SpaceX And/Or Rocketry In General

Mike Hewson
Mike Hewson
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robl wrote:During the landing

robl wrote:
During the landing sequence it appeared that the right paddle was missing some of the "honeycomb" connectors/bridges.  It was at this point that the video went "away".  Anyone else notice?

Absolutely! That's what I meant by sacrificing the vane :

vane_burn_gaps.jpg  

and here it is three seconds earlier :

vane_burn.jpg

.... that's ablation ie. the waffle iron was itself toasted/melted. Can't wait to see the state of the barrel overall. Or the other vanes.

Cheers, Mike.

( edit ) Keep in mind what this actually means : hypersonic air molecules ripping apart a metallic lattice. I eagerly await the kinematic/dynamic analysis on this ie. what was the relative speed of airflow when this happened ? Given a constant vane design/material then this qualifies as the hottest Falcon-9 re-entry to date. What performer this gadget is !

( edit ) Lovely shots you took BTW. It just streaked up into the sky. A hotrod. Did you hear much at all ? 

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

Mike Hewson
Mike Hewson
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It's not like Elon is shy

It's not like Elon to be shy about his goals :

elon_24hr_goal.jpg

Well I'll be a monkey's uncle, Oii ! Awesome. :-)))

Cheers, Mike.

( edit ) Of course it was all done in CGI .... :-)

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

archae86
archae86
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Mike Hewson wrote:Absolutely!

Mike Hewson wrote:
Absolutely! That's what I meant by sacrificing the vane :

I'm not sure about that.  I just now tried watching the critical moments at 0.25 speed at 1080p, and I think a viable alternate hypothesis is that the stage had gone past max heating and the "missing" links were some of the faster cooling ones.

Mike Hewson
Mike Hewson
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archae86 wrote:Mike Hewson

archae86 wrote:
Mike Hewson wrote:
Absolutely! That's what I meant by sacrificing the vane :

I'm not sure about that.  I just now tried watching the critical moments at 0.25 speed at 1080p, and I think a viable alternate hypothesis is that the stage had gone past max heating and the "missing" links were some of the faster cooling ones.

Fair enough. Or maybe alot of crap on the lens obscuring the parts too ? My bad ...

Also Elon looked incredibly tired and maybe close to tears. Big day for him.

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

archae86
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I may switch sides again.

I may switch sides again.  Someone posted this at NSF 

Musk: New design coming for Grid Fin.  Will be largest titanium forging in the world.  Current Grid Fin is aluminum and gets so hot it lights on fire... which isn't good for reuse.

On another point of interest, the folks over there consider it an open question whether this was a one-engine or a three-engine landing (as in someone proposes evidence on each side of that question).

Mike Hewson
Mike Hewson
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archae86 wrote:I may switch

archae86 wrote:

I may switch sides again.  Someone posted this at NSF 

Musk: New design coming for Grid Fin.  Will be largest titanium forging in the world.  Current Grid Fin is aluminum and gets so hot it lights on fire... which isn't good for reuse.

On another point of interest, the folks over there consider it an open question whether this was a one-engine or a three-engine landing (as in someone proposes evidence on each side of that question).

Well when we get to look at them, we'll know. Combusting aluminium was a huge problem with USS Stark in a Gulf conflict upon an Exocet strike, plus the HMS Sheffield in the Falklands. Aluminium is quoted to ignite at ~ 4100 K. We saw yellow/orange colors but that, being a very chemically impure situation up there, does not nail down the overall bulk temperature. In any case there may be pointwise oxidation. Let's call it an open question then .... either way they won't be using that grid fin again. :-)

I'll put my money on a three engine burn for landing, in order to guarantee top ooomph for this hover-slam. As you have indicated before three engines is more efficient for a given fuel load. But by doing that you trade-off some finesse in the terminal phase. The likely lesson is that this recovery was close to envelope. An outstanding example of how to trade energy types to achieve a goal.

Cheers, Mike.

( edit ) And that 20% of those hypersonic air molecules are oxygen !

( edit ) Could one, in the terminal phase, initially use three for main effect but then shut two down and leave the ( central gimballed ) one for the gentle touchdown ? Or have they already done that ?

( edit ) Cripes I overlooked that they got the fairing back too. Wow. After he has a good sleep Elon will wake up with a grin that could fit a banana sideways.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

Anonymous

Quote:It just streaked up

Quote:
It just streaked up into the sky. A hotrod. Did you hear much at all ? 

