Don't know about you guys, but if JC-SAT 16 were a steak, I'd say it was well done :
So on that I'd say the LOX flushing primarily went to payload K.E.
Cheers, Mike.
( edit ) Now if you compare that vane burn pattern with earlier ones ( going to GTO ) :
then there are extra panels overlaid on the barrel ( which I've marked in red on the top graphic ). It would seem the vane/panel combos could now be replaced in toto and leave a protected barrel segment for re-use ? Partition/localise the damage, modularise the burning bits and throw them away. There may well be further iterations on this design aspect with later experience ( it is a key component ) so watch that part of the barrel.
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 other thing I've yet to work out is the symmetry or otherwise of the vane burning. Sometimes it is all four, sometimes only opposite ones and sometimes adjacent ones. On the reasonable assumption that a vane which sticks out burns rather more than one kept flush, this reveals such usage on the way down. Most of it will be drag in hypersonic regime, this being a separate issue to the general carbonisation of the barrel with engine re-lights.
As far as I can tell the main mechanism to roll the barrel ( around the long axis ) is opposite vanes fully extended and suitably rotated to produce a nett torque. The JC-SAT 16 vane burns are like four fingers of which the middle two might at least be attributed to specific settings for torque.
The other obvious requirement - if not satisfied by asymmetric/triple engine burns down at the octaweb - is the need to change vehicle pitch and yaw. This is because after separation the booster has tangential velocity ( parallel to Earth's surface ) and it must transition to radial ( perpendicular to Earth's surface ). Do the vanes produce at least some of that ? I don't think the wee thrusters have the mojo ( in the denser/lower atmosphere ) to achieve that in the supersonic regime. These are the issues with a craft that has to function in three distinct aerodynamic modes ....
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
The video you posted is incredible. Looking at the reentry sequence was just magic. It is the only word that fits. As for understanding all the dynamics involved and how to manage them - well that is probably not within my scope. But that does not diminish the complexity of the effort. There is just too much going on.
Mike, if that is the view from earth looking up that offset is in the horizontal plane, not the vertical plane. Or they flew another rocket to put the camera in the right spot. I suspect this is footage of the second relight on the way down, not the hyper-sonic one at the top of the flight.
SpaceX has a new transporter ! One of 'dem synchronised wheelie gadgets. Cool. That's now dedicated for F9 booster work.
@AgentB : I note the lesser burnt vanes also don't have an adjacent barrel panel in place. If that is true and deliberate that implies - and why not - a choice of vane use by barrel ( long axis ) rotation prior to re-entry. My guess would be the less burnt vanes are down range, as you say in the wake, from the other two which are hence toward the nearside of the re-entry arc and doing most of the ablative work, simultaneously bleeding speed and causing further pitch down to get to vertical terminal path. Clearly they have learnt the hard way about having any horizontal/sideways drift in the last few hundred meters.
@robl : " There is just too much going on" Absolutely. How do you get the one craft to sequentially behave like three different ones ? This is the real design 'miracle' of the Falcon 9 .....
@Gary : could be right. The gimbaling will give two degrees of freedom on the path : left/right and long/short. But as the major challenge is neither going too far nor too little downrange ( rather than laterally ) I'd reckon the required pitch change is what the centre rocket is working on. By that I mean the deviation north/south would be way too far if deflected rocket thrust was used ie. excessive mojo for a subtle bearing change. After all the barge is placed downrange of the flight path, and not vice versa. However I'd love to see more onboard down-the-barrel footage from separation to secure landing. At a glance I think the vanes are out & flapping before the re-lights.
( edit ) FWIW : if I was a high school physics teacher I'd have SpaceX as an ongoing study in the syllabus. You would learn ever so much about mechanics, gravity etc. A great focus for all those aspects at that level. Heck, you could even give the tertiary students a decent run at it as well ! :-)
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
SpaceX has a new transporter ! One of 'dem synchronised wheelie gadgets. Cool. That's now dedicated for F9 booster work.
