Pulsar Ballistics

Robert_A_Woodward wrote:People are forgetting that the "kick" is momentum (mass * velocity), while the energy is mass * velocity * velocity. If the pellet of weapon B is 1/4 the mass of the pellet of weapon A, while the velocity for B is twice that of A, then the energy for B would be equal to that of A, but the "kick" would be half as much.

tlb wrote:I remember introductory physics pretty well (I was a physics major in college), so I do not know what led you to make this comment. When comparing a 10mm chemically driven bullet to the dart of a pulser, the dart is traveling about 8 times faster and we do not know how the masses differ (so the dart would have to have one sixty-fourth the mass to have the same energy and one eighth the momentum).

Robert_A_Woodward wrote:I did so because people were inventing possible momentum dumps and overlooking the reasons to believe that the pulser darts are much smaller than a 10mm bullet. I have also found a passage where a pulser was pushing the person that was firing it (probably because the rate of fire smoothed out all the little kicks).

It would be very useful if you were to present that text. There are schemes that can reduce the felt recoil, many work by spreading the momentum transfer over a longer period of time with springs and sliding masses. There are Honorverse devices that seem to violate Newton's Laws and we have no way of knowing how much has been done with the pulser, which is why the text you mention is needed.

We have been given that the dimensions of a pulser rifle dart are 4x37mm and of a military pistol are 3x24mm. What we have not been given is the density of the dart. The great resizing if warship weights could give us a lower limit on the density (warships have cavities to allow use by people). The material used to build domes is stronger and lighter than our construction materials. The forces acting on a hyper-velocity dart would require both.

Loren Pechtel wrote:

cthia wrote:To deal with the incessant kick of a gun in the Honorverse, an equal and opposite force is sent along the outside of the gun, thus cancelling each other out. A force muzzler. Hence, fuzzler. The opposite force hits a plate which disperses the energy. It is an ingenious mechanism perfectly "synchronizing" Newton's third law.

Which hits the shooter. You're not helping anything here. Honorverse tech is certainly capable of redirecting the force (assuming it could be made small enough), but I don't see any practical way to divert it in a harmless way.

Maybe maybe not.

My suggestion hinges on Honorverse materials and production techniques. Lots of things can be accomplished now if the strength of materials could be on par with the design. And also if manufacturing techniques were better. Consider the many phases the welding industry went thru before it became what it is now.

There are many laws of physics which I think will be harnessed in a future society where materials, tools and techniques have matured.

In fact, I allowed for the efficacy of Robert Woodward's post when I included in my own ...

cthia wrote:I'm suggesting using a counter force "fired" in the opposite direction of the kick. Akin to firing a blank in the opposite direction simultaneously while harnesting some of the excess force from Resultant A as well.

Akin to redirecting the spent exhaust created in an engine thru a turbocharger to derive more power. I don't know what mechanisms are used to launch projectiles in the HV. But the idea of blanks used in conjunction with harnessing some of the initial blowback seems viable. HV materials and techniques should allow ingenious applications of the laws of physics.

There's nothing to "hit" the user if the two forces are cancelling each other out. If today's engineering principles and materials could accomplish it, the plates would be dispersing simply compressed air!

The conservation of momentum mass and energy and rigid body dynamics using HV materials should astound 21st century man.

.

I certainly hit the jackpot inspiring interesting replies.
By my reckoning, a pulsar rifle dart masses a maximum of about 5 grams or 75 grains. Pistol projectile might be a maximum only 25 grains. Weber postulates a spitzer tip bullet, but I suspect that a more gracile design that is tapered on both ends would result in lower drag. Given the fact that drag force is proportional to velocity squared, reducing drag is imperative.

I can join the party ridiculing Weber's handwavium. However; given these low mass projectiles, conventional mechanisms to absorb recoil would be effective. Remember; Weber's pulsar weapons do not produce propellant gases that at to the recoil.

One of the features to me is muzzle velocity and impact velocity. I suspect that people wouldn't go to the trouble to build these weapons of the velocity didn't exceed what is reasonably possible with chemical propellants. Think in terms of 2 kilometres per second minimum but 5 kilometres per second desirable.

Remember; the skies of sound in skull bone is 4 kilometres per second. A projectile that exceeds that velocity will induce explosive hydrodynamic shock effects.

cthia wrote: I don't know what mechanisms are used to launch projectiles in the HV.
--- snip ---
HV materials and techniques should allow ingenious applications of the laws of physics.

