Pulsar Ballistics

TFLYTSNBN wrote:
Projectile mass is important to achieve penetration, but it is the sectional density, not the mass, that combines with velocity to yield momentum density that dictates penetration.


Even at "only" 2,000 meters per second, those long, slender, Honorverse Pulsar darts have enough momentum density to penetrate a human torso from the top of the skull to the butt. In fact over penetration with minimal wounding from impacts at more normal aspects should be an issue. The only thing that makes these long, slender, hyper velocity pulsar days truly effective is the certainty that they will yaw upon impact. Weber mentions that pulsar days are son stabilized. I haven't calculated the skin rate needed to stabilize them, but it is extremely high. Imagine a 3mm x 25 mm dart yawing upon impact then tumbling at high rpm as it travels through a body like a buzz saw.

BTW, I'm one of the guys that writes the external ballistics programs that "gun experts" use to calculate trajectories as well as doing the internal ballistics calculations needed to determine what recipes are safe for hand reloading.

Writes ballistics programs? Cool.

Then why the apple and orange comparisons and bring up red herrings like cannons into small arms discussions? Or rifles when pistols were the topic? You should know better than anyone that those are 3 completely different worlds and things don't scale up or down reliably in the firearms world.

I get the metric system use. I figure you are either not American or one of the science types that refuse to use the mundane, everyday system of measure (because, let's face reality, the only thing metric Americans deal with in everyday life is the 2 liter soft drink bottle) because you think metric is superior. For precision science use, it probably is, but most Americans still convert it in their head on the fly.

And what have I said that was inaccurate?

At that light a weight and well over 6000fps,the projectile is relying on the hydrostatic pressure of the passage of the projectile through the target for damage. The primary wound channel- the hole- is tiny and survivable unless it pierces something vital. A standard audio jack for earbuds or headphones is 3.5mm. That size hole isn't debilitating unless precisely placed. A 3mm projectile of that weight and at that velocity relies on the sudden transfer of energy into the target as it sheds velocity from the resistance of its' passage through the target.

For those I just lost, imagine a meteor strike in an ocean and the tsunami effect it causes. Now, scale it down to a 3mm meteor and make the ocean a human body that is mostly water.

The shock waves caused by the disturbance of the semi liquid medium (aka 'the body') by the sudden passage of the projectile will ripple out from the path of the projectile (the primary wound channel) causing massive damage. The secondary wound channel (think of it as the bruise around the actual hole) is going to be massive and immediately debilitating.

I've never had a issue with the whole exploding torso or head thing for that reason. Dump that kind of energy that fast into a human and things are going to fly apart and splatter the whole room.

Daryl wrote:More than a decade ago my team was testing bullet proof vests for use in Army helicopter crews. One interesting point we discovered was that the same 5.56 mm or 0.223 military round would penetrate one brand if fired from a Steyr AUG, but not if fired from a M16. Turned out to be that the Steyr had tighter rifling which precluded tumbling when it hit the kevlar.
For comparison I took my 30.06 along. Didn't tell them that I was using black tip AP. Went through the front, through the optional ceramic plate, through the plasticine torso, out the rear and kept going.

I think that I'd have an issue with that.

Chopper door gunners are going to face GPMG's and they are .30-'06 class- either 7.62x51 or 7.62x54 and it's not like AP is rare for either round. In some parts of the world old 7.92x57 Mauser LMG's and Brens from WWII are still possible, too.

Daryl wrote:More than a decade ago my team was testing bullet proof vests for use in Army helicopter crews. One interesting point we discovered was that the same 5.56 mm or 0.223 military round would penetrate one brand if fired from a Steyr AUG, but not if fired from a M16. Turned out to be that the Steyr had tighter rifling which precluded tumbling when it hit the kevlar.
For comparison I took my 30.06 along. Didn't tell them that I was using black tip AP. Went through the front, through the optional ceramic plate, through the plasticine torso, out the rear and kept going.

Not at all surprising. A lot of World War 2 veterans were dismayed when the M-1 Garand was replaced by the M-14 because the chambering why from 30-06 to .308. sand diameter bullet, but shorter cartridge cases with less powder.

You would be amazed at the sophisticated metallurgy and hear treating that is applied to the depleted Uranium sabot rounds for the Abrahms tank. Pure Uranium had some awesome physical properties but alloying with a bit of Tungsten and other metals can make it even tougher. You have to keep it from bending or breaking while also allowing the aluminum ballistic tip top shear off to expose the blunt end of the penatrator.

There were some improvements in powder between 1914 and 1955.

kzt wrote:There were some improvements in powder between 1914 and 1955.

Not as much as you'd think based on the period from 1855 to 1914. No major leaps forward but a lot of refinement of what had already existed.

There's a difference on paper and at extreme range between the 7.62x51 and the .30-'06 but not much that shows up anywhere else except one's a requires a long action and the other is shorter. Common bore diameter, common bullet weights (standard ball rounds were 150gr(M2 Ball)- for the '06 in the Garand and 147gr(M80 Ball)- in the M14- that's within the normal variance on mass produced bullets), same rim diameter and thickness,...

