Not sure where else to post this. Anywho, I'm working on a weapon for a game I plan on running here in a few months, set in the modern day/near future.
I'm not immediately concerned with game mechanics, although that what I'm working towards here... hopefully there are some smart people around who can at least give me some ideas here.
What would you guys suppose the raw destructive power of a 1kg Iridium slug traveling at 1000m/second to be?
What would you guys suppose the raw destructive power of a 1kg Iridium slug traveling at 1000m/second to be?
Depends on the shape of the projectile and the vulnerability of the target...
The faster the projectile, the higher the mass and the denser its material, the more chances that it will penetrate whatever target clean and through-and-through.
On a human being, a bullet that goes through-and-through is likely to cause less damage that a softer, slower bullet that does a lot of internal damage by decelerating and "squishing" inside the body. Yet, slower and softer projectiles have shorter range and are easier to block/deflect.
The science behind it all is to find the right balance against the right target.
Now, translate that in RPG terms and it makes no sense whatsoever...
You are not fast enough to be in relativistic land, so the mass is still effectively 1KG.
Total energy is 500 kJ. That is the same energy as a 1000 kg boulder falling 50 meters.
The spell compendium has a spell called cometfall, if drops a comet from 5ft/level. I believe the damage is 2d6 per 10 feet, so . I don't think the mass of the comet is around 400 lbs which is roughly 200 kg. That much kinetic energy translates to a drop of 750 feet which is 150d6.
So we are dealing with a much smaller object, that reduces the Area of Effect and greatly reduces the debris.
A direct hit would be 150d6, being in the the square where the slug hit the ground would probably be around 60d6. Everyone within 60 feet gets hit with 15d6 blast damage minus 1d6 for every 5ft, and gets bull rushed 1d20 + 15 - 1 per 5 ft.
Are you using a thor's hammer on your poor players?
What would you guys suppose the raw destructive power of a 1kg Iridium slug traveling at 1000m/second to be?Depends on the shape of the projectile and the vulnerability of the target...
The faster the projectile, the higher the mass and the denser its material, the more chances that it will penetrate whatever target clean and through-and-through.
On a human being, a bullet that goes through-and-through is likely to cause less damage that a softer, slower bullet that does a lot of internal damage by decelerating and "squishing" inside the body. Yet, slower and softer projectiles have shorter range and are easier to block/deflect.
The science behind it all is to find the right balance against the right target.
Now, translate that in RPG terms and it makes no sense whatsoever...
We are talking about a 1 KG slug, not a bullet. That is roughly 2.2 pounds of metal. No matter where that hit you it is going to do a lot of damage.
We are talking about a 1 KG slug
True enough. Whatever human part that is hit is probably gone, with appropriate consequences.
True enough. Whatever human part that is hit is simply gone.
We are talking about a 1 KG slug
And likely a lot of severe damage to the tissue around the part that was very violently ripped away.
Good points, if nothing else as a rule of thumb check the momentum. As said above your not relativistic, so that equation is easy. Then convert to force and that'll give you a rough idea.
Isn't the formula (Kg*M^2)/s^2?Total energy is 500 kJ. That is the same energy as a 1000 kg boulder falling 50 meters.
KE = 1/2 * m * v^2
Gravity PE = mgh
*nods thoughtfully* Thanks guys, thats what I was looking for. The weapon is an item of power that may be available to the players later on. I'm using a mashup of PFRPG and D20 Silver Age Sentinels, with some Rifts-like magic and technology flying around. The weapon is a "gun" for lack of a better term, forged by Hephaestus that generates its own "starmetal" ammunition. I've got a few other items of similar ilk, it seemed a good example.
I think I'm going to use a multiplier for the more advanced or bigger weapons, similar to how Star Wars does capital ship weapons. This thing here would be something on the order of 2d6+10 x 5 or some such I think. I'm guessing not much of an area of effect, but it would make large holes in buildings and whatnot, and could probably kill an Abrams in a couple of shots.
I know against a soft target just the air pressure from the round passing will cause significant damage if not outright kill you.
