Recoil of Gauss Rifle

[Davion]

Hello, I do not know if this has been ask before but do Gauss Rifles have recoil?  You are shooting a metal object down a gun barrel but it is doing it by magnets field so there is no push back like when you use regular shell

[Empyrus]

Recoil happens with electromagnetic acceleration system normally. Given the size and velocity of the slug, it has significant recoil. The Heavy Gauss Rifle more so, that can knock down the firing unit, as noted by the game rules.

[Robroy]

On yes there is. Remember the rule, for every action there is an equal and opposite reaction. It may not be gun powder that throws the slug down range, but the magnetic field is attached, for lack of a better word, to the gun. As the field acts on the slug, the slug also acts on the filed, and thus on the gun.

[Nightlord01]

On yes there is. Remember the rule, for every action there is an equal and opposite reaction. It may not be gun powder that throws the slug down range, but the magnetic field is attached, for lack of a better word, to the gun. As the field acts on the slug, the slug also acts on the filed, and thus on the gun.

Wow, I just hit post before I wrote anything, it's been a fun day.  :-\

On gauss rifle recoil, there will be some, but it won't be like a powder thrown projectile which generally uses energy far exceeding requirements to project the round, not to mention being able to use an open barrel system and allow the air being pushed out of the way to leave out gaps in the barrel rather than all being pushed out in a single direction.

[Bosefius]

At the start of this video (https://youtu.be/eObepuHvYAw) you can see the recoil.

[Robroy]

The powder charge contributes only a little to recoil. A lighter slug at a slower velocity out of a heavy gun will produce less recoil then a heavy slug at high velocity out of a light gun.

Even a light slug can produce high recoil the faster it is pushed down the barrel. As the faster it goes the more energy it takes and the more it pushed back against the gun.

[Sartris]

So you’re saying a 125kg slug suddenly accelerated to near Mach 5 is going to have a slight kick?

*lights Cray beacon*

[Empyrus]

So you’re saying a 125kg slug suddenly accelerated to near Mach 5 is going to have a slight kick?

*lights Cray beacon*

That's about 180 megajoules of energy, if i calculated right.

About 1700 meters per second muzzle velocity, which isn't that impressive given that modern tank guns can do that. But then again, a shell/KEP from a tank gun weights like 1/5th or 1/6th of a BT Gauss slug.

Either way, tank guns have a lot of recoil. A Gauss gun has much, much more recoil. Indeed, this is a problem with electromagnetic guns as i understand it, the electromagnetic coils need a lot of bracing, which adds weight to the weapon.

[Davion]

Thank you everyone for answering

[guardiandashi]

to be honest different people are actually talking about different things.

the OP had the common misconception that gunpowder causes the recoil in cannons (and all guns in general) when it would be more accurate, to say gunpowder is the energy source to make the weapon work.  The recoil is a combination of the force = Mass times acceleration ( F=MA )
and for every action there is an equal and opposite reaction

so to make it simple  lets say the shell weighs 10kg, and the gun weighs 1000 kg,
if the bullet is accelerated with 1000 units of energy --> then it will naturally be traveling ~100 speed
at the same time the gun will receive 1000 units of energy <-- and it will naturally be trying to move at 1 speed

with gauss weaponry the electromagnetic fields replace the pressure effects that the gunpowder detonation causes.

[RoundTop]

to be honest different people are actually talking about different things.

the OP had the common misconception that gunpowder causes the recoil in cannons (and all guns in general) when it would be more accurate, to say gunpowder is the energy source to make the weapon work.  The recoil is a combination of the force = Mass times acceleration ( F=MA )
and for every action there is an equal and opposite reaction

so to make it simple  lets say the shell weighs 10kg, and the gun weighs 1000 kg,
if the bullet is accelerated with 1000 units of energy --> then it will naturally be traveling ~100 speed
at the same time the gun will receive 1000 units of energy <-- and it will naturally be trying to move at 1 speed

with gauss weaponry the electromagnetic fields replace the pressure effects that the gunpowder detonation causes.

The difference with EM weapons vs gunpowder is duration. 

