Top Floors
"presumably for use by the rich execs who work at the top of it"
More likely the top floors will be a bar or a restaurant (or both!) with a express high speed elevators.
Hitachi has unveiled plans for two express lifts which will rocket up a China skyscraper at speeds in excess of the genteel 30mph (48kmph) British speed limit. Although the Japanese firm's latest creation would wind up on the slow lane of Blighty's motorways (if we imagine it were capable of Charlie and The Glass Elevator- …
> the top floors will be a bar or a restaurant ...
Given the speed of this lift (one assumes it goes down as fast as it goes up), then I think I'd pass on the prospect of taking the elevator down, after a meal. Just in case my lunch wasn't traveling quite as fast as the rest of me.
What cable? There is no cable!
The limiting factor for how many floors an elevator can travel is cable length, which is why most very tall buildings require you to get out of one elevator and into another part-way up. This elevator is different: it carries its own motor as part of the car (which was alluded to, though not explicitly stated, in the article). No cables means no limit on how many floors can be covered by a single elevator.
To make a fair comparison we need to consider how fast a car would go if it could go vertically.
The Toyota Aygo has a 67HP engine, i.e. 50kW. Assume it has a loaded mass of about a tonne (probably less but then you are not going to get full power out). So the maximum theoretical vertical speed is that which requires 50kW and a force of approx. 10000N, which works out neatly at 5m/s
The Hitachi lift achieves 70kph, or just under 20m/s. So, to put it into perspective, to achieve the same vertical speed with an Aygo would need about 268HP.
A Porsche 911 with 2 passengers and fuel weighs about 1650kg and produces a peak 294kW, so its theoretical limiting vertical speed would be just under 18m/s.
A lift which can climb faster than a Porsche 911 is not to be sneezed at.
And with the counterweight it's uphill both ways!
What counterweight? There is no counterweight!
The limiting factor for how many floors an elevator can travel is cable length, which is why most very tall buildings require you to get out of one elevator and into another part-way up. This elevator is different: it carries its own motor as part of the car (which was alluded to, though not explicitly stated, in the article). No cables means no limit on how many floors can be covered by a single elevator, and also means no counterweight.
"So, the more morbid part of my mind is trying to work out whether it would be best to work at the top, middle or bottom when one of these super high buildings collapses under the weight of its own hubris?"
Everybody inside will be dogmeat because even at the highest floors there's usually several hundred metres of non-occupied structure as the designer struggle to match the client demand for record heights with locations where there's not really the demand for that volume of space. But in the case of excessive hubris, I would guess you'd have an implosion, and a circular event horizon some way out from the building itself, and so the most important thing is to be a long, long way from the building, full stop.
But which way lets you go in style? The bottom floors just get squished - there's no fun in that! If you're trapped at the top though you get to break the windows and grab some pillows and make a desperate leap to safety - and, even though you'll still probably squish and die instantly on impact, you'll at least have a fun few seconds on the way down.
"Are the dynamic pressure effects so great when a lift is travelling at that speed?"
The lift covers over 1,400ft in 43 seconds. At that speed you'd climb Snowdon in less than a minute and a half - do you think you;d notice that? Actual pressure difference is probably only 15% over 400-500m, but I suspect you'd find that noticeable, verging on uncomfortable, particularly as going up there's be a depressurisation sensation that people aren't used to.
Mind you, at least something to give the Uighers something to target.
At 45MPH a 9% grade over a 1 mile stretch of road is more than sufficient to make babies cry as they don't understand why they were born, only to be killed by brain squishing so shortly after. It's also more than enough to cause nausea in those with inner ear problems and really ruin your day if you've got a bad sinus infection.
At 45MPH a 100% grade will be somewhat more uncomfortable if steps aren't taken. That's why the elevator has the nifty pressure system.
It being airtight isn't going to cause any problems no matter how close to the door you are when it opens, even if you went all the way up or down in a single trip (highly unlikely). The elevator has a pretty good idea of where it's at, vertically, and it knows where it's going to stop, ideally, and it makes constant pressure adjustments accordingly so there's no shocking pressure change when the doors open. The breeze generated by the doors moving will have a more noticeable effect on your hair (but it would be really great if everybody stumbled out every time looking like they had just parachuted to work in their suits :).