*nods thoughtfully* Thanks guys, thats what I was looking for. The weapon is an item of power that may be available to the players later on. I'm using a mashup of PFRPG and D20 Silver Age Sentinels, with some Rifts-like magic and technology flying around. The weapon is a "gun" for lack of a better term, forged by Hephaestus that generates its own "starmetal" ammunition. I've got a few other items of similar ilk, it seemed a good example.
I think I'm going to use a multiplier for the more advanced or bigger weapons, similar to how Star Wars does capital ship weapons. This thing here would be something on the order of 2d6+10 x 5 or some such I think. I'm guessing not much of an area of effect, but it would make large holes in buildings and whatnot, and could probably kill an Abrams in a couple of shots.
I know against a soft target just the air pressure from the round passing will cause significant damage if not outright kill you.
It would punch through an abrams if it hit square on, but tank armor is designed to make square on hits hard. Most things hit at an angle and glance off.
My AoE example was for it come straight down into the ground. The impact would send debris flying around. Of course the level of debris would depend on what the impact was on. If it landed in a dirt field it would sink in deeper and thus generate less debris and AoE than if it hit concrete or came down through the top of a building.
Instead of theory (formulas) and what not look at the real thing to determine the kill zone, and the injury zone, then it is an area of effect.....
That flying "debris" is not debris it is shrapnel....
Techinical point. Shrapnel is from pieces of the projectile flying away from the point of impact, usually because the projectile had explosives inside it(see fragmentation munitions). This damage is more from chunks of concrete and other stuff that are throw up by the impact. I called it debris because it is not intentional fragmentation.
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*nods thoughtfully* Thanks guys, thats what I was looking for. The weapon is an item of power that may be available to the players later on. I'm using a mashup of PFRPG and D20 Silver Age Sentinels, with some Rifts-like magic and technology flying around. The weapon is a "gun" for lack of a better term, forged by Hephaestus that generates its own "starmetal" ammunition. I've got a few other items of similar ilk, it seemed a good example.
I think I'm going to use a multiplier for the more advanced or bigger weapons, similar to how Star Wars does capital ship weapons. This thing here would be something on the order of 2d6+10 x 5 or some such I think. I'm guessing not much of an area of effect, but it would make large holes in buildings and whatnot, and could probably kill an Abrams in a couple of shots.
I know against a soft target just the air pressure from the round passing will cause significant damage if not outright kill you.
This sounds to me like DU (depleted uranium) rounds. A 20mm DU round will go clean through a tank and create a vacuum strong enought to rip the skin off of any critters inside said tank. A nasty bit o hardware that would leave most, if not all, creatures in its wake dead if not dismembered.
Is there a difference between kenetic energy and joules?
Kinetic energy is measured in joules, and the formula for kinetic energy is indeed 1/2 * mass * velocity squared.
The entry for kinetic energy on Wikipedia should clarify the derivation that's got you confused.
Even more fun Orders of magnitude for energy is here
"3.28×10^3 J, the kinetic energy of a 9.33 g NATO rifle cartridge fired at 838 m/s"
So a standard bullet is 3 kJ. We are talking about a projectile that has about 150 times that amount of kinetic energy.
FYI, one megajouls is the equivelant of 1/2 lb of TNT. If Charender's calculation is correct, that's only 1/4 lb of TNT. Consider how little that really is.
An M80 firecracker=about 1/4 stick dynamite..
what is the density of Iridium? does that have any effect on the damage it would inflict? Physics is one of the classes I need to take, but have never taken...I WANT to take it even.
I mean if it's only 1mm across instead of 1 inch across that should impact the game damage wouldn't you think? Perhaps causing damage to multiple targets linearly, as it doesn't slow, kind of like a unstoppable line of disintegration
FYI, one megajouls is the equivelant of 1/2 lb of TNT. If Charender's calculation is correct, that's only 1/4 lb of TNT. Consider how little that really is.An M80 firecracker=about 1/4 stick dynamite..
what is the density of Iridium? does that have any effect on the damage it would inflict? Physics is one of the classes I need to take, but have never taken...I WANT to take it even.
I mean if it's only 1mm across instead of 1 inch across that should impact the game damage wouldn't you think? Perhaps causing damage to multiple targets linearly, as it doesn't slow, kind of like a unstoppable line of disintegration
Actually in the case of a soft target, the higher density works against you. High density == smaller projectile == smaller area hit.
