Break Away Valves for Launch [duplicate] The Next CEO of Stack OverflowCould fuel be “hosed” (pumped) from the ground to a launcher?Is Asparagus Staging PossibleWhy rockets are not tossed up before launchWhat rocket uses the largest percentage of Fuel/Oxidizer before liftoff?How much fuel would one need to launch a 1kg object from 100,000 feet?How much fuel was used for a Space Shuttle launch?What is a typical energy demand and carbon footprint of a space launch?How do they get up-close views of far away spacecraft after launch?How far away can one see a NASA rocket launch?Good source for launch videosIs the pressurization of propellant tanks necessary for structural integrity?Odor of a rocket launch?Why rockets are not tossed up before launchReaction Drive Launch Catapult
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Break Away Valves for Launch [duplicate]
The Next CEO of Stack OverflowCould fuel be “hosed” (pumped) from the ground to a launcher?Is Asparagus Staging PossibleWhy rockets are not tossed up before launchWhat rocket uses the largest percentage of Fuel/Oxidizer before liftoff?How much fuel would one need to launch a 1kg object from 100,000 feet?How much fuel was used for a Space Shuttle launch?What is a typical energy demand and carbon footprint of a space launch?How do they get up-close views of far away spacecraft after launch?How far away can one see a NASA rocket launch?Good source for launch videosIs the pressurization of propellant tanks necessary for structural integrity?Odor of a rocket launch?Why rockets are not tossed up before launchReaction Drive Launch Catapult
$begingroup$
This question already has an answer here:
Could fuel be “hosed” (pumped) from the ground to a launcher?
5 answers
I forgot to hang up the fuel pump and broke it off and costed around 80 dollars to replace. While there I wandered could this be adapted to a rocket in some way?
How much fuel capacity would be saved if the fuel was fed to the rocket to keep it topped off until it has fully left the launch tower? The length of the fuel line and break away valve would be the height of the launch tower.
Could it be fed through an extended tower with a fuel line that travels aside the rocket not to burden the rocket with the weight of the fuel line or cause a whip in the fuel line?
https://sputniknews.com/science/201812291071085215-soyuz-launch-russia-uk-satellite/
launch fuel engines design-alternative
asked 2 days ago
MuzeMuze
1,3691264
$endgroup$
marked as duplicate by Russell Borogove, Nathan Tuggy, uhoh, Muze, Steve Linton 2 days ago
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
add a comment |
$begingroup$
This question already has an answer here:
Could fuel be “hosed” (pumped) from the ground to a launcher?
5 answers
I forgot to hang up the fuel pump and broke it off and costed around 80 dollars to replace. While there I wandered could this be adapted to a rocket in some way?
How much fuel capacity would be saved if the fuel was fed to the rocket to keep it topped off until it has fully left the launch tower? The length of the fuel line and break away valve would be the height of the launch tower.
Could it be fed through an extended tower with a fuel line that travels aside the rocket not to burden the rocket with the weight of the fuel line or cause a whip in the fuel line?
https://sputniknews.com/science/201812291071085215-soyuz-launch-russia-uk-satellite/
launch fuel engines design-alternative
asked 2 days ago
MuzeMuze
1,3691264
$endgroup$
marked as duplicate by Russell Borogove, Nathan Tuggy, uhoh, Muze, Steve Linton 2 days ago
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
$begingroup$
You should consider the amount of fuel feed into the tanks after lift off and compare it to the amount of fuel left in the hose and the weight of the hose itself after disconnection of the hose. If the hose with fuel weighs more than the added fuel, nothing was won.
$endgroup$
– Uwe
yesterday
$begingroup$
@Uwe that way I put the part about a shorter hose to run up aside it taking away the weight.
$endgroup$
– Muze
yesterday
add a comment |
$begingroup$
This question already has an answer here:
Could fuel be “hosed” (pumped) from the ground to a launcher?
5 answers
I forgot to hang up the fuel pump and broke it off and costed around 80 dollars to replace. While there I wandered could this be adapted to a rocket in some way?
How much fuel capacity would be saved if the fuel was fed to the rocket to keep it topped off until it has fully left the launch tower? The length of the fuel line and break away valve would be the height of the launch tower.
