Inertia.
Radiation, mainly heat.
Inertia.
INERTIA

square cubed law
shearing forces
fuel
deceleration
turning

galactic debris

Overheating. Seriously, cooling is one of the most difficoult things to do in space.

>>10098240
Would it be possible to put excess heat into a laser, or something, and dump it?

>>10098261
You need to install heat sinks.

>>10098240
>Expose heat sinks to the cold of space
>???
>Profit

or failing that

>Fail to understand how space works
>Expose heat sinks to what I believe to be the cold of space
>???
>Fuck I dunno

>>10098240

One of the "car talk" puzzlers was about a US satellite that malfunctioned. Turns out they put fans inside to cool it, not realizing it would be in a vacuum once deployed. Derp.

>>10098303

That does work to some extent, but not exactly that way. Space has no temperature, since it has no medium to conduct temperature through. The only way to get rid of excess heat in a vacuum is through radiaton, which works slowly and requires a large surface area, so radiating vanes outside the ship that you can pump the heat into are best. Of course the best solution in the first place is to try to regulate heat generation as much as possible.

Okay, how would that translate into shape?

Long flat ships?
Sausage/submarine ships?
flying saucers?
Deathstars?

>>10098303
>>10098284
>heat sinks
>sinks
RADIATORS god fucking dammit. Heat sinks sink heat. As in trap it. As in permanently.

Those things in you computer? Those are radiators. Why the fuck is the computer industry so retarded? Why?

>>10098465
The most efficient shape is a sphere. Smallest surface area for a given volume. Unfortunately, it's much more difficult to make a spherical internal space in a way that can be used efficiently, so we tend to go for square-based designs or suchlike.

http://www.projectrho.com/rocket/index.html

>>10098524
Square based? Don't you mean cylinder based designs?

>>10098485

>>10098560
Sorry. I'm just sick of seeing that term chronically misapplied in a way that logically makes no sense.

>>10098458
Ah, as I was posting the first bit I was all like "It can't be this simple... I'm fairly sure space doesn't work this way,"

Turns out I was right.

>>10098579

Different poster, but to be fair a heat sink is a convenient place to start the process of radiating heat from and it's useful to have around if you can't radiate heat away for awhile, for whatever reason.

>heat dissipation
Mass Effect had a pretty food idea.

>>10098458
I think the plan would be to refridgerate the bulk of the ship while dumping heat into some type of superheated gas, venting the gas at regular intervals.
You can't shoot heat with a laser because only FREE energy can be used for useful work like shooting lasers - transfer of Free energy will at most keep the temperature of a system stable.
A 1 kilowatt laser generates 1 kilowatt-hour of heat per hour that it is used.

>>10098675
>1 kilowatt laser
>1 kilowatt-hour of heat be hour
wat
MIND = BLOWN

>>10098465
It's quite likely that ships will be designed like spheres or cubes, and their size will have an upper limit placed on it by how much heat needs to be radiated.
Then, swarms of these ships will travel towards their targets.

Make it too long, bits will snap when you turn.

Too thick, overheat.
Too thin, radiation fries stuff.

Sphere with coolant tubes to carry heat to radiators is good, cylinder/cone for military narrow profiles.

>>10098609

Well to be fair it is almost that simple, all you need to do is pump heat into a substance capable of thermal radiation and expose it to space. It's just that a heat sink is an object designed to trap large amounts of heat over a long period of time so it doesn't cause problems elsewhere, and usually they don't radiate heat very effectively.

If you don't know, thermal radiation is when a heated object expels heat as low frequency radiation. When an iron is heated and starts to glow, it's radiating heat away, the glow is just the visible component. That's the only type of heat exchange that works through a vacuum since it doesn't need an intervening medium.

>>10098308

sounds bullshit to me bro.

How would you design a radiator for such a vessel? The best you could do would be to make a sphere, because the fancy-shmancy design you see in CPU radiators requires convection - heat doesn't transfer from one prong of the heatsink to the other. In space, it will, and there's no point to making a spiky design.

You know, there are these things called thermocouples that transfer heat energy to electricity?

