Ah, the old 'excess lateral velocity'. That'll do it.
One thing I've been thinking about : if it does land successfully, then does it just sit there hoping not to be blown over by a gust of wind or tipped over by a wave or knocked over by a stray seagull hitting it broadside ? How long before someone comes to secure it ? Anybody know ?
I guess for that matter once the barge landings become sufficiently reliable ( ie. not outrageously unsafe ) I'd imagine they would switch to returning to firm land sites.
Cheers, Mike.
( edit ) Mind you an important record has been broken : the fastest delivered coffee ever !! :-)
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
I guess for that matter once the barge landings become sufficiently reliable ( ie. not outrageously unsafe ) I'd imagine they would switch to returning to firm land sites.
I do think they have indicated intentions to use land sites.
But, without doing any formal calculations, I suspect for all three of their currently mentioned launch sites they would generally be able to "get to" a properly based barge burning less fuel than required to getting back to any land site. Now the cost of the extra fuel seems probably less than the cost of sending out and otherwise supporting a barge landing, but at the margin the difference could make the difference between recovery and no recovery for some missions for which the payload and orbital insertion goals would allow sea and not land. In other words, sometimes "just carry more fuel" is not an option.
If that is a tiny little sliver of possible missions, then I'd guess they'd drop the barges. But the fact they are building one for the west coast suggests to me that they envision using them for at least a subset of missions for a good while yet.
Folks who want to land helicopters on tiny spots on naval combatants who don't want to have to wait for low winds and low wave heights have used haul down and engagement devices. One such is called Beartrap by the Canadians.
This video show a particularly sporty landing--you can spot the beartrap as a rather nondescript rounded rectangular shape on deck right under where the bird finally comes down. I think the wind/wave combination here is probably beyond SpaceX's current intended capability.
A US Navy RAST system is somewhat similar. This recovery is less extreme than the video:
This article gives a pretty good working description of taking off and landing using the Canadian system, written from a pilot's perspective without extreme detail. Yes, I agree that it is far away from being a direct model for what SpaceX might try. But it does seem they are going to need something.
There's a snap here of the 1st stage at the barge.
Cheers, Mike.
Not sure if the photo was taken with a fish-eye lens or not but the horizon of the ocean is not horizontal. The rocket looks as though it is not vertical but if the oceanic swells are pronounced then it could be that the rocket is vertical but the barge is not horizontal. Difficult to say from the picture. In either case an outstanding effort.
There's a snap here of the 1st stage at the barge.
Cheers, Mike.
Not sure if the photo was taken with a fish-eye lens or not but the horizon of the ocean is not horizontal. The rocket looks as though it is not vertical but if the oceanic swells are pronounced then it could be that the rocket is vertical but the barge is not horizontal. Difficult to say from the picture. In either case an outstanding effort.
Looks like a fish-eye. Now apropos of the claws at takeoff : there are some frames getting dropped from that view. If you look at the fuel venting ( top of second stage ) you'll note the wispy bits are discontinuous. As you note the countdown clock is not jumpy, so I'd take that as the feed from that camera atop the lightning pole as being the cause. It is still the case that one claw retracts before another though.
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
My video from the SpaceX (not the NASA) feed stopped cold just before liftoff (T-12 seconds if I recall). I clicked around a bit, tried starting another browser, and finally got live video again just after second stage ignition (the engine bell was non-orange at first sight, and rapidly heated up).
Aside from that, I got little ghost circles or partial circles from time to time which I think signified that my software knew it was missing something in transmission to me.
Lastly I agree with Mike's comments: claw jerking set aside, there was clear discontinuity in the wisps rather often--not corresponding to either the ghost circles nor to failures of regularity of the clock in the same frame.
Ah yes, fuel. I am reminded of the exponential character of fuel loads. Another ten seconds of maneuvering at the barge is not another ten seconds of fuel in the tank at launch. It is ten seconds worth of extra fuel at launch plus even more fuel again to deliver that to the barge site. That 'fuel to carry more fuel' is required for all movements : going up, stuffing about, and coming down.
Those rolling deck landings are very challenging, and you can't stay up all day. The video mentioned they were near Australia but 700+ miles from any land divert, so I'd place them in the Great Australian Bight - south of South Australia say - where the Roaries Forties just howls.
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
2300 here. just saw a video of the landing. The 1st stage "knew" were the platform was and found it, but unlike the videos that had been referenced regarding the prototypes, this 1st stage was descending rapidly. At the last moment it appears to make an adjustment so as to be perpendicular to the platform but the descent appears to be too rapid. But hey. There is a big difference between launching from land to 1000 feet, holding, then descending and re-entry from space, dealing with winds aloft, etc., etc. They got some valuable data from this effort and next time will be better or spot on. My hat is off to the engineering team at SpaceX.
They're very close. The control inputs in those last few seconds before touchdown were too large, they appear to just need fine tuning of the approach. To hit the target (literally) twice in a row now bodes well for success though.
I wonder whether there was windshear and whether they have thought properly about the right way to deal with that. Those large-scale corrections in the last moments seem likely to be response to unexpected defection.
Just thinking out loud, a better guidance system scheme needs to "know" the wind by altitude for something like the last thousand feet at least, and choose a path on entry to final approach which will deliberately not do directional corrections for expected when shifts. But do the winds in the column of air above the barge keep their value for something like a radiosonde detection method to work, and if not, what? Maybe the radiosonde leaves behind an aerosol, and LIDAR from the barge can figure out the winds by looking at the backscatter?
The corrections in the video look far too high to be compatible with successful landing. The final vertical rate looks too high as well.
They have shown quite clearly the ability to arrive at the barge as desired, but I don't rate their current landing and post-landing capture as anywhere close to an operational system. Not saying they won't get there--but it needs work.
