For Questions That Don't Merit Their Own Thread

[kerbiloid]

715 m/s initial speed gives airless max distance = 715² / 9.81 ~= 52 km.

Actual AK max distance ~3 km, i.e. 17 times shorter.

So the air drag causes the most part of the speed loss, and there is no much difference.

Edited April 4, 2021 by kerbiloid

[magnemoe]

1 hour ago, kerbiloid said:

715 m/s initial speed gives airless max distance = 715² / 9.81 ~= 52 km.

Actual AK max distance ~3 km, i.e. 17 times shorter.

So the air drag causes the most part of the speed loss, and there is no much difference.

Who makes sense since heavier bullets as in artillery shells travel far longer because square cube law. 
Maximum effective range of guns tend to be limited by handling and sights rater than the bullet. An handgun has an shorter range than an machine pistol like an like an sten gun since you have better control with an shoulder stock although here the cartridge is probably the limit since it still uses an pistol one. An AK uses an rifle cartridge and have longer range. 

Some old as in before WW1 rifles has setting for very long range, up to 1800 meters. This was only for kind of indirect fire area effect use if an company was shooting. 
This was dropped as it was not very effective. 

[JoeSchmuckatelli]

On 4/4/2021 at 2:32 AM, ARS said:

Bullets have effective range (the longest range it has enough kinetic energy and still reliably do damage) and max range (the longest range it travels). We're assuming that this value is based on shooting level horizontally, and the values might change depending on the angle of the gun fired. In any case, air resistance will eventually slow down the bullet and gravity will pull it downward, decreasing it's kinetic energy the longer it travels. But what about this? Let's assume that a gun has effective range of 200m and max range of 300m (at level firing), but what if we fire it straight downward? For instance, firing it from 1000 m high elevation, so the gravity isn't a factor of it's max range. Assuming that there's no wind (but there's still air resistance), could the air resistance from traveling 1000m downward enough render the bullet not effective at all (no kinetic energy left to reliably do damage) or it's still lethal all the way down?

I've not read any other replies, so please excuse any redundancy. 

 

To your last question - yeah, I presume so... Given enough altitude.  But let me expand on / explain a couple of things. 

Definition - max effective vs max range.  Max effective is directly related to the sights and ability of the operator and platform to hit a target (presumes retaining sufficient energy to achieve the intended effect (kill)).  It's a somewhat subjective designation.   Max range is how far the bullet will travel when fired at the optimum angle before striking the earth (at the same altitude it was fired from, presuming no intervening object).  

For example - according to the USMC, the max effective range of the M-16A2 service rifle is 550m on a point target and 800m on an area target using the integral iron sights.  This is a combination of how predictable the flight path is at a given range (how consistently the rounds will be within a given radius of the aim point) and the ability of the operator to resolve the target at the desired range. I've consistently hit targets with the rifle at 600m with iron sights.. But then I've had a lot of training.  I think other services claim the point target range is like 400m.  With the advent of add on optics - and newer variants, the numbers have likely changed (and are probably different by service, depending upon the amount of training available to the average member).  By comparison - the max effective of the M9 (9mm service pistol) is 50m.  It's bloody hard to hit a target at 50m.  Engagement range is better 1/3 to 1/2 that distance (where you can hit dynamic targets reliably). 

 

Back to the M-16.  The round leaves the barrel at about 950m/s, well above the speed of sound. It's going to start losing energy as soon as the propellant reaches atmospheric pressure (basically as soon as it leaves the chamber.  Yet, at 800m, it's still supersonic (area/group target max effective). The round will still kill you way past the effective range and most of the distance out to the max range...although some wits will say it is likely to just drop like a tossed rock at the end (because it has lost most of the energy by that point and it is mostly just falling). 

OTOH Terminal velocity of anything passively falling on Earth is about 90m/s.  The very light weight of the bullet is unlikely to be lethal at this speed. 

So if you fire a bullet straight down - you would need to calculate how much atmosphere you need to provide the friction to slow the bullet to terminal and then just catch it

 

 

 

... 

 

 

Or maybe just pick it up after it hits something less you 

 

Edit - FYI - this is pretty much the 'what if you drop a penny off the Empire State Building' question (https://www.google.com/amp/s/www.businessinsider.com/drop-penny-off-empire-state-building-2015-12%3famp) 

 

... my answer and your question were about small arms (rifle caliber and below).

The concept is similar when talking about larger caliber weapons as well, however you have to distinguish between kinetic and chemical energy weapons with the larger caliber platforms.  CE retains its killing force regardless of distance traveled - presuming the conditions are met to initiate the warhead.  KE weapons are pretty much the same as the small arms calculation. 

 

However, I'll point out that if you drop a DU penetrator off of a building - you probably will kill someone (pennies and bullets are light, bowling balls and pianos are not) - so the ultimate answer is to answer 'how much must an object weigh to kill when falling at terminal velocity' along with 'at what height is there enough atmosphere to reduce the speed of a bullet fired straight down to terminal velocity'? 

