The booster from the recent TESS launch came back to port on the barge recently.
This USALaunchReport video is mostly ten minutes of overmagnified scans along the booster sitting on the barge in port, but if you hop around you can notice that the white piece of machinery some have called the Roomba is indeed under the launcher--so maybe they are on the way to having a good way to deal with safely securing the booster to the barge in more dynamic weather. You can also see that the booster is still really close to dead center in the yellow ring (maybe the next barge can be smaller--just as the second landing zone at the Cape was built smaller). Lastly you can see at least one fairing they picked up out of the drink (others say they can see two).
I'm currently reading a book entitled : "Ignition! An Informal History of Liquid Rocket Propellants" by John Drury Clark with a foreword by Isaac Asimov. It's a marvellous piece. I have the Audible version. Basically the guy spent a long career studying and testing such dangerous chemicals without blowing up himself or flattening any facility.
One aspect is highly relevant to SpaceX ie. why supply more oxygen to the combustion chamber than is required per strict stoichiometry ? The fuel used is essentially well purified kerosene with 12 carbon atoms ( dodecane variants ), and combined with LOX yields the highest density impulse ( of commonly used fuels ) bar hydrazine*. So if you want something non-corrosive/non-hypergolic/less-toxic/safer with the best bang per fuel mass carried then RP-1 is the choice. However the stoichiometry ( exact ratios either side of the reaction equation ) does not speak of an equilibrium point nor the typical time taken to reach it.
Here comes into play the chemical 'Principle Of Mass Action' which is more-or-less a way of completely burning the kerosene within the time available ie. before all is thrown out the back via the nozzle/bell. Most of the available chemical energy ( difference in electron bindings b/w products and reactants ) lies within dodecane deconstruction. Hence shove in more ( and lighter ) oxygen to leverage that optimally, including that trick of enhanced oxygen densification by super-cooling at load time. SpaceX Merlins are also cooled using liquid oxygen as well, and it's pretty much mandatory that it be so. Without that the excess temperature in the combustion chamber produced by complete kerosene burning would melt the engine. IIRC at thrust levels currently used the engine is within ~ 75 K of the alloy's melting point. It is possible that fuel still burning in the plume, after exit, perceptively contributes to thrust also ( see aerospike ).
There is a fine line being walked here b/w maximum impulse as per the rules of physics vs disintegration of the device. The next step up would be a successfulfull-flow staged combustion rocket engine from SpaceX. Full flow here means that the exhaust of sections called the pre-burners drives turbines ( sucking in more reactants ), and those turbine's exhausts goes into the combustion chamber ( complex diagram omitted ). That's an extra bite** of the chemical cherry. The Raptor is currently operating as oxidizer rich as above, but the intent is to become full flow. IIRC there is either one or two other full flow instances attempted ( the Russians ? ).
* Liquid hydrogen is the worst choice as regards this parameter ( less than 1/2 of RP-1's when using oxygen ). As it stands today this is why Blue Origin isn't going anywhere near another planet, or even the moon ...... recall that the Space Shuttle required assistance via, say, SRB's to merely achieve LEO. That dual-fuel design contributed to at least one major accident and, in retrospect, needless complexity IMHO.
** How much does one gain by full flow ? That depends upon the fraction of partially or unburnt fuel that would otherwise bypass the combustion chamber ie. how much of a pre-burner's turbine exhaust do you toss away via some other exit, without directed thrust production ? Hence the name full flow where all reaches the combustion chamber to then leave via the main bell.
Cheers, Mike.
( edit ) For that matter H2's volume density is the worst too, about 1/10th of kerosene.
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
Stuff it, here's the Wikipedia full flow engine diagram :
.... where a clever bit is in the control valves from one reactant that supplies the preburner for the other reactant. The pre-burners are relatively small chambers that, duh, burn a bit of both to spin up their respective turbines against output load. They add heat/kinetic-energy to the reactant flow inputting those turbos. Note that a pre-burner chamber is well off the strict stoichiometric ratio giving a reactant rich exhaust. A small increase in the minority reactant of a pre-burner chamber yields a disproportionately larger turbo output for the majority reactant. Apart from which reactant cools the bell, there is a nice symmetry in the design. Everything ultimately leaves though the nozzle.
That's Heat Exchanger not a Heat Exanger, whatever that is ! ;-)
Cheers, Mike.
( edit ) The clever bit is also a nasty bit, quite non-linear, meaning that the control valve settings depend essentially upon momentary engine power. If you get it wrong ..... maybe full RUD ! That's because you don't want too much pre-burning .... :-(
{ A 'typical' engine has only one pre-burner driving a single turbine shaft that pulls in more of both reactants in some ratio. Much less finicky as you don't have to closely correlate the activity of two non-connected turbos. }
( edit ) The current Raptor is rather closer to optimal efficiency than the vacuum Merlin, which is why it is being groomed for interplanetary work. Imagine a full flow Raptor : what a hot-rod ! :-)
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 booster from the recent
)
The booster from the recent TESS launch came back to port on the barge recently.
This USALaunchReport video is mostly ten minutes of overmagnified scans along the booster sitting on the barge in port, but if you hop around you can notice that the white piece of machinery some have called the Roomba is indeed under the launcher--so maybe they are on the way to having a good way to deal with safely securing the booster to the barge in more dynamic weather. You can also see that the booster is still really close to dead center in the yellow ring (maybe the next barge can be smaller--just as the second landing zone at the Cape was built smaller). Lastly you can see at least one fairing they picked up out of the drink (others say they can see two).