Ah, the old 'excess lateral
)
Ah, the old 'excess lateral velocity'. That'll do it.
One thing I've been thinking about : if it does land successfully, then does it just sit there hoping not to be blown over by a gust of wind or tipped over by a wave or knocked over by a stray seagull hitting it broadside ? How long before someone comes to secure it ? Anybody know ?
I guess for that matter once the barge landings become sufficiently reliable ( ie. not outrageously unsafe ) I'd imagine they would switch to returning to firm land sites.
Cheers, Mike.
( edit ) Mind you an important record has been broken : the fastest delivered coffee ever !! :-)
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
RE: I guess for that matter
)
I do think they have indicated intentions to use land sites.
But, without doing any formal calculations, I suspect for all three of their currently mentioned launch sites they would generally be able to "get to" a properly based barge burning less fuel than required to getting back to any land site. Now the cost of the extra fuel seems probably less than the cost of sending out and otherwise supporting a barge landing, but at the margin the difference could make the difference between recovery and no recovery for some missions for which the payload and orbital insertion goals would allow sea and not land. In other words, sometimes "just carry more fuel" is not an option.
If that is a tiny little sliver of possible missions, then I'd guess they'd drop the barges. But the fact they are building one for the west coast suggests to me that they envision using them for at least a subset of missions for a good while yet.
Folks who want to land helicopters on tiny spots on naval combatants who don't want to have to wait for low winds and low wave heights have used haul down and engagement devices. One such is called Beartrap by the Canadians.
This video show a particularly sporty landing--you can spot the beartrap as a rather nondescript rounded rectangular shape on deck right under where the bird finally comes down. I think the wind/wave combination here is probably beyond SpaceX's current intended capability.
Youtube video of Beartrap-asseted landing in heavy weather at sea
A US Navy RAST system is somewhat similar. This recovery is less extreme than the video:
This article gives a pretty good working description of taking off and landing using the Canadian system, written from a pilot's perspective without extreme detail. Yes, I agree that it is far away from being a direct model for what SpaceX might try. But it does seem they are going to need something.
RE: There's a snap here of
)
Not sure if the photo was taken with a fish-eye lens or not but the horizon of the ocean is not horizontal. The rocket looks as though it is not vertical but if the oceanic swells are pronounced then it could be that the rocket is vertical but the barge is not horizontal. Difficult to say from the picture. In either case an outstanding effort.
RE: RE: There's a snap
)
Looks like a fish-eye. Now apropos of the claws at takeoff : there are some frames getting dropped from that view. If you look at the fuel venting ( top of second stage ) you'll note the wispy bits are discontinuous. As you note the countdown clock is not jumpy, so I'd take that as the feed from that camera atop the lightning pole as being the cause. It is still the case that one claw retracts before another though.
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
My video from the SpaceX (not
)
My video from the SpaceX (not the NASA) feed stopped cold just before liftoff (T-12 seconds if I recall). I clicked around a bit, tried starting another browser, and finally got live video again just after second stage ignition (the engine bell was non-orange at first sight, and rapidly heated up).
Aside from that, I got little ghost circles or partial circles from time to time which I think signified that my software knew it was missing something in transmission to me.
Lastly I agree with Mike's comments: claw jerking set aside, there was clear discontinuity in the wisps rather often--not corresponding to either the ghost circles nor to failures of regularity of the clock in the same frame.
Ah yes, fuel. I am reminded
)
Ah yes, fuel. I am reminded of the exponential character of fuel loads. Another ten seconds of maneuvering at the barge is not another ten seconds of fuel in the tank at launch. It is ten seconds worth of extra fuel at launch plus even more fuel again to deliver that to the barge site. That 'fuel to carry more fuel' is required for all movements : going up, stuffing about, and coming down.
Those rolling deck landings are very challenging, and you can't stay up all day. The video mentioned they were near Australia but 700+ miles from any land divert, so I'd place them in the Great Australian Bight - south of South Australia say - where the Roaries Forties just howls.
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
I snapped a quick pic from
)
I snapped a quick pic from the NASA channel on my 82in DLP
2300 here. just saw a video
)
2300 here. just saw a video of the landing. The 1st stage "knew" were the platform was and found it, but unlike the videos that had been referenced regarding the prototypes, this 1st stage was descending rapidly. At the last moment it appears to make an adjustment so as to be perpendicular to the platform but the descent appears to be too rapid. But hey. There is a big difference between launching from land to 1000 feet, holding, then descending and re-entry from space, dealing with winds aloft, etc., etc. They got some valuable data from this effort and next time will be better or spot on. My hat is off to the engineering team at SpaceX.
They're very close. The
)
They're very close. The control inputs in those last few seconds before touchdown were too large, they appear to just need fine tuning of the approach. To hit the target (literally) twice in a row now bodes well for success though.
I wonder whether there was
)
I wonder whether there was windshear and whether they have thought properly about the right way to deal with that. Those large-scale corrections in the last moments seem likely to be response to unexpected defection.
Just thinking out loud, a better guidance system scheme needs to "know" the wind by altitude for something like the last thousand feet at least, and choose a path on entry to final approach which will deliberately not do directional corrections for expected when shifts. But do the winds in the column of air above the barge keep their value for something like a radiosonde detection method to work, and if not, what? Maybe the radiosonde leaves behind an aerosol, and LIDAR from the barge can figure out the winds by looking at the backscatter?
The corrections in the video look far too high to be compatible with successful landing. The final vertical rate looks too high as well.
They have shown quite clearly the ability to arrive at the barge as desired, but I don't rate their current landing and post-landing capture as anywhere close to an operational system. Not saying they won't get there--but it needs work.