If you were trying to take out a tank you want high density to penetrate armor, but when you hit something soft it destroys the small area it hits and leaves everything else intact.
A truck moving at 100 MPH is a lot deadlier than a bullet moving at ~1600 MPH, because the truck does damage to the person entire body, where the bullet only hits a small area.
It is shotgun vs rifle. The shotgun is much deadlier, because it spreads the damage over a larger area, but if they are behind soft cover or have body armor, you want the rifle for the penetrating power. A low density projectile acts more like a shotgun while a high density projectile would be more focused like a rifle.
Density just tells us how little or big the bullet is. This in turn will tell us how spread out the point of impact is, and therefore how much area the force is distributed over.
Iridium is really dense, consequently smaller bullets (for 1kg, hence the choice of metal), consequently smaller area of impact. It's pretty academic to think of the strict striking area of damage between different types of slugs - they're all pretty small.
A better experiment is to consider this in terms of real-world firepower. Gun experts will tell you a .22 is dangerous but lacks stopping power, a .357 is potent, and a .50 really knocks people around. The actual projectile from a .50 cal is somewhere around 25 grams of metal, so... 1/40th of a kg or so.
The 'average' fired 120mm projectile weighs 6-10 kg, and has a muzzle velocity of 1500+ m/s. So actually, the item we're discussing here is substantially less powerful than a solid shell from an M1A1 - 1/20th the power of such a shot at the upper end, but still 40x the energy of a heavier pistol.
Obviously it's still more than enough to blow away your average PC, or put holes in buildings, but I'd say it's hardly the "obliterate a city block" kind of blow suggested by some.
*ponders* I was going for output about on par with the main gun of an Abrams, need to do some more homework it looks like. Probably need to up the muzzle velocity, and maybe the round size. Thanks a lot for everyone's input.
Well something you may want to look at, a .50 cal round fired from a the M82 weighs .041kg and travels at 853 m/s (wikipedia is your friend). So somewhere around 14.916 KJ.
The object in question is about 33.5 times as destructive (has 33.5 times the energy) as a round from a M82 sniper rifle. Given that round removes limbs and punches through steel, I think we are talking a significant amount of damage here. D20 modern defined an unmodified .50cal sniper rifle as 2d12. 67d12 is pretty close to 'all the dice' i think.
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RPG Superstar 2015 Top 16, RPG Superstar 2013 Top 16
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I know against a soft target just the air pressure from the round passing will cause significant damage if not outright kill you.
Ayep. A near miss from a .50 cal can still kill a guy this way.
As a ballpark, the weapon you describe would probably be about as powerful as a single 30mm armor-piercing round from a GAU-8/A Avenger. Against a human target, you'd need a magnifying glass and a spatula to collect the remains. Against buildings and vehicles, it will poke big holes and have enough energy remaining to carry through and keep poking holes for a long distance. It would FUBAR the engine block of a car. It will be able to penetrate probably even the heaviest of vehicular armor. What a solid slug like that will NOT do is give you a big Hollywood fiery explosion. I'm no chemist, but Wikipedia says that iridium is very hard and brittle. I'd guess that there would be very little fragmentation from the projectile itself, although there'd be a little from whatever it hit. It'd be great for hole-poking, but not great for wrecking a big area.
EDIT:
so, is 1kg of Iridium 20mm? or only 5.57mm?
I think I'm probably going to up the mass of the rounds to 5 kilos ( I "think" that would make it about the size of a standard 20mm round or thereabouts, considering how dense Iridium is), and increase the muzzle velocity to 2000m/s. That should put it closer to the damage of an Abrams main gun. It will probably have superior penetration due to the smaller round and higher density and velocity, less explodey though. I'd imagine it'd punch through a couple of concrete walls without even noticing.
so, is 1kg of Iridium 20mm? or only 5.57mm?
I'm not 100% sure, thats one of the issues I've been having. I picture the rounds about 3cm in bore, and about 7cm long. I'm not sure how much Iridium that would actually be though.
I know its the densest naturally occurring element (that we know of)at 22.560(g/cm³).