Could it be fed through an extended tower with a fuel line that travels aside the rocket not to burden the rocket with the weight of the fuel line or cause a whip in the fuel line?
https://sputniknews.com/science/201812291071085215-soyuz-launch-russia-uk-satellite/
launch fuel engines design-alternative
asked 2 days ago
MuzeMuze
1,3691264
$endgroup$
This question already has an answer here:
Could fuel be “hosed” (pumped) from the ground to a launcher?
5 answers
I forgot to hang up the fuel pump and broke it off and costed around 80 dollars to replace. While there I wandered could this be adapted to a rocket in some way?
How much fuel capacity would be saved if the fuel was fed to the rocket to keep it topped off until it has fully left the launch tower? The length of the fuel line and break away valve would be the height of the launch tower.
Could it be fed through an extended tower with a fuel line that travels aside the rocket not to burden the rocket with the weight of the fuel line or cause a whip in the fuel line?
https://sputniknews.com/science/201812291071085215-soyuz-launch-russia-uk-satellite/
This question already has an answer here:
Could fuel be “hosed” (pumped) from the ground to a launcher?
5 answers
launch fuel engines design-alternative
launch fuel engines design-alternative
asked 2 days ago
MuzeMuze
1,3691264
asked 2 days ago
MuzeMuze
1,3691264
edited 2 days ago
Muze
asked 2 days ago
MuzeMuze
1,3691264
asked 2 days ago
MuzeMuze
1,3691264
asked 2 days ago
MuzeMuze
1,3691264
1,3691264
marked as duplicate by Russell Borogove, Nathan Tuggy, uhoh, Muze, Steve Linton 2 days ago
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
marked as duplicate by Russell Borogove, Nathan Tuggy, uhoh, Muze, Steve Linton 2 days ago
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
$begingroup$
You should consider the amount of fuel feed into the tanks after lift off and compare it to the amount of fuel left in the hose and the weight of the hose itself after disconnection of the hose. If the hose with fuel weighs more than the added fuel, nothing was won.
$endgroup$
– Uwe
yesterday
$begingroup$
@Uwe that way I put the part about a shorter hose to run up aside it taking away the weight.
$endgroup$
– Muze
yesterday
add a comment |
$begingroup$
You should consider the amount of fuel feed into the tanks after lift off and compare it to the amount of fuel left in the hose and the weight of the hose itself after disconnection of the hose. If the hose with fuel weighs more than the added fuel, nothing was won.
$endgroup$
– Uwe
yesterday
$begingroup$
@Uwe that way I put the part about a shorter hose to run up aside it taking away the weight.
$endgroup$
– Muze
yesterday
$begingroup$
You should consider the amount of fuel feed into the tanks after lift off and compare it to the amount of fuel left in the hose and the weight of the hose itself after disconnection of the hose. If the hose with fuel weighs more than the added fuel, nothing was won.
$endgroup$
– Uwe
yesterday
$begingroup$
You should consider the amount of fuel feed into the tanks after lift off and compare it to the amount of fuel left in the hose and the weight of the hose itself after disconnection of the hose. If the hose with fuel weighs more than the added fuel, nothing was won.
$endgroup$
– Uwe
yesterday
$begingroup$
@Uwe that way I put the part about a shorter hose to run up aside it taking away the weight.
$endgroup$
– Muze
yesterday
$begingroup$
@Uwe that way I put the part about a shorter hose to run up aside it taking away the weight.
$endgroup$
– Muze
yesterday
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
Theoretically yes. However there are concerns:
1) Propellant load is dangerous under the best circumstances. Add in all the vibration loads of an "on" rocket and you have a doozie.
2) Most rockets already have umbilicals that disconnect slightly after liftoff. The recent Rocketlab launch video has a good angle of this
3) It's a bit of added weight and complexity.
These are all surmountable, but then what would you be gaining? I'm sure someone can do a calculation (slightly related to this question) but I suspect it's a negligible amount of payload/mass gain.
answered 2 days ago
randomUsernamerandomUsername
34118
$endgroup$
$begingroup$
If you think about it it is saved weight need less fuel storage.
$endgroup$
– Muze
2 days ago
$begingroup$
Could you clarify?
