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-   -   EpDis: The Fall Of Night (http://www.b5tv.com/showthread.php?t=8435)

sleepy_shadow September 6th 05 18:49

Re: EpDis: The Fall Of Night
 
I deem the depiction fairly acceptable -- even if I too suspect the 'ballistically correct way of Sheridan "falling"'... would have required him to experience a bit more wind.

After all... once he's drifted away from the core region (assuming air matches the station's angular velocity, the linear velocity of air at core would be negligible)... he would experience increasingly fast air, trying to take him spinward (along with the stations's rotation)...

...but instead taking him spinward and outward (mass doesn't want to spin, but prefers going straight along its current velocity vector).

To some degree, air would succeed in taking him along spinward... due to which he would never experience wind speeds approaching the linear velocity of the station exterior... but he might experience wind speeds extending to half of that.

Finally, something with Sheridan's density could be predicted to thump down at an oblique angle (relative to ground) of say, 45 degrees...

...while a feather, having totally matched air speed, would float down vertically, and a strontium ball (having ignored air speed due to its density) would appear to make circles around the station core, continue making circles while drifting outward, and eventually hit a ground obstacle horizontally.

PillowRock September 6th 05 18:59

Re: EpDis: The Fall Of Night
 
Quote:

(assuming air matches the station's angular velocity,

I don't think that is a valid assumption for the entire radius of the station. The air would match the station speed at the "ground" level where there is a lot of surface area of contact acting on it. At the central core of the station I don't think that the air would have even the same angular velocity. The breezes there might actually be more influanced by the passing of the Core Shuttle cars.

I don't know what the function relating distance form "ground" to relative airspeed (either linear or angular) would be, though.

sleepy_shadow September 6th 05 19:08

Re: EpDis: The Fall Of Night
 
Heh. I don't know such functions either, especially for a zero-gravity environment. But think of it that way...

Ground accelerates air. Whenever the spinning part of the station has transfered too much momentum to the static part (via bearings and air)... the station presumably fires thrusters on the spinning part, and counter-thrusters on the static part, to correct pace.

But what decelerates air? Only the structures of the core, which necessarily must have significantly lower surface area (thus significantly lower ability to provide friction against air, especially given the necessarily low linear velocities "up there" in the center).

A gradient in the angular velocity of air may well exist (with the coremost air spinning lazily)... but it certainly *seems* likely to be heavily non-linear (in favour of the angular velocity of "ground").

PillowRock September 6th 05 20:04

Re: EpDis: The Fall Of Night
 
Quote:

Ground accelerates air.

But what decelerates air?

The air does.

The air is not even close to being a monolithic entity. It isn't all being moved in the direction that the ground is pushing it. The air ends up bouncing off of other parts of the air. Energy (with different force vectors) are imparted to the air by the core shuttle passing through, by the ventilation system of the station, by the jet packs used by maitenance and emergency response crews (remember that the existance of those things is mentioned in this very episode), among other things. In fact, all of that stuff, and the effects from it that are transferred from the air to the hull are the primary force acting to slow down the rotation, forcing energy to be put back into the system by burning fuel to push the hull around.

The effects of different currents within the air are not negligible. On Earth rivers flow more rapidly a little below the surface than they do at the surface because of friction with the atmosphere (the difference isn't as great as the difference at the bottom or along shore where the friction is with the river bed, but the difference does still exist).

sleepy_shadow September 6th 05 22:22

Re: EpDis: The Fall Of Night
 
Turbulence from ground does exist... but turbulences eventually cancel each other out. Given time to stablize, I think the whole air mass would start spinning fairly cohesively.

Core shuttles are streamlined little things, going back and forth in the presumably calmest part of the station... and now that I think of it... I actually suspect the core shuttle rails/tubes/infrastructure... belong to the spinning part of the station (ease of boarding).

Ground shuttles, and shuttles going back and forth along middle levels... might cause a bit of turbulence too, but again... they are streamlined little things.

Jet packs are likely a very small influence, since I cannot imagine any notable number of people constantly using them (and their users would likely try sticking to the upper reaches of the air mass, to conserve flight energy).

Only the station ventilation and air filtration system... seems a fairly big unknown (since nobody knows its throughput, and how it's supposed to be layed out). Its approximate thoroughput could be calculated, though... assuming most inhabitants *do* breathe "ordinary" air, and tecgnological processes don't consume more than living creatures.

That calculation, though... is hardball ecology, and I can't even start to approximate a result in such a short time.

PillowRock September 6th 05 22:51

Re: EpDis: The Fall Of Night
 
Of course, the most fundamental issue is that air, like everything wants to move in a straight line. That's the way its inertia is taking it. It is only because the hull is in the way that it doesn't continue moving tha way once the initial force is applied.

The air is constantly having force applied to it by the hull. And then that air moving transmits that force to the next layer of air, and so on. But the air is not an efficient transmitter of that energy. All of the turbulance is a source of drag.

Going back to the movement of water in rivers, the water continues in straight line until something forces it to change direction. If there is a bend in a river, a drifting boat that starts in the middle of the river does not stay in the middle as it goes around a bend. It goes to the outside of the bend, continueing straight ahead until it is close enough to the bank that the "rejector current" that is bouncing off of the bank can start pushing it away from the shore and redirect it. That truth about how the water moves is why there is always much more erosion on the outside of a river bend (that's the side where trees fall in because the ground has eroded away from their roots; the outside is also always the deeper side unless there are significant geologic reasons why not).

And the core shuttle cars didnt look that much more aerodynamic tome than present day metro cars, and I *know* they create a breeze.

Shaal Mayan September 9th 05 22:59

Re: EpDis: The Fall Of Night
 
Excellant ending to the second season.

macmaccaman September 10th 05 23:09

Re: EpDis: The Fall Of Night
 
I enjoy this episode a lot, more interesting elements added to the mix - understanding more of the Vorlons. I love the fact the "manipulation" of the alien races comes to the fore, brilliant revelation and I like how Londo can't see Kosh - nice follow on from Kosh's words in Midnight In The Firing Line: "they are alone...".
Though I felt that it was a bit of a betrayal really when I saw it "It was the year the great war came upon us all..." and it didn't really.

KoshFan September 12th 05 13:54

Re: EpDis: The Fall Of Night
 
Well, the opening shots had been fired -- what with the Shadows intervening in the Narn-Centauri War. And the first tentative steps had been taken towards fighting back by assembling the Army of Light, although that group had yet to do much by the end of S2.... the battle lines had been drawn.

Elipsis September 2nd 07 22:36

Re: EpDis: The Fall Of Night
 
Just watched this for the first time in proper sequence... absolutely epic. Lol at 27 "A" votes.

Did we ever get an answer if it was Londo who saw nothing or the entire Centari race?


Also, I loved the tension right before the Centari ship opened fire. Sheridan's reaction. "Oh hell. CLOSE BLAST DOORS." The entire battle sequence was epic. Seeing the piece of the station get blown off. omfg!


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