Battletech Gauss rifles and heat generation

[Sarevok]

In Battletech the Mechs are powered by fusion reactors. Firing energy weapons like lasers and PPCs can cause immense heat builds up since these weapons draw power from the reactor which must run hotter to supply the demand. Projectile weapons and missiles generate very little heat in comparision.

One curious exception is the Gauss Rifle. It has immense range and punch that can put a PPC to shame. Yet it generates no heat because it is a projectile weapon. It is understandable why similar hard hitting projectile weapons like the AC 20 don't produce heat problems. They are really futuristic cannons.

But a gauss rifle is a railgun, a type of weapon that consumes tremendous amounts of energy. In real world most warships and tanks do not have powerplants sufficient to support effective railgun weapons. There is talk of new powerplants for the proposed US navy future warship to support weapons like the railgun. So why does a PPC cause heat meters to spike so high yet a gauss rifle is barely noticed despite firing a 125 kilogram slug out to far distance ? Considering the Gauss rifle and PPC cause same damage the Gauss rifle too should have severe heat penalty for firing.

[Mr Bean]

This is a guess, a guess mind you that the Gauss rifle is very weight intensive because not only are it's coils heavy, but the capacitors it uses to hold the charge so it can fire to begin with. If the fusion generator is slowly charging the capacitors then just keeping them topped off it would not generate much heat. If there are a few capacitors in the bunch each good for a "shot" then no the Gauss rifle should not generate that much heat if each capacitor can be "dumped" to fire one shot. If I recall in Battletech all Gauss rifle's have horrible ROF's which lends into this theory that the gun itself is firing off of battery power and the generator is recharging the batteries slowly.

[Eviscerator]

If I recall in Battletech all Gauss rifle's have horrible ROF's which lends into this theory that the gun itself is firing off of battery power and the generator is recharging the batteries slowly.

Been a while since i've read BT, but in Blood Heritage Natasha told Phelan words to the ëffect "your gauss rifles get first crack at the reactor" and later in the Trial of Position the configuration of the firing order is crucial in Phelan's win.

So no, no batteries for your railgun , even Quick-charge battery packs aren't THAT quick.

[Connor MacLeod]

In Battletech the Mechs are powered by fusion reactors. Firing energy weapons like lasers and PPCs can cause immense heat builds up since these weapons draw power from the reactor which must run hotter to supply the demand. Projectile weapons and missiles generate very little heat in comparision.

Depends on the efficiencies involved for the beam weapons mainly. But as a rule projectile weapons and missiles typically carry their own "onboard" fuels in a more ocmpact manner, so cooling is less of an issue (although sustained firing of projectile weapons is still an issue - cf machine guns and such). Its all a matter of tradeoffs

One curious exception is the Gauss Rifle. It has immense range and punch that can put a PPC to shame. Yet it generates no heat because it is a projectile weapon. It is understandable why similar hard hitting projectile weapons like the AC 20 don't produce heat problems. They are really futuristic cannons.

This probably means (at least in part) their guass technology is better developed than beam weapons. Hardly a shock, since IIRC a similar case occurs with modern weapon (at least of comparable effect/power).

Damage mechanism also plays a role. A gauss weapon can rely as much on momentum as on KE for damage, whereas a beam weapon is more liekly to rely on energy for the damage mechanism. Needing more energy can mean cooling problems.

That siad this all smells vaguely of gameplay abstraction so I take alot of this with a massive grain of salt.

But a gauss rifle is a railgun, a type of weapon that consumes tremendous amounts of energy.

So do lasers and hypothetical particle beams. THey were in fact all part of the same project.

PS: railguns and coilguns (gauss weapons) are two different things. Do not confuse them.

In real world most warships and tanks do not have powerplants sufficient to support effective railgun weapons. There is talk of new powerplants for the proposed US navy future warship to support weapons like the railgun.

Actually I'm pretty sure providing the energy isnt so much the problem as is the capacitor/storage systems (size and the requisite stored amount of energy) One advantage chem propelled still have is a more compact powre source (realtively speaking) especially when it comes to small arms. Indeed there are certain hybrid weapons (electrothermal-chemical, or liquid propellant weapons) that have been proposed to match "current" railgun performance for example (around 2-3 km/s IIRC).

