Why does Gauss Rifle = no recoil?

[Todg]

None. The total energy transmitted remains the same.

BTW, conventional rounds accelerate over there whole time in the barrel - with the exception of .22lr, which typically reached max velocity after traveling about 14 inches (in barrel) at which point it starts losing velocity. Most other rifles won't reach peak velocity (i.e. continue accelerating) through 35-45 inches of barrel.

That is not to say that acceleration is uniform - it's dependent on propellant pressure.

 

[MistWolf]

The true formulae for figuring recoil also uses the velocity of the ejecta, which in the case of firearms, is a constant of roughly 4700 fps. I don't have the formulae handy- it's in one of my reloading manuals which is still in storage due to my recent move. I don't recall the numbers, but a gauss rifle firing it's 61 grain 4mm needle at 4800 fps generated no more recoil than an M16 of the same weight firing a bullet of about the same weight at a velocity of 3100 fps. I don't have the calculations I made all those years ago (before MT came into being) but it showed that anywhere from a third to one half the recoil is generated by the mass and velocity of the ejecta.

Recoil impulse, or felt recoil, is very important to controllability. A sharp, fast recoil impulse is more difficult for a human to control than a softer, longer one. This explains why many find the recoil impulse of a semi automatic more pleasant than that of a manual operated rifle of the same weight, configuration and caliber.

If we take the evolution of the gauss rifle a step further, the electro-magnetic field is replaced with gravatics. If the FGMP can use gravitics, so can the gauss. In any case, the weapon can be designed to use the technology of the day to reduce and control recoil. As mentioned earlier, a gravatic dampener or even intertial dampner technology can be utilized. One could even be fitted at the muzzle to act as a brake. With dampners in place, the gauss (or as we call it in our games, the battle railer) becomes even deadlier as now you can push velocities higher with a heavier payload- imagine a 7mm needle weighing 12 grams (about 180 grains) and an initial velocity of 4800 fps or more- with no more recoil than an M16A2

As far as the hypersonic crack goes, the sound will come to your ears from either the projectile itself, or what ever source it's reflected from. If a sniper were to fire a supersonic bullet along a line of telephone poles, for example, an obsever could trace the line of flight back to it's source by listening to the sound of the bullet passing along the poles

 

[MrMorden]

IMTU Gauss weapons are by no means recoilless, unless they have a garvitic field generator like some of the PGMP/FGMP weapons.

Also, the user can tune down the power, resulting in subsonic performance (but 1d12 instead of 2d12 damage).

 

[Ptah]

Gauss weapons might have considerably less recoil than a chemical projectile weapon with the same damage rating for the follwoing reasons. (but they would still have some recoil)

Gauss weapons may use low mass projectiles that they accellerate to very high velocity. Damage is often based of projectile kinetic energy thus mass times velocity squared (mv^2). Recoil, however, results from conservation of momentum (to every action there is an equal and opposite reaction), and momentum is mass times velocity (mv).

So small increases in velocity really increase the kinetic energy but not the recoil as much.

 

[far-trader]

Ballistics damage is much more complicated than simply the kinetic energy imparted to the target. And the proper formula is KE = 1/2 x M x (VxV)

Likewise Recoil in a ballistic sense is much more involved than simple momentum/reaction.

But then we've been through all this before

I don't expect anyone to change their minds.

 

[far-trader]

Realistically a weapon should be designed to control it's recoil sufficiently as to not impair it's normal function. So recoil shouldn't even come into play in the game. Except... when somebody goes beyond the normal function.

Like by converting a small pistol to full auto. Or a high-power rifle to some sawn off short stock "hand" gun. Or firing a weapon without properly bracing oneself. And so on. In other words, what far too many munchkins will want to do

Also in this category of weapons fired under extraordinary circumstances would be using them in low gravity or high gravity. Mix low gravity and most weapons, ranged and melee, means you go spinning out of control. Mix weapons and high gravity and you'll likely mess up for other reasons. One obvious exception to this are lasers.

Of course that's just one amateurs opinion, play it how you want it to work, as long as all concerned are having fun I wouldn't spoil it

 

[Ptah]

Originally posted by far-trader:
Ballistics damage is much more complicated than simply the kinetic energy imparted to the target. And the proper formula is KE = 1/2 x M x (VxV)

Likewise Recoil in a ballistic sense is much more involved than simple momentum/reaction.

But then we've been through all this before

I don't expect anyone to change their minds.

