Real Spaceship Shapes Versus Scifi Shapes

[Spacescifi]

 

The shapes IRL are optimal when they are oblong, because of air drag getting to space. The more drag the more propellant and the less payload carried.

 

So rocket shapes are and will always remain a practical shape for spaceships IRL.

 

The only thing close to scifi shapes that is practical at all is a ring for spin gravity.

Yet is easier still to just put long pods on tethers and spin.

 

As for the variety of shapes seen in scifi, they would be practical to me only if they could block gravity.

Since then drag would not matter as much.

 

So long gravity is on it does.

[Kerbart]

So what about ships assembled in space? To what extend does the drive system matter?

[XLjedi]

Artificial gravity aside...  Spaceships assembled in space just need to have propulsion systems that are properly aligned with the COM. 

At extreme speeds in the "c" percentage ranges:

Some might also argue that presenting as small a cross-section as possible when moving forward at stupid speed might also avoid impact damage from tiny space particles.  

[Spacescifi]

33 minutes ago, Kerbart said:

So what about ships assembled in space? To what extend does the drive system matter?

Oblong means you can place the crew section AWAY from the engines... since IRL efficient space rocket engines involve nuclear or some other radioactive shenanigans. Yes you can still get by with solid material (not scifi BTW) shielding, but in general even then putting a little extra space between the radioactive engine and the crew is is still just an extra precaution.

 

22 minutes ago, XLjedi said:

Artificial gravity aside...  Spaceships assembled in space just need to have propulsion systems that are properly aligned with the COM. 

At extreme speeds in the "c" percentage ranges:

Some might also argue that presenting as small a cross-section as possible when moving forward at stupid speed might also avoid impact damage from tiny space particles.  

 

Having a narrow frontal cross section lends itself to the rocket shape.

That said, we realky do not need ablative shielding or wide surfaces for slowing for reentry.... if we have a magnetic ionized field to deflect the oncoming atmospheric plasma. That on it's own will help slow the vessel in reentry without heating up the hull so much that ablative hull armor is required.

Furthermore the ionized magnetic field can be expanded to give even more slowing power during reentry. Deep atmosphere will likely blow off the ionized field, but by then hopefully the vessel is at more reasonable falling speeds.

 

Regarding high space speeds... I really would much rather we had jump or warp drives like scifi. With those you don't need the near infinite amounts of fuel required for cobstant acceleration.

Like one user pointed out, with rapid enough jump drives a vessel could pop in and out over a planet to get ANY planetary orbital transfer or speed matching it ever wanted. Without any propellant at all. Just falling.

With those, you realky could do any shape and it would be ok.

[kerbiloid]

The parts sticking out are either a poor tech level, or a bad design.
A proper future spaceship should have a shape to be swallowed without causing appendicite.

Upd.
They didn't understand this.

Spoiler

 

Edited March 13, 2020 by kerbiloid

[Spacescifi]

3 minutes ago, kerbiloid said:

The parts sticking out are either a poor tech level, or a bad design.
A proper future spaceship should have a shape to be swallowed without causing appendicite.

 

Usually I get you... not this time.

I have not the foggiest what joke you are on about this time.

6 minutes ago, kerbiloid said:

The parts sticking out are either a poor tech level, or a bad design.
A proper future spaceship should have a shape to be swallowed without causing appendicite.

Upd.
They didn't understand this.

  Hide contents

 

 

You can have any shape you want if you have sufficient high thrust and an ionized magnetized field for reentry.

 

IRL the millenium falcon could exist with a nuclear pusher plate blowing up mini nukes behind it. Reentry could be easy with the ionized field slowing descent until deep atmophere blows it off.

 

From there, old fashioned airbreathing rocket thrusters help land.

 

If we want realy advanced, we ditch the airbreathing rockets entirely and use MHD field ion dynamics to fly in air.

[kerbiloid]

12 minutes ago, Spacescifi said:

Usually I get you... not this time.

Any device should have a hull with as less parts sticking out as possible. Just a engineering culture.

Also sharp edges and corners are usually smoothed.

Edited March 13, 2020 by kerbiloid

[XLjedi]

5 minutes ago, kerbiloid said:

Any device should have a hull with as less parts sticking out as possible. Just a engineering culture.

IKR?   How many times has the Millennium Falcon scraped off that stupid comms dish!

Edited March 13, 2020 by XLjedi

[Spacescifi]

1 minute ago, kerbiloid said:

Any device should have a hull with as less parts sticking out as possible. Just a engineering culture.

That's what MHD would look like BTW.

Design  magnetic plasma field trick well enough and one can possibly reach orbital velocity in atmosphere.

Still would need an engine to regain some. lost orbital speed once they reach space, but far less propellant hungry than rocket launch to space.

[Kerbart]

1 hour ago, Spacescifi said:

Oblong means you can place the crew section AWAY from the engines... since IRL efficient space rocket engines involve nuclear or some other radioactive shenanigans. Yes you can still get by with solid material (not scifi BTW) shielding, but in general even then putting a little extra space between the radioactive engine and the crew is is still just an extra precaution.

But there are construction and other constraints that limit the oblong shape, hence my question.

Putting the crew cabin at a considerable (once we get into the hundreds insted of dozens of meters) distance from the COM will severely limit the turn rate of the ship (without the crew passing out)

If your drive system is powerful enough to generate gravity (as in The Expanse) structural design comes into place and a cone shape might be more desirable than a cigar shape.