Googling, the Ticonderoga class cruisers the US uses generate some 60 MW worth of power from their engines usstained, so I don't think there would be much potential problems with providing the energy. Its just a matter of storage and translating that energy into effective firepower (inefficiencies basically).

So why does a PPC cause heat meters to spike so high yet a gauss rifle is barely noticed despite firing a 125 kilogram slug out to far distance ? Considering the Gauss rifle and PPC cause same damage the Gauss rifle too should have severe heat penalty for firing.

Out of universe I'd say game balance. In universe its probably as I said: a combination of technical development (IE not as much research devoted to particle beam weapons as to lasers or gauss weapons) and the differences in damage mechanism (a stream of relativistic particles vs a large and presuambly hypersonic slug of matter.) If the energy output of the particle beam weapon is sufficiently large enough over the gauss weapon, then even at comparable efficiencies the PBW would generate more waste heat than the gauss weapon would.

[Sea Skimmer]

Actually I'm pretty sure providing the energy isnt so much the problem as is the capacitor/storage systems (size and the requisite stored amount of energy)

That’s not really an issue either so far as use in artillery goes, pulse alternators which are basically glorified flywheels would take up much less space or weight then existing warship propellant magazines. The trouble is making the railguns work reliably at all, right now they don’t and some of the technical problems have no clear solutions.

One advantage chem propelled still have is a more compact powre source (realtively speaking) especially when it comes to small arms. Indeed there are certain hybrid weapons (electrothermal-chemical, or liquid propellant weapons) that have been proposed to match "current" railgun performance for example (around 2-3 km/s IIRC).

The problem with just about all artillery weapons that exceed about 2,000 meters a second is barrel life becomes horrendously low. In the case of rail guns we are talking about a single digit lifespan as normal erosion is compounded by the arcing from barrel to armature. We could already make a completely conventional chemical gun shoot much faster then that, it’s just not worthwhile. As it is some tank guns shoot 1,800-2,000m/s but they have a barrel life of maybe 300 rounds. However even without superior velocity a rail gun is still very useful because of the more compact ammo and much higher ammo safety. Indeed an rail gun firing shrapnel shells and guided kinetic rounds would present almost no explosive hazard at all.

Potentially though rail guns could provide velocities of around 6,000 meters a second or even more. But then the US also already built a light gas gun that shot a projectile that was around 30 grains at something like 11,000m/s. Cool but not very useful.

Liquid propellant has little to do with velocity. Its advantage is the propellant could be binary, and thus completely safe from explosion in storage, and it can have higher density then powder allowing for more compact ammo. Also you can squirt exactly as much as you need into the firing chamber, rather then relying on adjusting the number of bagged charges you use and then having to discard the extras. But despite over 20 years of work, no one has yet come up with a completely satisfactory binary liquid propellant + feeding system to mix and load it into the gun safely

Now electrothermal guns, those are aimed at producing higher velocity then conventional guns of the same size, but not necessarily higher velocities in absolute terms (like imagine a 60mm gun that can produce the velocity of a 120mm gun with the same weight sabot shell). At the low even of the ETC spectrum are weapons which merely use an electrical impulse to ignite conventional powder in a more controlled manner then a primer charge. The idea is that if the burning is more controlled, you can maintain high pressure for longer, but without exceeding the peak pressure limit of the firing chamber. Some artillery pieces already use a laser ignition system as an interim step. At the top end meanwhile, the propellant is basically inert, and a huge electrical charge would flash it into plasma. Most research is in-between these extremes, and ETC weapons have been firing on test ranges for about 20 years as well.

Googling, the Ticonderoga class cruisers the US uses generate some 60 MW worth of power from their engines usstained, so I don't think there would be much potential problems with providing the energy. Its just a matter of storage and translating that energy into effective firepower (inefficiencies basically).

On a Ticonderoga the gas turbines are geared directly to the shafts, and generators are separately geared onto the turbines. Only a fraction of engine power can become electrical power, and that electrical power is already required by existing systems. Most engine power can do nothing but make the propellers spin. On DDG-1000 the gas turbines directly drive generators and nothing else. The propellers are turned by separate electrical drive motors. So all power is turned into electrical power by default, and all electrical power is combined together on a shipwide grid. That means engine power could be diverted in bursts into EM or laser weapons. Likewise it also means that small emergency generators could send power to the drive motors to creep the ship home if the main gas turbines break or are damaged. Electrical propulsion is nothing new, it was used in US battleships in WW1, but it was abandon for a long time because of its high weight and decreased emphasis on ship survivability.

