The Feasability of Mass Driver Weapons in Space

Oh hell yes!

Now on to world hunger! Lets go!

No, see, nobody is wrong about ending world hunger. If they aren't wrong my pointless motivation to correct them doesn't come into play, and I just sort of listlessly agree.

Uh...no. What's the second thing you're accelerating? The outer layer of the gun? Well what stops it from flying into space? The ship! So when that outer layer stops, it'll put exactly the same amount of force into the ship that you were trying to save. The only way you could counter the force of the projectile being fired one way would be to fire another projectile the other way. You can't fire the second thing and then stop it. When you stop it you get the force back.

...but it doesn't matter. Force is proportional to mass. So if a 1,000,000kg warship fires a 1kg mass at 1,000,000 kilometers per hour, the warship will be forced backwards at only 1 kilometer per hour. Pretty sure the engines can handle that. (In this case, the "projectile being fired the other way" is the ship's thrust).

I mean, look at real-world aircraft firing projectiles straight ahead. They don't have anything much resisting backwards motion, apart from thrust. Air resistance isn't doing much - doesn't stop the bullet, does it? They don't go flying backwards, do they? Sure, there's a limit to how much they might be able to fire in a burst for some extremely large cannons (hello A-10), but it's certainly not crippling. Why would it be for space ships?

Yay for mass drivers. Its like a 2 fat guys chucked at 75mph at a midget in the midle. Now thats destructive

Don't you mean backwards and not forwards?
Doesn't this mean that the projectile stays put?

It... it is?

Wait a sec: drunk, right?

Inertia.
Which mass do you want to propel at what speed?
That will give you the force.
Wich mass has a Kol battleship? It will not move.
Well theoretically a fraction of a millimeter...
Because of the same reason the Iowa was never pushed back even fireing all guns to one side.
Inertia.

Here are some articles on space warfare:

Detection

Weapons

Defenses

Warship Design

We're talking the "bridge" type railgun where the projectile completes the circuit driving it out of the chamber, not the coil-type one, right?

My geek sense is tingling quite happily. What a fascinating topic! Kudos to anyone able to contribute meaningfully. Which includes the midget comment.

Big gun go boom......oooooooooohhhhhhhhhh, do again!

The former is a railgun, the latter is a gauss gun. I couldn't really be bothered to see whether the original poster used the terms/technologies interchangably. From what I got out of the three or so seconds of actual reading I did, I believe he's referring to a gauss cannon. Railguns are relatively primitive in comparison, when you look at how they work.

Perhaps, but Railgun development is receiving military funding while coilguns remain Science Fiction.

What I find fascinating is the fact that a Terran type planet can be assumed to have a diameter of approximately 13,000Km (8000Mi) yet strike craft can launch from their hangars and make it to the other side of the planet in a few seconds. Once there, they can maneuver freely and turn quickly to engage an enemy fleet. Consider the accelerations! Who needs mass drivers when you have the technology to build intelligent missiles that are just as fast, and fully maneuverable!

OP hasn't really grasped conservation of momentum, there is no solution except to produce an equal force in the opposite direction. The issue of recoil is red herring anyway. It might seem like recoil is a big factor when weapons are sufficiently destructive but in actual fact it just isn't.

Consider the mass and momentum of a space vessle, quite a lot, going very fast. The projectile fired from a railgun or a gauss gun (previous poster right to illustrate the difference) wont weigh very much at all. If doing rather a lot of firing then recoil might become a small factor (as indeed it does with, say, an A10 Warthog opening up with the impressive GAU-8) but little more. And in terms of weapon to vehicle mass, I think it's safe to say the A10 will have a much higher weapon to vessle mass than a space craft - so this 'slight' recoil effect is an extreme situation.

One thing that is the case is that missiles are completely pointless in space. They necessarily need to reveal where they are by their motors, unless someone figures out a stealthy low energy way to derive mass acceleration... but it's not likely. And incoming missiles are just cannon fodder for energy weapons. Missiles are strickly a weapon that exists up to the point that energy weapons become effective. There are some exceptions. Such as using nuclear weapons as cover, rather than trying to hit or get near ships etc.

Concerning the interesting pros and cons of projectile weapons versus directed radiation weapons. It's obviously much easier to obtain a hit with a radiation weapon. If you can see it, you can shoot it until you're talking about very large distances. At which point beam collimation is a larger factor than potentially missing because target has moved unexpectedly (and there's no reason target would move unexpectedly, necessarily, since they have no warning) but OP is absolutely correct that a standard short duration high energy strike can have questionable results depending on armour.

One potential solution to ablative armour is to use an initial short burst to produce a cloud of plasma near the target and then to fire again producing a shockwave in close proximity with the vessle causing physical overpressure damage which could conceivably be as difficult to defeat as a projectile weapon.