Could you use radiators+thermocouples to turn heat energy to light energy in say laser form? It'd be 'quieter' than dumping IR radiation all round.

I would think a spinning cyllinder would work best, as it could have artificial gravity through centripetal force

>>10098738
Blackbodies radiate as T^4, right?
Does that mean that if you heat-pump massive amounts of heat into part of the ship (thus refridgerating the other parts), the ship will radiate faster?
Something like a Plasma tube or a Carbon block on the outside of a ship would work.

>>10098774

Pipes cover surface of sphere, pump heat conducting liquid through pipes, radiating material on outside of pipes, facing space. Unless I'm much mistaken, that would work. Of course it would light your ship up like a Christmas tree if anyone was looking, so it's not really ideal on a warship or anything, but should be fine for civilian use.

>>10098774
Surface area.

Make a structure with a MASSIVE surface area that'll radiate heat. Bigger the surface, faster it'll radiate. Also probably have to consider certain materials that radiate more...erm...fast.

For warships, the Mass Effect technique of using heat sinks and fluid thermal transfer mediums (liquid nitrogen, vent into space as a fine mist, radiates extremely quickly, suck it back up and recycle) is one of the best.

>>10098818
Thermocouples work on temperature GRADIENTS, not temperature itself. They turn free energy into electric potential.

>>10098818

Sorry, doesn't work, a thermocouple just gets electricity from the thermal gradient, it doesn't actually convert the heat into electricity. In fact the process generates some heat itself, if I'm not mistaken. Either way you end up with heat+electricity or heat+heat+electricity.

>>10098774
Spikes on opposite sides of the ship
???
Heat loss

A single flat sheet design would dump the most heat without reabsorbtion though..

>>10098840
For greater efficiency, you'll want to make some very delicate lattice structures out of really thin pipes and run your coolant through them to speed up the cooling process.

Remember the golden rule. Surface area = heat lost.

Not, like, mathematically. It's a proportional relationship or something.

>>10098837

Sure, that'd work fine.

Would it be possible to have small, disposable heat-sinks that, once 'full' could be ejected/fired as trash/projectiles? Bonus points for releasing heat onto enemy ships.

>>10098818
That said, to Heatdump, you can just heat a part of the ship so hot that it gives off the same spectrum as the Sun. ;)

Thus far Superheated Conducting Fluid being run around the outside of the ship seems to be the plan.

>>10098906
They'd have to be replaced eventually.

>>10098872
>>10098856
There'd be a gradient between ship and radiators, presumably.

Where does the energy come from if heat energy doesn't go down?

>>10098881

Of course that's correct, but ideally you wouldn't want anything that could be damaged or suffer shearing force from turning or acceleration. The ideal would be to not generate enough heat to need giant radiators under normal circumstances, but have some you can deploy in emergencies, I guess.

>>10098840

There's no stealth in space anyway. Your main drive is going to be outputting enough energy for enemies to detect you from hundreds of AU away anyway, so plastering your surface with radiators won't make much difference.

>>10098928
That's why retractable radiator arrays are a fairly good choice, for certain applications. You CAN build perfectly good radiators that also look pretty and stick them to a cruise liner to add to the aesthetic.

>>10098928
Have multiple fabric-type sail radiators, and be ready to jettson or pick them up when you turn.

>>10098974
A fabric can just be folded and stored when not in use, no need to throw them off.

>>10098906
>>10098881
Surface area = heat loss in convection. This works for the interior of the ship, but on the outside, a fine lattice reabsorbs most of its heat.

And yes, refridgerating most of the ship while heat pumping into a solid block of cheapass shit, then ejecting said cheapass shit, would work quite well.
Maybe a combination of the Radiator + Ejector could work - Jettison and replace the Radiator in emergency or high-heat conditions, and let it radiate in others.

>>10098927

Too complicated for me to really write out, I'm not good at descriptions, but this is what it is.

http://en.wikipedia.org/wiki/Thermoelectric_effect

>>10098927
Covering shit in thermocouples means you didn't bloody well design the engine properly. That's what engines are designed to do - recover free energy from temperature differences.