I know against a soft target just the air pressure from the round passing will cause significant damage if not outright kill you.Ayep. A near miss from a .50 cal can still kill a guy this way.
As a ballpark, the weapon you describe would probably be about as powerful as a single 30mm armor-piercing round from a GAU-8/A Avenger. Against a human target, you'd need a magnifying glass and a spatula to collect the remains. Against buildings and vehicles, it will poke big holes and have enough energy remaining to carry through and keep poking holes for a long distance. It would FUBAR the engine block of a car. It will be able to penetrate probably even the heaviest of vehicular armor. What a solid slug like that will NOT do is give you a big Hollywood fiery explosion. I'm no chemist, but Wikipedia says that iridium is very hard and brittle. I'd guess that there would be very little fragmentation from the projectile itself, although there'd be a little from whatever it hit. It'd be great for hole-poking, but not great for wrecking a big area.
EDIT: ** spoiler omitted **
The "explosion" would depend heavily on the shape of the projectile and what it hit. If the projectile was a long thin rod, it would punch through a concrete bunkers with ease. If the projectile was made wide and flat it would be less likely to punch through and more likely to shatter on impact.
so, is 1kg of Iridium 20mm? or only 5.57mm?
I'm not 100% sure, thats one of the issues I've been having. I picture the rounds about 3cm in bore, and about 7cm long. I'm not sure how much Iridium that would actually be though.
I know its the densest naturally occurring element (that we know of)at 22.560(g/cm³).
3cm bore is 1.5 cm radius. 1.5 * 1.5 * 7 * 3.1415 = 49.48 if it is a cylinder lets say 50 cubic cm.
That gives you a weight of 1.13 kg.
With a shape like that, it would be very likely to punch though anything it hits. I would make it attack as a ranged incorporeal attack as any normal armor would provide no protection. Force effects like shield or mage armor might give some protection, but that is up to you.
so, is 1kg of Iridium 20mm? or only 5.57mm?
I'm not 100% sure, thats one of the issues I've been having. I picture the rounds about 3cm in bore, and about 7cm long. I'm not sure how much Iridium that would actually be though.
I know its the densest naturally occurring element (that we know of)at 22.560(g/cm³).
3cm bore is 1.5 cm radius. 1.5*1.5*7.3.1415 = 49.48 if it is a cylinder lets say 50 cubic cm.
That gives you a weight of 1.13 kg.
With a shape like that, it would be very likely to punch though anything it hits. I would make it attack as a ranged incorporeal attack as any normal armor would provide no protection. Force effects like shield or mage armor might give some protection, but that is up to you.
Now take that round and cap it with a titanium cap, but split the iridium into hundreds of curved wedges that aren't straight, it hits the target, then penetrates the titanium cap which causes the wedges to fan and spin...shredding everything in huge cone...
Kind of like a penetrator round, but deadlier
so, is 1kg of Iridium 20mm? or only 5.57mm?
I'm not 100% sure, thats one of the issues I've been having. I picture the rounds about 3cm in bore, and about 7cm long. I'm not sure how much Iridium that would actually be though.
I know its the densest naturally occurring element (that we know of)at 22.560(g/cm³).
3cm bore is 1.5 cm radius. 1.5*1.5*7.3.1415 = 49.48 if it is a cylinder lets say 50 cubic cm.
That gives you a weight of 1.13 kg.
With a shape like that, it would be very likely to punch though anything it hits. I would make it attack as a ranged incorporeal attack as any normal armor would provide no protection. Force effects like shield or mage armor might give some protection, but that is up to you.
Now take that round and cap it with a titanium cap, but split the iridium into hundreds of curved wedges that aren't straight, it hits the target, then penetrates the titanium cap which causes the wedges to fan and spin...shredding everything in huge cone...
Kind of like a penetrator round, but deadlier
Ew, a tank shell sized frag round.
Even better, since this is a fusion of magic and technology, instead of a titanium cap, add a trigger spell that allows the user to make the round fragment at a certain distance. Now you don't need a point of impact to trigger the round, you set it to frag at a certain distance.
Creates a cone effect from the point of origin. Does 100d6 to anything within 5 feet of the frag point. Damage goes does by 5d6 ever 5 feet as the cone spreads. Reflex save for half.