@AgentB : I note the lesser burnt vanes also don't have an adjacent barrel panel in place. If that is true and deliberate that implies - and why not - a choice of vane use by barrel ( long axis ) rotation prior to re-entry. My guess would be the less burnt vanes are down range, as you say in the wake, from the other two which are hence toward the nearside of the re-entry arc and doing most of the ablative work, simultaneously bleeding speed and causing further pitch down to get to vertical terminal path. Clearly they have learnt the hard way about having any horizontal/sideways drift in the last few hundred meters.
Thanks for posting the transporter link, its really high res, and the first time i've looked closely at the scorch marks on both sides. The pattern is a mirror image on each side which suggest the approach is flatter presenting the lower surface. I guess there is a measurable amount of lift and a lot more drag and control that way.
I would expect that a glide (for very steep values of glide) approach is also a safer one, as if it all goes badly wrong high up (total control failure) the landing will be short, and rather loud.
It is quite a remarkable flying machine, a lot more than just a rocket.
Here's another view of the new transporter negotiating a difficult bend that the previous one couldn't ( I would say ). The sideways crabbing looks to be the key trick. As it would have of the order of 100 wheels I'll call it a centipede. :-)
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
Here's another view of the new transporter negotiating a difficult bend that the previous one couldn't ( I would say ). The sideways crabbing looks to be the key trick. As it would have of the order of 100 wheels I'll call it a centipede. :-)
Cheers, Mike.
Excuse me!!! But can someone tell me why my tires are scrubbing?
Actually both the new and the previous transporter used from port to hangar have lots of steerable wheels. On the previous one the part you might suppose just to be a trailer is also self-propelled (at very low speed, with the control box commonly carried along by a walking man). In that previous method, they did not hook up the tractor until after the first really twisty bit on the way out of the port. Now the road travel trailer to and from Texas is another matter.
Not so much scrubbing, but a lot of tires to keep in good shape. I imagine they have provided at least one full new set since winning the auction in 2014, and have otherwise spent far more getting it ready for service than the winning bid.
Don't know about you guys,
)
Don't know about you guys, but if JC-SAT 16 were a steak, I'd say it was well done :
So on that I'd say the LOX flushing primarily went to payload K.E.
Cheers, Mike.
( edit ) Now if you compare that vane burn pattern with earlier ones ( going to GTO ) :
then there are extra panels overlaid on the barrel ( which I've marked in red on the top graphic ). It would seem the vane/panel combos could now be replaced in toto and leave a protected barrel segment for re-use ? Partition/localise the damage, modularise the burning bits and throw them away. There may well be further iterations on this design aspect with later experience ( it is a key component ) so watch that part of the barrel.
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 other thing I've yet to
)
The other thing I've yet to work out is the symmetry or otherwise of the vane burning. Sometimes it is all four, sometimes only opposite ones and sometimes adjacent ones. On the reasonable assumption that a vane which sticks out burns rather more than one kept flush, this reveals such usage on the way down. Most of it will be drag in hypersonic regime, this being a separate issue to the general carbonisation of the barrel with engine re-lights.
As far as I can tell the main mechanism to roll the barrel ( around the long axis ) is opposite vanes fully extended and suitably rotated to produce a nett torque. The JC-SAT 16 vane burns are like four fingers of which the middle two might at least be attributed to specific settings for torque.
The other obvious requirement - if not satisfied by asymmetric/triple engine burns down at the octaweb - is the need to change vehicle pitch and yaw. This is because after separation the booster has tangential velocity ( parallel to Earth's surface ) and it must transition to radial ( perpendicular to Earth's surface ). Do the vanes produce at least some of that ? I don't think the wee thrusters have the mojo ( in the denser/lower atmosphere ) to achieve that in the supersonic regime. These are the issues with a craft that has to function in three distinct aerodynamic modes ....
