Quick Fire Questions (A Place to Ask and Answer)

[Warren_Paul]

It was a reference to all those tubes used to personalise the ships.

oh, ic...

droll humour by the bear...

 

[subtletylost]

Well the story is written in first person present tense and my character is supposed to be in the play but showed up late due to the prologue getting in her way. I kind of want to write it like she would see it but also sort of in third person with her thoughts interrupting every so often. I'll only make her watch one scene before she heads backstage.

 

[Warren_Paul]

Descriptions of what the performers do can be done exactly the same in 1st as 3rd I believe. infact, 1st makes it easier to get her thoughts in there.

EDIT:

I remembered a book I had read a short while back while researching romance scenes. Bullet by Laurell Hamilton opens with a school play. I've pulled out a short bit of a scene here, just to give you an idea. Hopefully I'm not breaking any rules by pasting it here? If so feel free to delete this post mods.

THE FIRST GROUP out was the two-year-old class. Five little girls in pink tights with sparkly itty-bitty tutus walked onstage holding hands in a line. The audience did a group “Awww.” They were almost illegally cute. The dance teacher was at the front of the stage, visible to the audience and the wide-eyed little girls

The Dance of the Sugar Plum Fairy from Tchaikovsky’s Nutcracker filled the air. It was one of the few classical pieces I knew well enough to name. The teacher began to move her arms. Most of the tiny girls followed her, but one of them just stared off at the audience with huge, fear-filled eyes. Were the toddlers good? No. But at that age it’s not about being a prodigy, it’s about showing up and being too cute for words. I wasn’t much for babies, older was definitely better, but even I couldn’t deny they were nearly painfully adorable

 

[Ursa major]

Well the story is written in first person present tense and my character is supposed to be in the play but showed up late due to the prologue getting in her way. I kind of want to write it like she would see it but also sort of in third person with her thoughts interrupting every so often. I'll only make her watch one scene before she heads backstage.

So did she really want to be in the play, or had she been forced into acting? Is she hoping that the person playing her part (her understudy? her friend?) will not shine, so that she will be reinstated for the next performance (assuming there is one)? Or is she pleased for her friend? Or relieved? Or worried that her friend will make a fool of herself (and it will be all her fault)?

The point I'm getting at is that while it may be important for your story that your character has missed being on stage, you must have an extra reason for describing (parts of) the play. Otherwise you could simply write that she sat through the performance feeling distraught/relieved/whatever, as appropriate.

So what does the description of the performance, and of your character's reaction to it, tell the reader that they would not otherwise know?

 

[Vertigo]

I have a question or two on atmosphere behaviour, or rather artificial atmosphere behaviour.

Given a cylindrical habitat such as an O'Neill Cylinder that is 10km diameter and 20km long and is spun to give a pseudo gravity of 1g on its inner surface, I'm trying to figure out how the air inside would behave.

If we assume it has sufficent air (with our normal proportions of Oxygen, CO2 and Nitrogen) to give a pressure of 1 atmosphere at the inner surface. How would the air pressure change as you moved closer to the axis of spin. Would it be the same as on Earth as you increase your altitude? I suspect not as the force of gravity on Earth is essentially the same as your altitude increases, whereas the pseudo gravity would change very significantly as you approach the axis of the habitat, eventually reaching zero at the axis. In digging around on this matter I have found some places that suggest there would be vacuum at the axis, others do not seem to consider this suggesting zero gravity sports being undertaken close to the axis (Clarke's Rama seems fall into the former category).

The second part of the question is where things might get really sticky for my idea. If you now give the habitat an engine that can accelerate it at say between 0.1g, this will cause "pooling" of the air at the aft end of the cylinder. Once again with that sort of acceleration does anyone know just how big that effect would be. In other words if we say the pressure at the stern is 1 atmosphere, what sort of pressure are we looking at at the front end? I'm hoping that with a 1g acceleration the sums would be much the same as on Earth. So the pressure at the bow would be the same as at 20,000m altitude. However since the acceleration is only .1g do you think it would be proportional so the front would have an air pressure equivalent to 2000m altitude?

