SpaceX And/Or Rocketry In General

Anonymous

archae86 wrote:Nice landing

archae86 wrote:

Nice landing indeed.  There was more than one camera going, and it appears that the NASA feed and the SpaceX feed made different camera selections most if not all the way down.  More than one person has posted a composite video to youtube using first one than the other.  If you have only seen one, you may enjoy seeing the other.

For example this one after eight seconds of promo starts with the NASA feed just as the re-entry burn lights up one engine, than goes on to three, and continues to touchdown, then switches to the version SpaceX broadcast.  This one only offers a maximum resolution of 720p60--you may be able to find higher.

The NASA feed, in particular, makes some of the variations in orientation of the stage to oncoming air more apparent than I realized.   They clearly are making some use of the (modest) lift available by holding the booster at an considerable angle of attack in the early hypersonic phase, but gradually reduce the angle of attack and get to near nothing late in the game.  

The SpaceX feed shows how the grid fin motions get larger and larger as aero forces available shrink with lower speed near the end.  I'm a bit surprised they don't just stow the things to a neutral position late in the game and rely purely on gimbal of the thrusting engine, but of course any utility they get out of the grid fins is a fuel savings.

Also the NASA footage shows the relight of the engines more clearly than I've noticed before, including the rather large "green flash" from the TEA-TEB ignition scheme, and makes crystal clear that this was a 1 engine goes to 3 re-entry burn with a single engine landing burn.

 

I had not seen the NASA feed - a completely different perspective.  Thanks for posting.  

archae86
archae86
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As I write it is just under

As I write it is just under an hour until the scheduled launch of a set of Iridium satellites from Vandenburg by a lightly used Falcon 9 first stage.

Grid fins are installed, but no legs, and no recovery is planned. 

This is a zero-width launch window, at 01:27:34 UTC.

https://www.youtube.com/watch?v=wtdjCwo6d3Q

 

 

 

archae86
archae86
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archae86 wrote:Grid fins are

archae86 wrote:
Grid fins are installed, but no legs, and no recovery is planned. 

No recovery, to be sure, but pretty much everything except the barge.  They did the burns (including landing burn), then blub, blub, blub.  Apparently.

I've not seen word on whether they had another try at working toward fairing recovery.

Oh, yeah, the ten satellites got to their starting blocks, so that appears to be 18 successful SpaceX launches for 2017.

Mike Hewson
Mike Hewson
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No recovery. Reason ? Is that

No recovery. Reason ? Is that block design out of date ?

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
archae86
Joined: 6 Dec 05
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Mike Hewson wrote:No

Mike Hewson wrote:
No recovery. Reason ? Is that block design out of date ?

Plenty of speculation from the peanut gallery but I do not believe that SpaceX has actually spoken to that point.

They have a pretty substantial stock on the ground of already used first stages from design revision levels which require substantial refurbishment cost. Maybe they just figured they could get more value out of doing some experiments than they'd get from recovering it.

Another speculation is that the West Coast recovery ship is not currently operational having been cannibalized to get the East Coast recovery ship back in service after some damage.

Personally, I guess that they are not yet at breakeven on getting their money back from performing a recovery, refurbishment and relaunch at that generation of the booster. The surprising bit is that they didn't value looking over the condition of things enough to spend the money for recovery ship operations if that is the real reason.

There was a ship named Mr. Steven out for this event which was spotted beforehand with odd metal arms widely believed to be designed to hold a net for attempted fairing recovery.  Observers assert that one of the two fairing pieces showed indications of cold gas thruster operations and possibly parachute retardation.  It seems almost sure that fairing recovery development continues, but is not at all mature.

This one launched in darkness, but the stage separation was in sunlight.  Many, many people recorded video of quite a show.

archae86
archae86
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archae86 wrote:Many, many

archae86 wrote:
Many, many people recorded video of quite a show.

Here is a video shot from Manhattan Beach with a Canon T3 looking through an Explore Scientific ED102CF apochromat: It is a bit close-in and shaky, but the smoke rings are absolutely awesome.

https://www.youtube.com/watch?v=nqr4rMVSpYo

By contrast this video shot from Alhambra is not so up-close and person--far less camera shake, no thrilled child on the sound track--stays zoomed out at a perspective that keeps both the second stage and the first stage in the same frame through the end of the first stage re-entry burn.  (The initial scene is a static night cityscape--the booster ascent is first seen as a modest new orange light near the right horizon about time 0:44).

https://www.youtube.com/watch?v=tE5C3O71Xqo

Maybe Elon can charge the whole city of LA for entertainment.

 

archae86
archae86
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There were pictures some days

There were pictures some days ago of the first Falcon Heavy horizontal indoors.  Today it rose vertical on the pad.  This does not mean launch is imminent.  Plenty of fit checks and such to go, then a static fire, then maybe more static fires (depending on what is seen on the first try), and only later actual launch.

Mind you, it could actually launch in January 2018, but the Heavy history of delay should give one caution.

Meanwhile, here is a picture:

And, yes, by all accounts Elon's old car really is up there inside that fairing.

 

 

archae86
archae86
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That picture was small enough

That picture was small enough to post.  I'll just give a link to a substantially higher resolution one, for those who like to reassure themselves that essential appendages such as landing legs and grid fins are on view.

FH in position for Dry Dress Rehearsal

Anonymous

There was pic on the local

There was pic on the local news of the heavy in the assembly building in a horizontal position.  The camera man took a pic of the engine bells.  27 of them.  it commands respect!

almost together

Mike Hewson
Mike Hewson
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Thanks for that ! It is now

Thanks for that ! It is now my new screensaver. I call it the Falcon 27 ... I'm getting goosebumps. We are getting back to the grunt level of the Apollo days. :-)

Cheers, Mike.

( edit ) It looks to me like there are some very heavy duty dampers b/w the cores.

( edit ) { Define yaw for this discussion as that rotation about an axis through the entire 3 core centre of mass, said axis being perpendicular to the plane of cores. Such yaw hence tends to laterally move the central core's fore end toward either side booster.}

I perceive a ( no doubt highly modelled ) troubling issue. That being the choice of method to achieve yaw movements, on the way up before separations of course. Does one use :

- the gimballing of one or more of the three central engines in each cluster.

- differential thrust of non-gimballed engines either side booster.

- combinations of the above.

IMHO : The key thing will be the peak aerodynamic load at speed when a downrange left/right flight path adjustment is required. When compared to pitch and roll, bad yaw control has the greatest chance of ripping the inter core connections. Early in flight with the centre of mass most forward, then at a given moment the relative wind ( opposite vector to the centre of mass velocity ) will least exacerbate yaw error ie. like a weather vane. But as the centre of mass moves back with fuel burn the yaw error will enhance - unless of course it is at quite a high altitude by then and aerodynamic load becomes trivial.

FWIW : If anyone cares, my odds would be 1 in 4 that any intact component gets to orbital speed ie. excluding RUD fragments.

( edit ) I don't think, as viewed, that the side boosters have mirror-symmetrical positioning of their engines. There appears to be a mild rotation notable with respect to their mounting points of the inter-core connections. 

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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