Quick Fire Questions (A Place to Ask and Answer)

Status
Not open for further replies.
Vertigo said:
It is possible that it would end up behaving in a similar way to Earth once again and I suspect this was ACC's thinking. In Rama the distance from the inner surface to the axis is about 4000m and that would be breathable though not without difficulty if you are not acclimatised. Which would fit with the extract I quoted above. I'm just wondering whether his figuring was really correct in this case.
.
Click to expand...

ACC tends to get his science spot on, so I'd accept that. Should be noted that the original proposal for such a spacecraft had a partial pressure atmosphere (oxygen levels same as what we're used to but much less nitrogen)

oh and centrifugal and centripital I get mixed up all the time, I could be wrong!

As for the High/Low pressure, yes I got it wrong way round 'cause I took the god eye view of the problem (me and my big head!) For a person standing on the inner surface of a rotating cylinder, the air (by friction) is moving along with you i.e. is essentially stationary relative to you - thus high pressure. The air in the centre of the cylinder is now rotating relative to you and thus generating low pressure in the centre.

But I don't think the pressure difference from rim to axis can be compared to pressure difference in the Earth's altitude, so be careful.

The reason is that in Earth's case the whole atmosphere remains in a strong gravitational field and thus the density/pressure relative to height is highly dependent on this factor (gases that do not achieve escape velocity will remain with us but Hydrogen and Helium flies off into space to explain in a short sentence).

In the O'Neill cylinder there is no gravity, but here the pressure difference is caused by the spin rate, so we should be able to work it out from that. I did a rough and ready calculation - but to be frank I think it's wrong :) - and got that in your case the pressure difference would be ~15% lower in the middle (that's compared to 40% lower for being 4000m up a mountain)
 
Thanks VB I think that's pretty much in line with what I was thinking (and hoping). I just had a horrible moment when I suddenly thought I'd got it all wrong. The real worry was the longitudinal acceleration. If that had generated too severe a pressue difference the whole concept would have fallen apart! The pressure drop towards the axis is harder to work out but much less important to me. I just needed a rough idea of the effect for incidental background stuff.

Not too worried about the exact gas mix. However, whilst the 50% pressure proposed for the O'Neill cylinder would make sense for an orbiting habitat, for one that is under accleration that longitudinal pressure drop could then become a much bigger problem. Although maybe not if the oxygen content is still what we would expect at around 2000m.
 
re: reduced pressures - Oxygen pressure is the most important and that is the same in this case.

As for your accelearation I'm assuming though that you won't be pushing at 0.1g for the whole journey, so that you could temporally start with everyone at the dense air end during the burn. What sort of speed where you aiming for? 10% of c? Only takes over a year or so at a constant 0.1g.

Of course when you have to deaccerelate then you'll have to shift everyone to the other end :)....
 
Well no actually the whole point of using a ramscoop drive is to be able to maintain drive right up until the point you switch to deceleration. I know the arguments about drag versus thrust with the ramscoop but that has not yet been resolved one way or the other. And, with more advanced tech giving (hopefully) more efficient nuclear engines, I am more optimistic than pessimistic about the outcome of that debate. In fact one of the things about ramscoops is that you really don't want to turn them off. The magnetic ramscoop itself provides a degree of shielding but if you shut down the drive then its drag immediately puts you into deceleration. You do still need to carry some reaction mass (quite a bit actually) for the inital acceleration and deceleration as the ramscoop can only operate at fairly high speeds (still to research exactly what speed that is thought to be).

However there should be no need to switch ends as an air pressure equivalent to 2000m is perfectly acceptable. When I was climbing in Bolivia there was a miners' camp near one of the mountains that we climbed that was permanently occupied at 5000m and the city of La Paz is spread out from about 3000m to 4100m! Also Everest, at 8848m has been climbed without oxygen*. So 2000m is no problem at all. Only being able to occupy half the cylinder whilst under drive was one of my big worries.

