Shielding concept

[Imperial528]

I'm a fan of both hard and soft sci-fi, although I prefer soft, mostly because it is the most widely available type in the genre. But what has always bugged me is that shielding has never really been explained. Hard sci-fi I've read usually doesn't have shields, and soft sci-fi hand-waves or technobabbles it into a black box machine.

So, I decided to come up with a way of making a shield that is possible in reality.

The idea is to have an electromagnet generate a sufficiently powerful field that it is capable of re-directing charged weapons (ions, plasma) and frying the electronics of guided weapons. In order for the field to not affect the ship, a second electromagnetic with a slightly less powerful field would be running at the opposite polarity of the main one, so that where the two fields overlap the charges cancel. Of course, the shield would need to spin a high rate indeed, in case the enemy reverses the polarity of his/her weapons.

Now, I'm not entirely sure if this would work or not, since I'm not very well educated past the basics when it comes to electromagnetism, and the internet isn't the best place to start learning.

[Isolder74]

One way to make it work is to use Ionized Plasma to make a wall between two magnetic fields. In labs this has been done and the result can stop bullets. The catch is that this method stops outgoing projectiles too but the magnetic fields can be manipulated to open holes to allow stuff out. Being magnetic field this can be done quickly but would require lots of complicated control software to seamlessly interact with weapons turrets, etc.

[Dave]

What kind of benefits do I get from this bulky, massive complicated arrangement that I don't get from a properly grounded layer of aluminum or copper foil wrapped around the outside of my ship?

[Imperial528]

Shields add another layer of protection. And for the universe I use this concept in the shield is less of a stop-all and more of a layer of defense to weaken incoming heavy weapons and outright stop weaker ones, makes the armor last longer.

And it's not too bulky, just two cylinders, one inside the other. It would be quite small if superconductors were used instead of normal wiring.

One way to make it work is to use Ionized Plasma to make a wall between two magnetic fields. In labs this has been done and the result can stop bullets. The catch is that this method stops outgoing projectiles too but the magnetic fields can be manipulated to open holes to allow stuff out. Being magnetic field this can be done quickly but would require lots of complicated control software to seamlessly interact with weapons turrets, etc.

I never thought of using plasma (I did think of lasers being trapped, but then realized that I'd be blind too).

[Formless]

The only way to protect yourself from laser fire besides the all purpose defense called armor is to... not get hit. If you could make a shield that protects you from lasers, you would basically be putting a blindfold over your own sensors. Charged particle beams have other problems that make them less ideal than lasers as a directed energy weapon, namely their weight and the fact that they have limited range due to blooming.

However, it should be stated that no offensive or defensive tactical system is a binary proposition. If you can get close enough to hit with a particle beam, they have better armor penetration than a laser (again though, if you fry the other guy's sensors he's pretty much out of the fight). However, that may not justify them as you get a lot of the same benefits from nuclear warheads, and projectiles have some of the best penetration out there. Just some things to think about.

[Imperial528]

You raise an interesting point. Could an electromagnetic field be manipulated like that?

[Cykeisme]

Could an electromagnetic field be manipulated like that?

You want a magnetic field that deflects lasers..?

Sensors and lasers won't be operating on the same wavelength - if you armor lets one through but absorbs the other, mission accomplished.

Mweh, what if your ship was hit by a beam from a directed-energy weapon that projected intense focused EM radiation on the same wavelength as your sensors?
Okay, nitpick :p

[Imperial528]

It can absorb them, doesn't have to deflect. Part of the defense against physical threats is that fire from energy weapons is recycled as part of the shield, in that it stays trapped in the field barrier until the shield is deactivated.

[Ford Prefect]

Now, I'm not entirely sure if this would work or not, since I'm not very well educated past the basics when it comes to electromagnetism, and the internet isn't the best place to start learning.

I have to commend you for unironically using the phrase 'reverse the polarity' in a conversation about science fiction.

Anyway, I've seen stuff like this before; Alastair Reynold's Revelation Space had a space suit which applied massive electrical currents to the point of impact of particle beams in an attempt to reduce the damage done, for example. To be honest the mathematics are a little beyond me, but I get the impression that this would not be a 'cheap' process, and would require pretty significant amounts of energy to do, and I seriously doubt you could really use it a 'generic sci-fi shield' sense in the real world. Of course, you can do thisngs in fiction that are otherwise impossible in the real world, but be a little cautious if you're looking to create a 'plausible' solution which may not really be all that plausible.

[Imperial528]

Oh yes, it would require vast amounts of energy, although using high-temperature (30 kelvin temperature) superconductors one could vastly reduce the energy requirements to less-than-ungodly levels.

I'm sure it would require less energy than the handwavium shields in most sci-fi though.

[Simon_Jester]

30 K is not high temperature and is not compatible with normal shipboard operations that involve anything generating waste heat.