>>10098950

It's true that there's no stealth in the long term, but short term stealth is possible. You couldn't really hide while accelerating or decelerating, but combined with drones, flares, ECM, etc, you could make the opponent unsure of your exact location for a limited time, say maybe a few seconds or minutes.

Additionally, in combat ships, you need to consider:

-Targeting profile
-Kinetic deflection
-Weapons fire reactive thrusters
-Laser/energy weapon insulation

>>10098987

Since mass is at an absolute premium on spacecraft, how is carrying along loads of "cheap-ass shit" just to jettison to carry away waste heat a good solution?

>>10098974
Sail radiators would work, as long as it was only one sail (to prevent the sails from radiating onto one another). However, I'm not sure how you'd unfurl or re-furl the sail; any mechanical parts you use to do so would be subject to large amounts of heat (as the sail is being used as a heatdump).

>>10098906
sure.

Inject superheated plasma into a device designed to expel the superheated plasma as a means of propulsion.

Fire these off when you need to dump heat quickly. They could also would like flares to distract heat-seaking missiles, or as cheap projectiles in close range laser "knife fights" where ships will be generating tons of heat and needing to keep their weapons systems cooled.

Just fire off these cooling cones mid-fight like cannon-balls, they'd accelerate until they ran out of plasma, and the kinetic force they gained would keep it going until it hit someone.

Hopefully an enemy ship, and not some random ship 30 years down the road traveling through the area.

>>10099026

Based on the design of the ship though there might be any number of places where you could get supplemental electricity from the ships normal operation, so you might as well. Of course that depends on if the ratio of the electricity produced to heat produced makes it worthwhile.

>>10098987
Idea: make your radiators out of something that's as EM-reflective as you can make it?

>>10099063
What would weigh more?
A heat-radiating sail, or
A sufficient supply of stuff that can be jettisoned?

Stealth also works at range.

Unless your SHIP IS HUGE or you are within a few hundred thousand KM they shouldn't spot you as more than a pixel-sized blip if you're coasting.

>>10099047

You also have to cool your habitation modules to about 3 degrees K which would kill your crew.

>>10099102

Generally being EM reflective and a good thermal radiator are mutually exclusive. For example, there's EM reflective shiny stuff inside a thermos for exactly the purpose of preventing thermal radiation from either side.

>>10099121
The problem is that a sail keeps working, but you'll run out of stuff to throw away eventually.

>>10099139

No, you just have to prevent the hull from radiating heat, and you can do that by cooling the hull and dumping the heat in a heat sink. That's why it's a short term thing, since you can only store so much heat this way before it's 'full'

/tg/ - Thermodynamics.

This is why we don't build any massive pyramids in the modern day and age - cooling a sufficiently large building is about 50 million different pains in the ass, as any fans or refridgeration units ALSO produce heat which needs to be blown / cooled out.

>>10099083
>as cheap projectiles in close range laser "knife fights" where ships will be generating tons of heat
At ranges plasma would damage boarding parties would do more damage.

Plasma's a gas. In space.

>>10099124

Sadly that's not entirely true. Any object that's radiating heat into space is pretty obvious no matter the range, unless you go to some crazy and mostly temporary lengths to prevent this. Also a ships drive would be crazy visible at any range if it's on a continuous burn.

>>10099179
The sail is impractical in a fight, it would only be used after you're safe.

Ejecting coolant is a fast, easy, less dangerous way to lose excess heat in the middle of a battle.

self-propelled cooling cones like the ones described above could also be usable, and would double as a kind of space flare.
Not sure they'd be effective as a weapon though.

>>10099121

Depends completely on the operational time you're looking for.

>>10099231
>Also a ships drive would be crazy visible at any range if it's on a continuous burn.

Not entirely, they can only tell where you WERE, not exactly where you are.

Stealth in space won't be about masking your heat signature, but instead making it unpredictable, and using distractions like flares to simulate other ships.

>>10099236
Now we're getting into role-dependent design.

>>10098485

Out of all this thread I honed in on this.

