4 ms·

So ironic Saturn-V is drawn as carrying 140 tons, while Apollo CSM is 30 tons and Lunar Module is 15 tons, yet Space Shuttle is drawn carrying just 27 tons. Def

by avmich 6y ago

So ironic Saturn-V is drawn as carrying 140 tons, while Apollo CSM is 30 tons and Lunar Module is 15 tons, yet Space Shuttle is drawn carrying just 27 tons. Definitely a case of apples and oranges.

Tuna-Fish 6y ago
They are listed with numbers about payload to (quite low) LEO. Apollo CSM and the Lunar Module were launched into a much higher-energy trajectory. The Saturn V could have launched 140 tons to LEO, it just never did. IIRC the most massive thing it ever launched was ~90 tons of Skylab.
- avmich 6y ago
  > They are listed with numbers about payload to (quite low) LEO. Then one should include the mass of Shuttle Orbiter. That the orbiter is used as a second stage... Saturn-V lists mass of third stage alright. > The Saturn V could have launched 140 tons to LEO, it just never did. No, it never could. It's a popular illusion. The only way to reach 140 was to count parts of Saturn V reaching orbit as payload. When you count payload only, that number falls. It's like counting the mass of Sputnik 1 adding the weight of the second stage of R-7. Or, in other words, a satellite with mass 140 tons couldn't be brought to LEO by Saturn V. To get Saturn V realistic number for LEO in similar sense to Shuttle's 27 tons (did Shuttle ever got 27 tons to orbit? Could it even be launched safely with 27 tons payload, given that it could only land with about 15 tons in the bay?), you should look at ~77 tons of Skylab. There is at least a hint that LEO payload is not all which gets to LEO.
  - bobthebuild123 6y ago
    I think you're confusing mass of the payload with something else. Mass of the payload to LEO is just how much mass is brought to LEO. According to "Alternatives for Future U.S. Space-Launch Capabilities" [0], the Saturn V did in fact bring 140 tons to LEO... [0] https://www.cbo.gov/publication/18196 https://www.cbo.gov/publication/18196
    - avmich 6y ago
      I think people are confusing the mass which appears on orbit with payload. Payload is (as meant when the word "payload" was created) rather the goal; in case of Saturn V it was Apollo stack which needed to be launched to the Moon. Similarly, in Space Shuttle case payload is something which is in the shuttle trunk; that's why typically a shuttle flies. Illustration for why 140 tons isn't the payload of Saturn V is that Saturn V wasn't able, or designed, to launch arbitrary 140 tons to LEO, and Skylab is a implicit confirmation of that. The definition of payload to LEO in case of higher-than-LEO missions can include booster stage and fuel, but then we have another strange case of Shuttle with IUS - the payload could fly higher, and was rather small, yet we don't consider Orbiter's mass as part of LEO payload in this case. Since, as another consideration, we usually consider Saturn V as a 3-staged rocket, not a 2-staged (as flew with Skylab) with a space booster stage which is used for LEO insertion as well as for subsequent translunar injection, it would be logical not to include 3rd Saturn's stage into LEO payload. Then Saturn V LEO payload becomes too small to be meaningful (TLI requires a lot of fuel). It would be better - here - to consider Space Shuttle LEO payload to include Orbiter's mass - that justifies large liftoff weight. As for what's Saturn V LEO payload, this question is better be met with clarifications.