As an additional note, the M1 tank has 1,500hp which is about 1.1 megawatts. But its engine was also designed in the 1970s, a newer engine of the same size might produce twice as much power. Only a tiny bit of this is fed into the alternator, but the US military has been intensively working on hybrid power plants for trucks and armored vehicles. They want this not only to save gas and potential power rail guns, but also just to recharge batteries for all the battery powered devices soldiers now have,

[Cykeisme]

Then again, if a BattleTech gauss rifle uses capacitors that allow a 'Mech to avoid building up excess reactor heat, why can't similar capacitors be used on lasers and PPCs?

Note that there is merit to the possibility, since in the game mechanics, damage to the gauss rifle itself will cause an explosion that will damage the 'Mech that carries it, supposedly due to its capacitors exploding. The effect is similar to storage bins of shells or missiles being damaged by enemy fire.
Afaik no other weapon in the game explodes when damaged.

[PainRack]

In Battletech the Mechs are powered by fusion reactors. Firing energy weapons like lasers and PPCs can cause immense heat builds up since these weapons draw power from the reactor which must run hotter to supply the demand. Projectile weapons and missiles generate very little heat in comparision.

One curious exception is the Gauss Rifle. It has immense range and punch that can put a PPC to shame. Yet it generates no heat because it is a projectile weapon. It is understandable why similar hard hitting projectile weapons like the AC 20 don't produce heat problems. They are really futuristic cannons.

But a gauss rifle is a railgun, a type of weapon that consumes tremendous amounts of energy. In real world most warships and tanks do not have powerplants sufficient to support effective railgun weapons. There is talk of new powerplants for the proposed US navy future warship to support weapons like the railgun. So why does a PPC cause heat meters to spike so high yet a gauss rifle is barely noticed despite firing a 125 kilogram slug out to far distance ? Considering the Gauss rifle and PPC cause same damage the Gauss rifle too should have severe heat penalty for firing.

The capacitors is actually the answer, although its only part of it.

You see, you're assuming that the heat is coming from the reactor. The inuniverse explaination is that its coming from the reactor AND the weapons. Its hard to argue how... canon some of the fluff and pictures of the weapons are but both lasers, PPC and Gauss rifles uses capacitors. Its a pity Patrick site is down as he stored some of this fluff.
Ok, so, on to the speculation bits.
The heat from the weapons emerges from the charging and discharging of the capacitors used in PPC/Lasers to discharge the radiation/etc from the weapons chamber. The PPC in particular draws plasma from the reactor and then weaponises it. At a rough guess, the numbers don't work but the heat is from this... leakage of radiation and whatsis.(The old 4th and 3rd Edt states that lasers does it damage via heat and the laser beam is generated via exciting a gas, argon IIRC although I'm not sure whether the text actually emerges from 3rd text or some other less canon fluff or even non canon fluff...)

The gauss rifle works however via magnets, so, heat from wasted energy is significantly less.

So... yup. Both lasers and Gauss rifles work via capacitors(I'm not so sure whether the Mechwarrior drawings of a PPC has them too). But the difference is that lasers charge up a gas, which leaks energy into the environment as waste heat whereas the Gauss rifle wasted heat is from the electromagnets.

[PainRack]

Second, energy weapons are not very effi cient at turning electricity
into laser or particle beams. A heavy laser weapon or PPC
can thus create more waste heat than energy going into the target.
The tubes and breeches of ballistic weapons also need good
cooling in the well-insulated structure of a BattleMech

TechManual.
I speculated on the mechanisms involved above.

[Sarevok]

Gauss rifle ammo is inert. Does not the gauss rifle itself explode if hit ? That seems to support the idea of the weapon storing energy in capacitors. Powerful capacitors can cause explosions if they discharge violently.

[Tanasinn]

Gauss rifles do have capacitors, yes, and that's what explode when a rifle gets hit with a critical hit.

I always figured that the game designers imagined the energy weapons "bleeding over" into their neighboring systems when they fire, resulting in the extra heat - this is also noticable with big missile racks and autocannons. Since the gauss rifle isn't an explosively-fueled or thermal weapon, I imagine that the designers figured it'd have low waste heat.