$endgroup$
– randomUsername
2 days ago
$begingroup$
You can off set the onboard fuel needed for the mission saving weight for heavier payload.
$endgroup$
– Muze
2 days ago
3
$begingroup$
@Muze Let's do some Fermi estimation. It takes a second for the rocket to reach the altitude shown in your diagram. The first stage operates for a hundred seconds. So 1% of the propellant mass could be saved by massively increasing the complexity and danger of launch.
$endgroup$
– Jacob Krall
2 days ago
$begingroup$
See also this quote
$endgroup$
– Jacob Krall
2 days ago
add a comment |
$begingroup$
Throwing some more bits at this alongside randomUserName's answer
The pipe size will be something you could climb up (half meter to meter diameter) so big and inflexible. Large diameter pipe becomes complex quite quickly in terms of the structure needed to support it both under pressure and hard vacuum as it drains.
It will be carrying at least one cryogenic fluid so tend to be inflexible and brittle. Generally pipe flexing at these temperatures are metal rotation joints or bellows rather than just a rubber tube as most flexible materials freeze.
The pressure to pump up 500 meters will be quite exciting, and need to handle what happens when the disconnect happens and the flow needs to stop abruptly.
At disconnect you will have plumbing with both fluids flowing. Stopping it is not really possible since there is going to be hundred of tons of fluid in motion in this pipe system, so it will need to vent. This is going to catch fire and burn off.
At disconnect you have a couple of hundred meters of flexible structure hanging in the air first guess at mass around 500 tonnes, that then falls through the rocket exhaust and lands on the pad. You do not get this back, and probably not the pad (see above)
The above two probably mean you need to purge the system with inert gas before disconnect, which reduces the system weight, flushes the flammables somewhat and maybe even means you could have a gas jet system to 'fly' the hose back down. All of this means that your actual useful fuel flow stops sometime before disconnect though, probably before the rocket has actually cleared the tower so net gain for the system is low.
The mass of the plumbing will be non trivial, off axis and hard to predict. This will make the flight control tricky, and tend to tip the rocket over.
In addition this coupling needs to be physically large to get the needed volumes through, and handle two different fluids. It then needs to disconnect reliably, since rocket is going to 100% crash if it fails to do so. Good rocket design normally involves only releasing the launch clamps once every single other ground interface has retracted, so only the launch hold downs need to be 100% reliable.
The disconnect point also needs to avoid spilling any of the fluids during flight.
This plumbing will need to feed multiple stages, and as noted around asparagus staging, cross feed is a complex beast and in fact a very similar and much simpler method to get the result from this question (rocket clear of tower and at speed with full tanks) would be for a rocket to fly with saddle tanks that jettison at 500 meters.
The actual mass of this assembly plus the fuel inside would need to be lifted by the rocket, so the gains are not 'free'.
It is worth noting that both refueling at sea and air are generally considered amongst the most dangerous things armed forces do that do not involve people shooting at you and this plan will involve many of the worst aspects of both plus cryogenics and operating rocket exhaust.
Fundamentally this becomes a new first stage, which possibly would be simpler as an actual first stage.
answered 2 days ago
GremlinWrangerGremlinWranger
2,808318
$endgroup$
add a comment |
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Theoretically yes. However there are concerns:
1) Propellant load is dangerous under the best circumstances. Add in all the vibration loads of an "on" rocket and you have a doozie.
2) Most rockets already have umbilicals that disconnect slightly after liftoff. The recent Rocketlab launch video has a good angle of this
3) It's a bit of added weight and complexity.
These are all surmountable, but then what would you be gaining? I'm sure someone can do a calculation (slightly related to this question) but I suspect it's a negligible amount of payload/mass gain.
answered 2 days ago
randomUsernamerandomUsername
34118
$endgroup$
$begingroup$
If you think about it it is saved weight need less fuel storage.
$endgroup$
– Muze
2 days ago
$begingroup$
Could you clarify?
$endgroup$
– randomUsername
2 days ago
$begingroup$
You can off set the onboard fuel needed for the mission saving weight for heavier payload.
$endgroup$
– Muze
2 days ago
3
$begingroup$
@Muze Let's do some Fermi estimation. It takes a second for the rocket to reach the altitude shown in your diagram. The first stage operates for a hundred seconds. So 1% of the propellant mass could be saved by massively increasing the complexity and danger of launch.
