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Thread: Armoring a radiator.

  1. #1
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    Armoring a radiator.

    What would be the best way to armor or otherwise protect the radiators on a combat spaceship?

    The vessel in question is capable of (Earth) atmospheric landings, with dual purpose radiator/wings. So droplet or dust designs are out. I'd want a mechanism that can withstand a few punctures and still function. If they can be retracted, great (but I'm not married to the idea). Uses a near term tech level (20-30 years?).

    Nuclear powered, probably an NTR. 70 meters long, main body is arrowhead shaped.
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    Store up a few thousand tons of ice to use as a heat sink, and fold the radiators up.

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    Quote Originally Posted by swampyankee View Post
    Store up a few thousand tons of ice to use as a heat sink, and fold the radiators up.
    On a 70 meter long craft?
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    I don't know what you wish to armor it from. Yes, I understand "attack", but what are they shooting: bullets, nuclear warheads? If it is bullets or something like that, can't you just make the radiator out of heavier gauge metal? Make it out of titanium sheets.
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    Quote Originally Posted by Swift View Post
    I don't know what you wish to armor it from. Yes, I understand "attack", but what are they shooting: bullets, nuclear warheads? If it is bullets or something like that, can't you just make the radiator out of heavier gauge metal? Make it out of titanium sheets.
    Assorted threats, mainly projectiles or fragments.
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    What would be appropriate defenses for things like radiation or lasers? (Yes, there are multiple kinds of lasers, so maybe let's just go with the best general case)
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    If the threat is slugs and such, then a blade like edge and a very hard metal along that edge would be good. You'd need the radiators to move a good bit to protect them like that because you want that edge facing the threat. More like butterfly wings than the swing wings of a fighter jet.

    If you had a railgun, the magazine could be in the radiator so that when the gun fires, you lose a bit of heat with each shot from the magazine. Obviously not even close to 1 for 1, but still better than nothing.
    Solfe

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    OK, I'll take these suggestions into account. Titanium butterfly.

    What about when they do get punctured? Any design elements that will make them more leak resistant or otherwise still useable even with gaping holes?
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    Quote Originally Posted by Noclevername View Post
    OK, I'll take these suggestions into account. Titanium butterfly.

    What about when they do get punctured? Any design elements that will make them more leak resistant or otherwise still useable even with gaping holes?
    Small leaks could probably be dealt with the way they are on car radiators - a substance in the radiator fluid that solidifies when exposed, in this case, to vacuum. For big holes, valve off that section.
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    Quote Originally Posted by Noclevername View Post
    What would be appropriate defenses for things like radiation or lasers? (Yes, there are multiple kinds of lasers, so maybe let's just go with the best general case)
    I'm not sure radiation would be much of a threat to the radiator. For lasers, making them reflective would help, but that might make them poorer radiators, would make the ship more visible by reflected light.

    Maybe the radiators could be covered by an electrochromic material, that would be one color (probably black) when you want to optimize it as a radiator, but change color when under attack to protect from lasers.
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    Cool! I didn't know such materials existed... outside of the movie MegaForce!
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    Clouds of gas, smoke, or dust to decrease effectiveness of energy weapons. Small decoys that duplicate ship signature in every way. Rotate ship to prevent energy weapon from heating one area excessively. Use shield (second spacecraft controlled to move between you and energy weapons). Use energy-cloaking device that makes ship undetectable for heat or radiation signatures. Design ship to reflect away radar and other bouncing-signal detectors. Narrow the firing profile of the ship to make it harder to hit, more likely shrapnel from shotgun bombs will bounce off instead of penetrating. Hide behind real space debris or rocks. Disguise ship as space debris or rock. Spoof electronic signals from enemy vehicles to disarm/turn aside missiles, disarm mines.
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    Not sure if this is something you'd wish to consider, might be too speculative, but perhaps you could forego radiators altogether and have your ship use a laser refrigeration system for dumping heat. The idea of using lasers to dump heat has been speculated about by a few people. Physicist turned novelist David Brin used the concept in his novel Sundiver.