[PainRack]

Gauss rifle ammo is inert. Does not the gauss rifle itself explode if hit ? That seems to support the idea of the weapon storing energy in capacitors. Powerful capacitors can cause explosions if they discharge violently.

Errr..... Its actually explictly stated in the technical description in TR 3050 as well as Battletech Compendium.

The Gauss rifle explosion IS due to the capacitors.

Game balance aside, nothing is mentioned of the capacitors for beam weapons and indeed, the technical drawings from Mechwarrior is of dubious canonity.

[Gil Hamilton]

The gauss rifle works however via magnets, so, heat from wasted energy is significantly less.

So... yup. Both lasers and Gauss rifles work via capacitors(I'm not so sure whether the Mechwarrior drawings of a PPC has them too). But the difference is that lasers charge up a gas, which leaks energy into the environment as waste heat whereas the Gauss rifle wasted heat is from the electromagnets.

Uh, why again are these magnets not getting hot? Electromagnets of any good power REQUIRE cooling systems, because you can merely churn large amounts of power through them at 100% efficiency. For example, in an NMR spectrometer, it's not uncommon for the magnets to be cyrogenically cooled, to prevent them from heating up to excess. Even the POS (piece o' shit) NMR we had in my undergraduate had a water line to it for its chiller (which bricked the NMR when a rainstorm inadvertantly flooded the unit).

A powerful coilgun like a Guass Rifle would NECESSARILY require a significant cooling system.

[PainRack]

Uh, why again are these magnets not getting hot? Electromagnets of any good power REQUIRE cooling systems, because you can merely churn large amounts of power through them at 100% efficiency. For example, in an NMR spectrometer, it's not uncommon for the magnets to be cyrogenically cooled, to prevent them from heating up to excess. Even the POS (piece o' shit) NMR we had in my undergraduate had a water line to it for its chiller (which bricked the NMR when a rainstorm inadvertantly flooded the unit).

A powerful coilgun like a Guass Rifle would NECESSARILY require a significant cooling system.

? The Gauss rifle has a waste heat of 1 afterall.

Or are you arguing its not hot enough? If anyone has any idea of how to scale the heat scale, I be glad to hear it.

[Cykeisme]

What Gil is saying is that the game mechanics don't make sense.
A gauss rifle using electromagnets should generate a lot of excess heat, much more than the inefficiencies of a laser of comparable wattage.

I always figured that the game designers imagined the energy weapons "bleeding over" into their neighboring systems when they fire, resulting in the extra heat - this is also noticable with big missile racks and autocannons. Since the gauss rifle isn't an explosively-fueled or thermal weapon, I imagine that the designers figured it'd have low waste heat.

From what little I remember of BattleTech (fluff and novels), isn't the heat from firing a weapon supposed to come from the reactor, because the reactor puts out more waste heat whenever it has to ramp up its power generation to feed hungry weapons?

[Chris OFarrell]

Partially. The energy weapons themselves are also not 100% efficient and so loose some of that energy to waste heat.

Of course, why this waste heat doesn't fry said energy weapons if its supposed to be as bad as said, *shrug*.

[Batman]

I always figured that the game designers imagined the energy weapons "bleeding over" into their neighboring systems when they fire, resulting in the extra heat - this is also noticable with big missile racks and autocannons. Since the gauss rifle isn't an explosively-fueled or thermal weapon, I imagine that the designers figured it'd have low waste heat.

From what little I remember of BattleTech (fluff and novels), isn't the heat from firing a weapon supposed to come from the reactor, because the reactor puts out more waste heat whenever it has to ramp up its power generation to feed hungry weapons?

Why, exactly, would the fusion reactor have to ramp up the power to fire a missile rack or autocannon?
While BT game rules DO make no real world sense by and large the waste heat for weapons coming from barrel heating/rocket exhaust (autocannon/missiles) or inefficiencies in the mechanism (energy/particle weapons) makes LESS no sense than the reactor being responsible for all of it.

[Gil Hamilton]

? The Gauss rifle has a waste heat of 1 afterall.

Or are you arguing its not hot enough? If anyone has any idea of how to scale the heat scale, I be glad to hear it.