TFLYTSNBN wrote:I certainly hit the jackpot inspiring interesting replies.
By my reckoning, a pulsar rifle dart masses a maximum of about 5 grams or 75 grains. Pistol projectile might be a maximum only 25 grains. Weber postulates a spitzer tip bullet, but I suspect that a more gracile design that is tapered on both ends would result in lower drag. Given the fact that drag force is proportional to velocity squared, reducing drag is imperative.

I can join the party ridiculing Weber's handwavium. However; given these low mass projectiles, conventional mechanisms to absorb recoil would be effective. Remember; Weber's pulsar weapons do not produce propellant gases that at to the recoil.

One of the features to me is muzzle velocity and impact velocity. I suspect that people wouldn't go to the trouble to build these weapons of the velocity didn't exceed what is reasonably possible with chemical propellants. Think in terms of 2 kilometres per second minimum but 5 kilometres per second desirable.

Remember; the skies of sound in skull bone is 4 kilometres per second. A projectile that exceeds that velocity will induce explosive hydrodynamic shock effects.

So you are estimate that a pistol dart weighs about one sixth to one ninth of a 10mm bullet (between 10 grams and 15 grams), which gives it a bit more momentum and more than 8 times as much energy (hyper-velocity is about 8 times the speed of a bullet).

Expecting the dart to have the structural integrity to remain in one piece means that any hydrodynamic shock is the least of a target's worries.

@cthia: it would be best to stick to those lines, rather than trying to invent what mechanism would actually be used in the Honorverse.

cthia wrote:Akin to redirecting the spent exhaust created in an engine thru a turbocharger to derive more power. I don't know what mechanisms are used to launch projectiles in the HV. But the idea of blanks used in conjunction with harnessing some of the initial blowback seems viable. HV materials and techniques should allow ingenious applications of the laws of physics.

There's nothing to "hit" the user if the two forces are cancelling each other out. If today's engineering principles and materials could accomplish it, the plates would be dispersing simply compressed air!

The conservation of momentum mass and energy and rigid body dynamics using HV materials should astound 21st century man.

.

Guns today have a form of that. A muzzle brake redirects the propellant gasses rearward counteracting some portion of the recoil (and also not having so much of the pressurized gasses blowing forward out the end of the muzzle turning it into a low efficiency rocket which adds to the recoil force.

But even though those don't come close being enough force pushing the gun forward to perfectly balance the recoil forces pushing the gun backwards they can still create a dangerous high velocity exhaust near the end of the gun that can injure anybody or any body part foolish or unlucky enough to get in their way.
The danger zone for those on a combat rifle is pretty small - but it's a major issue with tank guns since the redirected gases fighting the recoil are dangerous for any friendly infantry near beside the front of the tank's gun - for up to several meters on each side. (Exactly where troops are likely to be if working with the tank in a built up or urban environment)

The forces perfectly canceling out simply means the recoil balancing force shoves the gun forward exactly as hard and the recoil pushes it backwards. The gun experiences no net movement (though it does feel a compressing force; but one it should be able to easily to built to handle).
But the only way Newton knows to produce a forward force on the gun is to expend an equal and opposite force on something thrown, pushed, or blown, rearward from the gun - where it's mass * acceleration is equal to the bullet's mass * acceleration. And anything headed backwards from the gun with the same energy as the bullet took forward is going to be hazardous for anything behind the gun that it hits or impinges (including the shooter).

And you can't launch that backwards and then catch it again before it hit the shooter because the act of catching whatever it is (another bullet, high pressure gas, etc) will impart a new force on the gun shoving it backwards at your again.

Now, like a muzzle brake, you might be able to use basically a pair of gas rocket engines, angled off to the sides, so the exhaust doesn't hit the shooter. But that really only works when the shooter is standing alone in an open space. Have a couple folks from your squad near each other, or have the gun near a wall or obstruction, and those exhaust gasses either hit your squad-mates or rebound into you.

tlb wrote:

Robert_A_Woodward wrote:People are forgetting that the "kick" is momentum (mass * velocity), while the energy is mass * velocity * velocity. If the pellet of weapon B is 1/4 the mass of the pellet of weapon A, while the velocity for B is twice that of A, then the energy for B would be equal to that of A, but the "kick" would be half as much.

tlb wrote:I remember introductory physics pretty well (I was a physics major in college), so I do not know what led you to make this comment. When comparing a 10mm chemically driven bullet to the dart of a pulser, the dart is traveling about 8 times faster and we do not know how the masses differ (so the dart would have to have one sixty-fourth the mass to have the same energy and one eighth the momentum).