The 7.62x51 was developed because the US military wanted to have it's cake and eat it, too. They wanted a detachable box magazine rifle but they wanted to keep the '06, too, so a short action near-clone of the '06 was born. They pretty much shoved it down NATO's throats in spite of a rather nice intermediate round the British were developing that would have been much more suitable for a select fire, general issue rifle.

Heavens knows that the M14 isn't controllable on select fire by any stretch of the imagination. After the third round, you might as well be bird hunting because from shot #4 and on through the burst is headed for the sky. Yeah, the BAR in .30-'06 is controllable but it's also twice the weight AND has a lower cyclic rate of either 550 or 350 rounds per minute.

TFLYTSNBN wrote:Not at all surprising. A lot of World War 2 veterans were dismayed when the M-1 Garand was replaced by the M-14 because the chambering why from 30-06 to .308. sand diameter bullet, but shorter cartridge cases with less powder.

Not less powder per say, more a different round altogether that mimics the longer .30-'06. Different case, different internal dimensions, different pressure vessel normally means a variation in powder selection or charge weight.

More powder and less powder went out with the advent of smokeless. Even then, I can get you 150-200fps of variance by just changing grades or manufacturers of black powder and keeping the exact same powder charge and compression.

Since you are in ballistics, pull up load data on both cartridges using the same bullet or bullet weight and you'll see that the external ballistic characteristics are extremely similar out to about 800 yards. Even close enough for government work will do. Say the US 150gr .30M2Ball of WW2 fame for the '06 and the popular 147gr M80 Ball for the 7.62x51 and look at their performance.

If you really want to look into something interesting, try the link below. It's a short article written about testing BP buffalo gun rounds using equipment at Yuma Proving Ground.

http://powderburns.tripod.com/sharps.html

jtg452 wrote:

TFLYTSNBN wrote:Not at all surprising. A lot of World War 2 veterans were dismayed when the M-1 Garand was replaced by the M-14 because the chambering why from 30-06 to .308. sand diameter bullet, but shorter cartridge cases with less powder.

Not less powder per say, more a different round altogether that mimics the longer .30-'06. Different case, different internal dimensions, different pressure vessel normally means a variation in powder selection or charge weight.

More powder and less powder went out with the advent of smokeless. Even then, I can get you 150-200fps of variance by just changing grades or manufacturers of black powder and keeping the exact same powder charge and compression.

Since you are in ballistics, pull up load data on both cartridges using the same bullet or bullet weight and you'll see that the external ballistic characteristics are extremely similar out to about 800 yards. Even close enough for government work will do. Say the US 150gr .30M2Ball of WW2 fame for the '06 and the popular 147gr M80 Ball for the 7.62x51 and look at their performance.

If you really want to look into something interesting, try the link below. It's a short article written about testing BP buffalo gun rounds using equipment at Yuma Proving Ground.

http://powderburns.tripod.com/sharps.html

Great story!

What was that scientist thinking? In the absence of areodynamic drag, the maximum range of a projectile launched at 400 meters per second is 16,000 meters! Areodynamic drag obviously reduces the maximum range considerably. I suspect that this scientist had never heard of Jornees' formulae for approxiating the maximum range of projectiles. The range can be estimated by multiplying the caliber of a spherical Lead projectile in inches by 2,200 yards. If you make adjustments for projectile shape, sectional density, and drag coefficient, Jornees'formulae is reasonably secure for everything from BB guns to battleship guns.

If this scientist had actually attempted to derive the equations of motion, he would have known that the velocity and energy of a projectile traveling through a has decreases with distance. This decrease is an exponential decay function that is complicated by the fact that drag coefficient varies with velocity. Trying to increase range by increasing velocity is in most cases less effective than increasing projectile mass and reducing drag coefficient. I offer as an exhibit for your consideration the heavy weight projectile for the 16" guns on Iowa class battleships. The muzzle velocity was impressive compared to the 15" guns on the Bismarck, but the range was greater and the impact vehicle at long range was much greater.

If this scientists had wanted an easy education on long range shooting, he should have watched the movie Quigley Down Under. The shooting scenes were spectacular. The plot of the evil British hiring an American to exterminate the aborigines pleased me. Of course I also enjoyed looking at Crazy Cora's Cleavage.

TFLYTSNBN wrote:
Great story!

What was that scientist thinking? In the absence of areodynamic drag, the maximum range of a projectile launched at 400 meters per second is 16,000 meters! Areodynamic drag obviously reduces the maximum range considerably. I suspect that this scientist had never heard of Jornees' formulae for approxiating the maximum range of projectiles. The range can be estimated by multiplying the caliber of a spherical Lead projectile in inches by 2,200 yards. If you make adjustments for projectile shape, sectional density, and drag coefficient, Jornees'formulae is reasonably secure for everything from BB guns to battleship guns.