I'm saying your logic that a gauss rifle shouldn't heat up doesn't follow, because powerful electromagnets get HOT during operation. The game mechanic is screwy, but then again, "BattleTech" and "bizarre nonsensical rules" go hand in hand.

[Cykeisme]

Just summarizing here, correct any mistakes..

If weapon heat is supposed to be caused by inefficiencies in the weapon itself, it makes no sense that the gauss rifles cause only 1 point of heat, as electromagnets generate a lot of waste heat.
If weapon heat is supposed to be waste heat from the main reactor increasing its output, that makes no sense either since even though the gauss rifle has capacitors, they need to be recharged after firing.

Essentially the game mechanics aren't even internally consistent, and iirc the novels are based in the nonsensical game rules..?

[Darth Wong]

Just summarizing here, correct any mistakes..

If weapon heat is supposed to be caused by inefficiencies in the weapon itself, it makes no sense that the gauss rifles cause only 1 point of heat, as electromagnets generate a lot of waste heat.

Not to mention the friction caused by the sled sliding down the rails. Sea Skimmer touched on this already, but in case you didn't understand what he was talking about due to his terminology, a railgun is basically a sled that rides down a pair of rails. In order to work, electricity must conduct from one rail to the other rail, through the sled. This means that the sled must maintain electrical contact with the rails, so it must slide down the rails in contact with them. This means enormous friction heating, not to mention heavy wear on the rails. You can expect to literally vapourize away a little bit of the rails each time you fire the weapon, especially since there is extra heat associated with electrical conduction through the interface between the rails and the sled.

If weapon heat is supposed to be waste heat from the main reactor increasing its output, that makes no sense either since even though the gauss rifle has capacitors, they need to be recharged after firing.

That depends on what kind of muzzle energy and rate of fire we're talking about. It may be that the power level is actually quite small compared to the propulsion requirements of the vehicle.

Essentially the game mechanics aren't even internally consistent, and iirc the novels are based in the nonsensical game rules..?

It's a mech game. What do you expect? The whole genre is based on Japanese cartoons.

[Gil Hamilton]

It's a game that has 100 ton mecha that are enormous to the point that they dwarf modern tanks... except that modern tanks often way more than half that much, indicating that said mechas are actually mostly made of styrofoam. Then it made said tanks arbitrarily weak for no other reason than Battlemechs are Awesome and thus have to be the primary vehicle in the game. BattleTech largely comes down to designers that make up random numbers off the top of their heads.

[PainRack]

I'm saying your logic that a gauss rifle shouldn't heat up doesn't follow, because powerful electromagnets get HOT during operation. The game mechanic is screwy, but then again, "BattleTech" and "bizarre nonsensical rules" go hand in hand.

Errr... I didn't say that. I pointed out that the massive difference in heat scale comes from the way the weapons work. The waste heat is from the electromagnets.
The heat from the weapons emerges from the charging and discharging of the capacitors used in PPC/Lasers to discharge the radiation/etc from the weapons chamber. The PPC in particular draws plasma from the reactor and then weaponises it. At a rough guess, the numbers don't work but the heat is from this... leakage of radiation and whatsis.(The old 4th and 3rd Edt states that lasers does it damage via heat and the laser beam is generated via exciting a gas, argon IIRC although I'm not sure whether the text actually emerges from 3rd text or some other less canon fluff or even non canon fluff...)

The gauss rifle works however via magnets, so, heat from wasted energy is significantly less.

If you ARE talking about the disparity vis a vis numbers, I would like to point out that the heat scale and mech temperature doesn't scale well to real numbers. For example, immersion in lava/steam vs external 10 degree raise in temperature affecting the heat scale, high end is vapourisation of a few meters deep water, large enough to cover the Masakari in steam/fog.

Given the Masakari example, it should be instantly fatal for infantry to climb overheated mechs and mechs that are actively dumping out large amount of heat such as the Flashman(coolant and heat exhaust dumped out to the exterior).

Just summarizing here, correct any mistakes..

If weapon heat is supposed to be caused by inefficiencies in the weapon itself, it makes no sense that the gauss rifles cause only 1 point of heat, as electromagnets generate a lot of waste heat.
If weapon heat is supposed to be waste heat from the main reactor increasing its output, that makes no sense either since even though the gauss rifle has capacitors, they need to be recharged after firing.

Essentially the game mechanics aren't even internally consistent, and iirc the novels are based in the nonsensical game rules..?