What that guy just said went along the same lines as:

"Gay? GAY?! GAY MEANS CHEERY BRIGHT AND PLEASANT! MEN WHO HAVE SEX WITH OTHER MEN, THEY ARE HOMOSEXUALS! JESUS CHRIST WHY IS EVERY ONE SO FUCKING STUPID!"

>>10099220

This person has a strong point. Plasma is just highly positively charged gas at a high temperature. It's natural desire is to fly apart at high speed, so no matter the velocity it has when it's ejected, it's going to dissipate really, really fast and cool really, really fast due to that. Plasma is a very poor substance to just shoot our as a weapon.

>>10099205
You know that mission in Deus Ex where you blow up a generator by turning off its cooling?
Well, suppose that generator was giving power to a whole shitload of other cooling units.
And then, when the generator failed, all the other cooling units failed, and then MORE generators exploded.

Sound catastrophic and unlikely due to things just shutting down when they get too hot?
Well that shit happens in large enough buildings. One cooling unit fails, a portion of the building heats up, the high heat causes nearby systems to fail. Before long you have 40C heat inside on a 25C day.
And if your large building is a power plant of some kind?
Hoo boy, are you fucked.

>>10099289

Sorry, to shoot OUT as a weapon.

>>10099231
It's not the amount of heat, it's the cross-sectional area.

Space is huge. Your ship may be a torch but it's a pinprick sized ship. At a distance you just can't get a good resolution enough without GIANT TELESCOPE LENSES. How much light/em can enemy ships scan if their scanners are ship-sized?

>>10099257

That's completely true for close range stuff, like any sort of combat would be, and I (tried) to cover that in a previous post, but for long distance travel TO the fight, it's going to be pretty easy to track you due to the speed you're going at compared to any possible manouvers you could make, unless we go into Sci Fi stuff.

>>10098485
Because they're not radiators, they transfer energy by convection and conduction. Better to call em an extended surface.

>>10099303

Assuming there's any reasonable number of detectors it would be easy. All you have to do is scan an area for certain bands of radiation, discard known objects, and track any that show movement or are in an unexpected area. The reason that more = better for this is triangulation, so that a ship can't hide in the signature of a star or something, and even then it might not work due to the difference in intensity.

>>10099303
>>10099419

Oh yeah, forgot to add. Space might be huge, but no matter where you are you're searching the same spherical area around you, so it's not like you need any crazy types of sensors, just enough to scan the area around you every certain period of time for the sort of energy emitted by a ships drive.

You are all missing the simple solution. If your ship possesses any kind of reactant mass, use that as your working fluid. Sublimate or evaporate it prior to passing though your drive. Also works for excess water produced by fuel cells. Heated water may be dumped to the void.

>>10099467

A completely valid solution, and one sure to be part of the cooling of any ship we might use. However, it may or may not be enough on it's own and any slower than light interstellar ship would probably have long periods of time when the drive isn't firing, so other cooling solutions are most likely needed.

Spacecraft design is going to depend entirely on what it's made for.

If you want to protect your spacecraft from high-velocity projectiles, like say bullets, you want a slope and armor. The best design in this case is a cone, but you have to keep your nose pointed at the most dangerous thing all the time.

Alternatively you can use a sphere, which will have equal protection everywhere, but overall less protection than a cone. [Assuming equal mass and materials]

Another important consideration is the moment of inertia, or rotational intertia. Basically how quickly the spacecraft can spin around. A sphere has a big advantage here over a cone, but a cone gets the greatest benefit from turning quickly because all of its armor is in one direction.

You can juggle around the basic shapes like this all you want, maybe coming up with various odds and ends of cylinders and spheres and whatever.

Oh jesus fucking christ. *gets out old physics notes*
Angular resolution = roughly wavelength / lens diameter.

Wavelength of a 300K blackbody (I.e. a people) is 10 micrometers or so. Wavelength of a 3000K heatsink is 1 micrometer.

Angular resolution in radians = 10^-6 / ship diameter (3000K) or 10^-5 / ship diameter (300K).
The angle something (small) makes in radians is proportional to arc length / radius, or in this case, Ship length / distance.

