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Can't we just have reusable space ships with engines that burn some kind of fuel and we just replenish that fuel? It seems a waste to use rockets and replace t

Can't we just have reusable space ships with engines that burn some kind of fuel and we just replenish that fuel? It seems a waste to use rockets and replace the whole rocket or most parts of it after each flight.

actionfromafar 2y ago
This is exactly what the article describes. Only the fuel and oxidant need replacing.
- DeathArrow 2y ago
  Yes, I know. I am only asking why we don't do it and why we didn't do it until now.
  - actionfromafar 2y ago
    I think the reason can be the industry incumbents - there just isn't much money to be made with such a simple design, only a nozzle and combined fuel and oxidant tank in PET plastic which can be recycled, no moving parts.
  - gus_massa 2y ago
    It's a toy that can go up 50 feet or less. You can't scale it too much. To get to space you need like 100km (x6000) and then a lot of speed sideways to get to orbit. This model works with a drop of fuel that evaporates and mix with the air. In a real rocket you most inject the fuel and oxygen from the tanks into the very hot and high pressure burning chamber, so you need pumps.
Sharlin 2y ago
Heard about the Space Shuttle? Or the SpaceX Falcon 9? The reason it hasn’t been done in scale before SpaceX is that reusability is a hard problem to solve and it is/was more economical to use expendable launch vehicles than to develop recoverable and refurbishable stages. You might also like to read about single-stage-to-orbit (SSTO) which is something of a pipe dream. The rocket equation is a bitch. https://en.wikipedia.org/wiki/Single-stage-to-orbit https://en.wikipedia.org/wiki/Single-stage-to-orbit
- philjohn 2y ago
  The shuttle was a re-usable ship, the rockets used to get it into space were not reusable.
  - skissane 2y ago
    That’s not true… both the RS-25 SSMEs and the SRBs were reused - however, the extent of refurbishment required between flights was so extensive, time-consuming and expensive, that it erased much of the benefits of reusability
  - Sharlin 2y ago
    Not so. The solid rocket boosters were reused, as were the three SSMEs bolted to the orbiter itself. The only part that wasn’t reusable was the external fuel tank because bringing it back intact from almost orbital speeds would’ve been hilariously uneconomical. That said, refurbishing both the SRBs and the SSMEs after each use was labor-intensive and as such expensive.
  - usrusr 2y ago
    The SRBs were collected from the sea for reused and the upper stage was reused after landing horizontally. The only thing not reused was the upper stage drop tank. That single use drop tank was rather big, true, but not a rocket, not a rocket at all. The Soviet lookalike did use a single use rocket as its second stage, with the reusable part just being an orbiter.
    - Sharlin 2y ago
      Interestingly, the Buran’s Energyia launch vehicle could possibly have been made reusable exactly because the tank and the engines were one unit. At the expense of payload capacity, of course. And anyway the Soviets were confused about the whole shuttle concept because it didn't seem to make economical sense, reusable booster or not – but they assumed the Americans knew something they didn't.
      - usrusr 2y ago
numpad0 2y ago
Earth's gravity is too strong and human energy exploitation isn't large enough to allow for such reusable rockets. The rockets we humans fly look massive and shame to discard, but they're more like liquid fueled balloons than proper spaceships for their scales. e.g., the Al-Li metal layer of Shuttle ET was 0.1" thick at thinnest points yet those ET were 150ft+ tall. iPhone back covers are thicker than that. Rocketry gears are infuriatingly flimsy relative to their size, but they have to be because that's what it currently takes to fly to space. If we could build ships on the Moon from Lunar rocks out of a grinder, or if we could build an all-fusion spaceships, we can (relatively)easily have 2m thick radiation shielding, or 8km wide hulls, or anything we want. But we're not doing it, but are stuck with lox-fuel chemical propulsion, so we can only make them so durable.
- marsovo 2y ago
  More context on the external tank: https://archive.is/2017.03.30-030831/https://www.nasa.gov/mission_pages/station/expeditions/expedition30/tryanny.html https://archive.is/2017.03.30-030831/https://www.nasa.gov/mi... > The common soda can, a marvel of mass production, is 94% soda and 6% can by mass. Compare that to the external tank for the Space Shuttle at 96% propellant and thus, 4% structure. The external tank, big enough inside to hold a barn dance, contains cryogenic fluids at 20 degrees above absolute zero (0 Kelvin), pressurized to 60 pounds per square inch, (for a tank this size, such pressure represents a huge amount of stored energy) and can withstand 3gs while pumping out propellant at 1.5 metric tons per second. The level of engineering knowledge behind such a device in our time is every bit as amazing and cutting-edge as the construction of the pyramids was for their time.
  - MarkusWandel 2y ago
    The (early) Atlas ICBM was even less substantial than a soda can. There used to be one parked on the front lawn of our local science museum. It had to be kept inflated with pressurized air. When the time came to retire it and they let the air out... https://ottawacitizen.com/news/local-news/museum-shrugs-as-atlas-rocket-lies-wrecked-in-snow https://ottawacitizen.com/news/local-news/museum-shrugs-as-a... In service, of course, the necessary pressure would have been maintained by propellant boil-off.
bityard 2y ago
I don't think NASA is having any problem finding room in their budget for soda bottles.
snickerbockers 2y ago
not sure what this has to do with the middle-school science-fair project in the OP, but the whole "reusable shuttles" idea hasn't really panned out that well. The Russian Soyuuz rockets haven't changed much since the 70s and they have an excellent safety record compared to the space shuttles.

actionfromafar 2y ago

This is exactly what the article describes. Only the fuel and oxidant need replacing.