Robert_A_Woodward wrote:I did so because people were inventing possible momentum dumps and overlooking the reasons to believe that the pulser darts are much smaller than a 10mm bullet. I have also found a passage where a pulser was pushing the person that was firing it (probably because the rate of fire smoothed out all the little kicks).

It would be very useful if you were to present that text. There are schemes that can reduce the felt recoil, many work by spreading the momentum transfer over a longer period of time with springs and sliding masses. There are Honorverse devices that seem to violate Newton's Laws and we have no way of knowing how much has been done with the pulser, which is why the text you mention is needed.

We have been given that the dimensions of a pulser rifle dart are 4x37mm and of a military pistol are 3x24mm. What we have not been given is the density of the dart. The great resizing if warship weights could give us a lower limit on the density (warships have cavities to allow use by people). The material used to build domes is stronger and lighter than our construction materials. The forces acting on a hyper-velocity dart would require both.

From chapter 30 of _The Honor of the Queen_:

“They clawed down the Masadans who'd lurked in ambush, and Yu stuck out a foot. His toes hooked under one of the ladder rungs before the recoil of his pulser could push him away from it, and his leg muscles dragged him in close against the wall.” (the context being the Masadan takeover of the "Saladin/Thunder of God")

Jonathan_S wrote:

cthia wrote:Akin to redirecting the spent exhaust created in an engine thru a turbocharger to derive more power. I don't know what mechanisms are used to launch projectiles in the HV. But the idea of blanks used in conjunction with harnessing some of the initial blowback seems viable. HV materials and techniques should allow ingenious applications of the laws of physics.

There's nothing to "hit" the user if the two forces are cancelling each other out. If today's engineering principles and materials could accomplish it, the plates would be dispersing simply compressed air!

The conservation of momentum mass and energy and rigid body dynamics using HV materials should astound 21st century man.

.

Guns today have a form of that. A muzzle brake redirects the propellant gasses rearward counteracting some portion of the recoil (and also not having so much of the pressurized gasses blowing forward out the end of the muzzle turning it into a low efficiency rocket which adds to the recoil force.

But even though those don't come close being enough force pushing the gun forward to perfectly balance the recoil forces pushing the gun backwards they can still create a dangerous high velocity exhaust near the end of the gun that can injure anybody or any body part foolish or unlucky enough to get in their way.
The danger zone for those on a combat rifle is pretty small - but it's a major issue with tank guns since the redirected gases fighting the recoil are dangerous for any friendly infantry near beside the front of the tank's gun - for up to several meters on each side. (Exactly where troops are likely to be if working with the tank in a built up or urban environment)

The forces perfectly canceling out simply means the recoil balancing force shoves the gun forward exactly as hard and the recoil pushes it backwards. The gun experiences no net movement (though it does feel a compressing force; but one it should be able to easily to built to handle).
But the only way Newton knows to produce a forward force on the gun is to expend an equal and opposite force on something thrown, pushed, or blown, rearward from the gun - where it's mass * acceleration is equal to the bullet's mass * acceleration. And anything headed backwards from the gun with the same energy as the bullet took forward is going to be hazardous for anything behind the gun that it hits or impinges (including the shooter).

And you can't launch that backwards and then catch it again before it hit the shooter because the act of catching whatever it is (another bullet, high pressure gas, etc) will impart a new force on the gun shoving it backwards at your again.

Now, like a muzzle brake, you might be able to use basically a pair of gas rocket engines, angled off to the sides, so the exhaust doesn't hit the shooter. But that really only works when the shooter is standing alone in an open space. Have a couple folks from your squad near each other, or have the gun near a wall or obstruction, and those exhaust gasses either hit your squad-mates or rebound into you.

This reminds me of the time that I shot an elk at 950 Meters with a .50 BMG rifle. I was using the bolt action Barrett loaded with 650 grain bullets. I had a laser range finder, but back then civilian versions were reliable out to only about 500 meters. I could use my scope reticle to estimate range, but that was dependant on assumptions about the dimensions of the elk both my teenaged "ammunition bearer" and I had estimated the range at about 1,000 meters. Given the fact that the elk would run in response to the first shot, it was advisable to aim high so as to encourage it to come closer.