SL / distance = 10^-6 / SL
Distance = SL^2 * 10^6 (meters)

So a ship 100 metres long, assuming it has a 100m telescope on it, can see another ship at 10^11 metres, or 17 light-minutes out.

>>10099522
That's what the wastewater is for. Or just carry more reactant mass. Far simpler from a systems perspective to have one consumable for both.

>>10099419
Of course if there's a huge number of ships there's a better chance of someone spotting the pixel that is your ship (assuming its even a pixel wide), but you physically can't get a better resolution on it without a larger lens or interpolation, which requires both lenses to be relatively stationary to each other at micrometer levels of precision. A dedicated large satellite array would detect but ship sensors would necessarily be smaller.

>>10099545
This falls to 1.7 Light-minutes out for 300K ships, but that's still quite a detection radius. c-kinetic weaponry's effective radius would be in the realm of a light-second, or 10,000km, and a homing missile's effective radius would be somewhere around a few light-minutes.
Effectively, if you're in the ship's kinetic weapons range, it can see you.

>>10099560

Again, helpful, but I doubt that'd cover all the cooling needs you might have. Humans produce a great deal of heat, after all, so you'd need a truly monstrous amount of waste water if you wanted to have actual humans with you. I can't remember the exact value, but apparently a single humans body heat can melt several hundred pounds of ice a day.

>>10099545
Thank you for the calc kind sir.
17 light minutes in interstellar terms is not far at all. Ships between star systems would only be seen not long before they get there, depending on how fast they are. No time to reinforce, though.

>>10099419

also don't worry that 100 AU == 13.8 light-hours

This thread is awesome, good job guys,

>>10099603

It really wouldn't take a huge number of ships or incredible precision to spot and track something long before it came into any sort of range for combat. I'm not talking about looking for something light years, or even light hours away. A few light minutes would do, and that should be no trouble at all. After all, to fight something you more or less have to be going at the same speed as it or you risk just overshooting, and it takes a long time to decelerate with any sort of drive we can conceive of now.

>>10099656
Think strategically, not tactically. Stealth mid combat: not that useful. Stealth getting your fleet past the border patrol and into the colonies? Ace.

if combat isn't realistic, its not fun.realism is the best possible solution.

When any one portion of the spectrum is relied on heavily for detection and tracking, it is asking to be exploited.

I see decoy use here.

>>10099692

Reinforcing on an interstellar level is sort of silly with any sort of science or technology we can think of now. Heck, waging an interstellar war itself is pretty silly, probably not even possible.

Also, that was for a 100m telescope, no reason not to have ones that are many hundreds or thousands of km when you're talking about an interstellar civilization anyways.

>>10099685
Not really, the majority of heating will be produced by your electronics, which if powered by fuel cells, will produce enough wastewater (even after crew consumption) to handle cooling.

If you want some light reading on the topics:

http://books.google.com/books?id=31GqndM3fk8C&lpg=PP1&dq=space%20vehicle%20design&pg=PP1
#v=onepage&q&f=false

http://books.google.com/books?id=_KCNcxYPUZgC&lpg=PP1&dq=space%20mission%20analysis%20and%20
design&pg=PP1#v=onepage&q=space%20mission%20analysis%20and%20design&f=false

Space Mission Analysis and Design by Wertz and Larson is also a useful reference.

>>10099545
You're considering the spacecraft as radiating heat, not the radiators. To get a better estimate on how big or small it looks you'll need to know what area the radiators cover.

Additionally, this does not even begin to cover the engines which depending on their design are going to put out megawatts to gigawatts or even more. [1-5 Terawatts would be about right for what you need for quick interplanetary travel]

>>10099739

We'd love to think stealthy on a strategic level, but it's just not possible in space, sadly. You'll see them coming before the fight is joined, every time.

>>10099795

Oh yes, decoys, flares, etc would be a major part of any space combat. Possibly the biggest part, if you can get them small enough. Of course if they're big enough to be limited in number on the scale of an engagement, that's another matter.

>>10099801
Still. It's hardly 'no stealth in space'. Just no stealth right next to your opponent.