    - avmich 6y ago
      From https://www.cbo.gov/publication/18196 https://www.cbo.gov/publication/18196, the link above: "The payload of 140 metric tons is derived from weight data pro-vided in Richard W. Orloff, Apollo by the Numbers: A Statistical Reference, NASA SP-2000-4029 (National Aeronautics and Space Administration, updated September 27, 2005), available at http://history.nasa.gov/SP-4029/SP-4029.htm http://history.nasa.gov/SP-4029/SP-4029.htm. In that reference, 140 mt is the weight of the Apollo 17 command-and-service modules, the lunar module, the spacecraft/lunar module adapter, the instrument unit, and the S-IVB stage (the third stage of the Saturn V), including the fuel remaining in that stage needed to propel the Apollo command-and-service modules and lunar module from low earth orbit to the moon." So this number includes the S-IVB stage and unspent fuel. Which ought to raise the question of the definition of the payload - we don't usually consider launcher's parts among payload mass. > Mass of the payload to LEO is just how much mass is brought to LEO. No, it's usually not that simple - Space Shuttle here doesn't include Orbiter's mass (I think it's a mistake), Sputnik payload didn't include R-7 second stage (I think it's right), Energia doesn't have 0 LEO payload even though it releases the payload below LEO (I think this definition is also more meaningful).
deleted 6y ago
[deleted]
jccooper 6y ago
The chart is tons to LEO. Saturn V wasn't designed for LEO, but it certainly could have dropped that much there. (Skylab used a pretty fair fraction of that capability.) When you're comparing launchers you have to pick some baseline target orbit. LEO is a good lowest common denominator, but isn't quite fair as launch systems optimized for higher energy orbits (like the Saturn V) lose some of their advantage. But a higher orbit is even less fair to systems designed for LEO; choose anything else, like GEO or lunar insertion, STS would have a big fat 0.
- avmich 6y ago
  Yeah, I know, but the point is Saturn V is shown as carrying to LEO 140 tons - and 140 tons was actual translunar payload (Apollo CSM + LEM, ~45 tons) plus dry 3rd stage (~15 tons) plus unspent fuel in the 3rd stage (about 2/3 of initial load of 105 tons of fuel). At the same time Space Shuttle doesn't show the empty mass (a lot) and unspent fuel (very little) of Space Shuttle "second stage", which is Orbiter, and mentions only payload in the bay of that Orbiter. We could arbitrarily say Energia brings 0 tons on orbit - because it's, strictly speaking, a suborbital rocket, the payload needs to add some ~100 m/s of velocity to get to orbit, this was done to avoid getting empty stage to orbit (so no littering, no necessary maneuver to deorbit). Or, alternatively, we could say Energia brings 170 (!) tons to LEO - indeed, if one pays no attention to factual suborbital speed and adds mass of empty 2nd stage of Energia, which is 78-86 tons (http://buran.ru/htm/rocket.htm http://buran.ru/htm/rocket.htm), one gets this number. So it's important to carefully compare similar things. 140 tons for Saturn V is too different from 27 tons of Space Shuttle by method, not by result.
  - ggm 6y ago
    Thank you for a well reasoned argument. I would love some formalism of actual useful lofted weight, vs apparent weight lofted to some stated orbit. Getting 27 tonnes to LEO but leaving 50 tonnes in unstable orbit is not 77 tonnes of useful loft, to me (fictive example)

