SpaceX And/Or Rocketry In General

robl
robl
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Mike Hewson wrote:There's a

Mike Hewson wrote:

There's a promo featuring Mr Steven produced by the makers of the thrusters. Some neat moves !

Cheers, Mike.

 

a really great video, especially the top down views showing the level of control etc.  

archae86
archae86
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SpaceX has had a bit of a

SpaceX has had a bit of a launch lull, and especially has not entertained us with live video of landing first stages in some time.

That is about to change.

Sixteen hours from now the 4-hour launch window for Telstar 19 VANTAGE opens.   Here is the Youtube link.

https://youtu.be/xybp6zLaGx4

This is from the East Coast, so no attempt to do further trials on catching a fairing half in the air, but barge landing of the first stage is planned, and the recovery fleet is at sea.

Then on July 25 there is a West Coast launch planned with the seventh Iridium NEXT group of satellites.  That is also planned as a barge landing, and it seems a fair bet that Mr. Steven will be out having another try at attempting to catch a fairing half in mid-air.

Mike Hewson
Mike Hewson
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Nicely done. A few more

Nicely done. A few more details seen with this dark sky launch eg. the bow wave shedding thru maxQ, the onset of an ionic shroud ( causing loss of signal ) on descent when the first stage hits the upper atmosphere, the red hot glow of the engine turbo at full throttle on the second stage. What a beautiful shot of the booster exhaust rippling like a liquid on ascent before MECO. Plus they have the confidence to not bother with a loop-back manoeuvre like the old days, it just hammers on in ballistically until the terminal engine re-light. I'd assume these block fives can take more heat. I think they may have upped the camera resolutions.

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
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Mike Hewson wrote:Plus they

Mike Hewson wrote:
Plus they have the confidence to not bother with a loop-back manoeuvre like the old days, it just hammers on in ballistically until the terminal engine re-light. I'd assume these block fives can take more heat.

If they are returning to land, or have enough spare juice from doing the primary satellite launch mission to shorten the at-sea recovery distance, they use three burns:

1. Boostback cancels the entire forward speed and sends the stage back toward home
2. Re-entry slows the stage just before the air gets thick enough to notice--goal is to hold down heating during re-entry to just tolerable.
3. Landing starts when aerodynamic drag has taken the vehicle down to well subsonic, and is timed to just get the vertical speed to zero at the moment of contact.

Of these boostback has nothing to do with heat tolerance, just with choosing the location of landing.  So for maximum booster performance on the primary mission (mostly mass and initial speed of the satellite--though there are fiddly details on plane change and so on) one can omit the boostback entirely as was done today.  This means the recovery fleet has to go much farther downrange, which raises recovery fleet cost, and slows the cycle time.

Telstar was a heavy bird (a bit over 7000 kg) going to GTO (which is much more delta-V expensive than LEO), so it may be a tribute to increased Block 5 performance that first stage recovery was possible at all.

But, yes, somewhere Elon said the Block 5 included some mods to help deal with localized heating problems seen during hypersonic re-entry.  I speculate that the single reuse limit they have been observing on pre block 5 first stages may be related to that finding--but they have not said so.

 

 

 

 

 

archae86
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The video link has been

The video link has been posted for the next Iridium NEXT launch:

https://youtu.be/vsDknmK30C0

The webcast location currently advises 15 hours to go.

This is a West Coast (Vandenberg) launch.  It is a SpaceX Falcon 9 block 5 first stage, and at-sea recovery is intended.

The experimental fairing recovery ship, Mr. Steven, is reported to have left port and may reasonably be assumed to intend to recover one of the two fairing halves using the new, bigger, net.

Launch time is set for 4:39 a.m. Pacific time (1139 UTC), well before the 6:07 local sunrise time.  I don't know whether the sun phase will allow any interesting shapes aloft, but think it may be too early.  Probably both first stage recovery and (hoped-for) fairing recovery video will also be darker than one would wish.

 

Mike Hewson
Mike Hewson
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Probable good first stage

Probable good first stage landing on the drone ship. I think a bit off centre. If so, and undamaged, it is an epic result in the horrible conditions. 

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
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Mike Hewson wrote:Probable

Mike Hewson wrote:

Probable good first stage landing on the drone ship. I think a bit off centre. If so, and undamaged, it is an epic result in the horrible conditions. 

Cheers, Mike. 

Yep--you called it Mike.  The photo shows the Iridium 7 first stage landed on the barge.  Looks like two legs outside the yellow circle, but still well inside the outer circle.  The SpaceX commentator described the expected conditions a few minutes before landing as the worst for any of their attempts.  Maybe the tradeoff of considering postponing launches for bad drone weather vs. losing a valuable first stage won't be as troublesome as I have supposed.

In other news Mr. Steven again failed to catch the fairing half.  They "saw it", but wind shear was too much is the party line.

Mike Hewson
Mike Hewson
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Here's a view of the Block

Here's a view of the Block Five after the Iridium mission. It appears to be in excellent condition. There seems to have been a fragment of fairing recovered too.

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

robl
robl
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On another note:  On July 26,

On another note:  

On July 26, VSS Unity rose to an altitude of 32.3 miles and reached a speed of Mach 2.47, or almost two-and-a-half times the speed of sound, over California's Mojave Desert.  Vandenburg, do we have a go???

180726-virgin_galactic-al-1522_085a415e28cd0b430a114f55e01e34b4.fit-2000w.jpg

robl
robl
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Falcon 9 launch this

Falcon 9 launch this tuesday.  

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