Very little "rumble on this shot.  I believe this was due to a more eastern flight path out over the water.  The shuttles would have a southern trek and they would rattle the windows long after they had "gone by".  

I need to clarify something.  On this recycle effort are they recycling just the "tube" or are they including the engines?  Engine reuse would seem a bit bold and threaten to introduce a higher degree for potential failure.

archae86
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robl wrote:On this recycle

robl wrote:
On this recycle effort are they recycling just the "tube" or are they including the engines? 

definitely includes the engines

archae86
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Mike Hewson wrote: Cripes I

Mike Hewson wrote:
Cripes I overlooked that they got the fairing back too. Wow. After he has a good sleep Elon will wake up with a grin that could fit a banana sideways.

It seems that reports of successful fairing recovery got a bit ahead of the (considerable) accomplishment.  A transcript of the press conference yesterday has the following Elon comments:

Elon Musk wrote:
Oh, actually, one little bit of breaking news which .. The fairing, the big nose cone - the top of the rocket, that actually successfully landed as well. (Audience: Wow, laughter, applause) That was definitely the cherry on the cake. So we actually have a parachute that - the fairing has it's own thruster control system and a steerable parachute. So it's its own little space craft. So the thrusters maintain its orientation as it comes in, as it reenters, and then we thow out the parachute and the parachute steers it to a particular location, and I was just shown a picture of an intact fairing floating in the ocean, (Audience: with the SES logo on it, M: It's the wrong half.. E:It's the half without the M:it's got a US flag on it.) But, yeah, that's really exciting - cause that fairing over 5m diameter, it just - you can fit a bus inside that fairing, and it costs 6 million dollars to make that fairing, and at one point we were debating, should we recover it or not, and I was like, "Guys, imagine you had 6 million dollars in cash in a pallet flying through the air, and it was going to smash into the ocean - would you try to recover that? Yes, yes you would. So, rather than have it smash into tiny pieces, it looks that's looking quite promising. Yeah, so maybe what we'll have is i kinda like a bouncy castle for it to land on, and then aim to reuse the fairing as well

I think they are working toward actual fairing recovery gradually.  Yesterday was perhaps best compared to the "wet landings" during first stage recovery development before they developed and deployed the droneship.

I would not hold my breath on second stage recovery.  It has a lot more speed to kill than the first stage.  Assuming they are already doing atmospheric entry very near the speed limit for existing hardware, they would either need to reserve a great deal of fuel for the retro burn, or add/modify stuff to make the stage able to tolerate much higher atmosphere interface speed (heat shield...).   Maybe on some FH mission which has a great deal of spare oomph they'll do the big burn approach, but I doubt it will be commercially appealing any time soon.

Speaking of things that can be harder than they look, Elon 'fessed up that the Falcon Heavy center core needed considerable upgrading from the previous standard configuration to be viable.  He did not say whether all future cores would carry those upgrades (and that cost) but I'm guessing not.  That leaves the two side cores similar enough that he actually forecast the first FH launch would use two "flight-proven" side cores.

 

 

Mike Hewson
Mike Hewson
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Here is a great shot of the

Here is a great shot of the hotrod :

first_relaunch.jpg

... where you can also see the water deluge onto the strongback base, which has been redesigned to promptly retract after release. All to minimise damage to it. SpaceX just keeps learning and putting lessons back into design, and on a very short response loop. Their recovery from their failures is testimony. Elon has always openly thanked them all for the results. BTW I hear that they are hiring for technicians specifically now. I reckon that implies a revving up of the recycle loop.

I'd award SES ( whoever they are ) a full cajones award for taking on the first recycled booster for their product too. Elon has indicated that significant launch discounts are going to be applied once the research and development costs have been repaid. I think Gwen Shotwell said there are three or four customers in the future launch manifest who have agreed to take a recycled booster, although it wasn't quite clear if a mild discount was being applied for them ( ? 10% ).

As for the Heavy I guess there will have to be a specific centre core design. The engineering demands it really, as there will be thrust asymmetries to be accounted for to keep the whole gadget intact. Actually the thrust finesse of the merlins in such a large conjoined cluster now becomes a crucial control issue. The rotational moments are much higher for the off-axis engines. Plus failure modes. Who wants to write that code ? :-))

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

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