Now that would have been quite a ride. Between the large and abrupt acceleration of the rockets and the rather substantial rotational rates on multiple axes between trunk separation and main chute deployment, any paying customer would really get their money's worth. But once on the mains, it was really very nicely stable.
I can feel my brain sloshing around in my skull. That is a ride I think most would prefer to avoid, but its nice to know there is a fall back in the event its needed.
I learned from a press article that the SuperDraco engines of which eight provided the "go" for today's show are hypergolic fueled, deeply throttleable.
The news item mentioned two tons of propellant for these things on the Dragon. That is rather a lot. And hydrazine/nitrogen tetroxide is not my fondest wish of stuff to keep me close company.
On the plus side, these things serving for propulsive soft landing ought to give a much better ride than the Soyuz "bang and you're there" system. Throttle range is said to be 20 to 100 percent, and they don't necessarily need to fire all eight.
I learned from a press article that the SuperDraco engines of which eight provided the "go" for today's show are hypergolic fueled, deeply throttleable.
hypergolic: one where the propellants spontaneously ignite when they come into contact with each other. Certainly cuts down on weight, i.e., no hardware needed to "spark" ignition. But, Hmm, maybe just a 0/0 ejection seat will do, thank you very much.
That is what you would call a good escape plan. It can be triggered at any height right up to true orbit, which is a very reassuring feature. I think a reason why the lower trunk structure is kept until after the Draco burst is finished could be because it would form some shielding function from whatever might be exploding behind you .... in a real emergency instance where it is likely to be a full RUD ?? In any case in the history of catastrophic failures at rocket launches almost always throw material laterally, at least in the first instance. Also of note is that the particular trajectory in this test was obtained by differential throttling of the engines in real time as a closed feedback loop. Maybe the trunk also aids in directional stability by allowing the rockets to act with the centre of mass below ..... hmmmmm.
I reckon if I was offered the Super Dragon Ride at Movie World I'd probably go 'round all day. Get out, line up again, get out, line up again ... until either I passed out or my back gave way! :-) :-)
It's nasty stuff on the breakfast cereal that hydrazine/nitrogen tetroxide mix, but there is long experience of this combo. It figured prominently in the Apollo days. There the first really serious operational reliance was during Apollo 8, burning behind the moon to get the return boost back to Earth. Not just that it would fire at all, but also the specific performance to achieve the right subsequent path.
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
Looking at one thing and another my guess is that the 1st Falcon Heavy flight - as yet not precisely scheduled, but allegedly this year - could well be contingent upon a successful return-to-land demonstration for the Falcon-9 first stage. Why? Well, the Heavy is ~ 3 x Falcon-9 and it's quite a lot of expensive hardware to throw away at once otherwise. Also it would also look a tad silly to do so.
Cheers, Mike.
( edit ) Also I have been researching as to why the Russian Energia is not being mentioned in lift capacity comparisons. It has a quoted thrust of ~ 30 megaNewtons, so still well above Falcon Heavy at 17-20 megaNewtons. In any case the Heavy burns for longer and the Energia only sort of achieved it's goals in 1 of 2 test launches.
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
Looking at one thing and another my guess is that the 1st Falcon Heavy flight - as yet not precisely scheduled, but allegedly this year - could well be contingent upon a successful return-to-land demonstration for the Falcon-9 first stage. Why? Well, the Heavy is ~ 3 x Falcon-9 and it's quite a lot of expensive hardware to throw away at once otherwise. Also it would also look a tad silly to do so.
Cheers, Mike.
( edit ) Also I have been researching as to why the Russian Energia is not being mentioned in lift capacity comparisons. It has a quoted thrust of ~ 30 megaNewtons, so still well above Falcon Heavy at 17-20 megaNewtons. In any case the Heavy burns for longer and the Energia only sort of achieved it's goals in 1 of 2 test launches.
Mike, I was about to compose a post arguing that the Heavy was not so good a candidate for recovery, and that in any case I did not think they would delay first launch for the capability, when I did a little background checking to see if I could find something SpaceX had said about heavy recovery.
Imagine my surprise on finding this animation video from SpaceX showing Heavy recovery of three separate pieces--each piece considerably like the Falcon 9, and appearing to use the same recovery scheme, but landing not on a barge (or three!) but right back at the Cape.
One of my arguments against is that the most obvious customers for the Falcon Heavy are rather primitively risk-adverse. My personal guess is that use on operational launches of the Heavy will probably come after a string of successes on less sensitive Falcon 9 launches.