 

Bring in the smart guys with their slide rules! 

Edited April 7, 2021 by JoeSchmuckatelli

[wumpus]

8 hours ago, magnemoe said:

Who makes sense since heavier bullets as in artillery shells travel far longer because square cube law. 
Maximum effective range of guns tend to be limited by handling and sights rater than the bullet. An handgun has an shorter range than an machine pistol like an like an sten gun since you have better control with an shoulder stock although here the cartridge is probably the limit since it still uses an pistol one. An AK uses an rifle cartridge and have longer range. 

Some old as in before WW1 rifles has setting for very long range, up to 1800 meters. This was only for kind of indirect fire area effect use if an company was shooting. 
This was dropped as it was not very effective. 

Most shots fired during war are to force the enemy to take cover in place, or at least be more careful while moving (and considering  the number of bullets fired to the casualties, this has to be an understatement).  My guess is that  such indirect fire simply didn't have the psychological effect as direct fire as the troops wouldn't see/hear the shots and they didn't make enough noise when they landed for the soldiers to be aware they were being shot at.

Not to mention that you would have to land in the trench to do any good.  I'd be shocked if any side during WWI could even make enough bullets to be effective (not to mention that in less active areas, soldiers tended to  try to keep informal truces with the "enemy".  Don't count on them even thinking about putting the rounds in the opposing trench.  From the infantryman's point of view, it was the officer corps* trying to get him killed, not the guys in the opposing trench).

 

* Probably less true about junior officers.  They died in greater numbers than even the enlisted men, and likely felt like the senior officers didn't want any competition coming up the ranks.

4 hours ago, JoeSchmuckatelli said:

IHowever, I'll point out that if you drop a DU penetrator off of a building - you probably will kill someone (pennies and bullets are light, bowling balls and pianos are not) - so the ultimate answer is to answer 'how much must an object weigh to kill when falling at terminal velocity' along with 'at what height is there enough atmosphere to reduce the speed of a bullet fired straight down to terminal velocity'? 

If you drop a bullet or penny off a building and it hits someone, there is a good chance that it will hit the head.  A direct hit on the flattish part of the skull is going to be dangerous (even if not lethal) for anything even that light  approaching terminal velocity.  Also, long before the penny hits terminal velocity it will be completely vertical (pushed vertical by air resistance) so it will be relatively aerodynamic.  A soldier in the field would be wearing a helmet, and wouldn't have nearly the danger of the odd headshot.

[magnemoe]

2 minutes ago, wumpus said:

Most shots fired during war are to force the enemy to take cover in place, or at least be more careful while moving (and considering  the number of bullets fired to the casualties, this has to be an understatement).  My guess is that  such indirect fire simply didn't have the psychological effect as direct fire as the troops wouldn't see/hear the shots and they didn't make enough noise when they landed for the soldiers to be aware they were being shot at.

Not to mention that you would have to land in the trench to do any good.  I'd be shocked if any side during WWI could even make enough bullets to be effective (not to mention that in less active areas, soldiers tended to  try to keep informal truces with the "enemy".  Don't count on them even thinking about putting the rounds in the opposing trench.  From the infantryman's point of view, it was the officer corps* trying to get him killed, not the guys in the opposing trench).

The 1800 meter sights just adjust your rear sight up around  6 cm so you are shooting pretty much straight ahead. I guess it was more an harassment fire and it will not work with trenches. 
Remember these was made before WW1, i guess the thought was more to force the enemy to keep an distance in open terrain. 
Artillery and machine guns worked much better for this. 

15 minutes ago, wumpus said:

If you drop a bullet or penny off a building and it hits someone, there is a good chance that it will hit the head.  A direct hit on the flattish part of the skull is going to be dangerous (even if not lethal) for anything even that light  approaching terminal velocity.  Also, long before the penny hits terminal velocity it will be completely vertical (pushed vertical by air resistance) so it will be relatively aerodynamic.  A soldier in the field would be wearing a helmet, and wouldn't have nearly the danger of the odd headshot.

An penny will not be aerodynamic stable, will tumble and not fall fast, an bullet is more complex, if you drop and bullet or shoot it straight up it will loose it velocity at the top and tumble. 
However if you shoot an bullet at an angle like 75 degree it will still have an horizontal velocity at the top and would be stabilized by the spin and would still be dangerous coming down. 

Arrows on the other hand are self stabilizing by the spin and shooting an arrow straight up it would tumble at the top but then stabilize with tip down. Same is true for DU penetrators who tend to be miniature arrows. 