*Actually you couldn't survive at 8848m for very long. The height above which human life cannot be sustained (cell regeneration ceases I believe) is around 7500m (some tag it at 8000m but it is naturally a bit vague and different for each individual). This is rather colourfully known as the Death Zone in climbing circles. I believe the longest an individual climber has survived in the Death Zone is about 10 days.
 
The convention is to carry on with a speech mark at the start of the next para. without closing the ones in the first. so. eg

"I wanted to take a new paragraph but keep speaking.

"So I did..."

But some don't, they continue without the second "

So
"I wanted to take a new para

And keep speaking."

but, in my understanding, the first is the more proper.
 
The first way springs demonstrated is the same way as I was taught and the method I've seen writers on both sides of the Atlantic use.
 
Not sure where these questions should go, so I'll put it here and await moderation :)

I was just looking at Who's Online. Sandwiched in between the logged in Main Characters and the anonymous Guests, someone or something called Google Spider was viewing a thread about Gorgeous Book Covers.

Who or what is a Google Spider?

Is it poisonous?

Why is it judging a book by it's gorgeous cover?
 
Last edited:
DEO, always amusing...

anyway, to answer the question, a google spider is a bot used to catalogue pages and links for the search engine, so people can find your site.

but...

as far as I was aware, spiders search sites as 'guests', they don't actually have a user account... mysterious. ;)

Might be a new way of spiders working, or could be somebody's idea of a joke.
 
ok, then I stand by what I said. it was cataloguing pages to add to google. probably still poisonous, considering the way Google is going with privacy. ;)
 
alchemist said:
I don't!

So I went looking.

http://www.amazon.com/dp/0765316048/?tag=brite-21

Horizons by Mary Rosenblum. Even though it's the correct book, I still don't recognise the author's name. It's got 4 stars on Amazon; I'd give it 3.
Click to expand...

Hmm no ebook available and only very expensive hardback on Amazon UK (£18), unless going for third party sellers. Most others seem to have it listed but unavailable.

I'm always interested in books dealing with the same sor tof tech I am looking at but I'm not sure I want to spend that much. Might take a look on Abebooks for second hand copy.
 
David Evil Overlord said:
Not sure where these questions should go, so I'll put it here and await moderation :)

I was just looking at Who's Online. Sandwiched in between the logged in Main Characters and the anonymous Guests, someone or something called Google Spider was viewing a thread about Gorgeous Book Covers.

Who or what is a Google Spider?

Is it poisonous?

Why is it judging a book by it's gorgeous cover?
Click to expand...

Warren_Paul said:
DEO, always amusing...

anyway, to answer the question, a google spider is a bot used to catalogue pages and links for the search engine, so people can find your site.

but...

as far as I was aware, spiders search sites as 'guests', they don't actually have a user account... mysterious. ;)

Might be a new way of spiders working, or could be somebody's idea of a joke.
Click to expand...

Yeah, I think the name comes from the fact that they 'crawl' the 'web' (see what they did there?). Plus, you know. Google. They like their quirky things.
 
Question. Can I use the word pend as it is or do I have to throw an explanation in for those who don't know what it is? To be fair, I didn't know the word myself until yesterday.


Noun

pend (plural pends)

(Scotland) An archway; especially, a vaulted passageway leading through a tenement-style building from the main street, giving access to the rear of the building or an internal courtyard. [from 15th c.]
 
Some authors seem to fill their books with esoteric, obscure or archaic words. Never a bad thing to expand one's vocabulary but if done too much it can be annoying (Reynolds, Mieville, Attanasio I'm looking at you and I'm sure there are others).

So the occasional word should not be a problem and if your readers have to look it up then you've managed to educate a little as well as entertain! :D
 
Status
Not open for further replies.
Thread starter Similar threads Forum Replies Date
Toby Frost Quick question on titles Writing Discussion 7
Mouse Quick question about fire Writing Discussion 19
David Evil Overlord A quick question about FIRE Writing Discussion 14
David Evil Overlord A quick FIRE question Writing Discussion 16
T Quick Poll - Will Firely fly again? Firefly 3

Similar threads


Back
Top