...that the BOFH can get ahold of to perform career- (and life-) ending maneuvers on those annoying auditors or his authoritatively-naive boss.
PFY: So the boss's final uplifting moment was when he strutted into the new lift with our contract severance forms.
BOFH: The lift which had very recently had maintenance performed on it by what appears to be a mix-up between two separate orders filed by two different departments.
PFY: I'm still not sure why anyone would decide that attaching an experimental rocket engine to the bottom of a lift car would be a viable option.
BOFH: Or who would order such a thing for this company. Unfortunately, it appears that the electronic order forms for this maintenance and for the "rocket engine install" have been deleted by that virus that wiped out most of our financial databases. And the paper copies were probably lost in the fire resulting from the rocket engine's exhaust.
Police Officer: MM-Hmm, yes, very interesting.
BOFH: Will that be all, officer?
Police Officer: Not quite. Could you explain this, please?
PFY: It looks like a bolt cutter.
BOFH: Quite a big bolt cutter, in fact. What about it?
Police Officer: Do you know where I found it?
BOFH: Oh, do tell me.
Police Officer: It was attached to the cable anchor on top of the lift car. With the remains of a hydraulic ram attached to the handles. And some wires from the ram running to what's left of the control panel.
PFY: Yeah? And?
Police Officer: Why would that be there?
BOFH: Some sort of emergency release unit? Look, that's what the label says. "Emergency Release No 2."
Police Officer: I beg your pardon? Emergency release unit?
BOFH: Yes. In case the lift.... got stuck and the occupants... had to cut their way out.
Police Officer: I'm not satisfied with this. I shall be taking this for forensic investigation. You two will stay right here while I go down in the other lift.
<Ding><Whirr><Whirr><Clunk>
<CRUNCH><Whizzzzzzz><CRASH!><tinkle>
PFY: Was that...
BOFH: Yep. Emergency Release No 1.
We definitely need to bring some Douglas Adams spirit in elevator design !
"Not unnaturally, many elevators imbued with intelligence and precognition became terribly frustrated with the mindless business of going up and down, up and down, experimented briefly with the notion of going sideways, as a sort of existential protest, demanded participation in the decision-making process and finally took to squatting in basements sulking."
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Ok, I ought to be able to do the maths for this, but...
Assuming starting from 0 m/s, smooth acceleration to v-max, and then smooth deceleration back to 0 m/s, how much g does this thing pull?
Of course, my assumptions are probably wrong, as I would expect it to get to and from v-max much quicker. But still, it's a starting point.
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@TheVogon
Your analysis is flawed as it has a single period of acceleration which means you'll be existing the top of the tower at some considerable speed. Modeling the travel as a single period of acceleration is wrong - you have to use two equal periods of acceleration (with opposite signs) use the lifts maximum speed (20 m/s) as the limit and then have the remaining time traveling at top speed.
Assuming acceleration/deceleration at at a constant rate, the maximum speed is 20 m/s, the height traveled is 440m and the time taken is 43s, the lift accelerates for 11 secs at approx 1.82 m/s^2 (110m), then travels for 21 secs at 20 m/s (420m) and then decelerates at approx -1.82 m/s^2 for 11 seconds (110m). The acceleration encountered (net that of gravity) is therefore about +/- 0.185g.
nb. just checking my maths, I'd made a slip, so this is the formal derivation. Always show your work I was told...
Total distance = 440m
Total time is 43 secs
Top Speed is 20 m/s
Rate of acceleration and deceleration are identical
The take
a = rate of acceleration (will be -a for deceleration)
t = time take for acceleration (clearly time for deceleration will also be t)
Clearly the acceleration time (t) is simply the top speed (20 m/s) divided by acceleration rate so :-
t = 20 / a
The distance traveled during the acceleration phase is given by the equation
s = ut + 1/2 * at^2
where s = distance travelled
u = initial speed
a = rate acceleration
t = time
but u = 0, so we get
s = 1/2 * at^2
the distance (and time) traveled during deceleration will be identical. The time spent traveling at top speed will be the total time (43) less the time spent accelerating and decelerating (2t). Substituting for the t with 20/a (see earlier), and adding in the distance in acceleration and deceleration, we get.