I give the full quote from TechManual.

Heat Sources
First and foremost, the fusion engine generates heat, even with
all its effi cient energy conversion. The delicate balancing act of sustaining
fusion often results in a fusion engine producing more energy
than is needed. Since there’s more energy than needed, and
it’s not all converted into electricity, the excess is dumped as heat.
Second, energy weapons are not very effi cient at turning electricity
into laser or particle beams. A heavy laser weapon or PPC
can thus create more waste heat than energy going into the target.
The tubes and breeches of ballistic weapons also need good
cooling in the well-insulated structure of a BattleMech.

Like I said, its a mixture of both.
Also, lol. The game mechanics are game mechanics..... the technology and the numbers are something else altogether. The first is..... somewhat patchy, made worse by the plethora of alternate game systems now. The second has never been consistent, to the extent that FanPro has given up rationalising it altogether.
Even the huge TechManual/Total Warfare, for all its ballyhooed attempt to give a technical under the hood look into Battletech has the publishers giving precious few blurbs compared to the TRO and Mechwarrior fluff, which gave pictures and numbers.
Hell, anyone here has access to the old Battlemech communications ranges? Some of the lighter mechs have ranges of a few klicks only with no ability to hook up into satcoms.(well, presumably, since the Cyclops, Atlas, Phoenix Hawk and some select others are explictly stated to have said ability)

I wish somebody would actually go back and just retcon Comstar HPG times though. It was already suffering badly up to 3050, especially as the Clans gave us virtual instacomms from Clanspace to the InnerSphere, holding a virtual reality meeting connecting multiple starsystems together. The novels covering the 3057 invasion and etc destroyed it altogether.
In theory, Comstar messages were like snail mail. Take a few days to weeks to arrive, arrive everywhere from daily to weekly with isolated worlds being more isolated(well, the Mechwarrior RPG makes it worse than that). Now, we have the Lyran Alliance withdrawing from the Alliance 2 days AFTER the Marik invasion........ In theory, the messages from Thomas declearing war should still have been on the way. Hell, the response by Katherine Steiner Davion should had took days to reach the Chaos March.

[Cykeisme]

Not to mention the friction caused by the sled sliding down the rails. Sea Skimmer touched on this already, but in case you didn't understand what he was talking about due to his terminology, a railgun is basically a sled that rides down a pair of rails. In order to work, electricity must conduct from one rail to the other rail, through the sled. This means that the sled must maintain electrical contact with the rails, so it must slide down the rails in contact with them. This means enormous friction heating, not to mention heavy wear on the rails. You can expect to literally vapourize away a little bit of the rails each time you fire the weapon, especially since there is extra heat associated with electrical conduction through the interface between the rails and the sled.

Aren't railguns different from coilguns?
My understanding of railguns basically doesn't extend beyond Fleming's left-hand rule, but I thought the "gauss gun" (or "coilgun") was something different, and the projectile is not required to be in direct contact with the barrel.. I could be wrong, though.
From what others have stated here, though, even if it was a coilgun, powerful electromagnets get very hot as well, so the arbitrary game rules still don't make sense.

It's a mech game. What do you expect? The whole genre is based on Japanese cartoons.

Well, there are other fictional settings that make an effort at justifying the legged machines and remain internally consistent.. Dream Pod 9's Heavy Gear springs to mind (unfortunately I can't find many online sources to share).

[Connor MacLeod]

That’s not really an issue either so far as use in artillery goes, pulse alternators which are basically glorified flywheels would take up much less space or weight then existing warship propellant magazines. The trouble is making the railguns work reliably at all, right now they don’t and some of the technical problems have no clear solutions.

Have they been experimenting with artillery versions? I was under the impression that vehicle mounted railguns were some ways off yet. As for the reliability issue I could see that, as I recall the Navy prototype wasn't terribly efficient (understandable given the relatively new technologies..)

The problem with just about all artillery weapons that exceed about 2,000 meters a second is barrel life becomes horrendously low. In the case of rail guns we are talking about a single digit lifespan as normal erosion is compounded by the arcing from barrel to armature.

I knew about railguns but I wasn't aware it applied to other weaponry as well (coilguns, ETc, conventional, etc.) It makes sense though.

We could already make a completely conventional chemical gun shoot much faster then that, it’s just not worthwhile.

