In the split screen part of the replay when boosting back etc you can correlate by allowing for a delay of a few seconds on the right side display ( onboard view lags ). To be exact we don't quite know the aspect/setup of the ground based view on the left hand side, but you will note especially the transition of the 'lean' of the booster. By that I mean to come back to LZ-1 it must point in that general direction to both reverse it's downrange course to achieve that return to the cape, however before it reaches LZ-1 it must null that uprange component ( ie. groundtrack velocity ) to come down essentially vertically in the terminal phase. So it leans downrange yet again for a short time before assuming the vertical. Of course this happens while the altitude is going up and then down as well, indeed the apogee ( highest point of flight ) is announced for us. Fascinating ie. how do you land a pencil ?
Cheers, Mike.
NB I suspect that the groundtrack translations aren't truly nulled until quite late in the descent, so maybe only in the last few hundred feet of flight ? Does anyone know the altitude of that lowest cloud layer ?
( edit ) Indeed the viewpoint from the US Launch Report guys shows those lean changes, the effect of windage really low down on that, plus the double sonic boom is clearly heard.
( edit ) It surprises me how far and fast the expelled nitrogen moves away from the vehicle. Looks like a really big spray can! :-)
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
Epic LOL! Someone has found a portion of a 1959 Soviet sci-fi movie called "The Sky Calls" :
Yes, that's a rocket coming down to land on an offshore platform. :-)))
Even funnier : this is being quoted by The FLEEG Peoples* as 'proof' of the SpaceX hoaxing via CGI. Mind you, it's all just probably click-baiting etc.
Cheers, Mike.
* Flat Line ElectroEncephaloGraph : you have to kick the machine to see if it is working properly.
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
The launch video is currently available as a replay on youtube. I'd urge you to step up the display resolution option to 1080p and go to full-screen viewing.
If you want to skip the preliminaries, you can move to 14:00 and be late in the first stage burn. I found the video of the movements just after stage separation particularly beautiful and enlightening. They waste very little time in lighting up the boost-back burn after separation.
There is also new material most of the way down.
I hadn't realized that the first stage would continue to climb to more than double its altitude at second stage separation. Sep was at 75km, but first stage apogee was about 165km.
David
Miserable old git
Patiently waiting for the asteroid with my name on it.
I hadn't realized that the first stage would continue to climb to more than double its altitude at second stage separation. Sep was at 75km, but first stage apogee was about 165km.
Musk stole the idea from the Soviets ! - see Mike's pic below ....
Speaking of corrections, I was surprised at how active the nitrogen thrusters were between the boostback burn and the re-entry burn.
I read somewhere that there are alot of tiny thrusts to settle the fuel in the tanks ie. reduce the sloshing so the feed is good for re-fire. I don't think that makes much difference to the overall trajectory or orientation. Or at least any deviation induced can be readily corrected with primary rocket power and/or vane usage.
It is worth a mention that these Merlins have been re-starting at hypersonic speeds reliably for quite a while now ie. try lighting a cigarette in high winds ! Or alternatively imagine what would happen if they failed to re-start.
@Bill : I actually watched The Sky Calls with English subtitles but fortunately I only lost an hour and a quarter of my life. Consider it a period propaganda piece that compares 'collective altruistic effort' vs 'individual selfish gains'. Can you guess which was preferred ? :-)))
{ Mind you it wasn't a total loss. While browsing I did discover The Killer Shrews which I will watch tonite. }
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
Speaking of corrections, I was surprised at how active the nitrogen thrusters were between the boostback burn and the re-entry burn.
I read somewhere that there are alot of tiny thrusts to settle the fuel in the tanks ie. reduce the sloshing so the feed is good for re-fire. I don't think that makes much difference to the overall trajectory or orientation.
I would suggest the thrusters are key to orientation prior to the boost back, and then getting the orientation stable for re-entry and maybe at the bottom when at the hover stage on windy days? I hadn't thought about the fuel and oxygen sloshing around but it would be several hundred kilos bouncing around in two almost empty tanks.
I would think if there was any rotation (pitch / yaw) when engines were started it would be bad thing if there was an atmosphere about.
I'm still amazed about the flight controls. When you think about them, each have very large variations in their performance, the paddles will generate no change in direction at low speed or low pressures but at supersonic speeds that drag would be huge, the engine's gimbolling have greater effect depending on the thrust, but the thrust profile is very limited in time and power, the drag and lift from the fuselage's flight angle etc. Then there is variable of wind and pressure on decent.
... and it's all automated. (could a human be trained to land it?)
Speaking of corrections, I was surprised at how active the nitrogen thrusters were between the boostback burn and the re-entry burn.
I read somewhere that there are alot of tiny thrusts to settle the fuel in the tanks ie. reduce the sloshing so the feed is good for re-fire. I don't think that makes much difference to the overall trajectory or orientation.
I would suggest the thrusters are key to orientation prior to the boost back, and then getting the orientation stable for re-entry and maybe at the bottom when at the hover stage on windy days? I hadn't thought about the fuel and oxygen sloshing around but it would be several hundred kilos bouncing around in two almost empty tanks.
I would think if there was any rotation (pitch / yaw) when engines were started it would be bad thing if there was an atmosphere about.
I'm still amazed about the flight controls. When you think about them, each have very large variations in their performance, the paddles will generate no change in direction at low speed or low pressures but at supersonic speeds that drag would be huge, the engine's gimbolling have greater effect depending on the thrust, but the thrust profile is very limited in time and power, the drag and lift from the fuselage's flight angle etc. Then there is variable of wind and pressure on decent.