>>10099656
It looks like Small, Fast torpedos that are mass-driven about 10km out (cold), then quickly go hot and home towards the enemy ship, are the weapon of choice in ship to ship combat.
You can fire them at "I know the enemy's out there somewhere" range, and have the Torp's own sensors get a clearer view as it moves towards the faint smudge on the horizon.
The Torp only goes hot after 10km or so, or else the enemy vessel will know your exact location from the Torp's much greater temperature.
Such a torpedo might be able to home into the enemy ship from as far as a Light-hour away (or more), but can only be -targetted- when very close.

Of course, this lends itself to the idea of Counter-Torpedos, as the bright flare of the torpedo will be visible long before its cross-section is, meaning an anti-torp will be able to home in on the torp.

Beyond that, though, and you get into "we need little torpedos strapped to this big torpedo" territory that makes the warhead just not as cost effective as making the friggin' thing GO FASTER.

>>10099083
*CLANG*

WHAT THE FUCK WAS THAT?

>>10099289
I show up out of nowhere, to point out what seems to be a misunderstanding:
I believe the man was implying using the plasma to propel solid projectiles, not making projectiles out of plasma.
Also, The difference between a gas and a plasma is this: in a plasma, there are no coherent atoms, just free electrons and colliding nuclei. This is why plasma is considered to be a fourth "State" of Matter.

>>10099860

'No stealth in space' just turned in to 'Guess the real target out of two hundred.'

>>10099795
>I see decoy use here.

There are issues with that.

If you use a decoy, it has to more or less mimic your ship. This means it needs to have the same thermal output, and worse, the same acceleration and mass.

If the decoy is small, it won't need a big engine to reach the same speeds as the spacecraft it is mimicking - this however also means that its engine will be less powerful, so even if it travels at the same speed with the same acceleration as what it is mimicking, you can still tell it's a decoy because it's not as bright.

If you make the engine on the decoy as big and powerful as the one on your spacecraft, it will now accelerate more quickly and reach higher speeds and again you can see the difference.

>>10099808

Both good resources, but they're generally talking about, at most, interplanetary distances of relatively limited size and duration that we could more or less do now. Any sort of long term travel without the chance of resupply, such as interstellar, would be a very different thing.

>>10099848
Think theatre-level then.
If you can see a giant fleet headed your way from light years out, you can potentially build a defense. Not from light-minutes.

>>10099854
You don't need to burn ALL the time. Just for the accel and decel.

>>10099984

The decel has to come right at the end of your flight though, and it has to be as long and hot as the accel, unless you want to dramatically increase the time of the flight. If you want to coast in at more or less combat speed from outside the detection range of your enemies you're looking at adding years or decades to your travel time.

>>10099984
>You don't need to burn ALL the time. Just for the accel and decel.

And for the fastest transit, that means the engines are operating the entire time.

If you coast, you might be stealthy, but it's also going to take you years to get anywhere. Quite possibly by the time you arrive, there's no longer a war to fight, or the enemy has built himself another entire fleet.

>>10099956
Also if you're taking ship sized decoys on interstellar missions with ship-rated engines you might as well shove a crew in it and some guns.

Though a light inflatable decoy with a weak, very inefficient hot engine to simulate your ship's heat and acceleration might work.

>>10099984

I should point out that there would probably be detectors at strategic spots around any colonized system, and their size would likely give you much more time to see incoming enemies. Maybe even a light day or two, which should give you weeks or months to actually plan and execute a defense.

Spheres are a bad idea because for a given volume you're going to have less surface area from which to radiate heat than a cylinder of equivalent volume.

You also might want to use water for some of your heat dissipation needs. A good solid coating of ice around the ship could function as a heatsink, a water supply, and protection from high-speed particles (both cosmic rays and ordinary debris).

which is why the only real hope for shit to get anywhere is to develop some kind of warp technology. (warp in the context of warping space to make wormholes, Einstein stuff; none of that chaos shit)

>>10100084
Can you not just put yourself in decaying orbit and decelerate then while launching missiles?

>>10100208

Sure, but unless you want the orbit to be hundreds or thousands of years you'll already need to be really close and going pretty slow.

