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 Post subject: Stealth
PostPosted: Thu Jan 03, 2008 4:29 pm 
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First, let me start out with a disclaimer; I have read the arguments, and understand why there is no stealth in the TW. My question in this instance is whether or not it is physically possible to create a stealthy ship at all... not using TW tech; just theoretically.


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 Post subject: Re: Stealth
PostPosted: Thu Jan 03, 2008 4:43 pm 
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John Dearmore wrote:
First, let me start out with a disclaimer; I have read the arguments, and understand why there is no stealth in the TW. My question in this instance is whether or not it is physically possible to create a stealthy ship at all... not using TW tech; just theoretically.


An easier way to answer this is to rephrase the question:

Show me how you're going to stealth a ship.

Premise 1) You may not know where ALL the observing platforms are. Therefore, directional stealth is dubious at best.

Premise 2) Transit times are in weeks to months. Being stealthy for 12 hours isn't enough.

Premise 3) You have to apply at least two and probably seven or eight km/sec of thrust to get where you're going. You need to make sure this thrust doesn't cause you to show up like a second small *star* in the star system, exhibiting proper motion.

Premise 4) You don't get to keep the crew and ship running at liquid helium temperatures for two months. People have to work on these ships, live on these ships and otherwise be comfortable enough to do the job you want them to do.

Premise 5) In a society where interplanetary transits are routine, you can expect that full sky spherical star searches take under an hour; it's the equivalent of aircraft control radar. Your stealthy ship cannot occlude a star. Nor can it transit across the sun. Either will result in detection. Likewise, you can't reflect or reradiate in any way, shape or form indicative of a machined surface. It also can't re-radiate at anything other than standard black body temperature.

Rather than me try to prove it's impossible, you get to try to prove that it IS possible under those precepts, and Winch, Anthony and several others will come in and poke holes in your assumption set.

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 Post subject:
PostPosted: Thu Jan 03, 2008 5:03 pm 
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Define "theoretically."

:?

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 Post subject:
PostPosted: Thu Jan 03, 2008 5:15 pm 
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I intended no reflection on your game design, and did not mean to imply (if I did) that I was attempting to get you to include stealth in AV:T. I was simply asking as it relates to other space combat games without the technological limitations of the TW.

edit* Theoretically: Ken has stated 5 things that need to be overcome or circumvented; how do you get around these, with no limitations over technology, or really anything else.

I'm asking you all because you know more about this than I do, and because I was curious... perhaps that was a mistake.


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 Post subject:
PostPosted: Thu Jan 03, 2008 6:09 pm 
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Easy answer - there is no stealth in space.

Long answer - you have your people sitting in a vehicle that is roughly 273 Kelvin, against a background temperature of 3 Kelvin. So figure your ship is ninety times hotter than the background. This is assuming that the ship is the temperature of frozen water/ice, not if they had a 800+Kelvin reactor running.

Really long answer:
http://www.projectrho.com/rocket/rocket3w.html

Even more fun is when you calculate the power plant:
Specific Impulse * mass in kilograms * acceleration (in m/s^2) * 4.9 = Engine power in Watts
(I call this the triple point of rocketry - 1 SI * 1 kg * 1 m/s^2 = 4.9 Watts)

So a 1,000 ton ship, with 10,000 Specific Impulse, accelerating at 1G, will require a 480.2 GigaWatt reactor. (480.2 * 10^9 Watts)

As a comparison, the United States, in 2006, used 4.06 billion megawatt-hours. http://www.eia.doe.gov/cneaf/electricit ... pates.html

This converts to 4.06*10^15 Watt-hours in 1 year. 1 year has 8766 hours in it.

Dividing 4.06*10^15 Watt-hours by 8766 hours gives 463.15 *10^9 Watts.

If I did my math right, this one ship could handle all the power needs for the United States.

So there is really no steatlh in space, unless you start using alternate dimensions to dump the heat into so you have 3K exhaust, and find a way to hide the heat from the ship itself.

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 Post subject:
PostPosted: Thu Jan 03, 2008 6:54 pm 
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John Dearmore wrote:
I was simply asking as it relates to other space combat games without the technological limitations of the TW.


Curiousity is a wonderful thing - thermodynamics arguments can be a wonderful thing. Repeating the same thermo arguments three times a year for 8 years now stops being quite so wonderful. :)

The usual form of this question is this:

I give a long, math explanation.

Someone comes up with "What if I <insert solution>"

I show how solution fails to work. Giving lots of math.

Then they come up with "What if I <insert solution2>"

Repeat.

It generally goes 'round the maypole for 13 or 14 different solutions, none of which work...but no amount of explaining the math up front ever gets people to skip the attempts to wiggle out of it.

Insofar as other SF games do it - 99.9% of them just ignore thermodynamics, because the designers never thought about how it works. The ISS has almost twice the mass devoted to radiators to get rid of waste heat as it does to solar panels to collect energy.

