Psst, the events in the last few posts are spoilers and we have folk explicitly new to the show in the thread....
Babylon 5
- Thread starter Kail
- Start date
I've added a couple of spoiler tags. Obviously, I can't edit the posts that contain spoilers to which I was responding.
Perhaps Warner Brothers is looking into upgrading the special effects to High Definition or Ultra HD. This recent tweet from JMS might be a hint. Fingers crossed.
On the subject of artificial gravity inside the station, Babylon 5 has a radius of R=800m (not 420m as some sources state) so to produce an acceleration of one Earth gravity or g=9.81 m/s^2 at this radius, the cylinder must rotate at √(Rg) m/s or v=88.6 m/s, which is 319 km/h or 199 mph, not the 60 mph that Ivanova stated. Perhaps she was factoring in the expected acceleration on a falling man due to the air corotating with the cylinder. I'm assuming that the air corotates all the way from the inner surface to the axis so its speed measured by an observer in an inertial frame of reference would increase linearly with radius. I'm actually interested in estimating this now - I need to get a life.
The cylinder would rotate once every 56.7 seconds (2πR/v). That seems slower than what is depicted onscreen but I haven't timed it. Not worried about that as other things such as the scale of Starfuries with respect to the station seemed to be all over the shop in effects shots.
The cylinder would rotate once every 56.7 seconds (2πR/v). That seems slower than what is depicted onscreen but I haven't timed it. Not worried about that as other things such as the scale of Starfuries with respect to the station seemed to be all over the shop in effects shots.
Good to know. I'll willing invest in a HD version on Blu-ray. It doesn't even have to be UHD. The composite effects sequences, combining CGI and film, will be a pain to reproduce in HD, I guess, as didn't they lose all the film elements? I don't recall exactly how.
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According to the B5Scrolls interviews, the design size for the station was that the rotating section was five miles long, and a mile in diameter at its widest point. Though according to this calculator, that gives me even faster numbers than the ones you got and has the ground rotating at 200 mph.
Yes, I've corrected my post. Thanks
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The rotating section is definitely NOT 1 mile (nautical or statute) in diameter. It may be 1 mile in circumference...maybe.
https://www.b5tech.org/babylonproject/babylon5station/babylon5station.html
The physical proportions don't allow for it to be that large in diameter. If it's 5 miles (statute, I would assume) then it can't be anywhere near one mile across at any point.
https://www.b5tech.org/babylonproject/babylon5station/babylon5station.html
The physical proportions don't allow for it to be that large in diameter. If it's 5 miles (statute, I would assume) then it can't be anywhere near one mile across at any point.
I'll take 800m as the radius so that's a circumference of 5026m or 3.14 miles. The period of rotation is 2π√(R/g), which coincidentally is similar to the equation for the period of a simple pendulum.
Having done the calculations, assuming an initial radial velocity as high as u=10m/s (3m/s of that being the rotational velocity at 20m; the rest being from muscle power), the radial velocity is approximately uD/(D+ut) m/s so after 50 seconds with a drag factor D=300m (*) the radial velocity has dropped to 3.75 m/s and the radial distance travelled is Dln(1+(ut/D)) or about 294m. After 100s, the distance is 440m; 300s 719m. The time to travel radially 800m to the cylinder floor is about 402s or 6 minutes 42 seconds. He would meet the floor with a radial velocity of 0.7m/s or only about 2mph. However, the corotating air would speed his tangential velocity up so that its difference from the cylinder floor speed is R/((R/V)-((t+D/u)ln(1+ut/D)-t)). I won't state the figure I calculated as I don't have much confidence in the value of D (not to say my maths). Say this tangential velocity is 62m/s but the cylinder floor is moving at 88.6m/s so it's overtaking him or he's travelling backward relative to it. He'd hit the ground tangentially at 88.6 - 62 m/s, that is, 26.6m/s, 96km/h or 60mph. That's a big ouch even if he manages not to slam into the side of a building or other structure at a higher speed before he hits dirt, which seems not improbable to me. A big arrestor net or air cushion put in his path would be the easiest way of catching him.
There's a large uncertainty as the drag factor (D=300m) plays a big role both in slowing down the radial velocity and speeding up the tangential velocity. Decrease it too much and he takes hours not minutes to reach the ground although he does touch down safely or hits the side of something very slowly; increase it too much and he's a streak across the landscape or a stain on a wall. I suspect D=300m is on the low side as that corresponds to a sky diver maximising their cross sectional area.
