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I don’t know. People extend their sense of endearment towards space to SpaceX as it is the best positioned company. Americans have a ton of nostalgia about the

I don’t know. People extend their sense of endearment towards space to SpaceX as it is the best positioned company. Americans have a ton of nostalgia about the space race. Hollywood gave a lot of cool tales. A lot of emotions at play here. Take a step back and look at the technology. Sure reusable rockets are cool but still way short of what we need to make it economical at scale. People in 60s over achieved and it’ll be a long time before we surpass them. Even then we have a long way ahead. Maybe if there’s a breakthrough in propulsion, fuels etc that’ll give a 10x-100x efficiency improvement then we can hope for something in our lifetime. Otherwise I still see it as a niche activity. I don’t really get this “single point of failure” argument. Sure, I won’t deny that risk but it’s situated in a cosmic timescale. I don’t see it with any urgency just as I don’t see earth being swallowed by the Sun or the heat death of the universe with urgency. These are cataclysmic events.

panick21_ 5y ago
> Sure reusable rockets are cool but still way short of what we need to make it economical at scale. That is exactly what Starship is attempting to do. > People in 60s over achieved and it’ll be a long time before we surpass them. They could easily be surpassed with the same amount of money. > Maybe if there’s a breakthrough in propulsion, fuels etc that’ll give a 10x-100x efficiency improvement then we can hope for something in our lifetime. Full and rapid re-usability is exactly that break-threw. There is a reason every other method of transportation is very re-usable and much cheaper. Other fuels make it more expensive, not less. Cheaper then methane is unlikely whatever it is.
- avmich 5y ago
  >> People in 60s over achieved and it’ll be a long time before we surpass them. > They could easily be surpassed with the same amount of money. We're actually surpassing it every day. With the exception of manned Moon flights - largely because the lack of immediate need, and associated with that barrier of lacking specialized equipment like lunar lander - all or almost all manned and unmanned technologies are used on a substantially higher level today.
  - panick21_ 5y ago
    I was referring to the moon flights. Of course I know that most of technology is much better today. I just recently did some comparison between engines of Saturn 1B and Falcon 9 for example.
- techdragon 5y ago
  Cheapest fuel combinations from a logistics perspective, accounting for cost factors affecting shipping, handling, complexity of handling in the fuelling operations and storage inside the rocket, and cost impact on the rocket motor itself. Based on the "outsider analysis" that I performed a couple of years ago as a non-"aerospace engineer" who's way to interested in rocket engines. Leads to this: - Toxic -> Red Fuming Nitric Acid (RFNA) and pretty much any mix of liquid hydrocarbons of molecular weight / distillation fraction between Diesel and Kerosene (probably more generous than that) - Non Toxic -> Nitrous Oxide and Propane. This is of course not factoring in the price to performance ratio of the fuel choice which is why many rockets chose other combinations. This sort of math really only applies when you start thinking about things like "how expensive would it be to fuel a sea dragon sized rocket".
  - panick21_ 5y ago
    That could be potentially be true, I don't know enough he prices and supply chain. But It seem that this would only be a marginal improvement over metholox at best. SpaceX will get methane directly from methane production on site and will use solar power that is also be on site. Hard to see how one could beat that. What factory in your analysis made the difference?
    - techdragon 5y ago
      Cryogenic temperatures. They introduced a large number of additional costs. From boil off management systems to more expensive cryogenic pumps, to insulation materials and extra fuel to cover the fuel that boils off. Cryogenic fuel and oxidiser combinations are generally more powerful, but Litre for Litre, a cryogenic liquid costs more to get and keep around than a room temperature one, even one that needs to be kept at moderate pressure, cryogenic related costs didn’t get exceeded till you look at less common chemicals with higher bulk manufacturing costs. One big factor in favour of cryogenic fuel and oxidiser is they are much better engine and nozzle coolants in regeneratively cooled rocket engines. This is why they are so common. My analysis was based on Sea Dragon sized rockets with similarly simplistic engines not designed for reuse. The rapid reuse goals of SpaceX Starship pretty much demands regeneratively cooled rocket engines which are easiest with cryogenic at least a cryogenic oxidiser and once your working with one cryogenic liquid you may as well just go fully cryogenic with a cryogenic fuel to get even more cooling capacity.

panick21_ 5y ago

> Sure reusable rockets are cool but still way short of what we need to make it economical at scale. That is exactly what Starship is attempting to do. > People in 60s over achieved and it’ll be a long time before we surpass them. They could easily be surpassed with the same amount of money. > Maybe if there’s a breakthrough in propulsion, fuels etc that’ll give a 10x-100x efficiency improvement then we can hope for something in our lifetime. Full and rapid re-usability is exactly that break-threw. There is a reason every other method of transportation is very re-usable and much cheaper. Other fuels make it more expensive, not less. Cheaper then methane is unlikely whatever it is.

avmich 5y ago
>> People in 60s over achieved and it’ll be a long time before we surpass them. > They could easily be surpassed with the same amount of money. We're actually surpassing it every day. With the exception of manned Moon flights - largely because the lack of immediate need, and associated with that barrier of lacking specialized equipment like lunar lander - all or almost all manned and unmanned technologies are used on a substantially higher level today.
- panick21_ 5y ago
  I was referring to the moon flights. Of course I know that most of technology is much better today. I just recently did some comparison between engines of Saturn 1B and Falcon 9 for example.
techdragon 5y ago
Cheapest fuel combinations from a logistics perspective, accounting for cost factors affecting shipping, handling, complexity of handling in the fuelling operations and storage inside the rocket, and cost impact on the rocket motor itself. Based on the "outsider analysis" that I performed a couple of years ago as a non-"aerospace engineer" who's way to interested in rocket engines. Leads to this: - Toxic -> Red Fuming Nitric Acid (RFNA) and pretty much any mix of liquid hydrocarbons of molecular weight / distillation fraction between Diesel and Kerosene (probably more generous than that) - Non Toxic -> Nitrous Oxide and Propane. This is of course not factoring in the price to performance ratio of the fuel choice which is why many rockets chose other combinations. This sort of math really only applies when you start thinking about things like "how expensive would it be to fuel a sea dragon sized rocket".
- panick21_ 5y ago
  That could be potentially be true, I don't know enough he prices and supply chain. But It seem that this would only be a marginal improvement over metholox at best. SpaceX will get methane directly from methane production on site and will use solar power that is also be on site. Hard to see how one could beat that. What factory in your analysis made the difference?
  - techdragon 5y ago
    Cryogenic temperatures. They introduced a large number of additional costs. From boil off management systems to more expensive cryogenic pumps, to insulation materials and extra fuel to cover the fuel that boils off. Cryogenic fuel and oxidiser combinations are generally more powerful, but Litre for Litre, a cryogenic liquid costs more to get and keep around than a room temperature one, even one that needs to be kept at moderate pressure, cryogenic related costs didn’t get exceeded till you look at less common chemicals with higher bulk manufacturing costs. One big factor in favour of cryogenic fuel and oxidiser is they are much better engine and nozzle coolants in regeneratively cooled rocket engines. This is why they are so common. My analysis was based on Sea Dragon sized rockets with similarly simplistic engines not designed for reuse. The rapid reuse goals of SpaceX Starship pretty much demands regeneratively cooled rocket engines which are easiest with cryogenic at least a cryogenic oxidiser and once your working with one cryogenic liquid you may as well just go fully cryogenic with a cryogenic fuel to get even more cooling capacity.