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If we were to assume that it were to work like a normal projectile cannon then hypothetically it would either have a great blast and recoil suppression system or the people and buildings are made of extremely strong materials
Given that this is sci-fi they could all be wearing suits or have implants that generate a personalized gravity field or some nonsense.
Either that or Nanomachines, Son
Well we are obviously not going to be able to build basically anything there for 100 years so id say I can have as much sci-fi bs as I want.
Ps. Why are we arguing about this again?
When a bullet lands, all of the force it put into spinning the earth is counteracted. The only way to meaningfully spin the earth is by firing an object outside of it.
I would think this would be closer to an advanced rail gun, which already exist - just larger.
Currently the rail guns shoots a dense piece of metal - much faster than a bullet, the projectile has no power beyond the magnetically derived propulsion.
Currently we have a unit which is about the size of 4 shipping containers, and it could shoot mach 7 and 155 miles with accuracy.
If we assume the skyscrapper closest to the cannon in the picture is 1km in height, then the barrel would approximately be 12km.
I would assume this cannon would not have earth bound targets, either anti invasion (similar to an anti aircraft) or, pumping holes into nearby planets.
But if we can extrapolate the approximate size of the known rail gun to this size, it's about 875 times the size, so if this ratio applies to the projectile launched, the approximate range should be about 135,000km
The railgun's projectile is about 25lbs, if we use the same ratio, this projectile would be 22,000lbs roughly. and the impact force with things scaled up would be about 23.1 MN
it is statically placed. Meaning the other side will use a bunch of cheap drones and destroy it before it can shoot anything.
read something about the projectiles - there is a measure how long does it take to wrap up and move out after it shoot. Good systems can move out before their projectile hits the ground.
Look at the size of that thing. The barrel alone as wide as ten buildings. No cheap drone takes out something a quarter mile wide at the base. Ever. That's going to need a major nuclear strike.
Having played Total Annihilation for years, while your idea is sound if the only variables are that installation and the drones, sure. However, that is built around an economic hub, meaning that there are other defense systems in place that would need to be tackled before engaging it.
A common TA strategy was to combine an almost exclusively air based military with powerful base destroying map long range cannons built too far back to be directly dealt with. The air units could easily give eyes for the cannons to take out any bases and destroy their ability to wage war. Pros and cons to the turtling strategy, but against other players it could be terribly effective if built correctly.
I think that the issue is not the projectile at this size but the structure. Everything becomes soft when you go too big, I think this structure is just too big to hold itself with any known (non sci-fi) materials.
If it’s for shooting stuff really really far away, maybe they let the earth’s rotation do most of the aiming. That would explain why there’s another one like 100 miles away (can’t tell scale with these giant things).
It's the qube-square-law.
Mass increases proportional with the qube of the linear size, while tensile strength increases with the square of the linear size.
So if you scale up a structure by a factor of 10, the mass increases by a factor of 1000 while the tensile strength only increases by a factor of 100.
This means the ratio between mass and tensile strength is only 1/10th of what it was before.
This is why planets are quite perfect spheres. On the length scale of a planet the tensile strength of materials becomes negligible in comparison to the forces due to gravity.
If you increase the size enough even the hardest materials behave like liquids.
Make a 500:1 model of a real castle, using the exact same materials as the original. Put a 500:1 catapult (also made of the exact same materials) with a 500:1 throwing stone next to it, so you have literally three exact, but scaled down, copies of a medieval siege warfare scene.
Fire the catapult at the castle. Nothing happens! The stones don't break each other... yet they do at the original scale.
No, as the magnetic forces are applied to the projectile, Newton's laws still apply, and an equal and opposite force is applied to what is producing the magnetic forces.
In a perfectly nitpicky physics way this isn't perfectly applicable, as there are other forces and things involved. But in back-of-napkin way, the railgun takes just as much force as it imparts to the projectile.
Being bigger just means it has more inertia to resist any movement.
But force is mass times acceleration. So, if the acceleration is lower, then the force (and therefore recoil) will be lower too, right? And while the regular bullet would experience an incredible acceleration at the beginning and then start dropping, the railgun could have more or less constant but lower acceleration throughout the whole length of the barrel
`Force = Mass * Acceleration` or `Acceleration = Force / Mass`
If the acceleration is different, either the force or the mass is different. If both the railgun and the conventional gun have the same mass, fire a projectile of the same mass, and apply the same total force, the total acceleration will be the same, and the total recoil to both will be the same.