 

[Jo Zebedee]

Vertigo, I'd love to help, but I don't understand the question.

I've heard of a functioning alcoholic, but I'm wondering can you have someone who functions for a period during a semi breakdown. The character has had a breakdown perviously, alluded to, partially seen by the reader, about a decade before, and lives with very little sleep, a difficult relationship background, and generally high levels of stress. Now, the ante is upped for a space of 10 days, and he's threatening another breakdown.

There is a doctor who knows him well offering support - mostly emotional - and he is pretty resilient and has a lot of coping mechanisms off pat, but even so, is 10 days pushing it - allowing for a fair bit of adrenalin to keep him going.

 

[HoopyFrood]

I think this is the first time I'm gonna use the thread for its purpose since starting it! But I think it's a good sign that I am again. I hope.

Anyway, this may be changed to something more simple, but here goes.

When I were a wee lass, we had a gas fire, and on the pipe leading to it, there was a little tap like fixture halfway along it. My parents used to tell me not to touch it (it had a loose top that was fun to wobble, but I didn't ever dare turn it). If it were to be turned, would it let gas through?

 

[Warren_Paul]

I think this is the first time I'm gonna use the thread for its purpose since starting it! But I think it's a good sign that I am again. I hope.

Anyway, this may be changed to something more simple, but here goes.

When I were a wee lass, we had a gas fire, and on the pipe leading to it, there was a little tap like fixture halfway along it. My parents used to tell me not to touch it (it had a loose top that was fun to wobble, but I didn't ever dare turn it). If it were to be turned, would it let gas through?

If it is a gas heater like I know, then yes, it would let gas through.

Gas heaters have two controls, the dial that tells it how much gas to release and the button that ignites the gas. If it is a turning control then it is most likely the dial.

If you don't ignite the gas so it burns away, the room will fill with gas.


EDIT:

Or, if there is a tap on the pipe that leads to the heater, yet the heater also has a turning control like I mentioned above, then no, it would just be shutting off the valve so the heater can't get the gas.

 

[HoopyFrood]

Yeah, there was also that on the fire, but this tap was halfway along the pipe, not actually on the thing itself. We -- parents included -- didn't ever actually touch it, it wasn't needed, but I wondered if we had, if gas would be let through.

I may just use the actual dial thingy instead. Perhaps this is just my trying to find the answer to a background curiosity of my childhood.

 

[Warren_Paul]

Sorry, see edit I made. That would be to shut off the valve, so gas could never get through to the heater. You never touched it because it was always on, if you turned it, the only thing that would change is the heater would just stop working.

 

[HoopyFrood]

Ah! So it would have the opposite effect. I swear my parents told me the other way around. Probably to stop me playing with it by making me think I'd blow up the house.

Seems very obvious in hindsight!

OK, so definitely something else needed.

Cheers!

 

[Venusian Broon]

I have a question or two on atmosphere behaviour, or rather artificial atmosphere behaviour.

Given a cylindrical habitat such as an O'Neill Cylinder that is 10km diameter and 20km long and is spun to give a pseudo gravity of 1g on its inner surface, I'm trying to figure out how the air inside would behave.

I'm sure this is a exam question that I've had to do way in the past Certainly it's making my head hurt.

How would the air pressure change as you moved closer to the axis of spin. Would it be the same as on Earth as you increase your altitude?

So (correct me if my reasoning is wrong) the pseudo gravity is a result of the centripital force of the O'Neill cylinder rotating. Which means that anything not connected to the outer rim and rotating will not experience any force whatsoever. So the air will be effectively in zero g - but the air at the rim will be dragged around causing a flow to be set up.