[Imperial528]

A high temperature superconductor is any material that can achieve superconducting properties at 30K or above. There are several known materials that exhibit superconductivity at 30K or above, the highest being in the 160K range. And remember that a superconductor would not generate much waste heat, if any, due to the fact that a superconductor has no resistance to convert the electrical energy into heat in the first place. These superconductors can be maintained at their required temperatures using liquid nitrogen.

[Batman]

30 K is not high temperature and is not compatible with normal shipboard operations that involve anything generating waste heat.

I assume he meant high temperature for an ordinary superconductor (as in superconducting at 30 K). Which seems to be broadly correct.

[keen320]

Could someone tell me where to find the info on these electromagnetic plasma shield whatsits? I'm not saying they aren't real, I'd just like to look up the info and stuff myself instead of hoping people eventually post all there is to know about them. They sound interesting.

Also, I still don't see why it wouldn't be easier, cheaper, and just more practical to invest your effort in better armor rather than a force field. second, I suspect whatever force was using the ships might resist adopting "those newfangled energy shield," if they are like most militaries in history. Finally, armor is far more reliable, and you can just use more layers.

Although, it just occurred to me, an energy shield uses a lot of juice, but you don't have to replace it after a battle, like armor. I seriously doubt repairing heavy armor is as easy as recharging the shield would be.

[Imperial528]

It makes the armor easier to maintain, especially if you stumble on an enemy patrol of light ships, your armor won't get banged up and there is little chance that they could actually hit a sensitive system.

That and armor requires a lot of mass. And mass is fuel. And fuel is money.

[Simon_Jester]

It's not so much the cost as it is the mass penalty.

Each unit mass of armor added to the ship imposes an additional constraint on the amount of fuel you must add; in the extreme heavily-armored limit you wind up with a ship made of nothing but armor and fuel. If a shield generator grants superior protection (or that trading 20% of the armor belt for shields is more effective protection against the overall spectrum of threats on average, or whatever) on a kilogram-for-kilogram basis, it frees up tonnage. Which means either that the ship becomes faster (which also makes it more survivable since it can evade and reduce the enemy's kill probability), or it becomes more heavily armed (increasing its probability of scoring kills before the enemy gets a hit in).

[Imperial528]

Destructionater, fuel is not cheap. The SRBs on the space shuttle are by no definition dirt cheap, they each cost about 23 million USD.

A ship which has to propel itself past the light speed barrier through some handwavium would need much more potent fuel, at the very least it would need antimatter, which right now is the most expensive substance on Earth, coming in at about 60 trillion USD per gram.

Besides, all kinds of organizations cut corners in real life just to save a few pennies, who says a military won't? (It also improves the logistics, since if your standard ship needs more fuel, then you need to ship more of it, etc.)

[Imperial528]

The difference between a high-performance car and a space shuttle SRB is that the three hundred thousand dollar car is not 85% fuel when it is complete. An SRB is.

And even if we assume that the SRB's cost is 75% dedicated towards the vehicle itself, that still puts the fuel at about 10 dollars per kilogram. As compared to gas, which is about 94 cents per kilogram in my area. Hey, let's go further and say we assumed that 95% of the SRB's cost is for the vehicle itself, then the fuel comes to 2 dollars per kg. Hell, if I put in 94 cents per kg, the same as a kilogram of regular gas in my area, then fuel cost alone would come to at least four-hundred seventy thousand dollars. That's more than your Lamborghini.

[Rossum]

What about having one half of the ship be heavily armored while the other half is less armored and just make sure to keep the heavily armored section pointed towards the enemy? Or maybe just have a detached piece of heavy armor plating that can be moved around the ship to be repositioned as its needed, basically a an actual metal shield to provide additional protection along with the ships armor?

Space is very big so and the laws of inertia let things float around and rotate however they want. You can have your ship accelerate in a direction and then rotate the thing around to keep one heavily armored side always pointed at the enemy. You might get into trouble if two or more enemy ships are able to flank you and target the unshielded side... but you'd probably be in trouble anyway if that happened and you just had even armor all over the ship.

Or the ship could use a large robotic arm to rotate the heavy shield into position. Most ships might have a large robotic arm built in to allow them to perform rudimentary repairs on themselves or do other tasks (like grab cargo or pick up salvage or whatnot). In battle, they could use the arm to move around a big shield to protect against enemy fire. Since the shield wouldn't be welded to the ships frame, then any damage to the shield section could be dealt with by just replacing the whole shield once they stop for repairs. There could be standardized ship shields that are just sections of durable armor built large enough to cover the ships profile against enemy attacks. Sensors built around the shields rim could provide a detailed view of the enemies movements. Plus, while an enemy could concentrate fire against a ships hull to breach a specific section first, a movable shield could potentially be moved around in such a way that the damage is distributed evenly across its surface (give it a slight spin perhaps?).