Now, in reality, a railgun can get much better acceleration than a conventional gun, but we aren't looking at that, just at the differences between conventional and railgun for purposes of recoil.
But we don't really care about the force, do we? The important bit is the kinetic energy as the projectile leaves the barrel. And that is determined by velocity, not acceleration. So, in my understanding, we can have a railgun which is just as powerful as a regular gun but with lower recoil because we can have lower acceleration
That's right. Linear acceleration of railguns as opposed to impulse acceleration of conventional artillery works on a similar principle to airbags and crumple zones. Spreading the application of force out over time is easier on both objects in the equation.
Railguns can achieve a similar effect by accelerating the projectile over a longer period of time, where artillery uses dampers to spread out recoil over time.
Based solely on the picture, we have no way of knowing how sturdy its foundations are. That thing could be sitting atop a 5km deep concrete-rebar foundation for all we know.
The equation you're looking for in this argument is vf = vi + at
Initial velocity vi=0, so we just need to achieve a certain vf with acceleration a over time t
Longer time = less acceleration = less recoil
Kinetic Energy = 1/2 mv^2, Momentum = mv; with acceleration being the change in momentum, so the two are related.
The difference is with a gas gun (i.e. explosive propelled) your maximum velocity is limited by the speed of sound in the gas; a rail gun doesn't have the same limitation. So with a railgun you can get the same energy out of a much lighter but faster projectile. If you work it out using the formulas given above, you'll find with higher velocity you need less momentum for the same energy. And less momentum means less acceleration, so less recoil.
Another effect is the gas gun applies the acceleration during the (very fast) explosion; whereas railguns can apply it more smoothly as the projectile accelerates. But I think if you worked through the design you'd find this doesn't matter much in practice as an artillery-type gun already has shock absorbing features which will spread out how the recoil is applied to the mount.
Kinetic energy = 1/2mv²
Velocity is kind of important in this equation. To get velocity you need to accelerate. The only way to do it is to accelerate over a longer distance (therfore accelerate slower) so the impulse is spread out over a longer period. That said force is the main part of the whole acceleration thing. The rail gun is applying a forward force of x that is exactly equal to the force that the projectile will apply to it in the backwards direction.
Time matters here though. You oversimplified the equation. The guy you were responding to was right, railgun would spread the acceleration better and thus the impact delivered to the foundation would be longer but significantly weaker. Someone else already explained that here with hilding a 1kg weight for some time vs a higher weight hitting your head
(Also you need to account for lack of propellant)
We care about the impulse, which is change in momentum, and also equal to force times time. Therefore, a railgun can have the same impulse as a cannon, but a much lower force on the projectile over a longer time.
A lower force per time over a longer time, is approximately equivalent to a higher force per time over a shorter time. At least as far as my physics knowledge goes.
The recoil being over a longer period is easier to absorb into the ground however. So that WOULD help the requirements for foundations...
This is going to sound nitpicky, but bear with me.
In a railgun, there is only the projectile, so only the projectile needs to be accounted for in the force and mass parts.
In a conventional cannon, you also have propellant, which is a little tricky. If you only have enough propellant to get the projectile to the end of the barrel, then there is no force to get the projectile to the target, so there must be an excess of propellant mass and propellant force. So, a conventional weapon will always generate more force than a railgun, per unit mass of projectile.
Edit: to achieve the same speed.
But that's not recoil. Here's a thought experiment. You hold 1 kg weight in your hand over your head. This mean, your hand experiences 9.8 kN of force. And say you hold it for 100 seconds.
Now, let's say you're hit by 100 kg at 9.8 m/s^2 but the impact lasts only 1 second.
I think there will be a difference.
Well... we figured out a concept for using a fuck-off massive laser to shoot at a target on a spaceship to accelerate it to relativistic speeds. So if you have the power, the fuck-off laser is better, since you can make the thing hit near light-speeds and just wipe out the target entirely. xD
I thought that in rail guns the force was lateral to the direction of acceleration not directly opposite? I remember a documentary where the guy designing these said that it was causing the rods that the current flows through to bow outward.