DeathArrow 2y ago
Yes, I know. I am only asking why we don't do it and why we didn't do it until now.
- actionfromafar 2y ago
  I think the reason can be the industry incumbents - there just isn't much money to be made with such a simple design, only a nozzle and combined fuel and oxidant tank in PET plastic which can be recycled, no moving parts.
- gus_massa 2y ago
  It's a toy that can go up 50 feet or less. You can't scale it too much. To get to space you need like 100km (x6000) and then a lot of speed sideways to get to orbit. This model works with a drop of fuel that evaporates and mix with the air. In a real rocket you most inject the fuel and oxygen from the tanks into the very hot and high pressure burning chamber, so you need pumps.

Sharlin 2y ago

Heard about the Space Shuttle? Or the SpaceX Falcon 9? The reason it hasn’t been done in scale before SpaceX is that reusability is a hard problem to solve and it is/was more economical to use expendable launch vehicles than to develop recoverable and refurbishable stages. You might also like to read about single-stage-to-orbit (SSTO) which is something of a pipe dream. The rocket equation is a bitch. https://en.wikipedia.org/wiki/Single-stage-to-orbit https://en.wikipedia.org/wiki/Single-stage-to-orbit

philjohn 2y ago
The shuttle was a re-usable ship, the rockets used to get it into space were not reusable.
- skissane 2y ago
  That’s not true… both the RS-25 SSMEs and the SRBs were reused - however, the extent of refurbishment required between flights was so extensive, time-consuming and expensive, that it erased much of the benefits of reusability
- Sharlin 2y ago
  Not so. The solid rocket boosters were reused, as were the three SSMEs bolted to the orbiter itself. The only part that wasn’t reusable was the external fuel tank because bringing it back intact from almost orbital speeds would’ve been hilariously uneconomical. That said, refurbishing both the SRBs and the SSMEs after each use was labor-intensive and as such expensive.
- usrusr 2y ago
  The SRBs were collected from the sea for reused and the upper stage was reused after landing horizontally. The only thing not reused was the upper stage drop tank. That single use drop tank was rather big, true, but not a rocket, not a rocket at all. The Soviet lookalike did use a single use rocket as its second stage, with the reusable part just being an orbiter.
  - Sharlin 2y ago
    Interestingly, the Buran’s Energyia launch vehicle could possibly have been made reusable exactly because the tank and the engines were one unit. At the expense of payload capacity, of course. And anyway the Soviets were confused about the whole shuttle concept because it didn't seem to make economical sense, reusable booster or not – but they assumed the Americans knew something they didn't.
    - usrusr 2y ago

numpad0 2y ago

Earth's gravity is too strong and human energy exploitation isn't large enough to allow for such reusable rockets. The rockets we humans fly look massive and shame to discard, but they're more like liquid fueled balloons than proper spaceships for their scales. e.g., the Al-Li metal layer of Shuttle ET was 0.1" thick at thinnest points yet those ET were 150ft+ tall. iPhone back covers are thicker than that. Rocketry gears are infuriatingly flimsy relative to their size, but they have to be because that's what it currently takes to fly to space. If we could build ships on the Moon from Lunar rocks out of a grinder, or if we could build an all-fusion spaceships, we can (relatively)easily have 2m thick radiation shielding, or 8km wide hulls, or anything we want. But we're not doing it, but are stuck with lox-fuel chemical propulsion, so we can only make them so durable.

marsovo 2y ago
More context on the external tank: https://archive.is/2017.03.30-030831/https://www.nasa.gov/mission_pages/station/expeditions/expedition30/tryanny.html https://archive.is/2017.03.30-030831/https://www.nasa.gov/mi... > The common soda can, a marvel of mass production, is 94% soda and 6% can by mass. Compare that to the external tank for the Space Shuttle at 96% propellant and thus, 4% structure. The external tank, big enough inside to hold a barn dance, contains cryogenic fluids at 20 degrees above absolute zero (0 Kelvin), pressurized to 60 pounds per square inch, (for a tank this size, such pressure represents a huge amount of stored energy) and can withstand 3gs while pumping out propellant at 1.5 metric tons per second. The level of engineering knowledge behind such a device in our time is every bit as amazing and cutting-edge as the construction of the pyramids was for their time.
- MarkusWandel 2y ago
  The (early) Atlas ICBM was even less substantial than a soda can. There used to be one parked on the front lawn of our local science museum. It had to be kept inflated with pressurized air. When the time came to retire it and they let the air out... https://ottawacitizen.com/news/local-news/museum-shrugs-as-atlas-rocket-lies-wrecked-in-snow https://ottawacitizen.com/news/local-news/museum-shrugs-as-a... In service, of course, the necessary pressure would have been maintained by propellant boil-off.

bityard 2y ago

I don't think NASA is having any problem finding room in their budget for soda bottles.

snickerbockers 2y ago

not sure what this has to do with the middle-school science-fair project in the OP, but the whole "reusable shuttles" idea hasn't really panned out that well. The Russian Soyuuz rockets haven't changed much since the 70s and they have an excellent safety record compared to the space shuttles.