Though... as expected, having a huge material shield placed between a ship and an enemy also limits the attacks of the ship in question. Perhaps they could have small weapons systems that are attached onto the rim of the shield plate that could be used to attack the enemy? Like an array of lasers that poke out from the sides and fire at the opponent, the ship itself basically hides behind the shield and provides power to the weapons that return fire. Or maybe some missiles are on the shield as well that can detach and fire at the enemy without the ship itself exposing itself from behind the shield cover.

And, at the very least... if the ship is forced to lug around a detachable section of heavy armor material then it could potentially use it as a weapon by throwing it. Essentially the ship accelerates toward a stationary target, lets go of the shield, changes its own trajectory, and lets momentum send the shield crashing into whatever it was aimed at.

As long as the mechanism used to attach or hold the shield is practical in terms of cost (both financial and energy wise) then it should be cheaper to just have one big sheet of heavy armor that is able to provide cover for the whole ship then to have that same thickness or armor covering the entire ships surface.

Ships expecting heavy battle or dealing with multiple opponents might just go with the full covering of heavy armor, but for smaller ships (or ships with a budget) then a separate shield could be practical.

[Isolder74]

The above is also true of most military hardware. Most especially ships.

Think about a battleship or aircraft carrier. They cost lots to design develop and build to the standards required and then we get to the biggest problem of capitol ships in general is that there pretty much is only one customer for one and that customer is only going to buy a small number of them.

[keen320]

I think if you don't have a much more efficient launch system and engine than a chemical rocket, your not going to be fighting wars with your spaceships. If nothing else (and there is a lot else) 85% fuel makes your ship a flying bomb just waiting to go off. Of course, more efficient engines are often just as much handwavium in sci-fi as shields.

[Formless]

You mean the reaction mass. "Inert" and "propellant" are two words that never go together by definition.

In a steam rocket for example something (say, a nuclear reactor) heats the water, which expands out the back. All the water does is take advantage of Newton's Third Law, nothing more nothing less.

But that's just nitpicking, you know this stuff already.

[Simon_Jester]

I think if you don't have a much more efficient launch system and engine than a chemical rocket, your not going to be fighting wars with your spaceships. If nothing else (and there is a lot else) 85% fuel makes your ship a flying bomb just waiting to go off. Of course, more efficient engines are often just as much handwavium in sci-fi as shields.

That said, unless propulsion (including fuel) is an insignificant fraction of ship mass, adding extra mass is still a significant penalty. Every mobile artifact ever designed by man had some kind of mass budget; I don't think that would change in space warfare.

So if you could somehow get protection worth a thousand tons of armor without adding a thousand tons of mass, it would very much be worthwhile. Even if it wasn't the only kind of protection on the ship (say, because you need ablative materials to protect against attacks your magic shield won't cover).

[Imperial528]

I brought up the mass=propellant/fuel subject because it is a very real thing. This is especially true of rocketry, since one must carry his propellant with him, and in turn have enough propellant to do so. In a single launch, yes, preparing the vehicle (or in first-launch cases, assembly, design, construction, etc.) is more expensive than the propellant itself, over many launches (or just one or two large ones) the costs for propellant become enormous. If one can cut the mass of the vehicle itself, one can either cut propellant usage or have the ability to carry more cargo into orbit. And of course, fuel and propellants can only be used once. A crewman or vehicle can be used multiple times.

As an example, with the Space Shuttle orbiter, if mass was not such a concern as you say, why would Lockheed Martin (the manufacturer of the SS external fuel tank) stop painting the tanks to save an extra 272 kilograms of mass? And why would the Light Weight Tank and the more expensive and harder to produce Super Light Weight Tank also be made and used? Right now only the SLWT is used, despite the extra cost and longer production time over that of the SWT and LWT. So obviously, someone decided they wanted their (as you said, extremely cheap) propellant to get more bang-per-buck, and they went so far as changing the design to do that.


Anyway, back to fiction:

The warships in-universe which this device would be applied to are in the multiple-mile length range, and are quite bulky. Adding even a centimeter of armor to the ship could add hundreds of tons of mass, which would of course require more propellant being expelled from the engines to move it at the same speed, and more fuel being burned by the reactor to move the ship into the FTL state. If a shield weighs less than the added armor, takes up less space, makes the existing armor last longer, and makes enemy weapons less effective against that armor, why not use it?

[Sea Skimmer]

You mean the reaction mass. "Inert" and "propellant" are two words that never go together by definition.

Wow, just no you fail at that definition. When you’re going to nitpick you should at least try to be right you know. Propellant is a mass used to propel and object, nothing more nothing less. It very well can be inert, compressed CO2 is inert and will work fine as a propellant for example.