I'd just like to say it warms my heart to see a bunch of math geeks getting together to figure out how to blow things up with D&D rules.
Even better, since this is a fusion of magic and technology, instead of a titanium cap, add a trigger spell that allows the user to make the round fragment at a certain distance. Now you don't need a point of impact to trigger the round, you set it to frag at a certain distance.
Creates a cone effect from the point of origin. Does 100d6 to anything within 5 feet of the frag point. Damage goes does by 5d6 ever 5 feet as the cone spreads. Reflex save for half.
The magic version of a proximity fuse.
Long, long ago, I worked at Aberdeen Proving Grounds when the M-1 was still the XM-1. We used tungsten penetrator rods for most testing, as the depleted uranium rods had special handling requirements. Against most unarmored targets (and by unarmored, I mean anything with less than tank level armor) you wouldn't use the APFSDS (armor piercing fin stabilized discarding sabot), you'd use HEAT (high explosive anti-tank). If you had been expecting to engage soft targets, you might have brought along plain old high explosive fragmentation rounds but that's usually the artillery's job.
Because, as has been said above, you shoot APFSDS at a truck, you might go right through without actually blowing the truck up if you hit it in the cargo box while it's carrying MREs.
I know against a soft target just the air pressure from the round passing will cause significant damage if not outright kill you.Ayep. A near miss from a .50 cal can still kill a guy this way.
As a ballpark, the weapon you describe would probably be about as powerful as a single 30mm armor-piercing round from a GAU-8/A Avenger. Against a human target, you'd need a magnifying glass and a spatula to collect the remains. Against buildings and vehicles, it will poke big holes and have enough energy remaining to carry through and keep poking holes for a long distance. It would FUBAR the engine block of a car. It will be able to penetrate probably even the heaviest of vehicular armor. What a solid slug like that will NOT do is give you a big Hollywood fiery explosion. I'm no chemist, but Wikipedia says that iridium is very hard and brittle. I'd guess that there would be very little fragmentation from the projectile itself, although there'd be a little from whatever it hit. It'd be great for hole-poking, but not great for wrecking a big area.
EDIT: ** spoiler omitted **
But according to Mythbusters, it can't break glass. I know the human body is fragile and sympathetic vibrations can cause damage, but I'd like to see an actual case of this happening, considering they fired the rounds within inches of glass and the glass didn't even move. The air pressure from such a fast projectile would spread out in a wave, but it has no real surface area. Therefore, since this is a sniper rifle round and it is designed to travel far, I posit that the effect on the air surrounding the path of the bullet would be insignificant. If you had an F-14 fly past you now, yes I'm fairly sure you would sustain some injury to your outer layers of muscle and tissue.
30 years since my last physics class, but I have more recent exp. with an air brush. Prolonged exposure to high pressure air will raise a blister within a scarily few seconds. I still have a mark from this stupidity. My brush was capable of up to the 200 psi range and though I never set it near that high, it could still create an 'air' burn from mere friction. Take a can of compressed air for cleaning your computer and put it on a set spot on your skin and empty the can if you want to see what I mean. Air is capable move sailing ships of hundreds of tons and the buoyancy of simple air can create a bubble that will part the deepest sea. As humans are fundamentally bags of volatile liquids, enclosed in fragile membranes, they cannot be compared to glass, a solid that acts as a fluid in many ways.
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RPG Superstar 2015 Top 16, RPG Superstar 2013 Top 16
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But according to Mythbusters, it can't break glass. I know the human body is fragile and sympathetic vibrations can cause damage, but I'd like to see an actual case of this happening, considering they fired the rounds within inches of glass and the glass didn't even move. The air pressure from such a fast projectile would spread out in a wave, but it has no real surface area. Therefore, since this is a sniper rifle round and it is designed to travel far, I posit that the effect on the air surrounding the path of the bullet would be insignificant. If you had an F-14 fly past you now, yes I'm fairly sure you would sustain some injury to your outer layers of muscle and tissue.
