Undersea cities and bases
Been reading some old SF set in the depths of the ocean. It reminded me of numerous books, movies and TV shows set there.
Most of them have people living in large domes. Some (mostly TV & movies) have more "normal" cities with building connected by tubes. And the building are many stories tall.
Nice imagery. But neither will work.
Why? Because water pressure varies with depth. So does air pressure, but the difference in pressure between the bottom and top of the tallest building is a small fraction of an atmosphere (1 atm = ~15 psi or 1 kg/cm^2)
Underwater you get a 1 atm pressure difference every 32 feet (10 meters). That means a a 1 storey difference (~10 ft) is a third of an atmosphere.
If you've got a dome 100 meters in radius (1000 meters high) that's a 10 atmospher (150 psi or 10 kg/cm^2) difference. If you pressurize to match pressure at the bottom of the dome you'll have all that pressure trying to blow out the top of the dome. Very much not good.
If you set the pressure to match the pressure at top of the dome, you'll have all the pressure trying to get in at the bottom of the dome.
Neither situation is good for the dome.
Underwater towers? Every floor will have a 1/rd atmosphere pressure difference. This is somewhat doable, but you'd have to have airlocks between floors! And les not think about the elevators (decompressions times would be significant for a mere 10 floor change).
So for engineering reasons, undersea installations are only going to be one or two floors. Any larger height difference will require airlocks and all the fun that goes with them.
Now if you have "magic" materials that don't *care* about the pressures deep in the ocean (or force fields or the like) then you can just keep the installations at surface pressure and ignore this.
But if you go that route you've got to explain why these super-materials or force fields have made major changes to other things (like invulnerable armor)
This entry was originally posted at https://kengr.dreamwidth.org/1148941.html. Please comment there using OpenID.
Most of them have people living in large domes. Some (mostly TV & movies) have more "normal" cities with building connected by tubes. And the building are many stories tall.
Nice imagery. But neither will work.
Why? Because water pressure varies with depth. So does air pressure, but the difference in pressure between the bottom and top of the tallest building is a small fraction of an atmosphere (1 atm = ~15 psi or 1 kg/cm^2)
Underwater you get a 1 atm pressure difference every 32 feet (10 meters). That means a a 1 storey difference (~10 ft) is a third of an atmosphere.
If you've got a dome 100 meters in radius (1000 meters high) that's a 10 atmospher (150 psi or 10 kg/cm^2) difference. If you pressurize to match pressure at the bottom of the dome you'll have all that pressure trying to blow out the top of the dome. Very much not good.
If you set the pressure to match the pressure at top of the dome, you'll have all the pressure trying to get in at the bottom of the dome.
Neither situation is good for the dome.
Underwater towers? Every floor will have a 1/rd atmosphere pressure difference. This is somewhat doable, but you'd have to have airlocks between floors! And les not think about the elevators (decompressions times would be significant for a mere 10 floor change).
So for engineering reasons, undersea installations are only going to be one or two floors. Any larger height difference will require airlocks and all the fun that goes with them.
Now if you have "magic" materials that don't *care* about the pressures deep in the ocean (or force fields or the like) then you can just keep the installations at surface pressure and ignore this.
But if you go that route you've got to explain why these super-materials or force fields have made major changes to other things (like invulnerable armor)
This entry was originally posted at https://kengr.dreamwidth.org/1148941.html. Please comment there using OpenID.