(43 - 2t) * 20 + 1/2 * at^2 + 1/2 * at^2 = 440
expanding
860 - 40t + at^2 = 440
rearranging
420 = 40t - at^2
But, we know that t = 20/a so, substituting for t
420 = 800/a - 400/a
therefore
420a = 400
therefore
a = 20 / 21 m/s^2
But t = 20/a, so t = 21 secs
So this actually means accelerating at approx 0.95 m/s for 21 seconds, traveling at 20 m/s for 1 second and then decelerating at approx 0.95ms for 21 seonds. So about +/- 0.096g.
Rate of acceleration and deceleration aren't equal. You can, comfortably and safely, accelerate much faster than you can stop. But wait, there's more!
Acceleration and deceleration rates will vary on direction of travel, the forces on a speeding elevator going down are far greater than going up and passenger weight will have a huge impact as well.
I doubt actual weight is calculated on the fly, but distance and speed will sure as shit be dealt with in real time. An elevator going from L to 3 will have a slower rate of acceleration than one going from L to Top and likewise when going down.
If you apply the same amount of force used to halt a three floor transition as you use for full distance travel you would really, really give riders terrible scares and not a few injuries. Even in simple elevators the rate of upward acceleration is changed when someone presses a call button before full speed has been reached. Same with descending, but for comfort and safety's sake all but the oldest non freight or construction elevators will simply pass the call single onto another shaft if the descending car is too near, in relation to its speed, the floor with the pressed called button (that's often why you'll hear cars rumble past even though you thought you called it plenty early.
> Rate of acceleration and deceleration aren't equal. You can,
> comfortably and safely, accelerate much faster than you can stop.
Er, not sure about that. From the frame-of-reference of the body being accelerated/decelerated, it's identical. Relativity and all that.
Put another way, if you came to in a elevator and felt it suddenly accelerate upwards, was the elevator still and now ascending? Or was it descending at a constant speed and now stopping? You can't tell without looking at the lights.
"Your analysis is flawed as it has a single period of acceleration which means you'll be existing the top of the tower at some considerable speed"
No it isn't. I was assuming that even the most clueless would realise that a matching period of deceleration would be required. Hence why the distance used is 220m, not 440m, and the time is 21.5 seconds, not 43 seconds.
And your first calculations are all wrong. Unlike mine.
Been up in that one a few times (the current fastest lift in the world) and that's insanely quick. The doors are sealed to stop your ears drums imploding, and you feel really weak in the knees due to the acceleration.
At the time I figured that wouldn't be getting much quicker than that. This is about 10% faster ontop.
How does just ONE building in China rate a world class, bleeding edge elevator system? Worker's paradise, remember? Everyone shares equally, remember? Unless they intend to install this elevator system in EVERY building, they should not be able to install it in ANY building. There should be NO rich and poor in China - everyone should be equal. Either that, or the Communist system of government is a LIE and a SCAM. If they cannot provide it for everyone, then they should not provide it for anyone. There is no room for national pride in a worker's paradise.
Nuke icon because China is not being true to their Communist ideals.
I see we have a Westerner who has bought into the line that austerity, financial discipline and long work hours are the only way to get rich, or get elevators. All that stuff is bullshit (except the work long hours but, that's going to happen occasionally, but if it's the standard you're working wrong). I don't do any of those first two things and I've got several elevators.
Regardless, it's always a good idea to have visited a country before you start talking about how backwards it is. I find that attitude is probably the most prevalent in the US and UK and I chalk most of that up to the fact most of the people in those countries don't take enough time away from work to learn about the world so they're forced go take someone else's word for the state of things.
"everyone should be equal" + "not being true to their Communist ideals"
Well, cry me a river. Practical attempts at Communism have always meant that everybody is equal, some are just more equal than others.
May the gods have mercy and save you from actually living in a society with Communist ambitions.
"a loaded mass of about a tonne" (said the chap with the Aygo)
Actually, the lift motor only has to cope with the weight of the occupants, thanks to a counterweight. Still a fair amount of grunt required, though, and I'm really not sure about the pressurisation, intended to prevent ear-popping. Won't that be much worse when the doors finally open and the people waiting to go down are blown backwards..?
Are said by some people to be what is needed for taller buildings. As buildings get taller more and more of the interior needs to be turned into lift shafts in order to keep travel times down. If you could have more than one lift in a shaft then you'd have a much higher throughput.
This has a lot of similarities to PRT (personal rapid transit) systems.