My first guess is that because there are no forces on the air mass and gases hate a vacuam the entire cylinder would have to be 'kinda' uniform at 1 atmosphere (to ensure you have ~1 atmosphere at the ends). The rotation would probably set up a series of cells of air flows from the outside to the centre and back again because the motion of the air at the outside would set up low pressure zones - and if ACC thinks he can do sports in the centre then he's probably correct!

However since the acceleration is only .1g do you think it would be proportional so the front would have an air pressure equivalent to 2000m altitude?

That's the way I'd approach it and I can't see a flaw in your reasoning - essentially the force of the engine 'straps' the gravity of a 10% Earth on the back plate of the cylinder.

However I don't know if it then invalidates the reasoning behind the first part of the question. Cold tea towel round head time....

 

[Abernovo]

Vertigo, I'm not a physicist and VB has already answered the first part of the question.

However, I would have thought that a partial answer to both parts would be to include 'weather station' towers to actively move the air about. This should prevent pooling and stagnation, as well as creating airflow that would stimulate plants and create breezes for the people on board. With heat adjustment, they could probably also be used to control humidity and precipitation.

 

[Venusian Broon]

Vertigo

Have looked over the second part - and although it's not as simple as dividing everything by 10 the atmospheric pressure at 20k with gravity of 0.1g is broadly the same as 2k with gravity of 10g (perhaps a little bit lower)

I suppose it all happening in a spinning cylinder ultimately complicates things more. But to first appoximation should be right.

Abernovo - because the cylinder is constantly spinning (well I'm assuming that it is all the time) then because the air is being dragged at the edges and experiencing a bit of centripital force, it should be sufficient to set up self regulating flows of air so that stagnating and pooling would not occur (even when acclerated at 0.1g). I'm imagining there will be a constant low pressure zone (fast flowing air) at the edges and high pressure in the centre and the air chasing itself around in cells between both zones 'chasing the vacuam' so to speak.

You'd experience it as a constant breeze probably. Hopefully not a constant gale.

The impact of the 0.1g accelaration would I guess, strech these cells down a bit towards the end with the engine, so that it thins out at the front by the amount that you calculated, roughly ...

 

[chrispenycate]

All the gas in the cylinder would rotate, so would have weight. It's the stable condition with gasses, otherwise the Earth would rotate and the atmosphere stand still, causing permanent hurricanes at the equator.

So gas pressure would drop off with altitude, but as 'gravity' was falling off too, nowhere near as fast as on a planet, You're good for your muscle powered wings; at 10km with one bar at the 'surface', I doubt whether it'll have dropped off as far as 2,000 metres from Earth.

On the other hand, coming down is a positive feedback effect. More gravity the 'lower' (further out) you are, so the more tendency to fall. If you don't have safety lines (and who could enjoy flapping around on the end of a bungee cord?) it's a very dangerous sport, even given reserve parachutes. The increased lift of the densening atmosphere wouldn't come neat compensating. Do you absolutely have to have a whole gee on the shell? Half a gee, martian, and you'd be fine.

As for putting it in gear and going somewhere, it's a simple vector addition; one gee in this direction plus a tenth in this adds up to…

All your table tops would seem slightly off level, liquids would sit at an angle in glasses, and your flyers would have to expend a small amount of effort keeping up with the ship, but your atmosphere? A tiny bit dense at the stern, nothing to worry about (once the situation had stabilised, that is. There may be some interesting weather when the drive starts (incidentally, have you considered how much energy is required getting a tenth of a gee acceleration on that much mass will require? This is H-bombs per minute territory. Better stick to a hundredth gee, but not because of the atmosphere, or your passengers).

 

[Vertigo]

Thanks for that guys - relief about the longitudinal force. I was worried it would thin out to the equivalent of something like 20,00m which would be too thin to breathe. Interestingly enough it would seem to put an absolute limit on the amount of acceleration such a ship could have even if you could produce a powerful enough engine.

ACC had his people in space suits until they were half way out from the axis where the air was thicker. But later in the story they had the lightweiight man-powered craft that they flew at the axis. "It's very important not to over-exert yourself. Remember, the oxygen level here at the axis is still very low. If you feel breathless at any time, stop and hyperventilate for thirty seconds - but no longer."