    This Science Daily story, Powering lasers through heat, from 2012 relates an idea a couple of physicists at the University of Innsbruck had for a quantum cascade laser driven by a temperature gradient. From the article . . .

    "In such a temperature gradient driven laser, electrons are thermally excited in the warm area and then tunnel into the cooler area where photons are emitted."

    This produces a circuit where light particles are emitted and heat is absorbed from the system simultaneously. "Between the consecutive emissions of light particles a phonon is absorbed and the laser is cooled. When we develop this idea further, we see that the presence of phonons may be sufficient to provide the energy for laser amplification," says Kathrin Sandner. Such a laser could be powered without using electric current.
    I don't know if any further work has been done since with this concept.

    Perhaps you can invent a cooling system for your ship that has no conventional radiators but instead dumps heat by firing quantum cascade lasers. Turn a weakness into a strength. Dump your waste heat into your opponent, or deep space.

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    Heat radiation is a liability, per Sidewinder missiles.
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    One technique is to dump it into an heat reservoir which you can eject later, either as a discrete body or as a cloud of liquid, gas, etc. In the short term you're limited by how well you can insulate extreme temperatures from the rest of the spacecraft or from external visibility. In the long term you're limited by the amount of excess mass you have.
    Selden

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    Quote Originally Posted by Roger E. Moore View Post
    Heat radiation is a liability, per Sidewinder missiles.
    But it's an unavoidable liability for a spacecraft, especially one with a large power plant. Vacuum is the perfect insulator.
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    I had a silly thought about the radiators after watching a video about a self-solving Rubik's cube. If the radiator is modular, you could have replacement parts sitting within easy reach to account for damage. Eject the damaged part, the wing pops into a configuration where it can connect to a new part and then the whole structure rearranges itself to get the new part into place.

    Radiators are aluminium on the ISS, which isn't especially heavy and the new parts wouldn't be full of liquid while waiting. Damage will cause a leak and the leak will drop the pressure cooling the structure. Dropping the damaged section will remove more heat, as will adding a cool part. Then you have the process of pumping new liquid in from a tank, which also gets a temperature drop. It almost sounds like cheating entropy, but your limit is physical parts instead of heat. Too much damage will make everything worse, but a little damage could be beneficial. You don't need to have the part in the correct place to work, only connected to the modular system. Running too many motors to replace parts will make your ship hotter.
    Solfe

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    Quote Originally Posted by Solfe View Post
    I had a silly thought about the radiators after watching a video about a self-solving Rubik's cube. If the radiator is modular, you could have replacement parts sitting within easy reach to account for damage. Eject the damaged part, the wing pops into a configuration where it can connect to a new part and then the whole structure rearranges itself to get the new part into place.

    Radiators are aluminium on the ISS, which isn't especially heavy and the new parts wouldn't be full of liquid while waiting. Damage will cause a leak and the leak will drop the pressure cooling the structure. Dropping the damaged section will remove more heat, as will adding a cool part. Then you have the process of pumping new liquid in from a tank, which also gets a temperature drop. It almost sounds like cheating entropy, but your limit is physical parts instead of heat. Too much damage will make everything worse, but a little damage could be beneficial. You don't need to have the part in the correct place to work, only connected to the modular system. Running too many motors to replace parts will make your ship hotter.
    Sounds like a lot of added complication and mass.
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    Quote Originally Posted by Darrell View Post
    Not sure if this is something you'd wish to consider, might be too speculative, but perhaps you could forego radiators altogether and have your ship use a laser refrigeration system for dumping heat. The idea of using lasers to dump heat has been speculated about by a few people. Physicist turned novelist David Brin used the concept in his novel Sundiver.

    This Science Daily story, Powering lasers through heat, from 2012 relates an idea a couple of physicists at the University of Innsbruck had for a quantum cascade laser driven by a temperature gradient. From the article . . .



    I don't know if any further work has been done since with this concept.

