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Externally heated steam rocket

Why carry the weight of the heat source?
  (+4, -1)
(+4, -1)
  [vote for,

We have the tech to make a steam rocket but heating sources make it so that they can not compete against our current engines.

We also currently use mirror arrays to heat molten salt to extreme temperatures.

Can we not combine these two technologies in such a way that an adjustable solar array not only pre-heats the water but tracks the rocket after launch and imparts energy to it from the ground?

We could take the weight of the previous heat source on board as added fuel or exchange it for payload.

https://en.wikipedi...olar_thermal_rocket [a1, Jun 09 2022]

Ground based lasers https://en.wikipedi...ki/Laser_propulsion
[AwarmRay, Jun 09 2022]

LightCraft https://science.how...ight-propulsion.htm
Also similar; does away with propellant as well. [neutrinos_shadow, Jun 09 2022]

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       Interesting idea, but for the weight of that salt or water, you can have stuff that has the potential energy built in chemically no?   

       Still a neat idea. [+]
doctorremulac3, Jun 09 2022

       Just water as propellant.   

       As per [a1]'s link...
Two things;
Why ammonia? They don't explain.

       And why have any solar collectors on the craft itself adding drag and redundancy when all power can be ground-based?   

       It makes no sense to me.   

       Preheating the propellant on board is a problem because it is so difficult to shed excess heat in a vacuum. Components will likely overheat and fail, including any passengers.
AwarmRay, Jun 09 2022

       //Just water as propellant.//   

       //Why ammonia? //   

       What you're looking for here is phase change, liquid>gas, because the gas wants to be in a much larger volume and so that's what's generating the pressure under the craft. Water is perhaps the worst of the more obvious choices because it's phase change is ludicrously expensive in terms of energy, water is a real oddball. It's 2256kJ/kg, vs say ethanol at 800 & something. If you're trying to lose heat energy, water is top of the list, but we're not, we want to make pressure from energy, and in that regard, ammonia is twice as good, and it has a boiling point (-33) that might be more amenable to the task.
bs0u0155, Jun 10 2022


       Cool. What are the environmental effects of releasing copious amounts of ammonia into the atmosphere as opposed to water vapour?
Water may suck as a propellant but if the ground based heat source is passive and solar then as much as water sucks the environmental impact and carbon footprint of such a rocket launch would be effectively zero other than the "contrail" and that should offset an absolutely huge amount of propellant suckitude when balanced against a rain of ammonia and laser power costs I would think.

       I just like trying to reduce things down, to their might -have-been-possible thousands of years ago stage, so a steam rocket powered by a parabolic array might have been something oh say they might have been able to pull off in ancient Greece or Egypt.   

       I went from a homestead childhood to modern times without finishing highschool so that's kind of my zone. Ancient tech.
In a magical "someday" I will have freed up enough time to hire a tutor to rapidly catch me up on several whacks of things I was either denied or had to give up learning in order to survive and put myself in a place to be able to learn when I became mature enough to do so.
I had to choose and that's the choice I made.

       I would very much like to learn the language of mathematics someday.   


       It's like my mantra.   

       Atmospheric ammonia isn't uncommon, it's largely released from agriculture. Cow, chicken and pig shit mostly. It exists in the atmosphere in a dynamic equilibrium with plant growth. Essentially, it's used by plants if it's high enough concentration.
bs0u0155, Jun 12 2022


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