>>10100106
If you keep engines going, the inertia will have you speeding so fast it will take an immense amount of energy to decelerate. It'd be better to reach a terminal velocity then coast for maximum fuel efficiency.

>>10100196

This is probably true. Travel on an interstellar scale is more than possible with just a bit more progress than we have, but WAR on an interstellar scale probably won't happen without some sort of FTL, which might never be possible.

>>10100245

terminal velocity in space is light speed, and you'd never reach that anyways. Assuming you carry enough fuel, a constant burn (half acceleration, half deceleration) is by FAR the best route.

Given sufficiently advanced/powerful computers, stealth is impossible even if you coast in and find some way to completely hide your heat signature. All that has to happen is you have to occlude something at the wrong time.

A few extra years to get the drop on my enemy? Fuck yeah!

Better yet do an orbital slingshot, drop missiles and go to next target! Don't even need to slow down!!

best chance for stealth shit: have a way for all heat output to be stopped outright, and have it all contained inside. this will only last a very short while before any heat-sink or whatever /melts/. after the need for such stealth is gone, mother fucking open EVERYTHING to let heat out,

>>10100325

There's still the drive to worry about, and if they spot you while your engine's going then it doesn't matter if you're stealthy or not, because they'll know right where you are until your next engine burn.

So would this actually be a good shape for a ship?

I see all this talk of spheres and whatnot but a large flat surface that has a minimal profile in terms of combat (unless you opponent gets over or under you)

>>10100274
Not really. You'd have to occlude enough area on the opposing's ship's scanner to show up in the first place, at which point we're assuming they can see you anyway.

>>10100325
>>10100409

Forgot to add, at that point they just have to pop out a kinetic weapon at long range, and if you don't spot that then you're done, and if you do spot it you have to light your drive to avoid it. Also, before anyone mentions it, using a cold drive like expelling gas or something to slightly alter your trajectory is usually very visible, since most things you could chuck out for that purpose form easy to spot crystals.

>>10100413

It would work, but it would have to turn very slowly due to shearing forces, and a cylinder or cone would be equally good, while probably being more efficient. A cone would have good armor too, and might resist weapon fire to some extent.

>>10100413
No, it has lots of surface area for it's volume. Really, a sphere is preferable.

>>10100418

Different poster, but you'd be surprised the resolution some telescopes can get, and that's without a century or so of advancement on top of it. I'm not saying either of you is right, I don't know, but I wouldn't be surprised if it would work.

>>10100413
>>10100481
>>10100505

I should mention here that a sphere is clearly the best shape for a civilian ship or any sort, while a warship might be something else depending on the technology and weapons at the time.

>>10099692
At what range can you see a radiating object? Let's derp around for a bit.
Sun radiation on earth's surface:
164 Watts per square meter
Sun magnitude:
negative 26.73
Magnitude of a magnitude 4 star: 4
So let's BS it and say the Sun outputs 1,000,000 times as much light as something that can be easily detected.
that's 0.000,166 watts per square meter for something detectable; round that shit to 0.0001 W/square meter.
Suppose the Human Eye has a surface area of 1cm^2, so 0.000,000,01 Watts fall on it from a mag-4 star.

suppose 10^-8 Watts is a detectable power output against any given background (yes, I know it's bs and should be based on photon count vs. photon background, but whatever).

What's the wattage of a spaceship? Suppose it's somewhere around 1 Gigawatt (that's the output of a large power station at the moment, to give you a sense of magnitude). 1 Gigawatt over an entire sphere.
If you cut the ship's radiated wattage to 1% of its power output, then the ship can only be seen from 1/10th of the previous radius.

To detect a ship of that power, noting that a minimum of 10^-8 watts must fall on your detector, your detector must have a total size of 10^-17 times the sphere's area - or somewhere between 10^-8 to 10^-9 times the sphere's radius.

Flipping it, the Radius at which you can detect a 1 Gigawatt ship, from the background, is equal to 10^9 times the radius of your detection dish (in metres).
A 100m Dish sees a ship from 100 million kilometers out - or about 6 light minutes.
A 1km Dish sees it from a full light-hour out.
A 10m Dish sees it from half a light-minute out.