I agree ballistic damage is much more complicated in real life and other factors determine the ultimate recoil experienced. Yet many games model ballistic damage off of kinetic energy. And conservation of momemtum is the primary physical phenomena that causes recoil.

I left off the 1/2 factor on kinetic energy to emphasize that KE scales as v^2 whereas momentum scales as v. Just a physical suggestion why a guass weapon may have less recoil, it also explains why a laser has no perceived recoil. You are certainly sending out lots of energy but mv is small because m of the photon is small.

 

[Ptah]

Originally posted by far-trader:
Realistically a weapon should be designed to control it's recoil sufficiently as to not impair it's normal function. So recoil shouldn't even come into play in the game. Except... when somebody goes beyond the normal function.

Like by converting a small pistol to full auto. Or a high-power rifle to some sawn off short stock "hand" gun.

Like in The Rifleman

 

[Hyphen]

Dear Folks -

Originally posted by far-trader:
Realistically a weapon should be designed to control it's recoil sufficiently as to not impair it's normal function. So recoil shouldn't even come into play in the game. Except... when somebody goes beyond the normal function.

Wow, has this thread raised its ugly head again?

I always thought that the answers were:

1. It is a TL 12 weapon (that's about four above our current level). By then, weapon designers will be able to combine the new technologies (material, electronic, and gravitic) available at that TL to create a built-in recoil compensator. Not to eliminate recoil, but to reduce it for a TL 12 gauss rifle from Hi to Low.

2. One of the MT game designers sat next to a real-world weapons designer on a plane flight. Part of their discussion involved the gauss rifle. Apparently, the real-world weapon designer did some sketches or went thru some numbers or thought about it, and then said that if the projectile could be accelerated to supersonic speeds while still in the barrel, then the projectile could be designed in such a way as to NOT create a sonic "crack".

Who knows, maybe a needle that is spun at a very high rate and which tapers to a point at both the front and rear is silent, compared to a blunt-ended bullet (where the "crack" is the displaced air rapidly coming back together).

In any case, the designers went with what the expert had suggested, and wrote up the gauss rifle as silent.

Here's my Equipment Sheet: Gauss Rifle

Alternately, go to my website, then ==> Repair Bays ==> House Rules ==> Weapons Tables and drill down. There's more than just the gauss rifle available - the Light Rapid Fire (LRF) Gauss Gun is just filthy.

 

[Anthony]

Originally posted by far-trader:
Realistically a weapon should be designed to control it's recoil sufficiently as to not impair it's normal function. So recoil shouldn't even come into play in the game. Except... when somebody goes beyond the normal function.

Realistically, weapon design involves tradeoffs. Eliminating the last bit of recoil may not be worth the increase in weight or cost.

Recoil will be low enough to allow the weapon to be used in its normal role. That doesn't mean recoil will be irrelevant, it just means it's a tolerable irritant.

 

[MrMorden]

Originally posted by Hyphen:
[QB] Dear Folks -

Who knows, maybe a needle that is spun at a very high rate and which tapers to a point at both the front and rear is silent, compared to a blunt-ended bullet (where the "crack" is the displaced air rapidly coming back together).

But we do know. This is basic physics. Jet fighters are very efficient aerodynamically, and if you could find a way to eliminate sonic concussion, I'm sure the air force would like to talk to you (and pay you a lot).

Your idea of having the sonic boom happen inside the barrel is intriguing, but I think the problem is that unless the barrel is sealed (in which case where does the bullet go...) the crack is going to continue pushing outward.

If the barrel *were* sealed somehow, once the bullet left, it would be meeting a new airmass (the atmosphere) and a new sonic concussion would be generated.

A sonic boom is not really an event, it is a pressure wave that follows along behind the bullet. As long as a bullet stays above ambient speed of sound, the crack follows it and will be heard at any position the bullet passes.

The best solution is to turn down the power to make the round subsonic when you need quiet. Add HE needles if the damage reduction is too much for you. Of course, HE makes noise of its own...

 

[Fritz_Brown]

Originally posted by MrMorden:
Of course, HE makes noise of its own...

Yeah, but THAT noise is centered on the target, where it's less dangerous!

 

[far-trader]

Originally posted by Anthony:
</font><blockquote>quote:</font><hr />Originally posted by far-trader:
Realistically a weapon should be designed to control it's recoil sufficiently as to not impair it's normal function. So recoil shouldn't even come into play in the game. Except... when somebody goes beyond the normal function.

Realistically, weapon design involves tradeoffs. Eliminating the last bit of recoil may not be worth the increase in weight or cost.