Admittedly, my experience with .50 cal rounds is anecdotal. I haven't set up, say, a near miss of a block of ballistic gelatin with a .50 cal round. You're not likely to see an actual case of this happening indisputably, because whether the round impacts the target, destroying it, or near misses, destroying it, it's hard to tell from behind the sights. And while it is used in antimateriel sniper rifles such as the infamous Barrett, it's primarily a heavy machine gun round.
Not sure where else to post this. Anywho, I'm working on a weapon for a game I plan on running here in a few months, set in the modern day/near future.
I'm not immediately concerned with game mechanics, although that what I'm working towards here... hopefully there are some smart people around who can at least give me some ideas here.
What would you guys suppose the raw destructive power of a 1kg Iridium slug traveling at 1000m/second to be?
That's one megajoule of energy there, for something travelling at Mach 3. It's not going to be as much as a sabot round from a 120mm tank gun, I would guess (ball-park figure) about the same as round from a 30mm anti-tank gun, such as on the A10 tank destroyer.
Edit: no it's way more than that, a 30mm cannon has 155232 joules, or .15 megajoules. It's less than a full scale 120mm sabot round, but more by far than a 30mm chain gun or Aden cannon.
I'd just like to say it warms my heart to see a bunch of math geeks getting together to figure out how to blow things up with D&D rules.Math is a bit player in a question like this - mainly because there are so many data points (from shape, composition, and angle of the target to range, barrel length, and skill of the shooter) that this kind of problem doesn't break down into math. If you want to know how much force such a bullet would hit with in a vacuum given a certain propellant, that's fairly easy. If you want to know how much damage it does, that's a completely different animal.
Oh, I know the results are hardly going to be completely scientific. I'm just delighted by the community applying various bits and pieces of physics and weaponry knowledge in a collective attempt to answer the question "What would that hit look like in-game?"
So wonderfully geeky.
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Well, destructive power of a 1kg anything is nasty.
a colt 45 caliber bullet can kill a man but he might survive...
1 50 caliber rifle bullet is going to kill a man or remove the body part hit, probably won't survive...
These are in the FRACTIONS of a KG here...
simple answer for a 1 kg projectile... if a man is hit... he's dead.
I'd first like to say that this is an awesome thread so far. I love talk about applying D&D d20 stuff to real life physics.
30 years since my last physics class, but I have more recent exp. with an air brush. Prolonged exposure to high pressure air will raise a blister within a scarily few seconds. I still have a mark from this stupidity. My brush was capable of up to the 200 psi range and though I never set it near that high, it could still create an 'air' burn from mere friction. Take a can of compressed air for cleaning your computer and put it on a set spot on your skin and empty the can if you want to see what I mean. Air is capable move sailing ships of hundreds of tons and the buoyancy of simple air can create a bubble that will part the deepest sea. As humans are fundamentally bags of volatile liquids, enclosed in fragile membranes, they cannot be compared to glass, a solid that acts as a fluid in many ways.
A sniper round travels in the order of 3000 feet per second (or more, depending on what we are talking about here). For a "ballpark idea" we'll just say 3000. That would mean the "air pressure" would only be hitting you for 0.003 seconds.
"A few seconds" is a factor of thousands of times more effect. That 200 psi would turn into 0.2 psi or less for all the effect it would have on you when brought down to the time interval a passing bullet has.
Well, destructive power of a 1kg anything is nasty.
a colt 45 caliber bullet can kill a man but he might survive...
1 50 caliber rifle bullet is going to kill a man or remove the body part hit, probably won't survive...
These are in the FRACTIONS of a KG here...
simple answer for a 1 kg projectile... if a man is hit... he's dead.
HA! Which is heavier, 1 kg of iridium, or 1 kg of feathers!
Which now brings to mind the chicken gun.... imagine a thousand grams of feathers hitting someone at 1000 meters per second.
More importantly... would it be funny to see?
Which now brings to mind the chicken gun.... imagine a thousand grams of feathers hitting someone at 1000 meters per second.
More importantly... would it be funny to see?
Yes, British Rail once got hold of one of those to test the windscreens of their new Advanced Passenger Train back in the '70's. But no matter how strong they made the windscreens the chicken smashed through them with ease. Eventually, convinced they were doing something wrong, they wrote to NASA who had supplied the gun for advice. They received back only four words:
First, defrost the chicken.