Jump to content

Off world built spaceships


Spacescifi

Recommended Posts

5 hours ago, Spacescifi said:

For deep space missions I would add more more inflated bladders to it while in orbit. It will basically look like a rocket with a bunch of balloons strapped to the side walls.

This is a lot like some real concepts I've seen. Generally, in space you want something like balloon tanks. Cryogenics like LOX and methane mean you need insulation, so it's a bit harder than just making an aluminium balloon, but it's definitely possible and a very good idea, in fact. However, keep in mind that inflatable tanks only make sense if you can launch them deflated, then fill them with fuel once in space.

Pods are also nothing new, if you want a single-use colonization ship, hanging a landers off the sides it far better than trying to land the whole thing. Depending on the size, there could be a lot of them. However, they should have some way to access the main ship, or to connect together to gain more living space.

Link to comment
Share on other sites

3 hours ago, Dragon01 said:

This is a lot like some real concepts I've seen. Generally, in space you want something like balloon tanks. Cryogenics like LOX and methane mean you need insulation, so it's a bit harder than just making an aluminium balloon, but it's definitely possible and a very good idea, in fact. However, keep in mind that inflatable tanks only make sense if you can launch them deflated, then fill them with fuel once in space.

Pods are also nothing new, if you want a single-use colonization ship, hanging a landers off the sides it far better than trying to land the whole thing. Depending on the size, there could be a lot of them. However, they should have some way to access the main ship, or to connect together to gain more living space.

 

Ironically, inflatable reentry pods with balloons would be another boon. Basically kind of like inflatable lifeboats... just more futuristic.

Making them survive reentry would be a challenge to design an inflatable that won't burn up, but it would save on volume. Which is a limited resource on any realistic spaceship.

 

From what I have read, liquid methane requires passive cooling,  but. LOX requires active cooling for longer than a week missions.

 

I have a question. If I wanted to go cheaper, can I not just make a methane powder (as metallic methane development is not cheap) and burn it with a NTR?

No cryogenics required, or minimal ones at that? Or is their some innate benefit to using chemical over powdered methane and an NTR in orbit?

Granted, for landing or take-off use LOX and liquid methane, but in space I do not know why powdered methane and a nuclear thermal rocket cannot work.

 

Powdered methane is also being developed I read.

https://www.hydrogenappliances.com/methane.html

Edited by Spacescifi
Link to comment
Share on other sites

12 minutes ago, Spacescifi said:

Making them survive reentry would be a challenge to design an inflatable that won't burn up, but it would save on volume. Which is a limited resource on any realistic spaceship.

Surprisingly, it's not actually the case. If your pod can survive reentry, then it can probably survive being exposed to vacuum. Something built in space would not really need inflatables, you can carry stuff outside the main hull. Volume is fairly cheap in space. Of course, launch is a different matter, and that's where inflatables help.

There are some concepts of inflatable heat shields (the one in KSP, for instance, is based on a real NASA concept), so making an entire pod out of a similar material should be possible.

Quote

I have a question. If I wanted to go cheaper, can I not just make a methane powder (as metallic methane development is not cheap) and burn it with a NTR?

Methane hydrates are a very interesting topic. Yes, you could likely feed an NTR with them. You might want to dispense with silica (it could gum up the injector) and use normal methane clathrate as propellant, but the idea is good. The problem is with ensuring good reactor cooling, but I think it can be solved. Also, your specific impulse will be worse than with liquid methane, because water is heavier. Depending on the exact composition of the propellant, performance will be between methane and water NTRs. Raw specific impulse may not be that great (near the upper bound of what chemial engines can do), but the strong point of that set up is propellant volume. Also, you will have very good thrust, comparable to chemical engines.

This is not an engine for interplanetary ships, but you could use it for launch and landing, where low volume and high thrust give you an advantage. 

Link to comment
Share on other sites

4 hours ago, Dragon01 said:

Surprisingly, it's not actually the case. If your pod can survive reentry, then it can probably survive being exposed to vacuum. Something built in space would not really need inflatables, you can carry stuff outside the main hull. Volume is fairly cheap in space. Of course, launch is a different matter, and that's where inflatables help.

There are some concepts of inflatable heat shields (the one in KSP, for instance, is based on a real NASA concept), so making an entire pod out of a similar material should be possible.

Methane hydrates are a very interesting topic. Yes, you could likely feed an NTR with them. You might want to dispense with silica (it could gum up the injector) and use normal methane clathrate as propellant, but the idea is good. The problem is with ensuring good reactor cooling, but I think it can be solved. Also, your specific impulse will be worse than with liquid methane, because water is heavier. Depending on the exact composition of the propellant, performance will be between methane and water NTRs. Raw specific impulse may not be that great (near the upper bound of what chemial engines can do), but the strong point of that set up is propellant volume. Also, you will have very good thrust, comparable to chemical engines.

This is not an engine for interplanetary ships, but you could use it for launch and landing, where low volume and high thrust give you an advantage. 

 

What if I used methane hydrate powder ALONG with LOX, mix it and burn it with a NTR?

Is this really good for launching as opposed to the tough to handle LH/LOX mix?

Could this even serve as a substitute launch vehicle?

 

Thanks for the chemistry knowledge. I find it fascinating that the chemical fuel to a large degree decides how good your rocket engine is, with nuclear thermal reactors only enhancing it to a specific degree.

I also like that that everything hss a cost. It's like a game with clearly defined rules which can still be tweaked.

High thrust equals short rocket burn, but long burn means low thrust. Anything different involves so much heat that it becones another engibeering issue to be solved.

Edited by Spacescifi
Link to comment
Share on other sites

10 hours ago, Dragon01 said:

This is a lot like some real concepts I've seen. Generally, in space you want something like balloon tanks. Cryogenics like LOX and methane mean you need insulation, so it's a bit harder than just making an aluminium balloon, but it's definitely possible and a very good idea, in fact. However, keep in mind that inflatable tanks only make sense if you can launch them deflated, then fill them with fuel once in space.

Pods are also nothing new, if you want a single-use colonization ship, hanging a landers off the sides it far better than trying to land the whole thing. Depending on the size, there could be a lot of them. However, they should have some way to access the main ship, or to connect together to gain more living space.

Actually you don't really need insulation, just shade. 

Magnesium is slightly less dense than aluminum for the same applications.  

Polyethylene is one of our lightest and best materials for balloons, although it loses flexibility at liquid oxygen temperatures.  Kevlar and teflon are very good for cryogenic applications.  

Edited by farmerben
Link to comment
Share on other sites

This thread is quite old. Please consider starting a new thread rather than reviving this one.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...