of Raptor).

[sanman]

Hi, congrats on the great landing. So just regarding Musk's comment that he initially thought the booster had exploded instead of landed, just due to the coincidence of the sonic boom arriving at the same time as touchdown - is that particular accidental timing something that's likely to reoccur again in the future?

[NovaSilisko]

Only if you're precisely the same distance from the pad that he was, with a trajectory that brings the stage back down to transsonic at the same time.

(edit: or any appropriate combination of location and flight trajectory that makes the sound arrive at the same time the stage lands...)

[Kabloona]

For traditional "Sooting" to occur, you would need a fuel rich combustion with unburnt carbon in it to condense on the target surface (much like in diesel engines when under high load)
Is Merlin using such a fuel rich mixture?

The gas generators likely burn fuel rich, and their exhaust goes overboard after turning the turbines.

 - Ed Kyle

You can see this nicely from stage 1 onboard aft-facing camera views that SpaceX has shown in previous daytime launches. When the atmosphere thins out, the plume stops afterburning and turns dark and sooty.

[foragefarmer]

https://twitter.com/elonmusk/status/679145544673923072

Any guesses on what the hose is for that the two workers are holding?

Fire hose.

Isn't the diameter of that hose too small to be a fire hose?

It is the correct diameter for a "brush truck" hose that sits in a reel that can be pulled out at a moments notice and rolled back onto the reel easily. Knowing how Spacex likes to save money they probably bought a used brush fire truck off gov auctions when they were setting up LZ1. If the return had failed spectacularly they would have likely ended up using the truck for its originally intended purpose.

[cambrianera]

https://twitter.com/elonmusk/status/679145544673923072

Any guesses on what the hose is for that the two workers are holding?

Fire hose.

Isn't the diameter of that hose too small to be a fire hose?

It is the correct diameter for a "brush truck" hose that sits in a reel that can be pulled out at a moments notice and rolled back onto the reel easily. Knowing how Spacex likes to save money they probably bought a used brush fire truck off gov auctions when they were setting up LZ1. If the return had failed spectacularly they would have likely ended up using the truck for its originally intended purpose.

The "handles" at the end of the hose clearly indicates this is an high pressure gas hose.
"Handles" are part of the harness tie, conceived to avoid dangerous whip movement of the hose in case of breakage of the interface between hose & coupling.

[DatUser14]

Anyone get a good screen capture of the sign with the falcon heavy on it? In the Preshow of the tour of the factory. Here is the best I could find

[Zed_Noir]

...
I really hope that they come up with a mobile derector soon.

Maybe Elon will buy a few used military AVLB tanks for this purpose.

Like the German Biber bridge laying vehicle.

[Marslauncher]

I know on the F9R in McGregor there was a circular loop on the top on the vehicle that they were able to latch on to directly from the crane as I watched them do it, I am doubtful this has the same on it though.

[deltaV]

IIRC when a core is transported cross country most of the weight is on 2 axles of wheels under the mid-rear of the stage. A just-posted photo in the update thread suggests that they used a 20+ axle trailer to transport it from the landing zone to another part of the Cape. Something tells me that trailer could haul something much, much heavier than a Falcon 9 and they're using it just because it was readily available.

[Ohsin]

I know on the F9R in McGregor there was a circular loop on the top on the vehicle that they were able to latch on to directly from the crane as I watched them do it, I am doubtful this has the same on it though.

It appears it gets caught by clamps on inter-stage that hold second stage.

[meekGee]

I know on the F9R in McGregor there was a circular loop on the top on the vehicle that they were able to latch on to directly from the crane as I watched them do it, I am doubtful this has the same on it though.

It appears it gets caught by clamps on inter-stage that hold second stage.

At least now we know where it went

[Dante80]

And how it went too. SpaceX had (as expected) built the stage for easy recovery and moving around..

[mmeijeri]

Have the legs been retracted or removed?

[rpapo]

Looks like they took off the legs and attached the rotisserie rings they normally use in the HIF.

[saliva_sweet]

Can't help wondering what would happen if they just filled the tanks and lit a fire under it. Would it fly to space? They can keep analyzing, measuring, xraying and scrutinizing till they're all old and gray and end up none the wiser.