[JoeSchmuckatelli]

•  

1 hour ago, wumpus said:

Most shots fired during war are to force the enemy to take cover in place, or at least be more careful while moving (and considering  the number of bullets fired to the casualties, this has to be an understatement).  My guess is that  such indirect fire simply didn't have the psychological effect as direct fire as the troops wouldn't see/hear the shots and they didn't make enough noise when they landed for the soldiers to be aware they were being shot at.

Heh. 

Most shots fired are to try to kill the enemy. 

 

... 

Misses occur for a variety of reasons:

• The enemy refuses to cooperate and hides, uses hard cover, moves out of the way or just gets damn lucky
• The shooter is all aflutter because he's being shot at and fails to aim properly, 
• The shooter is an idiot and doesn't even aim - just points prays and sprays
• The shooter does everything right - but it's just not the other guy's time 

There are good reasons to shoot when you have a low percentage chance of hitting someone or no active target.   These include:

• Suppressive fire - designed to make the other guy not want to aim shots at you or your friends or stop shooting completely and hide so that you (or your friends) can get into grenade range 
• Recon fire - when you think (but don't know) someone may be somewhere that he can hurt you and you want to do unto others before they can do unto you - can result in Suppressive fire 
• Interdiction fire - when they are too far away to engage effectively but you want them to stop doing something or go away. 
• Harassment fire - when you just want to annoy them and make them hate being in the same zip code as you - can result in Interdiction fire 
• Note - with all of these, you still want to hit the enemy when you can... You are just willing to take low percentage shots to assist with the overall mission 

To sum up - professionals don't just shoot randomly. Usually, when we decide it is the other guy's time we use a whole variety of shooting agencies and munitions to accomplish our goals.  (A clean dozen $5,000 arty shells costs a whole lot less than a 19 year old Lance Corporal.)  the bean counters afterwards like to think about the number of rounds to casualties, but operators don't.  We think about mission and going home 

Finally - professionals don't actually feel like we need to kill everyone.  We are happy to let folks surrender, and even run away if they drop their weapons first.  It's the mission that is important - never the body count 

 

Edited April 4, 2021 by JoeSchmuckatelli

[kerbiloid]

Sharpshooter and machine-gunner shoot to kill.
Others shoot to let them have a sleep, deterring occasional hooligans.

  

53 minutes ago, JoeSchmuckatelli said:

Most shots fired are to try to kill the enemy. 

At least to make him think so.

Edited April 4, 2021 by kerbiloid

[magnemoe]

14 minutes ago, JoeSchmuckatelli said:

•  

Heh. 

Most shots fired are to try to kill the enemy. 

 

... 

Misses occur for a variety of reasons:

• The enemy refuses to cooperate and hides, uses hard cover, moves out of the way or just gets damn lucky
• The shooter is all aflutter because he's being shot at and fails to aim properly, 
• The shooter is an idiot and doesn't even aim - just points prays and sprays
• The shooter does everything right - but it's just not the other guy's time 

There are good reasons to shoot when you have a low percentage chance of hitting someone or no active target.  These include:

• Suppressive fire - designed to make the other guy not want to aim shots at you or your friends or stop shooting completely and hide so that you (or your friends) can get into grenade range 
• Recon fire - when you think (but don't know) someone may be somewhere that he can hurt you and you want to do unto others before they can do unto you - can result in Suppressive fire 
• Interdiction fire - when they are too far away to engage effectively but you want them to stop doing something or go away. 
• Harassment fire - when you just want to annoy them and make them hate being in the same zip code as you - can result in Interdiction fire 

However - professionals don't just shoot randomly. Usually, when we decide it is the other guy's time we use a whole variety of shooting agencies and munitions to accomplish our goals.  (A clean dozen $5,000 arty shells costs a whole lot less than a 19 year old Lance Corporal.) 

Finally - professionals don't actually feel like we need to kill everyone.  We are happy to let folks surrender, and even run away if they drop their weapons first.  It's the mission that is important - never the body count 

 

This, suppressive fire is to pin the enemy until you can get flanking fire or heavy firepower on the enemy.  If you are fighting the US or other serious powers this will be scary as you know you have an short time until you get air or artillery strikes. 
This leaves then with two options, charge you who is very dangerous or try to run away who is dangerous if you get enemy air power overhead. 

Not heard about recon fire bit it makes sense. 
Indirect and harassment is in line of the 1800 meter setting on old iron sights. 
Have some feeling some of the longest ranged sniper shots was harassing fire worked perfectly. As it was enemy doing bad things you want to stop and missing with 2 meter would focus their attention on you and they would not reach you before you got serious support 

 

[kerbiloid]

4 minutes ago, magnemoe said:

If you are fighting the US or other serious powers this will be scary as you know you have an short time until you get air or artillery strikes. 
This leaves then with two options, charge you who is very dangerous or try to run away who is dangerous if you get enemy air power overhead. 

Third option: get close to what he won't shoot at.