$endgroup$
– Jacob Krall
2 days ago
$begingroup$
See also this quote
$endgroup$
– Jacob Krall
2 days ago
add a comment |
$begingroup$
Theoretically yes. However there are concerns:
1) Propellant load is dangerous under the best circumstances. Add in all the vibration loads of an "on" rocket and you have a doozie.
2) Most rockets already have umbilicals that disconnect slightly after liftoff. The recent Rocketlab launch video has a good angle of this
3) It's a bit of added weight and complexity.
These are all surmountable, but then what would you be gaining? I'm sure someone can do a calculation (slightly related to this question) but I suspect it's a negligible amount of payload/mass gain.
answered 2 days ago
randomUsernamerandomUsername
34118
$endgroup$
$begingroup$
If you think about it it is saved weight need less fuel storage.
$endgroup$
– Muze
2 days ago
$begingroup$
Could you clarify?
$endgroup$
– randomUsername
2 days ago
$begingroup$
You can off set the onboard fuel needed for the mission saving weight for heavier payload.
$endgroup$
– Muze
2 days ago
3
$begingroup$
@Muze Let's do some Fermi estimation. It takes a second for the rocket to reach the altitude shown in your diagram. The first stage operates for a hundred seconds. So 1% of the propellant mass could be saved by massively increasing the complexity and danger of launch.
$endgroup$
– Jacob Krall
2 days ago
$begingroup$
See also this quote
$endgroup$
– Jacob Krall
2 days ago
add a comment |
$begingroup$
Theoretically yes. However there are concerns:
1) Propellant load is dangerous under the best circumstances. Add in all the vibration loads of an "on" rocket and you have a doozie.
2) Most rockets already have umbilicals that disconnect slightly after liftoff. The recent Rocketlab launch video has a good angle of this
3) It's a bit of added weight and complexity.
These are all surmountable, but then what would you be gaining? I'm sure someone can do a calculation (slightly related to this question) but I suspect it's a negligible amount of payload/mass gain.
answered 2 days ago
randomUsernamerandomUsername
34118
$endgroup$
Theoretically yes. However there are concerns:
1) Propellant load is dangerous under the best circumstances. Add in all the vibration loads of an "on" rocket and you have a doozie.
2) Most rockets already have umbilicals that disconnect slightly after liftoff. The recent Rocketlab launch video has a good angle of this
3) It's a bit of added weight and complexity.
These are all surmountable, but then what would you be gaining? I'm sure someone can do a calculation (slightly related to this question) but I suspect it's a negligible amount of payload/mass gain.
answered 2 days ago
randomUsernamerandomUsername
34118
answered 2 days ago
randomUsernamerandomUsername
34118
answered 2 days ago
randomUsernamerandomUsername
34118
answered 2 days ago
randomUsernamerandomUsername
34118
34118
$begingroup$
If you think about it it is saved weight need less fuel storage.
$endgroup$
– Muze
2 days ago
$begingroup$
Could you clarify?
$endgroup$
– randomUsername
2 days ago
$begingroup$
You can off set the onboard fuel needed for the mission saving weight for heavier payload.
$endgroup$
– Muze
2 days ago
3
$begingroup$
@Muze Let's do some Fermi estimation. It takes a second for the rocket to reach the altitude shown in your diagram. The first stage operates for a hundred seconds. So 1% of the propellant mass could be saved by massively increasing the complexity and danger of launch.
$endgroup$
– Jacob Krall
2 days ago
$begingroup$
See also this quote
$endgroup$
– Jacob Krall
2 days ago
add a comment |
$begingroup$
If you think about it it is saved weight need less fuel storage.
$endgroup$
– Muze
2 days ago
$begingroup$
Could you clarify?
$endgroup$
– randomUsername
2 days ago
$begingroup$
You can off set the onboard fuel needed for the mission saving weight for heavier payload.
$endgroup$
– Muze
2 days ago
3
$begingroup$
@Muze Let's do some Fermi estimation. It takes a second for the rocket to reach the altitude shown in your diagram. The first stage operates for a hundred seconds. So 1% of the propellant mass could be saved by massively increasing the complexity and danger of launch.