Recoil is felt as the pressure over time when firing the weapon. For explosive firing methods (eg: gunpowder), you get a high initial spike in pressure, as it starts to move the bullet. This then lessens as the projectile moves down the weapon, and ceases when it exits the barrel. So you have a high spike at the beginning, and then it lessens. Some weapons used recoil dampers, which are basically springs. These take that high spike and spread out the impetus over more time. This has the effect of feeling like there is less recoil (there isn't, it is spread out over time). See http://www.cleverinsite.com/ShotgunRecoil.html for some graphs.

Now an EM weapon is different. It accelerates the projectile constantly. So instead of high initial followed by lesser amounts, it is a set amount for the duration it is in the barrel. This spreads the recoil over the entire time it takes to leave the barrel. It has less of a peak at the beginning, as it spreads it over time. But this also means it will shove back longer. So this will look like a straight acceleration line (no curves), and the recoil will be a set amount for the entire time.

[glitterboy2098]

That's about 180 megajoules of energy, if i calculated right.

About 1700 meters per second muzzle velocity, which isn't that impressive given that modern tank guns can do that. But then again, a shell/KEP from a tank gun weights like 1/5th or 1/6th of a BT Gauss slug.

Either way, tank guns have a lot of recoil. A Gauss gun has much, much more recoil. Indeed, this is a problem with electromagnetic guns as i understand it, the electromagnetic coils need a lot of bracing, which adds weight to the weapon.

Given the aerotech ranges, which is a better guide, more like 7500m/s (around mach 20)

[marcussmythe]

Also important to note the differnce between momentum and energy.  A laser can deliver a phenomenal amount of energy, but generates no recoil because it has no momentum.

This is in part why laser drives and laser sails are such hideous consumers of energy for the acceleration they can deliver, by my limited understanding.

[Alsadius]

Not quite true. Light does have momentum - energy divided by speed equals momentum in the case of photons. It's just that the speed is very high, so the momentum per energy is very low. (For normal objects well below light speed, energy divided by half the speed equals momentum, and of course the speed is much lower as well).

In practice, it can be ignored. A 100-watt light bulb that's turned on for an hour produces about as much momentum as a jellybean falling two inches.

[guardiandashi]

Not quite true. Light does have momentum - energy divided by speed equals momentum in the case of photons. It's just that the speed is very high, so the momentum per energy is very low. (For normal objects well below light speed, energy divided by half the speed equals momentum, and of course the speed is much lower as well).

In practice, it can be ignored. A 100-watt light bulb that's turned on for an hour produces about as much momentum as a jellybean falling two inches.

not exactly true either, its that while the energy(velocity) is extremely high the mass of a photon is extremely low, so when F= MV and you insert values, the non moving mass of a photon is so close to zero, that for all practical purposes it has no mass, and all its effective mass when moving is due to relativistic mass increase.

note this isn't exactly right ... but its close

[Caedis Animus]

I wonder how much recoil the Gauss SMG has.

[marcussmythe]

Not quite true. Light does have momentum - energy divided by speed equals momentum in the case of photons. It's just that the speed is very high, so the momentum per energy is very low. (For normal objects well below light speed, energy divided by half the speed equals momentum, and of course the speed is much lower as well).

In practice, it can be ignored. A 100-watt light bulb that's turned on for an hour produces about as much momentum as a jellybean falling two inches.

No momentum on a scale meaningful to everyday human experience.  :)

[RoundTop]

I wonder how much recoil the Gauss SMG has.

Probably less than a modern SMG. The difference is that it would be a constant push back, rather than the rapid impulses of modern SMGs. So you make sure you brace properly, then hold for the constant recoil (since for a gauss weapon, you could dump the ammo in one after another, with no need to reset the breech).  This would actually be more predictable than a modern SMG, since it is constant, not bouncing around.

[klarg1]

Probably less than a modern SMG. The difference is that it would be a constant push back, rather than the rapid impulses of modern SMGs. So you make sure you brace properly, then hold for the constant recoil (since for a gauss weapon, you could dump the ammo in one after another, with no need to reset the breech).  This would actually be more predictable than a modern SMG, since it is constant, not bouncing around.

Wouldn't there be a slight interruption between each round? I'm assuming it's not feeding ammunition into the breach before the previous round leaves the barrel.

[Caedis Animus]

Wouldn't there be a slight interruption between each round? I'm assuming it's not feeding ammunition into the breach before the previous round leaves the barrel.