by avmich 6y ago

So ironic Saturn-V is drawn as carrying 140 tons, while Apollo CSM is 30 tons and Lunar Module is 15 tons, yet Space Shuttle is drawn carrying just 27 tons. Definitely a case of apples and oranges.

Tuna-Fish 6y ago

They are listed with numbers about payload to (quite low) LEO. Apollo CSM and the Lunar Module were launched into a much higher-energy trajectory. The Saturn V could have launched 140 tons to LEO, it just never did. IIRC the most massive thing it ever launched was ~90 tons of Skylab.

avmich 6y ago
> They are listed with numbers about payload to (quite low) LEO. Then one should include the mass of Shuttle Orbiter. That the orbiter is used as a second stage... Saturn-V lists mass of third stage alright. > The Saturn V could have launched 140 tons to LEO, it just never did. No, it never could. It's a popular illusion. The only way to reach 140 was to count parts of Saturn V reaching orbit as payload. When you count payload only, that number falls. It's like counting the mass of Sputnik 1 adding the weight of the second stage of R-7. Or, in other words, a satellite with mass 140 tons couldn't be brought to LEO by Saturn V. To get Saturn V realistic number for LEO in similar sense to Shuttle's 27 tons (did Shuttle ever got 27 tons to orbit? Could it even be launched safely with 27 tons payload, given that it could only land with about 15 tons in the bay?), you should look at ~77 tons of Skylab. There is at least a hint that LEO payload is not all which gets to LEO.
- bobthebuild123 6y ago
  I think you're confusing mass of the payload with something else. Mass of the payload to LEO is just how much mass is brought to LEO. According to "Alternatives for Future U.S. Space-Launch Capabilities" [0], the Saturn V did in fact bring 140 tons to LEO... [0] https://www.cbo.gov/publication/18196 https://www.cbo.gov/publication/18196
  - avmich 6y ago
    I think people are confusing the mass which appears on orbit with payload. Payload is (as meant when the word "payload" was created) rather the goal; in case of Saturn V it was Apollo stack which needed to be launched to the Moon. Similarly, in Space Shuttle case payload is something which is in the shuttle trunk; that's why typically a shuttle flies. Illustration for why 140 tons isn't the payload of Saturn V is that Saturn V wasn't able, or designed, to launch arbitrary 140 tons to LEO, and Skylab is a implicit confirmation of that. The definition of payload to LEO in case of higher-than-LEO missions can include booster stage and fuel, but then we have another strange case of Shuttle with IUS - the payload could fly higher, and was rather small, yet we don't consider Orbiter's mass as part of LEO payload in this case. Since, as another consideration, we usually consider Saturn V as a 3-staged rocket, not a 2-staged (as flew with Skylab) with a space booster stage which is used for LEO insertion as well as for subsequent translunar injection, it would be logical not to include 3rd Saturn's stage into LEO payload. Then Saturn V LEO payload becomes too small to be meaningful (TLI requires a lot of fuel). It would be better - here - to consider Space Shuttle LEO payload to include Orbiter's mass - that justifies large liftoff weight. As for what's Saturn V LEO payload, this question is better be met with clarifications.
  - avmich 6y ago
    From https://www.cbo.gov/publication/18196 https://www.cbo.gov/publication/18196, the link above: "The payload of 140 metric tons is derived from weight data pro-vided in Richard W. Orloff, Apollo by the Numbers: A Statistical Reference, NASA SP-2000-4029 (National Aeronautics and Space Administration, updated September 27, 2005), available at http://history.nasa.gov/SP-4029/SP-4029.htm http://history.nasa.gov/SP-4029/SP-4029.htm. In that reference, 140 mt is the weight of the Apollo 17 command-and-service modules, the lunar module, the spacecraft/lunar module adapter, the instrument unit, and the S-IVB stage (the third stage of the Saturn V), including the fuel remaining in that stage needed to propel the Apollo command-and-service modules and lunar module from low earth orbit to the moon." So this number includes the S-IVB stage and unspent fuel. Which ought to raise the question of the definition of the payload - we don't usually consider launcher's parts among payload mass. > Mass of the payload to LEO is just how much mass is brought to LEO. No, it's usually not that simple - Space Shuttle here doesn't include Orbiter's mass (I think it's a mistake), Sputnik payload didn't include R-7 second stage (I think it's right), Energia doesn't have 0 LEO payload even though it releases the payload below LEO (I think this definition is also more meaningful).

deleted 6y ago

[deleted]

jccooper 6y ago

The chart is tons to LEO. Saturn V wasn't designed for LEO, but it certainly could have dropped that much there. (Skylab used a pretty fair fraction of that capability.) When you're comparing launchers you have to pick some baseline target orbit. LEO is a good lowest common denominator, but isn't quite fair as launch systems optimized for higher energy orbits (like the Saturn V) lose some of their advantage. But a higher orbit is even less fair to systems designed for LEO; choose anything else, like GEO or lunar insertion, STS would have a big fat 0.

avmich 6y ago
Yeah, I know, but the point is Saturn V is shown as carrying to LEO 140 tons - and 140 tons was actual translunar payload (Apollo CSM + LEM, ~45 tons) plus dry 3rd stage (~15 tons) plus unspent fuel in the 3rd stage (about 2/3 of initial load of 105 tons of fuel). At the same time Space Shuttle doesn't show the empty mass (a lot) and unspent fuel (very little) of Space Shuttle "second stage", which is Orbiter, and mentions only payload in the bay of that Orbiter. We could arbitrarily say Energia brings 0 tons on orbit - because it's, strictly speaking, a suborbital rocket, the payload needs to add some ~100 m/s of velocity to get to orbit, this was done to avoid getting empty stage to orbit (so no littering, no necessary maneuver to deorbit). Or, alternatively, we could say Energia brings 170 (!) tons to LEO - indeed, if one pays no attention to factual suborbital speed and adds mass of empty 2nd stage of Energia, which is 78-86 tons (http://buran.ru/htm/rocket.htm http://buran.ru/htm/rocket.htm), one gets this number. So it's important to carefully compare similar things. 140 tons for Saturn V is too different from 27 tons of Space Shuttle by method, not by result.
- ggm 6y ago
  Thank you for a well reasoned argument. I would love some formalism of actual useful lofted weight, vs apparent weight lofted to some stated orbit. Getting 27 tonnes to LEO but leaving 50 tonnes in unstable orbit is not 77 tonnes of useful loft, to me (fictive example)