$endgroup$
– Jacob Krall
2 days ago
$begingroup$
See also this quote
$endgroup$
– Jacob Krall
2 days ago
$begingroup$
If you think about it it is saved weight need less fuel storage.
$endgroup$
– Muze
2 days ago
$begingroup$
If you think about it it is saved weight need less fuel storage.
$endgroup$
– Muze
2 days ago
$begingroup$
Could you clarify?
$endgroup$
– randomUsername
2 days ago
$begingroup$
Could you clarify?
$endgroup$
– randomUsername
2 days ago
$begingroup$
You can off set the onboard fuel needed for the mission saving weight for heavier payload.
$endgroup$
– Muze
2 days ago
$begingroup$
You can off set the onboard fuel needed for the mission saving weight for heavier payload.
$endgroup$
– Muze
2 days ago
3
3
$begingroup$
@Muze Let's do some Fermi estimation. It takes a second for the rocket to reach the altitude shown in your diagram. The first stage operates for a hundred seconds. So 1% of the propellant mass could be saved by massively increasing the complexity and danger of launch.
$endgroup$
– Jacob Krall
2 days ago
$begingroup$
@Muze Let's do some Fermi estimation. It takes a second for the rocket to reach the altitude shown in your diagram. The first stage operates for a hundred seconds. So 1% of the propellant mass could be saved by massively increasing the complexity and danger of launch.
$endgroup$
– Jacob Krall
2 days ago
$begingroup$
See also this quote
$endgroup$
– Jacob Krall
2 days ago
$begingroup$
See also this quote
$endgroup$
– Jacob Krall
2 days ago
add a comment |
$begingroup$
Throwing some more bits at this alongside randomUserName's answer
The pipe size will be something you could climb up (half meter to meter diameter) so big and inflexible. Large diameter pipe becomes complex quite quickly in terms of the structure needed to support it both under pressure and hard vacuum as it drains.
It will be carrying at least one cryogenic fluid so tend to be inflexible and brittle. Generally pipe flexing at these temperatures are metal rotation joints or bellows rather than just a rubber tube as most flexible materials freeze.
The pressure to pump up 500 meters will be quite exciting, and need to handle what happens when the disconnect happens and the flow needs to stop abruptly.
At disconnect you will have plumbing with both fluids flowing. Stopping it is not really possible since there is going to be hundred of tons of fluid in motion in this pipe system, so it will need to vent. This is going to catch fire and burn off.
At disconnect you have a couple of hundred meters of flexible structure hanging in the air first guess at mass around 500 tonnes, that then falls through the rocket exhaust and lands on the pad. You do not get this back, and probably not the pad (see above)
The above two probably mean you need to purge the system with inert gas before disconnect, which reduces the system weight, flushes the flammables somewhat and maybe even means you could have a gas jet system to 'fly' the hose back down. All of this means that your actual useful fuel flow stops sometime before disconnect though, probably before the rocket has actually cleared the tower so net gain for the system is low.
The mass of the plumbing will be non trivial, off axis and hard to predict. This will make the flight control tricky, and tend to tip the rocket over.
In addition this coupling needs to be physically large to get the needed volumes through, and handle two different fluids. It then needs to disconnect reliably, since rocket is going to 100% crash if it fails to do so. Good rocket design normally involves only releasing the launch clamps once every single other ground interface has retracted, so only the launch hold downs need to be 100% reliable.
The disconnect point also needs to avoid spilling any of the fluids during flight.
This plumbing will need to feed multiple stages, and as noted around asparagus staging, cross feed is a complex beast and in fact a very similar and much simpler method to get the result from this question (rocket clear of tower and at speed with full tanks) would be for a rocket to fly with saddle tanks that jettison at 500 meters.
The actual mass of this assembly plus the fuel inside would need to be lifted by the rocket, so the gains are not 'free'.
It is worth noting that both refueling at sea and air are generally considered amongst the most dangerous things armed forces do that do not involve people shooting at you and this plan will involve many of the worst aspects of both plus cryogenics and operating rocket exhaust.