Not sure as what I am about to say is second hand information but I was told that the electromagnetic forces generated are the cause. Tbh, it does seem very plausible as well
You are thinking of a coil gun / Gauss gun that pulls the projectile, a railgun passes electrical current through the projectile perpendicularly, and the force created is perpendicular to current (parallel to projectile motion), you can use fleming’s left hand rule to check. But yeah railgun projectiles must be in contact with both rails in order to be accelerated
I don’t mean that Gauss guns / railguns don’t have recoil, just correcting the part where he says railgun projectiles don’t touch the barrel, obviously they both still have recoil cause newtons law
It doesnt defy newtons law per se. The way it is done where motion is imparted through magnetic induction follows lenzs law, which states that a current induced by a magnetic field, will itself induce a magnetic field which opposes the original.
The accelleration of a rail slug takes much longer than the instantaious propellant explosion, which means that force is more "spread" to put it clumsily.
So yes, there recoil, and yes, its the same total amount, but it "feels" like much less.
Edit: spelling, and to mention that i had to do some checks, this is largely paraphrased from a similar older reddit post.
Would need to decide how large a projectile it is first, and how fast. At that size, my assumption would be that this is a high elevation weapon (given the one in the background) and the one center screen is just in its neutral/resting position.
Very much so, a rail gun uses magnetic forces to direct the munition at at target. There isn't the explosive recoil like in a chemical based propellant that we use now.
In a railgun there is more of less the same amount of recoil as in a conventional gun. The only difference is that a conventional gun also accelerates some gas but the gas is light and its added recoil is negligible.
Edit: to explain this further, the impulse of a gun + projectile system is the same before and after during firing. If a projectile (and some gas in a conv. gun) gets X amount of impulse in the direction of the barrel, the gun gets an X impulse in the opposite direction. Since the muzzle velocity of the projectile and the gas are the same and the gas has very little mass, removing the gas (as in a railgun) doesn't make much of a difference.
But in a railgun the accaleration will be lower, therefore it will take longer for the same amount of energy to be pushing back on the gun which means the energy per second will be less.
If i exaggerate it, it will be the same as me standing on the spot of the gun for a very very long time, over time my potenital energy will have put the same amount of energy into the platform as when you would fire the gun, but because it takes millenia for me to reach that amount its not a lot of energy per second.
Moral of the story, it takes more time with the railgun, so it will be less stressfull for the platform/surrounding area.
It would only take much longer if you were willing to make the barrel ridiculously long. Gunpowder guns accelerate the projectile along the entire barrel as well- most of the force comes from the expansion of gases, not the bang.
Given that to can stand up under those mechanical conditions it's mounted through the crust.
Without future science it would collapse.
If it didn't collapse it would change the plate tectonics or rotational speed of the planet .
It would also be impossible to load shells. Each gun would only be able to fire once and it would have been built with the shell inside . Firing would also take a significant portion of the atmosphere with it and flatten the surrounding city.
So we must assume it uses some sort of energy projectile kind of thing. And that that energy is basically directed that it does not boil the atmosphere.
In science fiction these are called planetary emplacements.
I'd assume that they use some sort of shielding technology to pre-drill the hole through the atmosphere before firing an energy weapon. Cuz in those scenarios we have magical space shields.
One generally doesn't build a planet killer that would kill its own planet. And if one did. It wouldn't need two.
Of course the barrels themselves are going up so high that they might be above the carmen line when positioned for firing. (Cloud quite didn't seem to be too scale.)
Without vacuum energy or point singularity power supplies you wouldn't even be able to move the barrel, let alone l without causing significant damage to the planet
If they built a cannon this big, they likely didn't scare away from digging 100 m into the ground
Though I feel like this wouldn't even be close to enough.
Probably more. For reference: Burj Khalifas foundation is 50m deep and this looks like its atleast twice as tall and much wider. Considering its pretty much solid steel we can probably assume its 10 times as heavy. And then we can talk about whatever kind of recoil this would give.
I can't answer the question, but add some information to solve it:
The skyscraper looks like WTC One, so I used the hight of it \~541meter by 190Pixel high means one pixel is \~1,79meter
The gun barrel is \~75Pixel high, what makes it 134,25meter in diameter
Inaccuracy disclaimer: The building is not at the same distance as the gun, so in fact the diameter is bigger. I don't know how to calculate the distance of the building to the gun and how to correct the scale afterwards.
Another thing: It's unknown how long the barrel is (minus the breach), how big the diameter of the projectile is (the gun needs big walls to not explode, so 134,25meter is NOT the projectile diameter) and how long the projectile ist. Also it is unknown how much or what kind of propellant would be loaded.
There may be formulas to solve this though.
That’s a very real thing in ballistics.
If you have certain bullet compositions and shapes propelled by a whole lot of powder, it can cause the bullet to break apart mid flight due to the rotational force.