Seen by an inertial observer, the trajectory of a body inside the cylinder only intersects the inside surface, it isn't accelerated toward it. The centrifugal acceleration that a comoving observer on the inside surface experiences is a result of the reaction against the surface which is constantly changing their tangential velocity vector as a centripetal acceleration toward the axis. This reaction against the surface is felt as an attractive force akin to gravitational acceleration acting on a mass. For a small R cylinder, the person might notice apparent strange effects due to the different distances of different parts of their body from the axis of rotation. Such effects happen even on Earth due to its rotation but they are tiny.
I did wonder if it is possible to breath near the axis. I reckon the air pressure at a distance r from the axis to be exp(-(R^2-r^2)/2(H^2)) of the air pressure at the cylinder surface where the scale height H is cR/V = 3160m, c being the speed of sound in air, 350m/s for air at a temperature of 290K (approx. 17°C or 63°F). So the pressure at the axis is 94% of that at the cylinder surface.
(*) I used the typical minimal terminal velocity of w=54 m/s for a sky diver to estimate the drag factor D at 300m ((w^2)/g terminal velocity squared divided by gravitational acceleration g=9.81m/s^2), which is equal to 2m/ρAC where m is the mass, ρ the air density, A the cross-sectional area and C the drag coefficient. It's easier to work out D from w and g than from m, ρ, A, and C. The acceleration due to the drag force is then simply (v^2)/D. I expect D=300m is an underestimate.
The air density should vary similarly to the pressure from about 94% at the axis to 100% at the surface but given the other uncertainties, I didn't factor it in. Intermolecular collisions in the air give rise to momentum transfer and macroscopic properties such as viscosity. If such collisions couldn't transfer momentum from the cylinder to make the air corotate, the people on the surface would be subject to a constant hurricane force wind. As it is, I suspect that such O'Neill cylinders might be subject to disruptive atmospheric phenomena should localised vortices form - horizontal whirlwinds?
No doubt I screwed up somewhere - it's been a long time since I attempted such calculations and my assumptions might be invalid. For example, I've assumed air pressure is Earth standard of 101.325 kPa, which is probably incorrect as many O'Neill designs use a 20:30 oxygen to nitrogen ration at half this pressure to reduce the pressure on the cylinder walls. Half the pressure would mean half the density for the same temperature and thus half the drag force.
Having done the calculations, assuming an initial radial velocity as high as u=10m/s (3m/s of that being the rotational velocity at 20m; the rest being from muscle power), the radial velocity is approximately uD/(D+ut) m/s so after 50 seconds with a drag factor D=300m (*) the radial velocity has dropped to 3.75 m/s and the radial distance travelled is Dln(1+(ut/D)) or about 294m. After 100s, the distance is 440m; 300s 719m. The time to travel radially 800m to the cylinder floor is about 402s or 6 minutes 42 seconds. He would meet the floor with a radial velocity of 0.7m/s or only about 2mph. However, the corotating air would speed his tangential velocity up so that its difference from the cylinder floor speed is R/((R/V)-((t+D/u)ln(1+ut/D)-t)). I won't state the figure I calculated as I don't have much confidence in the value of D (not to say my maths). Say this tangential velocity is 62m/s but the cylinder floor is moving at 88.6m/s so it's overtaking him or he's travelling backward relative to it. He'd hit the ground tangentially at 88.6 - 62 m/s, that is, 26.6m/s, 96km/h or 60mph. That's a big ouch even if he manages not to slam into the side of a building or other structure at a higher speed before he hits dirt, which seems not improbable to me. A big arrestor net or air cushion put in his path would be the easiest way of catching him.
There's a large uncertainty as the drag factor (D=300m) plays a big role both in slowing down the radial velocity and speeding up the tangential velocity. Decrease it too much and he takes hours not minutes to reach the ground although he does touch down safely or hits the side of something very slowly; increase it too much and he's a streak across the landscape or a stain on a wall. I suspect D=300m is on the low side as that corresponds to a sky diver maximising their cross sectional area.
Seen by an inertial observer, the trajectory of a body inside the cylinder only intersects the inside surface, it isn't accelerated toward it. The centrifugal acceleration that a comoving observer on the inside surface experiences is a result of the reaction against the surface which is constantly changing their tangential velocity vector as a centripetal acceleration toward the axis. This reaction against the surface is felt as an attractive force akin to gravitational acceleration acting on a mass. For a small R cylinder, the person might notice apparent strange effects due to the different distances of different parts of their body from the axis of rotation. Such effects happen even on Earth due to its rotation but they are tiny.
I did wonder if it is possible to breath near the axis. I reckon the air pressure at a distance r from the axis to be exp(-(R^2-r^2)/2(H^2)) of the air pressure at the cylinder surface where the scale height H is cR/V = 3160m, c being the speed of sound in air, 350m/s for air at a temperature of 290K (approx. 17°C or 63°F). So the pressure at the axis is 94% of that at the cylinder surface.