Fundamentally this becomes a new first stage, which possibly would be simpler as an actual first stage.
answered 2 days ago
GremlinWrangerGremlinWranger
2,808318
$endgroup$
add a comment |
$begingroup$
Throwing some more bits at this alongside randomUserName's answer
The pipe size will be something you could climb up (half meter to meter diameter) so big and inflexible. Large diameter pipe becomes complex quite quickly in terms of the structure needed to support it both under pressure and hard vacuum as it drains.
It will be carrying at least one cryogenic fluid so tend to be inflexible and brittle. Generally pipe flexing at these temperatures are metal rotation joints or bellows rather than just a rubber tube as most flexible materials freeze.
The pressure to pump up 500 meters will be quite exciting, and need to handle what happens when the disconnect happens and the flow needs to stop abruptly.
At disconnect you will have plumbing with both fluids flowing. Stopping it is not really possible since there is going to be hundred of tons of fluid in motion in this pipe system, so it will need to vent. This is going to catch fire and burn off.
At disconnect you have a couple of hundred meters of flexible structure hanging in the air first guess at mass around 500 tonnes, that then falls through the rocket exhaust and lands on the pad. You do not get this back, and probably not the pad (see above)
The above two probably mean you need to purge the system with inert gas before disconnect, which reduces the system weight, flushes the flammables somewhat and maybe even means you could have a gas jet system to 'fly' the hose back down. All of this means that your actual useful fuel flow stops sometime before disconnect though, probably before the rocket has actually cleared the tower so net gain for the system is low.
The mass of the plumbing will be non trivial, off axis and hard to predict. This will make the flight control tricky, and tend to tip the rocket over.
In addition this coupling needs to be physically large to get the needed volumes through, and handle two different fluids. It then needs to disconnect reliably, since rocket is going to 100% crash if it fails to do so. Good rocket design normally involves only releasing the launch clamps once every single other ground interface has retracted, so only the launch hold downs need to be 100% reliable.
The disconnect point also needs to avoid spilling any of the fluids during flight.
This plumbing will need to feed multiple stages, and as noted around asparagus staging, cross feed is a complex beast and in fact a very similar and much simpler method to get the result from this question (rocket clear of tower and at speed with full tanks) would be for a rocket to fly with saddle tanks that jettison at 500 meters.
The actual mass of this assembly plus the fuel inside would need to be lifted by the rocket, so the gains are not 'free'.
It is worth noting that both refueling at sea and air are generally considered amongst the most dangerous things armed forces do that do not involve people shooting at you and this plan will involve many of the worst aspects of both plus cryogenics and operating rocket exhaust.
Fundamentally this becomes a new first stage, which possibly would be simpler as an actual first stage.
answered 2 days ago
GremlinWrangerGremlinWranger
2,808318
$endgroup$
add a comment |
$begingroup$
Throwing some more bits at this alongside randomUserName's answer
The pipe size will be something you could climb up (half meter to meter diameter) so big and inflexible. Large diameter pipe becomes complex quite quickly in terms of the structure needed to support it both under pressure and hard vacuum as it drains.
It will be carrying at least one cryogenic fluid so tend to be inflexible and brittle. Generally pipe flexing at these temperatures are metal rotation joints or bellows rather than just a rubber tube as most flexible materials freeze.
The pressure to pump up 500 meters will be quite exciting, and need to handle what happens when the disconnect happens and the flow needs to stop abruptly.
At disconnect you will have plumbing with both fluids flowing. Stopping it is not really possible since there is going to be hundred of tons of fluid in motion in this pipe system, so it will need to vent. This is going to catch fire and burn off.
At disconnect you have a couple of hundred meters of flexible structure hanging in the air first guess at mass around 500 tonnes, that then falls through the rocket exhaust and lands on the pad. You do not get this back, and probably not the pad (see above)
The above two probably mean you need to purge the system with inert gas before disconnect, which reduces the system weight, flushes the flammables somewhat and maybe even means you could have a gas jet system to 'fly' the hose back down. All of this means that your actual useful fuel flow stops sometime before disconnect though, probably before the rocket has actually cleared the tower so net gain for the system is low.
The mass of the plumbing will be non trivial, off axis and hard to predict. This will make the flight control tricky, and tend to tip the rocket over.