... and it's all automated. (could a human be trained to land it?)
I'm desperately trying to remember where I read it, but the implication was that there were either two strengths of thrusters, or the one thruster type with varying thrust. The word 'ullage' comes to mind.
It is an amazing craft that has three very different modes/categories of operation, for which SpaceX has successfully encompassed plus transitions. For the most part it is in unstable equilibrium ie. a pencil standing on it's end. For example get a long narrow cardboard tube and then run around with it sitting on the palm of one hand. Try to keep it pointing upwards. You will see the basic issue : it can go really wrong, really quickly. There is a precious envelope of safety.
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 wrote:There is also
)
An EM instagram showing the cool video bits, shows nicely the fuselage angle to the line of flight.
This is serious power :
)
This is serious power :
In the split screen part of the replay when boosting back etc you can correlate by allowing for a delay of a few seconds on the right side display ( onboard view lags ). To be exact we don't quite know the aspect/setup of the ground based view on the left hand side, but you will note especially the transition of the 'lean' of the booster. By that I mean to come back to LZ-1 it must point in that general direction to both reverse it's downrange course to achieve that return to the cape, however before it reaches LZ-1 it must null that uprange component ( ie. groundtrack velocity ) to come down essentially vertically in the terminal phase. So it leans downrange yet again for a short time before assuming the vertical. Of course this happens while the altitude is going up and then down as well, indeed the apogee ( highest point of flight ) is announced for us. Fascinating ie. how do you land a pencil ?
Cheers, Mike.
NB I suspect that the groundtrack translations aren't truly nulled until quite late in the descent, so maybe only in the last few hundred feet of flight ? Does anyone know the altitude of that lowest cloud layer ?
( edit ) Indeed the viewpoint from the US Launch Report guys shows those lean changes, the effect of windage really low down on that, plus the double sonic boom is clearly heard.
( edit ) It surprises me how far and fast the expelled nitrogen moves away from the vehicle. Looks like a really big spray can! :-)
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
Epic LOL! Someone has found a
)
Epic LOL! Someone has found a portion of a 1959 Soviet sci-fi movie called "The Sky Calls" :
Yes, that's a rocket coming down to land on an offshore platform. :-)))
Even funnier : this is being quoted by The FLEEG Peoples* as 'proof' of the SpaceX hoaxing via CGI. Mind you, it's all just probably click-baiting etc.
Cheers, Mike.
* Flat Line ElectroEncephaloGraph : you have to kick the machine to see if it is working properly.
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
There is a landing video
)
There is a landing video compilation posted on Youtube by SciNews which includes some angles I'd not seen before.
They seem to be deploying the legs later than in the early attempts.
In the third and fourth views the final corrections by thrust vectoring are quite apparent.
Speaking of corrections, I was surprised at how active the nitrogen thrusters were between the boostback burn and the re-entry burn.
archae86 wrote:The launch
)
I hadn't realized that the first stage would continue to climb to more than double its altitude at second stage separation. Sep was at 75km, but first stage apogee was about 165km.
David
Miserable old git
Patiently waiting for the asteroid with my name on it.
David S wrote:I hadn't
)
Musk stole the idea from the Soviets ! - see Mike's pic below ....
.
Ariane 5 VA236 to GTO between
)
archae86 wrote:Speaking of
)
I read somewhere that there are alot of tiny thrusts to settle the fuel in the tanks ie. reduce the sloshing so the feed is good for re-fire. I don't think that makes much difference to the overall trajectory or orientation. Or at least any deviation induced can be readily corrected with primary rocket power and/or vane usage.
It is worth a mention that these Merlins have been re-starting at hypersonic speeds reliably for quite a while now ie. try lighting a cigarette in high winds ! Or alternatively imagine what would happen if they failed to re-start.
@Bill : I actually watched The Sky Calls with English subtitles but fortunately I only lost an hour and a quarter of my life. Consider it a period propaganda piece that compares 'collective altruistic effort' vs 'individual selfish gains'. Can you guess which was preferred ? :-)))
{ Mind you it wasn't a total loss. While browsing I did discover The Killer Shrews which I will watch tonite. }
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
Mike Hewson wrote:archae86
)
I would suggest the thrusters are key to orientation prior to the boost back, and then getting the orientation stable for re-entry and maybe at the bottom when at the hover stage on windy days? I hadn't thought about the fuel and oxygen sloshing around but it would be several hundred kilos bouncing around in two almost empty tanks.
I would think if there was any rotation (pitch / yaw) when engines were started it would be bad thing if there was an atmosphere about.
I'm still amazed about the flight controls. When you think about them, each have very large variations in their performance, the paddles will generate no change in direction at low speed or low pressures but at supersonic speeds that drag would be huge, the engine's gimbolling have greater effect depending on the thrust, but the thrust profile is very limited in time and power, the drag and lift from the fuselage's flight angle etc. Then there is variable of wind and pressure on decent.
... and it's all automated. (could a human be trained to land it?)
AgentB wrote:Mike Hewson
)
I'm desperately trying to remember where I read it, but the implication was that there were either two strengths of thrusters, or the one thruster type with varying thrust. The word 'ullage' comes to mind.
It is an amazing craft that has three very different modes/categories of operation, for which SpaceX has successfully encompassed plus transitions. For the most part it is in unstable equilibrium ie. a pencil standing on it's end. For example get a long narrow cardboard tube and then run around with it sitting on the palm of one hand. Try to keep it pointing upwards. You will see the basic issue : it can go really wrong, really quickly. There is a precious envelope of safety.
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