If it fed that fast, that magazine would be empty in record time.

Speaking of, I really wish the Gauss SMG was more prevalent in Battletech artwork. Always makes me want to do a Zone Mortalis-style Battletech game where IS or Clan special forces have special, unique rules/units, and it's infantry-only.

[Nebfer]

Over on a what If debate a few days ago, some one noted that Gauss rifles should be producing a fair bit of heat, you know all that current in a short amount of time, and that their not to dissimilar in some aspects to particle cannons which produce a fair bit of heat (as they fire charged particles via electromagnetic accelerators...)... So why do they not produce a fair bit of heat?

The Guy who pointed this out was going with the idea that they must be using some of that 125kg ammo mass as "expendable" coolant (25kg worth in fact), even though this is mentioned no where in the fluff (Gauss slugs are noted multiple times in the novels to be 125kg)... In fact Gauss rifles are mentioned to be rather cool running in Tech manual.

[Daryk]

Superconductors could take care of most of the heat generated by high current.

[Empyrus]

Superconductors could take care of most of the heat generated by high current.

This is what i've always assumed to be responsible for the Gauss rifle's low heat. (Also assuming they're room-temp superconductors, not exactly feasible to keep the Gauss rifle cooled down to liquid nitrogen or helium temperature.)

I do why superconductors aren't used more in energy weapons, if they're responsible for BT's Gauss rifle's low heat. Like, the PPC is a particle beam weapon, so it is accelerated with electromagnets as well. Superconducting PPC should probably generate less heat than it does. Then again, it could be that superconductors are just so difficult to make even in BT universe they're reserved for few things only.

[Maingunnery]

This is what i've always assumed to be responsible for the Gauss rifle's low heat. (Also assuming they're room-temp superconductors, not exactly feasible to keep the Gauss rifle cooled down to liquid nitrogen or helium temperature.)

I do why superconductors aren't used more in energy weapons, if they're responsible for BT's Gauss rifle's low heat. Like, the PPC is a particle beam weapon, so it is accelerated with electromagnets as well. Superconducting PPC should probably generate less heat than it does. Then again, it could be that superconductors are just so difficult to make even in BT universe they're reserved for few things only.

Maybe most of the PPC heat comes from generating the required particles?

[klarg1]

This is what i've always assumed to be responsible for the Gauss rifle's low heat. (Also assuming they're room-temp superconductors, not exactly feasible to keep the Gauss rifle cooled down to liquid nitrogen or helium temperature.)

I do why superconductors aren't used more in energy weapons, if they're responsible for BT's Gauss rifle's low heat. Like, the PPC is a particle beam weapon, so it is accelerated with electromagnets as well. Superconducting PPC should probably generate less heat than it does. Then again, it could be that superconductors are just so difficult to make even in BT universe they're reserved for few things only.

Maybe bulky cooling systems, and weighty conductors are responsible? The Gauss Rifle is twice the size of a PPC. It could also be part of the rifle's inconvenient exploding problems.

[PreacherPatriot1776]

This is what i've always assumed to be responsible for the Gauss rifle's low heat. (Also assuming they're room-temp superconductors, not exactly feasible to keep the Gauss rifle cooled down to liquid nitrogen or helium temperature.)

I do why superconductors aren't used more in energy weapons, if they're responsible for BT's Gauss rifle's low heat. Like, the PPC is a particle beam weapon, so it is accelerated with electromagnets as well. Superconducting PPC should probably generate less heat than it does. Then again, it could be that superconductors are just so difficult to make even in BT universe they're reserved for few things only.

I always thought the heat came from the plasma coming directly from the fusion reactor and heating up a containment unit that would build the required energy into a ball.

[cray]

I saw the Cray signal lit, but the question was answered pretty well already. I always like to think of an everyday example of magnetic recoil.

Magnetic acceleration is no different than any other form of acceleration: the action of slug is going to generate a reaction in the magnet.

You know this from your everyday life. If you take a magnet up to a big piece of metal - like a refrigerator - you:
1) Will feel the magnet pulled toward the metal
2) Will see the refrigerator doesn't magically, reactionlessly jump to the magnet

The interaction of magnet and metal is a two-way street. Therefore, when you light up a Gauss rifle there will be recoil as the rifle is drawn backwards during the launch of slug.