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 Post subject:
PostPosted: Thu Jan 03, 2008 10:10 pm 
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Which is why "not limitations over technology" is meaningless. Are you allowing anything that we can possibly imagine? Tactical faster-than-light? Perpetual motion devices? Drawing power from hyperspace?

If you posit "within the realm of science as we know it, then AV:T actually pushes a bit past that (the drives, mostly).

Todd Kes wrote:
So there is really no steatlh in space, unless you start using alternate dimensions to dump the heat into so you have 3K exhaust, and find a way to hide the heat from the ship itself.

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 Post subject:
PostPosted: Thu Jan 03, 2008 11:18 pm 
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Ken Burnside wrote:
Curiousity is a wonderful thing - thermodynamics arguments can be a wonderful thing. Repeating the same thermo arguments three times a year for 8 years now stops being quite so wonderful. :)


I know, and I guess I should have worded my question in such a way as not to instigate such a conversation. The question I intended to ask (but apparently didn't succeed, for which I apologize) was strictly: Are there conditions (such as not having a crew on board the ship) that get around some of the problems with stealth. Assuming that drive flare is not a problem.

Ethan: Primarily circumstances such as the above (I don't know if computers can operate in such low temps, but the scientific space probes we send out have some kind of electronics on them)

edit*Again, I am not asking specifically in the TW setting, this is simply my own interest about another setting.


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 Post subject:
PostPosted: Thu Jan 03, 2008 11:27 pm 
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John Dearmore wrote:
Ken Burnside wrote:
Curiousity is a wonderful thing - thermodynamics arguments can be a wonderful thing. Repeating the same thermo arguments three times a year for 8 years now stops being quite so wonderful. :)


I know, and I guess I should have worded my question in such a way as not to instigate such a conversation. The question I intended to ask (but apparently didn't succeed, for which I apologize) was strictly: Are there conditions (such as not having a crew on board the ship) that get around some of the problems with stealth. Assuming that drive flare is not a problem.


If you want something that runs as low power output as a modern space probe, maybe.

However, that's sort of like asking if you can make a Burke class DD (~9,000 tons) work from the engine on a VW bug.

Doing anything useful in space, in a reasonable time frame, takes power. And lots of it. That's going to get noticed in a universe where IR sensors exist.

Think of it like this:

Imagine a blowtorch. Pretty hot, pretty bright.

Got that fixed in your mind?

OK. Now, imagine the same blowtorch out on the Ross Ice Shelf in the dead of the Antarctic winter on a perfectly clear, moonless night.

Seems like it'd stick out, yes?

OK, now, you're looking for it with good night vision goggles that will pick up anything that's significantly warmer than -40C.

Seems pretty hard to hide, yes?

OK, now, imagine that, instead of comparing that temperature difference from a measly blowtorch over nice, balmy Antarctic Sea Ice, you've dialed it up past 11, and broken the knob somewhere.

Oh, and you have radio tracking collars on every penguin, the penguins only move at about 3 feet per month, and don't have blowtorches, so it's hard to confuse the blowtorch with a penguin.

And you have several months to notice that blowtorch out there moving in ways that are decidedly un-penguinlike. :)

Now, here's the kicker...that blowtorch isn't the drive. It's JUST the reactor system on the ship and the heat dissipation system.

If the drive were on, you'd be wondering why you were seeing nuke flashes several times per second.....

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 Post subject:
PostPosted: Thu Jan 03, 2008 11:30 pm 
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In your other setting, does a ship generate onboard power, yes or no?

If yes, it generates about 4x as much waste heat as it generates usable energy.

Where does the waste heat go?

How much of it is there?

How much radiator surface do you have, and at what temperature?

As temperature of radiator increases, so does radiation efficiency - and so does visibility.

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 Post subject:
PostPosted: Thu Jan 03, 2008 11:49 pm 
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So it was a stupid question...

Apology offered, as I seem to have inserted my foot in my mouth. :wink:


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 Post subject:
PostPosted: Fri Jan 04, 2008 4:01 am 
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John Dearmore wrote:
So it was a stupid question...

Apology offered, as I seem to have inserted my foot in my mouth. :wink:


Apology accepted - and not quite a stupid question. But one that causes a bunch of us to go "Oh, no. Here we go again...batten down the hatches! The math is coming hard and thick!"

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 Post subject:
PostPosted: Fri Jan 04, 2008 12:56 pm 
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John, as Ken said, not a stupid question--although the phrasing was a little loose! :wink:

My reply wasn't meant to be hostile in any way, and my apologies if the terse phrasing left that impression. I think you can see how "no technological limitations" might lead to "Hunh?" responses ...

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Stop laughing.


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 Post subject:
PostPosted: Fri Jan 04, 2008 1:49 pm 
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Ken Burnside wrote:
Oh, and you have radio tracking collars on every penguin, the penguins only move at about 3 feet per month, and don't have blowtorches, so it's hard to confuse the blowtorch with a penguin.




I want a penguin with a blowtorch!

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 Post subject:
PostPosted: Fri Jan 04, 2008 2:49 pm 
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Thankyou both. :) And I'll work on that phrasing. :wink:


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