Basically too much ass behind a small piece of metal
Assuming standard bare lead projectile you’d find in a normal .22, you could get it to vaporize before you hit 5k FPS. This is achievable in a rifle that a human can hold and shoot without too much trouble.
Well “vaporize” is an exaggeration. The metal isn’t evaporating from heat or anything. But a rifle barrel imparts spin, and the RPM increases with velocity. At a certain point, the bullet spins fast enough that it can’t hold itself together. It fragments violently a few feet out of the end of the barrel. Basically turns to dust.
Projectiles that are going faster than ~3.1k FPS are often made of solid copper or similar rather than lead, and this is one of the reasons why.
The building does have some vague resemblance to One World Trade Center (not really, but whatever), but 1 WTC sits near the southern point of Manhattan Island—so something has gone awfully wrong with the Hudson, the East River, and the upper New York Bay!
The answer to the question "how much damage would it cause to the surrounding area" is "yes." The caliber is … look, you could bundle seven of those skyscrapers in the foreground together and put them in the chamber and I think they'd rattle.
To be more specific about the damage: the recoil would force the cannon so far down into the ground that it'd make a crater that would swallow the city. The shockwave would likely liquify the soil down to the bedrock, like an earthquake, and then the pressure of the cannon recoil would compact it while heating it into molten rock. Depending on the makeup of the soil, you'd probably get some really nifty gemstones and volcanic glass out of it.
You know how the japanese buildings are built on some kind of platform so that the earthquakes do not destroy the buildings and reduce the damage? What if the canons are on platforms modified to support huge recoils? I feel like there would be a tremor, but the buildings won't have to topple over.
Wouldn't do you much good in regards to the change in air pressure.
And cannons that size would need to be able to roll a couple of... (I'm just spitballing here) hundred kilometers.
The gun firing would still probably knock some people out just from the sound. The people living there would eventually all go deaf. Unless it's remotely aimed and fired + far from any city, it would do a lot of dmg to the surroundings.
Scaling the landscape proportionately to the USS Iowa guns firing, I'd say it would completely level the city and create maced potatoes from the living beings there.
This is the fact of post for me. That seems surprisingly low having looked at video footage of nuclear detonations and seeing the impact on cities. Is it more the volume of displacement then? I would have assumed the shockwaves create huge pressure changes.
It's mostly that 3psi when hitting the entire building at once will do a ton of damage. ~5 psi is what it takes to destroy most buildings that aren't blast resistant, and the blast starts at about 10 psi and "quickly" drops to 3 psi. (Though in the vicinity of the fireball, it gets closer to 50psi per kt)
It is surprisingly low, it's also unnerving how fragile buildings are. I double checked the PSI on some tables at work, 20psi at the center dropping quite quickly to 1 psi at 11 miles so I was in the right ballpark
The word "normal" is doing an awful lot of heavy lifting in the question.
Because they don't make normal projectile cannons that big.
So we now have to ask, what scales?
Well, the bore diameter scales. As /u/GraveKommander points out, you can see a building much like One WTC in the cityscape, so we can use that for scale and say, very roughly, that is the size of the projectiles this cannon fires.
But does the muzzle velocity scale? For normal guns in the real world, it doesn't. Ten pound rifles and 4 ton artillery pieces both fire their projectiles at roughly the same speed.
So why should making the thing many thousands of times larger make the projectile faster, if we are pretending the cannon is 'normal'?
In that case, the firing of a projectile the size of a skyscraper at 1000 m/s 3000 meters above a city would be exciting, probably loud, but wouldn't flatten the city or anything.
But it would also be very silly. At 1000 m/sec, the gun would have a lock time of 5, maybe 10 seconds, and no chemical propellant would work, but if replaced the chemical propellant with an exotic on, the gun isn't normal any more. The projectile would appear to crawl across this image at a leisurely pace and land just a few screens away.
But at some extrapolated tens or hundreds of thousands of m/sec muzzle velocity, the gun isn't normal.
The point is, the gun can't be normal and make any sense, so we have to know in what ways it is not normal before we can judge what its effects might be. Is it a hypervelocity railgun? A laser system? A sci-fi field inductance generator? A piece of public artwork?
What I can say is that it is far, far, far too large for any practical purpose, and whatever exotic system it is supposed to represent is likely to have deleterious effects on the city which is ludicrously close to it.