And that's probably the strategy that would be employed. Also beam weapons are essentially free. If you have a sufficient power source you can basically lay a good brunt of that on a specific part of a vessel repeatedly. However follow up strikes are likely to be essentially blind aimed since the resulting plasma and radiation would make meaningful on the fly aiming pretty much impossible. However given the extreme difficulty in moving any space going vessel rapidly, you don't really need to see it. Your computers can maintain a firing solution based on your vector and target vector.

So the reality of the physics involved lead to space combat scenarios rather different from anything seen in sci-fi. Generally it's all about stealth. If you can be seen, you're already in trouble. Any weapons fired at you, there's no cover, no where to hide, it's a bad situation. So you need to try close range without being seen first. It's highly likely that real space combat vessels will be doing some exotic things such as duplicating stars behind them on their leading faces.

Which will probably be foiled by stealthy micro probes dotted in defensive space with side looking cameras that can spot movements in the start field given that it's probably only really practical to fake up a star field from some angles, eg where you're pointing - at the target being attacked. It remains a question of when detection occurs, and who fires first.

At some point a vessel may decide the game is up. Say, for example, approaching on one side of a planetary body and then swinging around in more or less immediate firing and detection range.

At which point they would be highly advised to create a pre-emptive armour. How? Well, at that point no more thrust corrections for a start. Then a cloud of camoflaging material which serves to obscure and deflect radiation. A kilometer wide cloud of spinning bits of tinsel foil, for example. Remember this has the same momentum as you do in space, so you can chuck out a lot of obscuring cheap garbage to keep the enemy guessing. Net effect; a shiny blob just came out from behind the planet, or perhaps was triggered as soon as any incoming fire occured in the case of a lack of a close in approach aid such as this.

Firing energy weapons at the cloud is going to be tricky. It will instantly result in a mass of radiation making visual even more difficult and hampering the ability of radar to try resolve a more solid body within. Defender gets to choose the make up of their tinsel 'chaff', if you like, and naturally the make up will be chosen to form a plasma of a particular make up which is naturally reflective of millimeter wave radar and so on.

Defenders aren't helpless though. Energy weapon strikes will produce plasma detonations which will do a pretty good job of dispursing plasma and tinsel. Aimed repeatedly at the strategic points it should be possible to blast the cloud away and offer a peak inside. But it's going to be like trying to place shots on a target at night with a searchlight shining in your eyes. And of course you'd be taking shots with projectile weapons just in case. Likely some sort of fragmentation effect to maximise hit chance and with projectile weapons made of a certain material which makes impacts highly obvious, assisting subsequent targetting.

What chance for an attacker? Well, they need to resolve defensive positions and try to fire first. Once it kicks off, their ability to gather intelligence and target will be severely compromised. They'll need to rely on visual data come in from probes launched away from the vessel at about the same point the 'comet shroud defence' came online. But it may be somewhat tricky to get data from your cameras, particularly if defender starts throwing nuclear railgun slugs your way.

Consider though, that each of these vessels isn't really a space craft at all. It's got munitions, counter-measures, rudimentary drive and a bunch of computers. And it wasn't just one that showed up. Oh no. Many, many of these weapons platforms.

It's going to be a hellish noisy battlefield. Where it's all about who fires first, resolving things in the blink of an eye amidst cataclysmic releases of radiation which is what each force needs to do in order to try come out on top.

Sadly there wont be large battleships blasting away with pretty coloured beams. Nor fighters having dog fights around their respective carriers. Most battles will be conducted at massive range with large amounts of unmanned munitions probes such as I've described here.

Not much room for starbucks then but deeply intriguing in it's own way I think.

@Above post,

Try reading the Detection and Weapons articles I posted. There is no stealth in space, that site makes a good argument why.

Missiles obviously won't have stealth, but they will be maneuverable, longer-ranged in comparison to DE weapons, and deal a bigger boom. The DE point defenses have to keep the beam on the missiles, which means they'd have to have lots of complex ball-turrets and targeting comps at least as powerful as the missiles' ECCM. And if the missiles outnumber the laser turrets, a few will hit and knock out a large chunk of them, meaning more missiles will hit in the next volley.

Laser shots also are NOT free all-you-want spam-fire weapons. They are highly inefficient and generate significant waste heat. A radiator cannot be armored because it has to radiate this waste heat, and will thus be the prime target of kinetic slugs, missiles, or opposing beams. The solution is a heat-sinking coolant, but the available amount of non-vaporised coolant is limited. Thus laser shots are limited.

Also, the cloud idea results in double-blindness - the ship inside can't see out, while the ship outside can see the cloud and punch through it with blind kinetic slugs, or vaporise it with lasers. There can be no 'stealth probes' that won't get destroyed early on, so the cloud idea flops. Even an ion-engine spacecraft can be detected from 1 AU with existing sensors.