    Perhaps you can invent a cooling system for your ship that has no conventional radiators but instead dumps heat by firing quantum cascade lasers. Turn a weakness into a strength. Dump your waste heat into your opponent, or deep space.
    Lasers would have to be thermodynamically almost 100% efficient to act as heat dumping, wouldn't they?
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Noclevername View Post
    Sounds like a lot of added complication and mass.
    It is complicated.
    Solfe

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    Armor is very heavy, particularly for something as large-surface area as a radiator. Retractable panels that pull into a small, protected section would work. Backup cooling when under fire could be provided by a single-pass evaporative (or sublimator?) cooling system, as long as the water (or whatever the fluid was) reserves held out.

    For suitability after punctures, I would suggested pulling from animal circulation systems. Nanobots would be circulated (or injected upon damage) that would take the place of platelets - clotting up around the puncture to limit coolant loss. For larger damage, valves would isolate sections of the radiator panels.

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    Quote Originally Posted by Solfe View Post
    If the threat is slugs and such, then a blade like edge and a very hard metal along that edge would be good. You'd need the radiators to move a good bit to protect them like that because you want that edge facing the threat. More like butterfly wings than the swing wings of a fighter jet.
    Would it be easier to just turn the spacecraft's nose to face the threat? The main hull armor would be more effective that way anyway, since it's a pointy angle.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    I might have found a solution to your problem.

    https://arxiv.org/pdf/1809.09196.pdf
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    Mark Twain, Life on the Mississippi (1883)

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    Quote Originally Posted by Roger E. Moore View Post
    I might have found a solution to your problem.

    https://arxiv.org/pdf/1809.09196.pdf
    Before I click on it, what is it?
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    Sheesh, everyone is wrong. You turn on your Ion Shields. Ion shields deflect any and all inbound "missiles" and absorb all radiant energy weapons.

    But if that doesn't work simply retract the radiators into the hull.
    Last edited by DaCaptain; 2018-Sep-26 at 01:48 AM.
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    Quote Originally Posted by Noclevername View Post
    Would it be easier to just turn the spacecraft's nose to face the threat? The main hull armor would be more effective that way anyway, since it's a pointy angle.
    That does work, but if you can put your nose on the enemy while reducing the visibility of the radiators, that's best. Can't hit what you can't reach.

    There has to be some sort of economy to a fight. You have missiles and beams. They are very different weapons, so they have to have very different purposes. Defending everything equally well can't really be an option. As I am picturing the scenario, I would think that missiles would be awesome for smashing soft targets like radiators with little energy cost. Beam weapons are killers but have a high energy cost, forcing the use of supplemental missiles. Since you have both, it is easy to envision an attacker launching missiles first, then a barrage of beam weapons as the missiles arrive at the target. No kill like overkill.

    Of course, a captain won't willing step into the kill zone, so he has to now consider avoiding absolutely deadly fire while also preventing a cheap hit to the radiator and other soft bits. That is a game of cat and mouse, where the danger is sliding up and down the scale.
    Solfe

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    Quote Originally Posted by DaCaptain View Post
    But if that doesn't work simply retract the radiators into the hull.
    Right. I suggested as much in the OP.

    But retraction is only viable until it isn't. If your heat sinks are at capacity, you have no options but extend the radiators or vent coolant, and coolant runs out real fast.
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    Quote Originally Posted by Noclevername View Post
    ...and coolant runs out real fast.
    What kind of power level are we talkin' here?

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    Quote Originally Posted by VQkr View Post
    What kind of power level are we talkin' here?
    Well, the ship is a 70x40x30 meter arrowhead/wedge with room for crew & some cargo, assume power output equivalent to 3x the best closed cycle nuclear achievable in that volume with today's tech.

    (Tech level is efficient small fusion reactor, so the 3x factor is kind of arbitrary. No hard numbers available. Hard rad/neutron emissions are handwaved away.)
    Last edited by Noclevername; 2018-Sep-26 at 11:43 AM.
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    Quote Originally Posted by Noclevername View Post
    Before I click on it, what is it?
    Directed Energy Interception of Satellites

    Harrison Shea,b,∗, Will Hettelb, Phillip Lubinb
    Selden

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