Finallyif the hull needs to be pressurized choosing a stubby cylinder or even a ball shape might be worth considering over an oblong shape simply because less hull plating is needed.

 

All together I’m not so convinced that the oblong shape is that obvious the single solution.

[sevenperforce]

56 minutes ago, Spacescifi said:

You can have any shape you want if you have sufficient high thrust and an ionized magnetized field for reentry.

IRL the millenium falcon could exist with a nuclear pusher plate blowing up mini nukes behind it. Reentry could be easy with the ionized field slowing descent until deep atmophere blows it off.

Ionized field shield doesn't do enough for entry. You can use it for aerocapture into a lower orbit though.

[Spacescifi]

1 hour ago, Kerbart said:

But there are construction and other constraints that limit the oblong shape, hence my question.

Putting the crew cabin at a considerable (once we get into the hundreds insted of dozens of meters) distance from the COM will severely limit the turn rate of the ship (without the crew passing out)

If your drive system is powerful enough to generate gravity (as in The Expanse) structural design comes into place and a cone shape might be more desirable than a cigar shape.

Finallyif the hull needs to be pressurized choosing a stubby cylinder or even a ball shape might be worth considering over an oblong shape simply because less hull plating is needed.

 

All together I’m not so convinced that the oblong shape is that obvious the single solution.

 

When I say oblong I mean longer than wide only... the length is up to reason.

I am the one who made the thread about size matters remember?

 

 

1 hour ago, sevenperforce said:

Ionized field shield doesn't do enough for entry. You can use it for aerocapture into a lower orbit though.

 

I am sure with sufficient power and gas density of the field bubble it is possible.

 

May not be easu, but one can do s lot with magnets, air, and plasma.

 

Edited March 13, 2020 by Spacescifi

[XLjedi]

I'm thinkin... 

Spoiler

Large cubes are maybe the way to go! 

...and the Star Trek Next Gen model designer that week was like,  "Damn, I totally forgot I was supposed to start designing a Borg ship 3 weeks ago and it's due to production in an hour-and-a-half!"  Whatever shall I to do?

 

[Kerbart]

1 hour ago, Spacescifi said:

I am the one who made the thread about size matters remember?

Obviously not  but that was indeed what I had mind.

I think we agree on what atmospheric craft would look like but I also think that 90% or more will not be atmospheric and will have a ball/cube like shape, simply to save on materials needed and to keep angukar momentum down during maneuvers. I think that “The Expanse” does a good job in depicting how such ships would look like.

[sevenperforce]

19 hours ago, Spacescifi said:

 

20 hours ago, sevenperforce said:

Ionized field shield doesn't do enough for entry. You can use it for aerocapture into a lower orbit though.

I am sure with sufficient power and gas density of the field bubble it is possible.

May not be easu, but one can do s lot with magnets, air, and plasma.

Magnetic flux drops off with the cube of distance, so the square-cube law really punishes this kind of approach. With the high-efficiency nuclear engines you're discussing, any appreciably-sized ship will soon need more mass associated with the magnetic entry shield than it would take to simply uses retropropulsion all the way down.

[Spacescifi]

5 hours ago, sevenperforce said:

Magnetic flux drops off with the cube of distance, so the square-cube law really punishes this kind of approach. With the high-efficiency nuclear engines you're discussing, any appreciably-sized ship will soon need more mass associated with the magnetic entry shield than it would take to simply uses retropropulsion all the way down.

 

Well this is the best I can do with my understanding of current physics science.

If there was a way to magnetize gases.... actually... there is.

 

Scifi cannot predict everything, but where there is a will, there is a way that the universe will always provide for us.

In other words, based on this alone, I believe there is a way to safely do reentry using some sort of electromagnetic shenanigans without a prohibitive amount of mass/weight.

 

 

https://physicsworld.com/a/optical-centrifuge-magnetizes-molecular-gas/

 

 

[magnemoe]

22 hours ago, Kerbart said:

Obviously not  but that was indeed what I had mind.

I think we agree on what atmospheric craft would look like but I also think that 90% or more will not be atmospheric and will have a ball/cube like shape, simply to save on materials needed and to keep angukar momentum down during maneuvers. I think that “The Expanse” does a good job in depicting how such ships would look like.

Out of atmosphere depend on many factors, do you have spin gravity. Do you have an radioactive engine and how radioactive then idle. 
How long will you burn and at how high trust, how large radiators do you need. 

[Spacescifi]

23 hours ago, Kerbart said:

Obviously not  but that was indeed what I had mind.

I think we agree on what atmospheric craft would look like but I also think that 90% or more will not be atmospheric and will have a ball/cube like shape, simply to save on materials needed and to keep angukar momentum down during maneuvers. I think that “The Expanse” does a good job in depicting how such ships would look like.

 

Non-atmospheric craft are by nature modular contraptions, which implies some rocket boosted them to orbit. A bunch of small craft screwed or bolted together to become one multimodular contraption with an engine strapped to it.

The Expanse's most well known ship, the Rociante, DOES NOT look like the kind of thing someone built in orbit, because if they did, it would have taken either a long time or a lot of launches to construct it. Unless they used project Orion but they don't appear to know of it nor use it.

Which is why the human faction in my scifi definitely will use project Orion, aerospikes, and NTTR, since popular media scifi is ignorant of them all for the most part.

The only other IRL way I know of to get a whole ship or group of ships to orbit in one piece is project Orion.

Edited March 14, 2020 by Spacescifi