The need for crews is also one that is mainly an SF thing. I agree that the space combat 'ships' will probably be unmanned drones with propulsion, armor(to withstand near-misses and short DE bursts), particle/laser beams, a few missiles for extra punch, fuel, and of course the computers. It would have to be a semi-autonomous drone since battles would be rather hard to control on the tactical level with light-speed communications technology. Sensors would be very important, and hence they'd have to be mounted on separate probes(which would not be stealthy, mind you), with the probes being covered in armor and point defense but offensively unarmed.

The combat drones are beginning to remind me strangely about Advent Bombers. They're semi-autonomous drone craft, with a particle beam, light armor, and very strong propulsion system, but no sensors of their own. The big difference lies in that actual combat drones would not be so compact, so sleek, or so fast or so agile as Bombers.

The article linked claiming there's no stealth in space purely talks about drives, I pointed out you don't thrust. Thereby negating that entire argument. It kind of works like this, any drive entering a system will be seen for donkeys. It also gives means such large and obvious momentum means even if you shut off WAY out, it's not hard to figure out where you'll be. So inbound craft need to use planetary bodies for slingshots and then shut off the drive. This turns the incoming trajectory into a wide parabola arc. Still not ideal, but a sufficiently large region of space that stealth has meaning.

Also there are propulsion mechanisms that will be invisible to the observer anyway such as any kind of particle stream drive, ion drives etc. This isn't much thrust, but it can be used to alter trajectory after main drive shut off sufficiently to add another random element. The combination of the two ends up creating a sort of a curved sausage of space of possible trajectories. Of course only part of that ends up coming near the target but it's pretty much needle in haystack given the size of the vehicles.

Secondly, lasers are free all you want weapons. The heat generated is comparitively little given the mass of the vehicle. Typically one would use a ballast of significant heat carrying capacity such as plain cheap H2O, useful as reaction mass and an excellent energy weapon ablative too. You'd have to fire a lot for a long time before you had to worry about needing a radiator. That's not something a weapons probe has to worry about, it wont be firing much. A defensive operation such as moon or orbital station would use radiators, but they wont care.

I get the impression you're talking about medium sized vessels zipping around firing lasers at eachother. This is not a realistic scenario.

And besides, it's simply not reasonable to claim lasers will be just as inefficient as they are now. Already solid state lasers with larger than 30% efficiencies are being implemented in the battlefield research programs today, let alone hundreds of years in the future.

The cloud idea is pretty tested by folks who think about such things a lot, I'm afraid it stands up to more than your 30 second analysis It doesn't work with thrust again for obvious reasons, the cloud goes one way, vessel goes another doh. Stealth probes work just peachy. They're extremely cheap and highly numberous. There's no effective way to destroy them all. Again this is a pretty well thought out concept, it's not something I invented.

The weapons drone sees out because it has the probes. Defenders don't have the same luxury due to the way optics works. They're looking at roughly the same pin-point so that radiation makes it hard to resolve anything. Meanwhile weapons probe is looking from hundreds or even thousands of distant eyes. There's a lot of fun maths you can do there too building up a highly detailed 3d model of the environment with such data, meaning it only actually has to work for a fraction of an instant and you have all of the target topography and firing solutions necessary. At which point the only thing the sensors need to view is weapons signatures.

Again, the sensors probes aren't all killable in that time frame. They're about the size of a tennis ball and they'll be spread out thousands of kilometers.

You're clearly right about drones being semi autonymous. Defensive positions are not going to advertise themselves so they wont be visible at extreme range. Weapons drones need to make their own firing solutions, generally they'd send their probes ahead.

An attacker's problem, really, is that if someone isn't firing you still don't know they're there. At some point you want to approach right? There's no safe way to do so, something can be waiting for you. If only we had 'energy signature detectors' eh?

The unfortunate scenario is that it would probably be necessary for massive nuclear overkill on anything in orbit. Once orbit is attained there's not a lot anyone in a planetary gravity well can effectively do and it's surrender time.

OP: Good try, but no cigar gun for you. If you can fire a gun in space without recoil, you can also invent a perpetual motion machine and sit on Newton's grave and laugh.

Um, care?

I was about to make this point. No way around Newton's third law, I'm afraid.

The secondary magnetic coil system could be useful, though, as it will effectively 'damp' the impulse from firing the projectile. The moving cannon can be slowed gradually, meaning recoil from the shot will be distributed over a longer period of time. This will allow the engines to compensate.