We decided that my ammunition bearer would spot any misses to help me correct my point of aim. He knelt beside me with high magnification binoculars. My first shot was an obvious miss. The elk turned and started running downhill, towards us. I asked the kids where my shot hit. His response, "I don't know. The backblast from the muzzle brake knocked me over.". I really put my shoulder into the rifle for the second shot so I could spot my own miss. I then used the impact point in the scope reticle as my sim point. Third shot put the elk down.

Unfortunately; the elk was on a steep hillside with rimrocks in a deep canyon. My teenaged ammunition bearer and another teenager panicked. They thought that the elk was getting away. It was actually rolling downhill towards us and closet to a Jeep trail where we could load it up to haul it out. (I've actually dragged an full grown elk out by myself in one piece. Took me all day and into the night. Very unfun.). The two teenagers started shooting at the elk as it rolled down the hill and soared over a few small cliffs. Both kids knew how to take cycle a bolt action rifle. One of the kids had 20 rounds in a bandolier. He shot then all. His hit rate was impressive.

When we began dressing the elk, we found a neat. .50 caliber hole punched through is spine, right above its provide. I had been adding for the center of mass hoping to hit the heart and lungs. We found over a dozen other .30-06 and 7mm magnum holes in it. Actually found the bullets just on the inner side of the hide. Didn't get much meat out of it.

It sounds as though the only purpose of that story was to make fun of the teenagers that were hunting with you, otherwise it was a waste of meat and ammunition.

Back to the ballistics of a pulsar. When in OTL we can only get about 8 g for about 10 minutes, having a 5 MT SD accelerate indefinitely at 500 g, indicates that Honorverse physics is different, either intrinsically, by handwavium, or due to as yet undiscovered physics (similar time backwards had no electricity); then handling the recoil of a hand weapon is trifling in comparison.

tlb wrote:It sounds as though the only purpose of that story was to make fun of the teenagers that were hunting with you, otherwise it was a waste of meat and ammunition.

The story wasn't exactly complimentary to the teenagers, but they were on their first elk hunt.

It does serve the purpose of demonstrating what the difficulties of having some type of recoilless pulsar would be.

Fortunately; Weber's descriptions of pulsar weapons suggests that while they are hypervelocity weapons, they fire relatively low mass projectiles which keeps the recoil impulse within the realm of what is common for conventional firearms.

Anyone who shoots (as Weber dies) understands that the reciprocating mass of the slide (telescoped bolt) on a semiautomatic pistol reduces the felt recoil as compared to a revolver or bolt action pistol. Your can take this principle even further by having the entire barrel as well as the bolt and bolt carrier assembly reciprocate to absorb recoil. The Barrett semiautomatic, .50 caliber rifles use this type of system as well as a muzzle brake to reduce the recoil force on the shooter.

You could also utilize the counter recoil principle in which the bolt, bolt carrier and barrel assembly are restrained until firing then released to move forward under spring tension then the projectile is accelerated at nearly the full forward position. The momentum exchange stupid the forward travel of the bolt, bolt carrier and barrel assembly and pushes them back again. The are issues with maintaining accuracy.

All of this discussion ignores the reality that Honorverse Pulsar weapons are hypervelocity but the projector masses are very small plus there are no propellant gases to add to the recoil. As a result, they would probably be no more difficult to shoot than conventional firearms.

A major issue with Pulsar weapons would be areodynamic drag. Drag force is roughly proportional to velocity squared. (The drag coefficient varies with velocity). A closer approximation of that velocity decreases with distance as an exponential decay function. Think of it as analogous to respective decay but with a half distance rather than a half life. As an example, certain 12 gauge shotgun slugs will lose about half their kinetic energy during the first 100 meters of travel and half of their muzzle velocity within about 200 meters. However; they are still traveling at about 700 feet per second at 200 yards which will make them very lethal. More areodynamic projectiles with higher sectional densities of the type used by rifles have much longer half distances.

Honorverse Pulsar projectiles will trend to experience far more areodynamic drag because they are jupiter velocity. However; Weber describes the projectiles as long, slender days which have low cross sectional area and very low drag coefficient. I would expect a pulsar dart that has a muzzle velocity of say 5 kilometres per second to stop be doing along at about 2 kilometres per second at 1,000 meters.