Firing hundreds of KM in some cases, accurate within a few hundred feet? How is that possible? And how do they “dial in” new coordinates exactly? It all seems like magic to me
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The most basic answer is math. The science of ballistics is all just math. The weight of the projectile, the angle it’s fired at, the charge of the propellant, the length of the barrel, gravity, wind resistance, temperature, the curvature of the earth, humidity, moon phase, (maybe not moon phase). All these things are factors that can be put in a calculation to accurately predict where that projectile will hit.
The oldest forms of artillery like trebuchets and stuff were just tested a lot and they worked out how far they fired with all the variables. Modern guns are treated the same way but modeling that is a lot easier with computers now.
Lots of work ahead of time
Someone at the test range has to nail down the parameters of the gun so they know how fast the shell comes out and how it slows with distance
Then someone has to do the hard math to figure out where each possible combination of angles and powders will land. This is just a projectile motion calculation from a physics class but with the added joy of air resistance.
The first programmable electronic general purpose digital computer was ENIAC and its very first task was calculating artillery firing tables. This takes data about angle of the gun, weight of the projectile, temperature of the air, amount of powder, temperature of powder, and does all the calculations in advance to say where a shell will land with given conditions. The end result is basically a book of tables
Once all the hard math is done, the artillery man just needs to know where he is relative to the target (distance, angle, and height), what the temperatures are, and what the wind is and the book says “set to 37.3 degrees elevation with 4 charges”
Some newer artillery pieces have computers on them which can do the calculations on the fly based off a target location that’s selected and the known position of the artillery. They’re still doing the same calculations as ENIAC but they can do it in milliseconds instead of hours
So artillery in the modern age is directed at targets by artillery observers or forward observers, sometimes FISTers: soldiers that utilize a menagerie of methods to watch over a battlefield and give the coordinates of targets to the artillery pieces firing. This can be done either by sending coordinates to a fires direction center, a headquarters where battlefield intel is needed in conjunction with firing artillery, or straight to the artillery pieces themselves.
Lasers, GPS, maps, compasses, binoculars, and drones among many methods to find the coordinates for a target. What’s called a fire mission is conducted where a round is dropped at initial coordinates given to artillery pieces and then by direction from the observer, the guns adjust and fire until rounds hit target. If you’ve ever heard ‘fire for effect’, that is what is called in for the typical bombardment of accurate rounds on target. Of course, if you’re aided by GPS, and computers and such, the initial fire mission might just be a fire for effect without the need to adjust rounds. Communication between entities is the key to accurate artillery fire.
Lot of math, the way they ‘dial’ it in is by firing 1 round waiting for it to hit then an observer sends instructions on how far off they were and the next shot is shifted accordingly.
Basically, everything above a range of 50km is smart ammunition of either 155mm artillery and larger shells or rocket artillery. Both aren’t just bombs that you fire and then drop out of the sky. They are actually small computers with an array of sensors and steering capabilities.
Rudamentally similar to a car’s GPS such ammunition knows where it is during flight and can just extrapolate its flight path based on physics formulas. Then it uses fins, gimbal or similar methods to adjust its path to steer it to the GPS coordinates uploaded. The newest ones have an accuracy of feet not hundreds of feet.
Relevant (https://www.youtube.com/watch?v=bZe5J8SVCYQ) on how rockets know their position.
Nobody is firing artillery much over 50km in combat conditions. The max range for a traditional unguided round is ~30km. Most anything over that is using a guided round with some sort of rocket booster.
There are a few experimental systems that could get out to 150km, but they are using guided rocket assisted rounds. The guided rounds use fins + GPS to reach the target.
Unguided rounds are, as other have mentioned all about math and knowing the exact location of where it was fired from. Also millimeter wave radar to determine the exact winds all the way to the target and tracking the first round to adjust the following rounds.
Former 13B field artillery guy, here. Basically it works like this…there’s 3 positions: the target, the ones looking at the target, and the ones shooting at the target. The ones looking at the target send the coordinates of the target to the ones shooting at it. The shooters adjust the artillery so it’s pointing at the given coordinates and target, and shoot. Target hit. But not always. The ones watching sometimes have to adjust right or left, in or out, and sometimes the shooters can F up the “translation” of the coordinates.
As other said it’s math, but it’s also having ways to accurately know where the target is. Forward observers call the targets (now things like drones and uavs do also). They have known reference points they can used to quickly get a fix on something. In some cases it can be land marks or even just points on a map. Say location called X5 is the town water tower, and there is a tank 100 meters west and 20 meters south of X5. The drone operator or FO calls in the strike 100 west and 20 south of X5. This gives the input for the math, and makes it very fast. They can then dial it in from there (10 meters south from the first shot, etc.).
A bunch of complete and excellent answers here. The only thing left for me to add is that, even after all of the above, there is still sometimes a game of darts to play.
You know in the movies you hear people say things like “fire for effect”. They say that because its a movie and it sounds cool. duh.
Ok, really though, its something different from firing for adjustments.
Basically, the spotter is like “hey I see a bunch of trucks and stuff. Lets blow it up. Gimme… about 10 rounds of High explosive. That should do it.”
But first… shoot one round and I’ll make adjustments”
Then the arty guy is like “ok. 1 round. shot it. Should hit in 30 seconds…. ok hitting in 10 seconds look for it”
BOOM
Spotter watches, and then calls back the adjustment “ok uhhh go left 6 0 meters and add 1 0 meters distance”
shoots again
“ok that was too far left, come back right 3 0 meters”
shoots again
“Ok. That got it, FIRE FOR EFFECT” = we’re on. We’re done adjusting onto the target. Now go ahead and shoot that batch of 10 to cause destructive effects on the target. Let’s mess them up.”
GPS helps. This gives the artillery battery pieces accurate locations, and accurate relative locations for each gun in the battery. The forward observer also knows where they are, and this helps them locate the target zone extremely accurately. The GPS co-ordinates of the target are fed into the targeting computer, and math does the rest.
Modern artillery also use radar or other mechanisms to track the spotter shell in flight – this fills in a bunch of unknown quantities such as wind direction and speed, and any other atmospheric conditions. This allows the entire battery to correct for these factors even before the spotter shell has impacted.
The guns will be networked – this allows the co-ordination of a vast amount of firepower. Multiple rounds fired from multiple guns on multiple trajectories all timed to drop on to and blanket the target area within a few seconds – no time to react, and no place to hide.
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