Sentinel-3B_launch Small but
)
Sentinel-3B_launch
Small but nice.
They retrieved two fairings :
)
They retrieved two fairings : one perfect, the other trashed. :-(
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
SpaceX to launch first ‘Block
)
SpaceX to launch first ‘Block 5’ rocket from Cape Canaveral
launch is for today 5/10/18: Read more about it here: http://www.wesh.com/article/spacex-to-launch-first-block-5-rocket-from-cape-canaveral/20649562
T - 58 seconds and holding,
)
T - 58 seconds and holding, ABORT ABORT ABORT
Do it all again tomorrow.
The Goddess of Rocketry has
)
The Goddess of Rocketry has been kind ! Splendid work. :-)
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
Bangladesh???
)
Bangladesh???
MAGIC Quantum Mechanic
)
Well, Azerbaijan, Laos, and Estonia each have one, among others. Bangladesh is just working to keep up with the Joneses.
I'm currently reading a book
)
I'm currently reading a book entitled : "Ignition! An Informal History of Liquid Rocket Propellants" by John Drury Clark with a foreword by Isaac Asimov. It's a marvellous piece. I have the Audible version. Basically the guy spent a long career studying and testing such dangerous chemicals without blowing up himself or flattening any facility.
One aspect is highly relevant to SpaceX ie. why supply more oxygen to the combustion chamber than is required per strict stoichiometry ? The fuel used is essentially well purified kerosene with 12 carbon atoms ( dodecane variants ), and combined with LOX yields the highest density impulse ( of commonly used fuels ) bar hydrazine*. So if you want something non-corrosive/non-hypergolic/less-toxic/safer with the best bang per fuel mass carried then RP-1 is the choice. However the stoichiometry ( exact ratios either side of the reaction equation ) does not speak of an equilibrium point nor the typical time taken to reach it.
Here comes into play the chemical 'Principle Of Mass Action' which is more-or-less a way of completely burning the kerosene within the time available ie. before all is thrown out the back via the nozzle/bell. Most of the available chemical energy ( difference in electron bindings b/w products and reactants ) lies within dodecane deconstruction. Hence shove in more ( and lighter ) oxygen to leverage that optimally, including that trick of enhanced oxygen densification by super-cooling at load time. SpaceX Merlins are also cooled using liquid oxygen as well, and it's pretty much mandatory that it be so. Without that the excess temperature in the combustion chamber produced by complete kerosene burning would melt the engine. IIRC at thrust levels currently used the engine is within ~ 75 K of the alloy's melting point. It is possible that fuel still burning in the plume, after exit, perceptively contributes to thrust also ( see aerospike ).
There is a fine line being walked here b/w maximum impulse as per the rules of physics vs disintegration of the device. The next step up would be a successful full-flow staged combustion rocket engine from SpaceX. Full flow here means that the exhaust of sections called the pre-burners drives turbines ( sucking in more reactants ), and those turbine's exhausts goes into the combustion chamber ( complex diagram omitted ). That's an extra bite** of the chemical cherry. The Raptor is currently operating as oxidizer rich as above, but the intent is to become full flow. IIRC there is either one or two other full flow instances attempted ( the Russians ? ).
* Liquid hydrogen is the worst choice as regards this parameter ( less than 1/2 of RP-1's when using oxygen ). As it stands today this is why Blue Origin isn't going anywhere near another planet, or even the moon ...... recall that the Space Shuttle required assistance via, say, SRB's to merely achieve LEO. That dual-fuel design contributed to at least one major accident and, in retrospect, needless complexity IMHO.
** How much does one gain by full flow ? That depends upon the fraction of partially or unburnt fuel that would otherwise bypass the combustion chamber ie. how much of a pre-burner's turbine exhaust do you toss away via some other exit, without directed thrust production ? Hence the name full flow where all reaches the combustion chamber to then leave via the main bell.
Cheers, Mike.
( edit ) For that matter H2's volume density is the worst too, about 1/10th of kerosene.
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
Stuff it, here's Wikipedia's
)
Stuff it, here's the Wikipedia full flow engine diagram :
.... where a clever bit is in the control valves from one reactant that supplies the preburner for the other reactant. The pre-burners are relatively small chambers that, duh, burn a bit of both to spin up their respective turbines against output load. They add heat/kinetic-energy to the reactant flow inputting those turbos. Note that a pre-burner chamber is well off the strict stoichiometric ratio giving a reactant rich exhaust. A small increase in the minority reactant of a pre-burner chamber yields a disproportionately larger turbo output for the majority reactant. Apart from which reactant cools the bell, there is a nice symmetry in the design. Everything ultimately leaves though the nozzle.
That's Heat Exchanger not a Heat Exanger, whatever that is ! ;-)
Cheers, Mike.
( edit ) The clever bit is also a nasty bit, quite non-linear, meaning that the control valve settings depend essentially upon momentary engine power. If you get it wrong ..... maybe full RUD ! That's because you don't want too much pre-burning .... :-(
{ A 'typical' engine has only one pre-burner driving a single turbine shaft that pulls in more of both reactants in some ratio. Much less finicky as you don't have to closely correlate the activity of two non-connected turbos. }
( edit ) The current Raptor is rather closer to optimal efficiency than the vacuum Merlin, which is why it is being groomed for interplanetary work. Imagine a full flow Raptor : what a hot-rod ! :-)
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