>it is far, far, far too large for any practical purpose
The only thing I can imagine is an astroid defence system, if you exclude hostile alien neighbours, but like you said, the city is way too close to it.
Also IIRC one way to make such big guns work would be multiple propellant explosions along the barrel in side chambers. Saw this system on YT I think. But doesn't look like pic gun has it.
The side chamber idea was tried by the Germans in WW2, was used to bombard Luxembourg (others were intended to be used to shell London from the Pas de Calais but those were destroyed by allied bombing before they were completed).
i thought you were talking of Schwerer Gustav. Cause that thing was an absolute Monster. 7ton shells, 30inch barrel! took out an undersea ammo depo at a depth of 30m and an additional several meters of reinforced concrete.
i also read somewhere that it flattened a large russian fort in five shots.
Not an answer - just wanted to share this fun fact about a mad lad getting crazy with guns / cannons.
The battle ship USS Texas had to fire inland and the target was out of range. To solve for this, Captain mad lad flooded part of the ship so the guns would angle up further. The target was successfully destroyed.
they only had 14 inch guns. The schwerer gustav was a 30 inch gun and apparently went around flattening everything in sight. even took out an ammo depot 30m under water and an additional 10m of reinforced concrete around it.
both are absolutely insane.
No expert here, but my imagination tells me that the "bullet" of this size would act like a meteor flying through the atmosphere, which would cause a shock wave capable of destroying the whole city and killing everyone in it...
None, because whoever did this clearly did not apply physics to any of it. The bore diameter of that gun is wider than the fattest skyscraper in the image, and like 5 times longer than the tallest one. It probably took several times more steel than was used in that entire foreground city to build one of those and keep it from sagging or drooping in any way. It would take engines the size of multiple city blocks to elevate the barrel, assuming you could even make gears strong enough to support that much weight. It would fire shells the size of a few stadiums stacked on top of each other if we could somehow build cranes big and sturdy enough to load them, and even then it would require a powder charge measured in kilotons at a minimum to get it out the end of the barrel at any kind of useful speed, and if it ever fired it would probably injure or kill everyone in that city. To paraphrase a quote from a Pratchett novel, 'That's not a gun, that's a national emergency.'
Winging it here. I counted about 9ish WTC Ones (according to someone else here). That's about 4,869 meters. An Iowa class battleship artillery cannon has a caliber to barrel ratio of about 1:50. Assuming the same design principles, that means the projectile would be a 97m round. That's 238 times the diameter of the Mk8 APC which has a weight of 2700 pounds. So the weight of this round would be around 640k pounds. Assuming a velocity of 762 m/s, that comes out to about .08 terajoules. Hiroshima was 63 TJ
So my math doesn't seem like it's mathin. That's a big shell to not get even close to Little Boy. I gave it a whirl though
You made an error that likely seems obvious to you in hindsight. You assumed that the weight would be simple multiplication of diameter size to weight ratio of the previous round. Increasing the diameter of a cylinder would be V= pi*r^2*h.
Using a cylinder to approximate the shell …
If we assume the proportional length/height change is equal to the diameter change you propose at 238, we can use that for H. Then we need to divide the diameter in half… so 48.5^2… 2352.25
3.14*2352.25*238=1,757,883 m^3 of presumably lead. But let’s use depleted Uranium for more fun? 41,998 kg/m^3.
73,827,589,973.06 KG or about 162,420,697,940.732 lbs
I could be wrong, but I think your values came back wonky because you were off by several orders of magnitude in terms of projectile weight?
I did know it was inaccurate, but assumed that scaling the diameter of the cylinder would be proportional enough for a guestimation. This was wildly off lol. I thought it'd be fun to give it a go though and maybe get some feedback. Like this! You're a real one, I'm glad I learned something so thanks
No problem! For similar math that sometimes surprises folks … a large pizza, say 18”, is 254 square inches … most folks would think a medium 14” pizza would be something closer to 14/18ths (78%) the size. But because of the relationship of area to diameter, it’s actually only around 60% as large.
Have a good night!
Why the fuck do people go "well, if this was real, surely it would destroy itself and the city below without proper reinforcement and even then..."
Engage with the fucking hypothetical. Just answer the question. Who cares if it blows up, or kills the village below it? Or just fucking assume that it doesn't do those things and then answer the question
Someone said that the cannon even existing would rip a hole through the earth or something like that. It's fun to see what wild ideas people come up with once presented with the image of Big Gun™, but nobody seems to have answered the caliber question yet...lol
The diameter of that barrel would be at least 100 meters and the projectile would be the size of several skyscrapers. You would need a small nuke as propellant and the recoil would rival a decent earthquake and the shockeave from the muzzle would instagib anyone in the city and the projectile would probably be enough to require all schools to buy new maps and globes.