True, but as I recall they either need enormous calibres (140mm+) or insanely long barrels (I recall experiments that had barrel lengths rivalling or exceeding 16" guns in size. All I can think of ATM is that Gerard Butler guy, tho.)

As it is some tank guns shoot 1,800-2,000m/s but they have a barrel life of maybe 300 rounds. However even without superior velocity a rail gun is still very useful because of the more compact ammo and much higher ammo safety. Indeed an rail gun firing shrapnel shells and guided kinetic rounds would present almost no explosive hazard at all.

No argument here. Since we're on the topic of velocity though, I've read that velocities greater than 2-3 km/s are not neccesarily desirable in an anti-tank weapon since that is roughly the threshold for hypervelocity. I was wondering if you had some thoughts on that you could share?

Potentially though rail guns could provide velocities of around 6,000 meters a second or even more. But then the US also already built a light gas gun that shot a projectile that was around 30 grains at something like 11,000m/s. Cool but not very useful.

The light gas gun also has an extremely long barrel IIRC.

Liquid propellant has little to do with velocity. Its advantage is the propellant could be binary, and thus completely safe from explosion in storage, and it can have higher density then powder allowing for more compact ammo. Also you can squirt exactly as much as you need into the firing chamber, rather then relying on adjusting the number of bagged charges you use and then having to discard the extras. But despite over 20 years of work, no one has yet come up with a completely satisfactory binary liquid propellant + feeding system to mix and load it into the gun safely.

really? I remember reading up on the FCS concepts and they mentioned liquid propellants alongside other methods like railguns and ETC guns. I was under the impression it gave better performance than solid propellants (even if it was a slight improvement.)

Now electrothermal guns, those are aimed at producing higher velocity then conventional guns of the same size, but not necessarily higher velocities in absolute terms (like imagine a 60mm gun that can produce the velocity of a 120mm gun with the same weight sabot shell). At the low even of the ETC spectrum are weapons which merely use an electrical impulse to ignite conventional powder in a more controlled manner then a primer charge. The idea is that if the burning is more controlled, you can maintain high pressure for longer, but without exceeding the peak pressure limit of the firing chamber.

Yeah, that's how I understand it to work. ETC guns are more an intermediate step (simply enahncing chem propellant with a bit of electricity) whereas an ET gun is almost purely run by electricity. IIRC its the ET guns that were supposed to be the competitors with railguns.

Some artillery pieces already use a laser ignition system as an interim step. At the top end meanwhile, the propellant is basically inert, and a huge electrical charge would flash it into plasma. Most research is in-between these extremes, and ETC weapons have been firing on test ranges for about 20 years as well.

I heard about the laser ignition. Part of me has wondered if that might be utilized in a manner similar to the ETC concept to improve efficiency.

IIRC the Russians also experimented with a "Travelling charge" concept, but I havent found alot of data on that either.

On a Ticonderoga the gas turbines are geared directly to the shafts, and generators are separately geared onto the turbines. Only a fraction of engine power can become electrical power, and that electrical power is already required by existing systems. Most engine power can do nothing but make the propellers spin. On DDG-1000 the gas turbines directly drive generators and nothing else. The propellers are turned by separate electrical drive motors. So all power is turned into electrical power by default, and all electrical power is combined together on a shipwide grid. That means engine power could be diverted in bursts into EM or laser weapons. Likewise it also means that small emergency generators could send power to the drive motors to creep the ship home if the main gas turbines break or are damaged. Electrical propulsion is nothing new, it was used in US battleships in WW1, but it was abandon for a long time because of its high weight and decreased emphasis on ship survivability.

As an additional note, the M1 tank has 1,500hp which is about 1.1 megawatts. But its engine was also designed in the 1970s, a newer engine of the same size might produce twice as much power. Only a tiny bit of this is fed into the alternator, but the US military has been intensively working on hybrid power plants for trucks and armored vehicles. They want this not only to save gas and potential power rail guns, but also just to recharge batteries for all the battery powered devices soldiers now have,

Oh you're right, there's no way to rig a railgun onto a Ticonderoga. I was just trying to use it as an example of power outputs we might expect a ship's poweprlant to provide (I'd assume the DDX would be roughly similar in performance). I do like the M1 Abrams example, that's another one I hadn't thought of.