In addition this coupling needs to be physically large to get the needed volumes through, and handle two different fluids. It then needs to disconnect reliably, since rocket is going to 100% crash if it fails to do so. Good rocket design normally involves only releasing the launch clamps once every single other ground interface has retracted, so only the launch hold downs need to be 100% reliable.
The disconnect point also needs to avoid spilling any of the fluids during flight.
This plumbing will need to feed multiple stages, and as noted around asparagus staging, cross feed is a complex beast and in fact a very similar and much simpler method to get the result from this question (rocket clear of tower and at speed with full tanks) would be for a rocket to fly with saddle tanks that jettison at 500 meters.
The actual mass of this assembly plus the fuel inside would need to be lifted by the rocket, so the gains are not 'free'.
It is worth noting that both refueling at sea and air are generally considered amongst the most dangerous things armed forces do that do not involve people shooting at you and this plan will involve many of the worst aspects of both plus cryogenics and operating rocket exhaust.
Fundamentally this becomes a new first stage, which possibly would be simpler as an actual first stage.
answered 2 days ago
GremlinWrangerGremlinWranger
2,808318
$endgroup$
Throwing some more bits at this alongside randomUserName's answer
The pipe size will be something you could climb up (half meter to meter diameter) so big and inflexible. Large diameter pipe becomes complex quite quickly in terms of the structure needed to support it both under pressure and hard vacuum as it drains.
It will be carrying at least one cryogenic fluid so tend to be inflexible and brittle. Generally pipe flexing at these temperatures are metal rotation joints or bellows rather than just a rubber tube as most flexible materials freeze.
The pressure to pump up 500 meters will be quite exciting, and need to handle what happens when the disconnect happens and the flow needs to stop abruptly.
At disconnect you will have plumbing with both fluids flowing. Stopping it is not really possible since there is going to be hundred of tons of fluid in motion in this pipe system, so it will need to vent. This is going to catch fire and burn off.
At disconnect you have a couple of hundred meters of flexible structure hanging in the air first guess at mass around 500 tonnes, that then falls through the rocket exhaust and lands on the pad. You do not get this back, and probably not the pad (see above)
The above two probably mean you need to purge the system with inert gas before disconnect, which reduces the system weight, flushes the flammables somewhat and maybe even means you could have a gas jet system to 'fly' the hose back down. All of this means that your actual useful fuel flow stops sometime before disconnect though, probably before the rocket has actually cleared the tower so net gain for the system is low.
The mass of the plumbing will be non trivial, off axis and hard to predict. This will make the flight control tricky, and tend to tip the rocket over.
In addition this coupling needs to be physically large to get the needed volumes through, and handle two different fluids. It then needs to disconnect reliably, since rocket is going to 100% crash if it fails to do so. Good rocket design normally involves only releasing the launch clamps once every single other ground interface has retracted, so only the launch hold downs need to be 100% reliable.
The disconnect point also needs to avoid spilling any of the fluids during flight.
This plumbing will need to feed multiple stages, and as noted around asparagus staging, cross feed is a complex beast and in fact a very similar and much simpler method to get the result from this question (rocket clear of tower and at speed with full tanks) would be for a rocket to fly with saddle tanks that jettison at 500 meters.
The actual mass of this assembly plus the fuel inside would need to be lifted by the rocket, so the gains are not 'free'.
It is worth noting that both refueling at sea and air are generally considered amongst the most dangerous things armed forces do that do not involve people shooting at you and this plan will involve many of the worst aspects of both plus cryogenics and operating rocket exhaust.
Fundamentally this becomes a new first stage, which possibly would be simpler as an actual first stage.
answered 2 days ago
GremlinWrangerGremlinWranger
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answered 2 days ago
GremlinWrangerGremlinWranger
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answered 2 days ago
GremlinWrangerGremlinWranger
2,808318
answered 2 days ago
GremlinWrangerGremlinWranger
2,808318
2,808318
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You should consider the amount of fuel feed into the tanks after lift off and compare it to the amount of fuel left in the hose and the weight of the hose itself after disconnection of the hose. If the hose with fuel weighs more than the added fuel, nothing was won.
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– Uwe
yesterday
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@Uwe that way I put the part about a shorter hose to run up aside it taking away the weight.
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– Muze
yesterday