If we assume that the spacecraft has directional engines (which it must have for efficient multi-directional travel), then the thrust vector can simply be altered to compensate for the recoil from the mass driver. Since the entire process can be automated, it's certainly possible for a ship to travel in a straight line no matter the impulse from the weapons. The only net effect would be a slight reduction in forward momentum, proportional to the cosine of the angle between the pre- and post-shot thrust vectors (which as pointed out, for a ship which is significantly more massive than the projectile, will be virtually negligible).

All this assumes that game-time is 1:1 proportional to real-time. Which means that the population of a planet can double in a matter of minutes. Which is a far bigger "plot-hole" than any physics-related mumbo-jumbo.

Wow they sure build those capital ships fast, and the crew training, 2,500 trained naval sailors for a Kol in how many seconds?

Yah not real time.

hey, i didnt bother to read all this stuff, but in any case.
The recoil created by a mass driver compared to the mass of a ship. Conservation of momentum holds up against it and prevents the ship from flying away.
Any movement created is compensated by the engines tata problem solved.

Let's face it, Sins is no simulation, it's as much fantasy as Warcraft is and for countless reasons. There might be scientific _references_ to the things we are playing with but there is, quite fine as far as I'm concerned, a complete ignorance of real science and what reality would look like in Sins. As soon as you point out the first unrealistic thing that comes to mind about space simulation games/programs/films then you find you can completely blow it away with reality. I very much doubt any of us will live during a period of humanity experiencing inter planatery battles so just go with the fantasy and enjoy it.

I do think it's kind of cute though that you guys want to argue what a realistic space battle would be like. It kind of reminds me of that viral email of a black and white photo of some guy in early 20th century describing what the personal computer will look like in people's homes.

The system described by OP is of course moronic as someone else already pointed out. You're just adding another step in conveying the momentum to your ship. Somehow the most stupidly easy solution does not occur to anyone: you shoot mass out the front of your ship and just use your ship's thrusters to counter the force. Those thrusters are already designed to accelerate that ship quite some, so they can easily counter that force. And yeah, remember that it's not speeds that are applied but momentum, and no matter how heavy your bullet, it's not going to be more than a tiny fraction of your ship's weight, so even at freakishly fast speeds you'd only be nudged back slightly (further helped by the fact that you probably want to have more than ONE shot and so have the rest of your ammunition on board, meaning that you'd only get the full force when you shoot your very last round, and once you're out of ammo, you want to be moving AWAY from the fight anyway)

Not only drives. ANY radiator. The life support system of a ship, the nuclear/fusion reactor. And if FTL exists, than the signature of that propulsion(if any, but no one knows yet) will give away the ship.

If your trying to be stealthy in a sufficiently huge region of space, keeping FTL and sublight drive off, then you have no Delta-V and if you see an enemy with your passive sensors, you either open up your engines to intercept and get seen, or fly past harmlessly. It would be a bizarre coincidence if you're already on intercept course.



Ion drives are visible from 1 AU(according to that article at least) with existing sensors and will still take a while to change the direction of a craft larger than our existing ion drive spacecraft.



If you're going to have a huge Kol anyway, you may as well carry tons of missiles or kinetic slugs as well. True that you won't get as many missiles/slugs as you will get laser shots, but each hit(from a fusion-warhead missile) will be more deadly than a burst of laser light.

As for a combat drone(the term "weapons probe" doesn't have as good a feel to it), you're right, it won't be firing much. So it won't have to carry too many missiles/shells either.

A moon-based weapons platform doesn't need to care about supply. They can use the moon itself as a laser heatsink and they probably have an in-house missile/shell factory to boot. A moon would also have provision for some serious heavy-duty kinetic-kill hypervelocity weapons, and a decent supply of slugs from the factory would keep them running well.



No. I think you're getting the impression that I was talking about Advent strike craft. They are medium sized vessels, not zipping around, but still beweaponed with lasers and missiles. Probably ugly too, unless the designer intended them to be for atmospheric entry as well.



Give me your source. It's an inflexible idea that puts your ship into a purely defensive role.



I don't see how this will work for a very long time without nanotech. And how do you plan to spread these drones?

The size of Sputnik sounds more realistic, but the spreading problem remains to be answered.
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Your ideas sound like the enemy has no offensive at all, and all your drones("probe" just doesn't sound right, again) are ominously cruising, with their drives, reactors, and all their other heat-emitting stuff turned off, towards the hapless planet with a half-dozen orbital turrets in place, with the poor turrets being engineered, programmed, and controlled by such inept morons that they can't even stand up to a bunch of Voyagers surrounded in a tin foil cloud, with lasers and nuke missiles, and their mega-stealthy tennis ball companions(*gasp*).

What if the enemy also has tennis balls and battle-Voyagers heading the other way? What do you do then - change course(allowing yourself to be seen) to intercept while the enemy does the same, or try to race for the enemy planet?