[nova_dew]

There is also the Ionocraft experiment which will visually show the forces acting on a Gauss rifle.

An electronic force gives a charge to the air, giving thrust that acts on the ionocraft, In the case of a Gauss rifle replace the air with a ferrous slug. Ok it's not quite the same but close enough for a visual representation

Thanks mythbusters for exposing me to that and i think this is possibly the time it will be relevant.

the question is not does a Gauss recoil but how much felt recoil is felt by the mech and by the pilot and how much of the mass of a weapon is mainly for dampening the felt recoil? Shouldn't the Gauss rifle on a Hollander have greater mass than the one on a Pillager to account for the mass difference of the mech's? Ok im getting silly here just to point out that one should never bring real world physics into a game, it just causes head aches   :D

[SteelRaven]

the question is not does a Gauss recoil but how much felt recoil is felt by the mech and by the pilot and how much of the mass of a weapon is mainly for dampening the felt recoil? Shouldn't the Gauss rifle on a Hollander have greater mass than the one on a Pillager to account for the mass difference of the mech's? Ok im getting silly here just to point out that one should never bring real world physics into a game, it just causes head aches   :D

This would actually in part explain why the Gauss on the Hollander and the AC/20 on the Hunchback looks so massive compared to the Pillager, Highlander or Atlas: Stands to reason the smaller mech would need a larger recoil system. It would also explain why the 3039 DC Gauss Hunchback had balance issues, a Gauss system may require different recoil system than a traditional Hunchback that probably uses something similar to a  exhaust gas system of a recoilless rifle.     

[Von Jankmon]

So you’re saying a 125kg slug suddenly accelerated to near Mach 5 is going to have a slight kick?

*lights Cray beacon*

I doubt that the mass of the ammunition entirely comprised of ammunition.  8 shots per ton doesn't mean 1/8th ton per shot. About half the mass is taken up by ammo feed to the gauss rifle, though some of that mass is also accounted in the gun, there is the magazine, which at least doesnt need to be hardened plus the loading access.

At a guess about half the mass is munitions, slightly more perhaps as you don't need to insulate/isolate the magazine against heat too much.

60kg slugs are sounding more realistic.

[cray]

I doubt that the mass of the ammunition entirely comprised of ammunition.  8 shots per ton doesn't mean 1/8th ton per shot. About half the mass is taken up by ammo feed to the gauss rifle

Nope, the ammo mass is entirely ammo or nearly so. Any of the feed mechanism is accounted for in the weapon's mass.

[glitterboy2098]

so 125kg moving at 7500 m/s

that translates to..

[cray]

so 125kg moving at 7500 m/s

7500m/s?

Well, a Gauss rifle has a long aerospace range: 20 hexes, 360 kilometers. That requires a minimum of 6km/s to cross in 1 turn (60 seconds). So 7.5km/s is possible. But practically speaking you'd want a much higher velocity. Given 60 seconds, even a lumbering bulk like a Behemoth or Aegis can dodge by over 18km. You'd want flight times down to a fraction of a turn, like under 10 seconds to have a chance of hitting a fighter at 360 kilometers range.

That pushes muzzle velocities into tens of kilometers per second.

[glitterboy2098]

was using the minimum velocity needed to cross the space distance. i agree it is probably quite a bit higher.

[Von Jankmon]

Nope, the ammo mass is entirely ammo or nearly so. Any of the feed mechanism is accounted for in the weapon's mass.

 8 shots per ton is a balance mechanism.  There is some give on the construction statistics.

Take Arrow IV for example, its a 15 ton launcher plus 5 shots per ton, yet normally depicted as a 5 shot 16 ton missile launcher, rarely with more ammo than that.  Most set ups don't even have a feed mechanism, just five tubes, all full.

Arrow technology possibly varies, the Capcon uses over big rockets on a simpler firing rail in the Catapult, Clan Wolf might use more compact rockets in a more complex mechanism in the Naga. It amalgamates into the same thing.