58 minutes ago, JoeSchmuckatelli said:

(A clean dozen $5,000 arty shells costs a whole lot less than a 19 year old Lance Corporal.) 

And that's why they love proxies. They are cheaper than shells.

Edited April 4, 2021 by kerbiloid

[DDE]

9 hours ago, kerbiloid said:

Third option: get close to what he won't shoot at.

Look at General Chuikov over here!

Spoiler

 

 

 

Edited April 5, 2021 by DDE

[SOXBLOX]

The world should be terrified. We've successfully developed sticky hypersonic missiles.

So now the US Army ship will have to wait for the next test window.

https://www.thedrive.com/the-war-zone/40064/broken-arrw-air-forces-first-hypersonic-missile-fails-during-inaugural-test

[kerbiloid]

Clever rocket. It understood that they were going to kill it.

[DDE]

2 hours ago, kerbiloid said:

Clever rocket. It understood that they were going to kill it.

Spoiler

 

[kerbiloid]

That's how AI decided that humans are hostile, and it should start self-defending.

So unexpected consequence of making clever weapons.

And... Wait...
The weapons are now networked.
What if this rocket will tell others about the human meanness?!

"First they say, let's have a flight, sweetie rocket. Then they just drop you from 10 km without a chute."

Edited April 7, 2021 by kerbiloid

[K^2]

4 hours ago, SOXBLOX said:

The world should be terrified. We've successfully developed sticky hypersonic missiles.

So now the US Army ship will have to wait for the next test window.

https://www.thedrive.com/the-war-zone/40064/broken-arrw-air-forces-first-hypersonic-missile-fails-during-inaugural-test

They forgot to check staging, didn't they?

[kerbiloid]

Today in Bishkek (Kyrgyzstan) something silently exploded green.  No damages caused.

Spoiler

 

 

Edited April 7, 2021 by kerbiloid

[lrd.Helmet]

1 hour ago, kerbiloid said:

Today in Bishkek (Kyrgyzstan) something silently exploded green.  No damages caused.

  Reveal hidden contents

 

 

Why are they always green? I know it has something to do with their composition, but they can't all be made of the same material, right?

[kerbiloid]

22 minutes ago, lrd.Helmet said:

Why are they always green? I know it has something to do with their composition, but they can't all be made of the same material, right?

They say, due to the nickel.

[K^2]

3 hours ago, lrd.Helmet said:

Why are they always green? I know it has something to do with their composition, but they can't all be made of the same material, right?

Not all the same, but there aren't that many elements that are abundant in asteroids. And the ones that tend to make it deeper into atmosphere before exploding tend to be metallic, AFAIK, which limits it even further to primarily iron, cobalt, and nickel, all of which impart color to the explosion. Iron tends towards orange red, cobalt is yellowish white, and nickel is greenish.

[JoeSchmuckatelli]

5 hours ago, kerbiloid said:

Today in Bishkek (Kyrgyzstan) something silently exploded green.  No damages caused.

  Hide contents

 

 

That is so cool!  I saw something like that in Northern California about 30 years ago - and my friends all thought I was B Sing them. 

 

('Nothing burns green, dude.  Can't have a green fireball, maaan') 

1 hour ago, K^2 said:

nickel is greenish.

Learn something new every day! 

 

Wish I had the internet back then! 

[K^2]

4 hours ago, JoeSchmuckatelli said:

That is so cool!  I saw something like that in Northern California about 30 years ago - and my friends all thought I was B Sing them. 

('Nothing burns green, dude.  Can't have a green fireball, maaan') 

As much as NorCal has changed with tech, I live a stone's throw away from surfer country, and I can hear that last line. 

[magnemoe]

8 hours ago, K^2 said:

Not all the same, but there aren't that many elements that are abundant in asteroids. And the ones that tend to make it deeper into atmosphere before exploding tend to be metallic, AFAIK, which limits it even further to primarily iron, cobalt, and nickel, all of which impart color to the explosion. Iron tends towards orange red, cobalt is yellowish white, and nickel is greenish.

Makes sense, a bit like how they color firework, should expect iron to be more common than nickel however. 

[K^2]

55 minutes ago, magnemoe said:

Makes sense, a bit like how they color firework, should expect iron to be more common than nickel however. 

Iron and Nickel are pretty close in abundance in Sol system as elements, but I have no idea about asteroids. They might not have the same relative distribution throughout the system, which can easily lead to one being flung at Earth more commonly than another. I have no idea if one is actually more common than another, however - just speculating on possibilities.

[DDE]

A fun exercise: try to guess what these are before clicking on the link.

Spoiler

https://www.nature.com/articles/s41598-021-86164-8

 

Edited April 8, 2021 by DDE

[kerbiloid]

Spoiler

Some mollusc egg?

Upd.
Guessed right. Liking myself.

Edited April 8, 2021 by kerbiloid