If this scientist had actually attempted to derive the equations of motion, he would have known that the velocity and energy of a projectile traveling through a has decreases with distance. This decrease is an exponential decay function that is complicated by the fact that drag coefficient varies with velocity. Trying to increase range by increasing velocity is in most cases less effective than increasing projectile mass and reducing drag coefficient. I offer as an exhibit for your consideration the heavy weight projectile for the 16" guns on Iowa class battleships. The muzzle velocity was impressive compared to the 15" guns on the Bismarck, but the range was greater and the impact vehicle at long range was much greater.

If this scientists had wanted an easy education on long range shooting, he should have watched the movie Quigley Down Under. The shooting scenes were spectacular. The plot of the evil British hiring an American to exterminate the aborigines pleased me. Of course I also enjoyed looking at Crazy Cora's Cleavage.

The civilians involved were the owners of the company that made Selleck's rifles for the movie, their shop foreman and the guy that taught Tom how to run a Sharps.

The bullets aren't spherical. They are cylindrical with a rounded end and about half the length of your index finger.

jtg452 wrote:

TFLYTSNBN wrote:
Great story!

What was that scientist thinking? In the absence of areodynamic drag, the maximum range of a projectile launched at 400 meters per second is 16,000 meters! Areodynamic drag obviously reduces the maximum range considerably. I suspect that this scientist had never heard of Jornees' formulae for approxiating the maximum range of projectiles. The range can be estimated by multiplying the caliber of a spherical Lead projectile in inches by 2,200 yards. If you make adjustments for projectile shape, sectional density, and drag coefficient, Jornees'formulae is reasonably secure for everything from BB guns to battleship guns.

If this scientist had actually attempted to derive the equations of motion, he would have known that the velocity and energy of a projectile traveling through a has decreases with distance. This decrease is an exponential decay function that is complicated by the fact that drag coefficient varies with velocity. Trying to increase range by increasing velocity is in most cases less effective than increasing projectile mass and reducing drag coefficient. I offer as an exhibit for your consideration the heavy weight projectile for the 16" guns on Iowa class battleships. The muzzle velocity was impressive compared to the 15" guns on the Bismarck, but the range was greater and the impact vehicle at long range was much greater.

If this scientists had wanted an easy education on long range shooting, he should have watched the movie Quigley Down Under. The shooting scenes were spectacular. The plot of the evil British hiring an American to exterminate the aborigines pleased me. Of course I also enjoyed looking at Crazy Cora's Cleavage.

The civilians involved were the owners of the company that made Selleck's rifles for the movie, their shop foreman and the guy that taught Tom how to run a Sharps.

The bullets aren't spherical. They are cylindrical with a rounded end and about half the length of your index finger.

Agreed. However; if you calculate the ballistic coefficient for a bullet from a Sharps rifle then calculate the diameter of a spherical projectile with the same ballistic coefficient, Journees' formula will estimate the maximum range with reasonable accuracy.

The interesting thing to me was that the Dixon shot at Adobe Walls was possible with the factory barrel sights.

The use of tang sights for extended range or precision shooting- like Selleck portrayed in Quigly Down Under- was a common bit of personalization. The fact that it was extremely possible to reach that sort of range with the standard rear sight is what impressed me.

-A bit of historical back story to put it into context-

Billy Dixon had the reputation of being one of the best shots on the buffalo plains among his own peers- professional hunters that made their living shooting big animals.

As the hunting parties (hunters shot, and their assistants skinned and transported the hides in wagons, so for every shooter there would be 4-6 more in the party) retreated to an outpost some merchants from Dodge had put together at the abandoned Adobe Walls site, Dixon lost his personal Sharps (chambered in .44-77- a cartridge known for having good accuracy) during a river crossing just a day or two before the attack.

The rifle he used during the fight was a 'loaner' from the stocks of one of the merchants from Dodge. According to what I've read, it was a standard 1874 Sharps "Business Rifle" in .50-90. Since it was a new, unsold rifle, it would have been bone stock without any extras like a Vernier or Soule tang rear sight.

On the other hand, legend has it that the Indian on the horse also had the misfortune to be sitting right in the middle of the hunter's impromptu rifle range.

Shooters shoot and you aren't going to get 2 or more together for long before some sort of shooting contest starts. Especially when you have money burning a hole in your pocket (the Dodge City merchants were there to buy hides and sell supplies) and, maybe, have partaken in a bottle or two of liquor and a meal that wasn't salt pork and beans cooked over an open fire.

There's also a problem with the distance of the shot. The claims have ranged from 800 yards all the way out to the 1500+ yards that Dixon's wife had put into the biography that she had written and published after his death. The 1400 yard number Venturino mentions is based on a US Army survey party that arrived at the Walls long after the battle and the merchants and hunters had vacated the premises for the safety of Dodge City.

Either way, Dixon himself never claimed to have made the shot. He admitted that he fired at the Indian in question but also said that several others were shooting, too. When hemmed up on the issue, he would say that he didn't know if he was the one that hit him, but, if he was, then it was a 'scratch shot' or just luck.