If you think about the customers for Heavy launches, you may find an additional reason to discount Energia use. I don't think NRO would appreciate a fully Russian booster nearly so much as they do mere rocket engines with a strong Russian heritage--which have given them indigestion. Anyway, I think that Energia booster (confusingly the name applied both to an organization and to a particular booster) has nothing resembling a current manufacturing base. Might as well propose to start up building Saturn V's again.
For others with a bit of curiosity on this relic of the Soviet space shuttle program, here is a not bad overview article Energia overview
Mike, I was about to compose a post arguing that the Heavy was not so good a candidate for recovery, and that in any case I did not think they would delay first launch for the capability, when I did a little background checking to see if I could find something SpaceX had said about heavy recovery.
Imagine my surprise on finding this animation video from SpaceX showing Heavy recovery of three separate pieces--each piece considerably like the Falcon 9, and appearing to use the same recovery scheme, but landing not on a barge (or three!) but right back at the Cape.
One of my arguments against is that the most obvious customers for the Falcon Heavy are rather primitively risk-adverse. My personal guess is that use on operational launches of the Heavy will probably come after a string of successes on less sensitive Falcon 9 launches.
If you think about the customers for Heavy launches, you may find an additional reason to discount Energia use. I don't think NRO would appreciate a fully Russian booster nearly so much as they do mere rocket engines with a strong Russian heritage--which have given them indigestion. Anyway, I think that Energia booster (confusingly the name applied both to an organization and to a particular booster) has nothing resembling a current manufacturing base. Might as well propose to start up building Saturn V's again.
For others with a bit of curiosity on this relic of the Soviet space shuttle program, here is a not bad overview article Energia overview
Agreed. There is considerable subtlety in the Musk/SpaceX approach which makes it both more interesting and more risky. I vaguely recall several years ago Elon's comments in generality - alas I've forgotten the detail or a reference to it - about the task of reaching orbit from this planet with the chemical fuels as actually available ( he's a very deep thinker ). The take home messages were :
- the margin is only of the order of 5% at the utmost best case ie. mildly greater surface gravity and/or mildly less fuel energy density and we'd fail to even reach low Earth orbit.
- you can only tweak/optimise a little. Even a 0.5% improvement is a marvellous gain. There is no 'killer app' that will arrive one day to solve that.
Hence Mars - at one third gee surface - would be a doddle to launch or return from. But for the same reason however it doesn't have an atmosphere that natively supports our oxidative metabolism. No where near it. And it is oxidation that gets you to orbit ie. the best performers include LOX. A lovely catch-22 there.
I interpreted that to mean : given that you need to achieve ~ 7 km/sec for each and every kilo to low Earth orbit and then another 4 km/sec to leave Earth's vicinity to travel around the solar system then ( short of the miraculous ) one has to construct large ventures in orbit first by very many up/down hops, and then go from there. Hence hardware re-usability.
The other aspect is design re-usability ie. don't keep inventing different wheels. Don't keep re-certifying radically new approaches. Thus 1 x Heavy = 3 x Falcon-9's. They have the same interstage and upper shroud/stage. A Falcon-9 has nine identical engines. A Dragon has three interior modes and thus roles. One type of leg strut for those bits that return. This is high-tech LEGO writ large.
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
Nicely done. Cheers, Mike
)
Nicely done.
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
Now that would have been
)
Now that would have been quite a ride. Between the large and abrupt acceleration of the rockets and the rather substantial rotational rates on multiple axes between trunk separation and main chute deployment, any paying customer would really get their money's worth. But once on the mains, it was really very nicely stable.
I can feel my brain sloshing
)
I can feel my brain sloshing around in my skull. That is a ride I think most would prefer to avoid, but its nice to know there is a fall back in the event its needed.
I learned from a press
)
I learned from a press article that the SuperDraco engines of which eight provided the "go" for today's show are hypergolic fueled, deeply throttleable.
More from Wikipedia
The news item mentioned two tons of propellant for these things on the Dragon. That is rather a lot. And hydrazine/nitrogen tetroxide is not my fondest wish of stuff to keep me close company.
On the plus side, these things serving for propulsive soft landing ought to give a much better ride than the Soyuz "bang and you're there" system. Throttle range is said to be 20 to 100 percent, and they don't necessarily need to fire all eight.
RE: I learned from a press
)
hypergolic: one where the propellants spontaneously ignite when they come into contact with each other. Certainly cuts down on weight, i.e., no hardware needed to "spark" ignition. But, Hmm, maybe just a 0/0 ejection seat will do, thank you very much.