So ACC figured on significantly lower air pressure at the axis. I believe the idea is that the air at the inner surface of the cylinder would indeed be rotated by being dragged along but evntually that drag would get all the air rotating and hence being pushed outwards. Eventually an equlibrium would be reached with the air at the surface moving faster than at the axis (I believe that was also talked about in Rama) This would tend to push the air out to the rim but not with as much force so it would be "held back" by relatively low pressures. So I belive ACC is right that it would be low pressue at the axis and high at the "surface". My concern is just how low. Rama had a diameter of about 8km and I am looking at a diameter of about 10km so it would be comparable.

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.

Edit: Chrispy got in whilst I was typing and that seems to agree with what I was thinking. Thanks Chris. Re the engines - this is going to be significantly advanced alien tech. I am looking at a massive ramscoop engine. And don't forget you have a 10km diameter stern which gives an awful lot of space for engines!

Re the apparent slope. I figured a while back that a 0.2g longitudinal acceleration and a 1g centrifugal (or should that centripetal) force force give an apparent slope of about 2 degrees (it's an easy enough calculation to make). However what makes it worse is that a ramscoop ship does not invert to decelerate but just uses the magnetic scoop as a brake. Therefore the shift from acceleration to deceleration would be from two degress one way to two degrees the other way (assuming the same deceleration as acceleration which is not necessarily the case with a ramscoop). I actually imagined buildings being on platforms that would automatically adjust to compensate for that.

Re the sports I've always thought such sports would be massively dangerous for exactly the reason you suggest. n fact again I think ACC covered that problem with the dragonfly craft in Rama.

 

[alchemist]

Vertigo, I'd love to help, but I don't understand the question.

I've heard of a functioning alcoholic, but I'm wondering can you have someone who functions for a period during a semi breakdown. The character has had a breakdown perviously, alluded to, partially seen by the reader, about a decade before, and lives with very little sleep, a difficult relationship background, and generally high levels of stress. Now, the ante is upped for a space of 10 days, and he's threatening another breakdown.

There is a doctor who knows him well offering support - mostly emotional - and he is pretty resilient and has a lot of coping mechanisms off pat, but even so, is 10 days pushing it - allowing for a fair bit of adrenalin to keep him going.

The simple answer is -- everybody's different. I've seen previously normal people become psychotic after 4 days of no sleep and mild overindulgence. I've seen people function very well under severe stress for a long time.

It really depends on how you define things. For most people, the definition of breakdown (not a clinical term) is that they can't function at all.

Does your character's name begin with K? I suspect that under pressure, he may get symptoms of PTSD i.e. flashbacks to previous trauma, avoidance of things that remind him of it, jumpiness. He may still be able to kick ass very effectively. He may also be able to think logically. He may see that he's avoiding things but feel unable to do anything about it.


@ Vertigo -- wiser heads have spoken. The one book I read about an O'Neill cylinder, the air pressure appeared the same at the axis. That's all I got.

 

[Jo Zebedee]

Does your character's name begin with K?

Of course; poor sod. (I will be really really nice to him in the third book, promise. ) That was kind of my take on it - that it's kind of PTSD, with nightmares, lack of sleep etc, but as you say, still able to kick ass, but it's whether or not I'm pushing the boundaries of common sense. (I think I built him up that he can cope, but everyone has limits....) I also think to have him humming and singing his way through life was likely to get laughed out of town...

 

[alchemist]

It sounds plausible and only serves to make him appear more heroic.

Go on, put him through the ringer (again).

 

[Vertigo]

Springs, I think he would cope so long as he knew the pressure was likely to be at that level for only a short while. You'd be amazed how much stress and discomfort a person can stand, so long as they know it will not go on indefinitely. If it is likely to be indefinite then despair could easily set in.

Alchemist - you don't happen to remember the name of that book do you?