Which is ... actually quite similar to the distance at which it's resolved. >.>

Also, "Part of your comment isn't allowed to be posted" error happened. The name of the specific power station that outputs 1 Gigawatt is the Hoover Dam; apparently 4chan must think I'm planning to sabotage it or something.

>>10100507
We're assuming if more than one photon from the ship hits the sensor it's detected.

Photon number is per heat * cross sectional area.

Even a 100% efficient telescope can't analyse <1 photon. See the above calc.

>>10100533
>>10100546
>>10100561

Two things, were you considering any sort of ships drive in that, or just the radiated waste heat?

Second, for an interstellar civilization under any sort of threat of attack, a 100km or 1000km dish would really be a big surprise.

>>10100599

Fair enough, point accepted.

>>10100629

yea dude, i would not be suprised at all to see standard ships to ahve dished or whatever as large as the ship itself. possible 10km +

So yeah. Space battles will be between c-fractional torpedos that can home on targets, and have an operational range of between 1 light-minute and a light-hour, vs. some shorter range countermeasures against the torpedoes.

So basically ... Air combat of today. But with the distances of engagement multiplied by a million.

>>10100629
You mean 'not really' a surprise perhaps?
Also thanks calcfags. You did the quantification for my only qualified argument.

>>10100668

Well I was thinking fixed orbital observatories or just a giant dish near the colonies, rather than on a ship itself. On a ship it'd naturally be much smaller, I imagine.

I'm thinking of stuff in the context of an invasion of an inhabited system by an outside force, rather than a meeting of several enemies in a third area, or something.

>>10100703

Yeah, I meant not a surprise, my bad.

>>10100691

It's entirely possible, but I'm not sure how things would actually end up. It might end up that decoy or flares are good enough that long range torpedo's wouldn't be able to home well enough.

If you are using a liquid coolant, why not use it as a propellant so you cool down AND start moving at the same time?

Also: Ship battles in empty space are probably not going to happen very often unless the battles are arranged by the commanders. Most likely they would take place near a habituated or contested planet, moon, or maybe an asteroid field (not actually in it, that would be stupid).

It doesn't scale as well as you'd think up to 100km.
Sure, you increase the resolution, but you still need to get enough photons to raise it above the background radiation - the background radiation you'd soak up increases.

>>10100712
But unless you have REALLY BIG arrays you still won't get lightyear distance resolution.

Unless you managed to fine tune interpolation.

Colonies might be the most at risk.

>>10100842
>maybe an asteroid field (not actually in it, that would be stupid)
Not really all that stupid.

Real asteroid fields are nowhere near as dense as movies and vidya would have you believe. Most asteroids are thousands of kilometers apart.

>>10100894
With interpolation I hear you can use two 10km sized arrays 100km apart to simulate a 100km dish resolutionwise but only get 10km*2 dishes worth of photons.

>>10100691
I doubt it. Self-propelled explosive munitions in general will be losing their relevance in the near future. Even now, the technology to intercept and destroy missiles with automated laser defenses has be proven to work, and that's in-atmosphere.

In space, lasers would suffer much less from dissipation, and could easily pick off missiles and torpedoes from long ranges. Considering that the mass of a laser defense system would be less than the mass of the number of missiles needed to overwhelm it, missiles would not be a practical weapon in battles between technologically equal vessels.

I imagine that railguns and energy weapons would be the dominant tools of space combat.

Gravity sheer of passing planetary bodies at high speed.

In space, if you touch plane metal to another plane piece it will instantly fuse into one piece (no oxide layer) so metals have to be coated and handled accordingly.

As radiation and debris build up against the hull in flight, even if properly proofed the resulting ionised plasma can produce bursts if not clouds of plasma over the hull. This is not just a temperature and pressure issue but can also screw with propulsions, sensors and any shields/weapon systems if you happen to have any.

>>10100984
>Most asteroids are thousands of kilometers apart.
That's like point-blank range.

Also, I don't think anyone mentioned:

mass.
it costs a fucking fortune to put things into orbit. even if you have orbital elevators, it still isn't cheap until money is no object. mass increases fuel use.