Recoil will be low enough to allow the weapon to be used in its normal role. That doesn't mean recoil will be irrelevant, it just means it's a tolerable irritant. </font>[/QUOTE]That's what I meant, but guess I wasn't clear enough

Thanks for the reinforcement Anthony.

 

[Crashlogic]

well i would point out using an online recoil calculator may not be a valid recoil comparison without knowing how the algorithm factors in the powder charge. Setting the power charge to 0 doe snot eliminate that variable from the equation, and using a gauss rifle would elminate, not zero, that variable. Thus the comparison is somewhat suspect.

My under standing is that a bullet leaves a gun from the force of the propellant being vented in one direction. Thus the bulk of recoil is not from the bullet but from the propellant. Also the bullet is basically pushing back against the gun to move forward.

My understanding is that the gauss needle is suspended in a anti-gravity field and propelled along the barrel by fluctuationws in the gravity field causing accelleration of the projectile. If the projectile is suspended from gravity, and is pulled along the barrel rather than pushed I don't think you would have at all the same recoil mechanism as you would in a chemical gun. just a thought.

 

[Anthony]

Your understanding of basic mechanics is flawed. Setting propellant weight to zero should in fact have the same effect as gauss munitions (the normal propellant factor is that you just add propellant weight * K to recoil)

 

[mike wightman]

...the gauss rifle generates an electromagnetic field along the length of the barrel...

LBB4 Mercenary, page 36

 

[Crashlogic]

Ok so its electromagnetic and not gravintational, sill is not the needle suspended in a frictionless medium and acellerated dow the barrel by the magnets? Or is there some mechanical aspect that gives it a push.

My understanding is that energy transer can happen diferently in a electromagnetic system, which appears to then violate the conservation of momentum as momentum from the field is trnaslated to mechancial systems. Which could mean that recoil is more easily compensated for than in a chemical weapon.

 

[Pickles]

Put simply, the coil 'pushes' against the needle. The needle 'pushes' back against the coil. That translates into recoil (although probably not much).

Of course, if someone were to use grav-propulsion in a gun, you've got a reactionless gun. Are there minimum size limits to thruster plates? Would rounds have to be self-propelled?

 

[veltyen]

Not nessersarily Bromgrev,

What you have descibed is a coilgun
This is a gauss weapon in that there is a magnetic feild involved, but has problems generating the high velocity needed to replicate a Traveller "Gauss Rifle" due to back inductance in the coil. Certainly it looks cool (for example the gauss weapons out of fallout) and it is a possibility.

The coilgun isn't the only gauss weapon available, there are at least two other electo-magnetic projectile designs. The Railgun is a somewhat better fit for the traveller weapon. It relies on the principle that the area of a circuit wants to get bigger while there is a current flowing through it. For example a loop of wire stretched so that it is nearly two parrallel wires will push against each other to become wider. In the same way a railgun works, three sides of the circuit (the two rails and one end) are fixed, the last segment of the circuit is completed by the munition. Forcing a large burst of current into the circuit causes it to expand with much force, pushing the munition down the barrel to expand the circuit.

Similar to the idea of using thruster plates is the Mass Driver. This is similar to the coilgun, but each munition has its own coil and power source to push against the magnetic inductance of the projecting coil, this gets arround the induced flux in the projectile (the problem that happens with coilguns). The buckets can also be made re-useable, at which point you don't loose expensive electronic gear each time you fire.

None of these get arround any kind of recoil though as nothing in the above designs avoids the issue of momentum. Recoil can always be minimised however, say by using a moving carriage for the firing mechanism, or by venting gases directly away from the direction of travel of the munition.

Personally I don't think any of the above three solutions are what a GR uses, at which point handwavium gets arround any recoil issues.

 

[Pickles]

Originally posted by veltyen:
Not nessersarily Bromgrev,

What you have descibed is a coilgun

Hmm ... I was going by the definition on my favourite online reference source. It seems Mr. Gauss's name is taken in vain by every form of electromagnetic gun on the drawing board.

Personally I don't think any of the above three solutions are what a GR uses, at which point handwavium gets arround any recoil issues.

Agreed, all present-day e-mag guns require far too much energy to be practical in a carbine-sized package. I've always just handwaved them to be coilguns IMTU for those who wanted to know more about their innards.

Which works for recoil, too - I can't imagine any gun-toting culture getting to TL12 and not having reduced felt recoil to zilch. The technology is just sufficiently advanced to look like magic to me.