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, The video you posted
)
Mike,
The video you posted is incredible. Looking at the reentry sequence was just magic. It is the only word that fits. As for understanding all the dynamics involved and how to manage them - well that is probably not within my scope. But that does not diminish the complexity of the effort. There is just too much going on.
Mike Hewson wrote:The other
)
It would be interesting to know the flight angle of attack.
My guess is the angle is not zero for most of the return, and so that will leave one of the four vanes in the wake, and the others exposed.
Edit: returned to the flight path calculations link posted earlier .... the answer is looking at the graph, as much as 12 degrees!
Mike, if that is the view
)
Mike, if that is the view from earth looking up that offset is in the horizontal plane, not the vertical plane. Or they flew another rocket to put the camera in the right spot. I suspect this is footage of the second relight on the way down, not the hyper-sonic one at the top of the flight.
SpaceX has a new transporter
)
SpaceX has a new transporter ! One of 'dem synchronised wheelie gadgets. Cool. That's now dedicated for F9 booster work.
@AgentB : I note the lesser burnt vanes also don't have an adjacent barrel panel in place. If that is true and deliberate that implies - and why not - a choice of vane use by barrel ( long axis ) rotation prior to re-entry. My guess would be the less burnt vanes are down range, as you say in the wake, from the other two which are hence toward the nearside of the re-entry arc and doing most of the ablative work, simultaneously bleeding speed and causing further pitch down to get to vertical terminal path. Clearly they have learnt the hard way about having any horizontal/sideways drift in the last few hundred meters.
@robl : " There is just too much going on" Absolutely. How do you get the one craft to sequentially behave like three different ones ? This is the real design 'miracle' of the Falcon 9 .....
@Gary : could be right. The gimbaling will give two degrees of freedom on the path : left/right and long/short. But as the major challenge is neither going too far nor too little downrange ( rather than laterally ) I'd reckon the required pitch change is what the centre rocket is working on. By that I mean the deviation north/south would be way too far if deflected rocket thrust was used ie. excessive mojo for a subtle bearing change. After all the barge is placed downrange of the flight path, and not vice versa. However I'd love to see more onboard down-the-barrel footage from separation to secure landing. At a glance I think the vanes are out & flapping before the re-lights.
Also more footage from the Veteran's indicates alot of big bits & bobs turning up at Pad 39A ( 3:30 onwards ) ie. the Heavy launch site.
Cheers, Mike.
( edit ) FWIW : if I was a high school physics teacher I'd have SpaceX as an ongoing study in the syllabus. You would learn ever so much about mechanics, gravity etc. A great focus for all those aspects at that level. Heck, you could even give the tertiary students a decent run at it as well ! :-)
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:SpaceX has
)
Thanks for posting the transporter link, its really high res, and the first time i've looked closely at the scorch marks on both sides. The pattern is a mirror image on each side which suggest the approach is flatter presenting the lower surface. I guess there is a measurable amount of lift and a lot more drag and control that way.
I would expect that a glide (for very steep values of glide) approach is also a safer one, as if it all goes badly wrong high up (total control failure) the landing will be short, and rather loud.
It is quite a remarkable flying machine, a lot more than just a rocket.
Here's another view of the
)
Here's another view of the new transporter negotiating a difficult bend that the previous one couldn't ( I would say ). The sideways crabbing looks to be the key trick. As it would have of the order of 100 wheels I'll call it a centipede. :-)
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:Here's
)
Excuse me!!! But can someone tell me why my tires are scrubbing?
Actually both the new and the
)
Actually both the new and the previous transporter used from port to hangar have lots of steerable wheels. On the previous one the part you might suppose just to be a trailer is also self-propelled (at very low speed, with the control box commonly carried along by a walking man). In that previous method, they did not hook up the tractor until after the first really twisty bit on the way out of the port. Now the road travel trailer to and from Texas is another matter.
Not so much scrubbing, but a lot of tires to keep in good shape. I imagine they have provided at least one full new set since winning the auction in 2014, and have otherwise spent far more getting it ready for service than the winning bid.