That is what you would call a
)
That is what you would call a good escape plan. It can be triggered at any height right up to true orbit, which is a very reassuring feature. I think a reason why the lower trunk structure is kept until after the Draco burst is finished could be because it would form some shielding function from whatever might be exploding behind you .... in a real emergency instance where it is likely to be a full RUD ?? In any case in the history of catastrophic failures at rocket launches almost always throw material laterally, at least in the first instance. Also of note is that the particular trajectory in this test was obtained by differential throttling of the engines in real time as a closed feedback loop. Maybe the trunk also aids in directional stability by allowing the rockets to act with the centre of mass below ..... hmmmmm.
I reckon if I was offered the Super Dragon Ride at Movie World I'd probably go 'round all day. Get out, line up again, get out, line up again ... until either I passed out or my back gave way! :-) :-)
It's nasty stuff on the breakfast cereal that hydrazine/nitrogen tetroxide mix, but there is long experience of this combo. It figured prominently in the Apollo days. There the first really serious operational reliance was during Apollo 8, burning behind the moon to get the return boost back to Earth. Not just that it would fire at all, but also the specific performance to achieve the right subsequent path.
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
Looking at one thing and
)
Looking at one thing and another my guess is that the 1st Falcon Heavy flight - as yet not precisely scheduled, but allegedly this year - could well be contingent upon a successful return-to-land demonstration for the Falcon-9 first stage. Why? Well, the Heavy is ~ 3 x Falcon-9 and it's quite a lot of expensive hardware to throw away at once otherwise. Also it would also look a tad silly to do so.
Cheers, Mike.
( edit ) Also I have been researching as to why the Russian Energia is not being mentioned in lift capacity comparisons. It has a quoted thrust of ~ 30 megaNewtons, so still well above Falcon Heavy at 17-20 megaNewtons. In any case the Heavy burns for longer and the Energia only sort of achieved it's goals in 1 of 2 test launches.
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
This launch yesterday quietly
)
This launch yesterday quietly slipped by. At first I thought it was the "little engine that could". It just never seemed to get going. But then ....
RE: Looking at one thing
)
Mike, I was about to compose a post arguing that the Heavy was not so good a candidate for recovery, and that in any case I did not think they would delay first launch for the capability, when I did a little background checking to see if I could find something SpaceX had said about heavy recovery.
Imagine my surprise on finding this animation video from SpaceX showing Heavy recovery of three separate pieces--each piece considerably like the Falcon 9, and appearing to use the same recovery scheme, but landing not on a barge (or three!) but right back at the Cape.
youtube posting of SpaceX heavy launch and recovery animation
One of my arguments against is that the most obvious customers for the Falcon Heavy are rather primitively risk-adverse. My personal guess is that use on operational launches of the Heavy will probably come after a string of successes on less sensitive Falcon 9 launches.
If you think about the customers for Heavy launches, you may find an additional reason to discount Energia use. I don't think NRO would appreciate a fully Russian booster nearly so much as they do mere rocket engines with a strong Russian heritage--which have given them indigestion. Anyway, I think that Energia booster (confusingly the name applied both to an organization and to a particular booster) has nothing resembling a current manufacturing base. Might as well propose to start up building Saturn V's again.
For others with a bit of curiosity on this relic of the Soviet space shuttle program, here is a not bad overview article Energia overview
RE: Mike, I was about to
)
Agreed. There is considerable subtlety in the Musk/SpaceX approach which makes it both more interesting and more risky. I vaguely recall several years ago Elon's comments in generality - alas I've forgotten the detail or a reference to it - about the task of reaching orbit from this planet with the chemical fuels as actually available ( he's a very deep thinker ). The take home messages were :
- the margin is only of the order of 5% at the utmost best case ie. mildly greater surface gravity and/or mildly less fuel energy density and we'd fail to even reach low Earth orbit.
- you can only tweak/optimise a little. Even a 0.5% improvement is a marvellous gain. There is no 'killer app' that will arrive one day to solve that.
Hence Mars - at one third gee surface - would be a doddle to launch or return from. But for the same reason however it doesn't have an atmosphere that natively supports our oxidative metabolism. No where near it. And it is oxidation that gets you to orbit ie. the best performers include LOX. A lovely catch-22 there.
I interpreted that to mean : given that you need to achieve ~ 7 km/sec for each and every kilo to low Earth orbit and then another 4 km/sec to leave Earth's vicinity to travel around the solar system then ( short of the miraculous ) one has to construct large ventures in orbit first by very many up/down hops, and then go from there. Hence hardware re-usability.
The other aspect is design re-usability ie. don't keep inventing different wheels. Don't keep re-certifying radically new approaches. Thus 1 x Heavy = 3 x Falcon-9's. They have the same interstage and upper shroud/stage. A Falcon-9 has nine identical engines. A Dragon has three interior modes and thus roles. One type of leg strut for those bits that return. This is high-tech LEGO writ large.
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