Or how about vehicle design, the engine mass is for the engine, foot down on canon there, and the transmission is made of thin air.  The additional mass for tracks is calculated indirectly through modifiers to engine mass in suspension levels, and this value is further diluted if the vehicle has a fusion engine, which presumably doesnt effect transmission mass much.  Consequently it is wrong to take anything other than a holistic approach.

Back to the gauss rifle for a further explanation.  If a guass rifle is arm mounted with torso mounted ammo the ammo feed will weigh more and take more space than if the ammo magazine was in the arm adjacent to the gauss rifle.  however this mass is amalgamated and simplified and it works as is.  By it also means that you have to accept that the mass of the weapon and its ammo is the mass of the weapon and its ammo and it might not be possible to subdivide this down.  With so many variables to add we cannot just take the mass of a ton of gauss ammo and divide it by eight to get an estimate of shot mass.  Place that ammo two locations away from the weapon and it might take a sizable proportion of the tons allocation for additional feed mechanism to get there.

If this is not enough consider a targeting computer.  Why would a targeting computer for a gauss rifle weigh more than one for a small laser, its software right?  On a computer board in the main control hardware.   targeting computer might cost a lot but its mass is negligible,  however the targeting computers mass comes from the fine control waldos it uses to auto correct aim for you which will weigh more to zero in a gauss rifle for target assist more than it would for a small laser.  We could accurately consider a targeting computer as a 0 mass 0 critical slot component in the head, but with additional mass in fine adjustment waldos all over the mech, but we call it all 'targeting computer'.

[Hellraiser]

Hello, I do not know if this has been ask before but do Gauss Rifles have recoil?  You are shooting a metal object down a gun barrel but it is doing it by magnets field so there is no push back like when you use regular shell

Check out the Hunchback fluff about the 3039 prototype Gauss Rifle variant.

Or this mini for it.

http://camospecs.com/Miniature/Details/4055/hunchback-hbk-4g

[Daemion]

7500m/s?

Well, a Gauss rifle has a long aerospace range: 20 hexes, 360 kilometers. That requires a minimum of 6km/s to cross in 1 turn (60 seconds). So 7.5km/s is possible. But practically speaking you'd want a much higher velocity. Given 60 seconds, even a lumbering bulk like a Behemoth or Aegis can dodge by over 18km. You'd want flight times down to a fraction of a turn, like under 10 seconds to have a chance of hitting a fighter at 360 kilometers range.

That pushes muzzle velocities into tens of kilometers per second.

Even that's being a little conservative, there, Cray.  Granted, with the advanced sensors and combat computers BT is supposed to have in its combat craft, you might be able to lead a shot like that pretty handily.  But, same said computers can also be put to use calculating course corrections to still dodge that shot, and it doesn't take more than a couple seconds to be out of the projectile's path. So, you're wanting something closer to 1-2 seconds, or faster.

[Arkansas Warrior]

8 shots per ton is a balance mechanism.  There is some give on the construction statistics.

Take Arrow IV for example, its a 15 ton launcher plus 5 shots per ton, yet normally depicted as a 5 shot 16 ton missile launcher, rarely with more ammo than that.  Most set ups don't even have a feed mechanism, just five tubes, all full.

Arrow technology possibly varies, the Capcon uses over big rockets on a simpler firing rail in the Catapult, Clan Wolf might use more compact rockets in a more complex mechanism in the Naga. It amalgamates into the same thing.

Where are you getting that?  I’ve seen Arrow IV launchers depicted in the art as having 5 tubes, but I don’t think I’ve ever heard them as a 16 ton unit with no ammo feed mechanism.  Besides, as was mentioned earlier, it’s pretty well established in the fluff that Gauss rounds weigh 125kg.  Why not assume that the feed mechanism’s weight is accounted for in the weight of the weapon?

[SteelRaven]

It's honestly kinda pointless to argue the actual weight and mass of a fictional weapon on a fictional machine, it's not like BT ammo bins follow any logical reloading mechanics to begin with. 

 

[marcussmythe]

Your saying my LL AC/20 Bins cant feed my RA  AC/20?  Heresy!

[Ice_Trey]

For sure there is, it's just within manageable levels for a Battlemech.

However, not so for the Heavy Gauss Rifle, which actually requires a modified piloting check each time you fire one.

Also, the prototype version of the standard Gauss Rifle had a similar drawback, but was resolved by the time the production model came out.