(*) I used the typical minimal terminal velocity of w=54 m/s for a sky diver to estimate the drag factor D at 300m ((w^2)/g terminal velocity squared divided by gravitational acceleration g=9.81m/s^2), which is equal to 2m/ρAC where m is the mass, ρ the air density, A the cross-sectional area and C the drag coefficient. It's easier to work out D from w and g than from m, ρ, A, and C. The acceleration due to the drag force is then simply (v^2)/D. I expect D=300m is an underestimate.
The air density should vary similarly to the pressure from about 94% at the axis to 100% at the surface but given the other uncertainties, I didn't factor it in. Intermolecular collisions in the air give rise to momentum transfer and macroscopic properties such as viscosity. If such collisions couldn't transfer momentum from the cylinder to make the air corotate, the people on the surface would be subject to a constant hurricane force wind. As it is, I suspect that such O'Neill cylinders might be subject to disruptive atmospheric phenomena should localised vortices form - horizontal whirlwinds?
No doubt I screwed up somewhere - it's been a long time since I attempted such calculations and my assumptions might be invalid. For example, I've assumed air pressure is Earth standard of 101.325 kPa, which is probably incorrect as many O'Neill designs use a 20:30 oxygen to nitrogen ration at half this pressure to reduce the pressure on the cylinder walls. Half the pressure would mean half the density for the same temperature and thus half the drag force.
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B5tech is fanfic. Old fanfic. I'm talking about the original design intent by the people who made the show.
Ron Thornton Interview said:
The page with the quote links to a sidebar with this image illustrating the scale as designed.
As designed, the large open section in the center, with garden and the core shuttle monorail and everything, was one mile in diameter from floor to floor. The five miles in length starts at the back of the rotating drum, and continues up to the spot where it tapers to a dome, stopping right at the beginning of the neck that connects to the docking sphere. The cobra bays, command sphere, zero-g docking spine fork, and the whole reactor assembly sticking off the back, didn't count. "Self contained world five miles long" specifically referred to the habitat section of the station, not the industrial areas.
The Babylon 5 security manual does not agree. I agree it's probably incorrect.
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The B5 Security Manual is filled with a lot of inaccuracies that don’t match the actual show. It can’t be taken as a reliable source of information.
The book is sanctioned by Warner Bros but I agree it's not a good reference source.
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You mean Londo didn't once get so drunk he beat a former telepath(??) to death during a bar fight, and Morden never pressed criminal charges against Sheridan for destroying all life in the galaxy?
Next you'll tell me Lyta Alexander hasn't been deaf from birth and is constantly scanning everyone around her and figuring out what they're saying from their thoughts.(Though if I were going to counter that what I explicitly, repeatedly say is the "original size as designed" isn't the canon size, I'd use "And Now For A Word," which explicilty sites a total length of eight-point-whatever kilometers.)
"The Babylon Project was our last, best hope for peace, a self-contained world five miles long located in neutral territory, a place of commerce and diplomacy for a quarter of a million humans and aliens, a shining beacon in space, all alone in the night." implies to me the whole station is five miles long not just the cylindrical section. But, hey, I suppose size matters to some people.
I forget where I read it, but I'm pretty sure the way they worked things out behind the scenes; the "five miles long" wasn't thought to be from the tip for the forward docking arms to the back end of the fusion reactor, it was just the carousel itself (i.e. the part people actully lived and worked in.) So from C'n'C to grey sector, basically. The full superstructure is probably closer to six miles. So with that in mind, the width of about 1 mile at the carousel's widest point does actually line up damn near exactly.
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Making the station bigger only ruins the jeopardy of the scene even further. However, that's only if one is anal enough like me to do the calculations. It looks a reasonably perilous scenario at a casual viewing.
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I mean hitting the inner surface of a cylinder rotating at about 60mph is going to be bad news no matter how fast or slowly you approach it or what angle you make contact. Jump out the back of a car going 60, or slowly lower yourself out the back of a car going 60. Either way you're having a bad day, and quite probably your last one ever.
I've corrected my calculations earlier. Air resistance helps somewhat but if he hit the surface tangentially or smacked into some obstacle on the surface at 60 mph - he'd be screwed.
I also suspect that atmospheres in O'Neill cylinders are tricky beasts and are likely not as tame as depicted. Cyclonic-type dust suckers come to mind.
I also suspect that atmospheres in O'Neill cylinders are tricky beasts and are likely not as tame as depicted. Cyclonic-type dust suckers come to mind.
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B4 is said to be the biggest of the Babylon stations.
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