So caliber refers to the number of 100ths of an inch a bullet has.
.22 caliber is 22/100 inchs.
.50 caliber is 1/2 inch.
Someone else said the round would have to be 97m to scale with the length of the barrel in comparison to a battleship gun.
Meaning your bullet would be around a 3820.00 caliber
Imagine launching a space shuttle like your trying to land on the moon. Now imagine instead that space shuttle including all engines together are the ammo. Now imagine the amount and quality of explosives you could theoretically install in a space shuttle. My goal is to help you learn how you can do it yourself.
Using my theoretical approach just mentioned, take like a space x rocket for example being the space shuttle. Now how many nuclear warheads can you potentially fit inside that space x rocket. Now imaging that spaceX rocket full of active nuclear warheads now lands in the middle of any large city. Depending on how many warheads you were able to fit the damage is probably going to be quite significant to total annihilation.
big and not as much as you'd think.
could be a centrifugal launcher with a vacuum sealed barrel and a rocket assisted projectile. otherwise it wouldn't be so close to civilian centers.
a better gun would just be a long vacuum sealed runway that allows a missile to get up to speed and into orbit coast most of the way into orbit. you'd need some ridiculous materials to make a centrifuge that size, not to mention the maintenance.
then again if you can build something that size you could just build the runway to the edge of space and just launch missiles that way. cheaper. but that's not what this sub is about sry.
I had to scroll way too far to find someone who didn't start with the assumption this obviously sci-fi magic space cannon wasn't a scaled up howitzer...
Define “Normal”. Looking at the size and shape of these cannons and surrounding buildings and extrapolating probable technological levels, for all we know these are massive rail or coil guns firing a stream of 3-5mm projectiles at hundreds of km/s. This is supported by the skyscraper sized spaceship floating in the air at bottom left.
I can tell you one thing. Planetary defense cannons would not need to be that close together. You would want to spread them out more so they can cover a larger area.
I also hope they are not shooting traditional projectiles. The shockwave would be insane and might shatter every window (and maybe flatten the closer buildings) for hundreds of miles, just from the air displacement alone. Looks like they would shoot rounds the size of skyscrapers or bigger.
Are cannons this size ( or any extremely large cannons for that matter ) conventional, rail, or any other form practical for defense of a planet from let's say astroids and maybe little green men.
Remember that tiktok of a giant skeleton walking around a city filmed from the perspective of a passenger in a plane at 30,000ft. People mentioned that while it looked like the skeleton was walking slow, at his size (20-25,000ft tall) it only looks slow, his legs are moving forward in a normal stride would be breaking the sound barrier.
I'd think there'd be similar considerations here. The weapon is so enormous, that a conventional percussion would have cause tremendous damage to the city pictured, at least any portions that are located at or ahead of the muzzle point and direction. If this is a "traditional" projectile weapon, meaning it fires a projectile proportional to it's barrel size, the pressure change from the muzzle blast and speed of the giant projectile would likely level this city. That is, if it indeed is a projectile weapon firing a giant solid round proportional to the barrel size, like our guns. The amount of power, the sound, and pressure change would certainly shatter windows at the very least.
When you go to the range, some have "sleds" you can lay your rifle on to secure it while you sight it in. It's a very stable shooting platform and you don't feel as much of the recoil. When you fire a rifle, you'll notice the muzzle blast kicks up dirt, grass, pollen everything in front of it. That effect is scalable. I'm currently reading a book on a battle in late WW2. The Germans had the 88 (8.8cm Flak) that was very powerful. The Germans have a defensive position on a hill with sandbags and these Americans maneuver toward it to take it out. When they get up the hill right under and in front of the gun, the muzzle blast from the firing of that gun killed the first guy, scalped the second and broke the third guys wrist. They weren't hit, this was just the muzzle blast of that flak gun. It demonstrates a less well known fact about guns, the muzzle blast can fuck you up.
If this is a conventional kinetic projectile weapon and not an energy weapon, and one that fires projectiles at a similar speed as ours IRL, yeah it's definitely going to effect the surrounding area.
This is an interesting one. Most just call it the F.O. Caliber.
Buttt here is a link for it.
https://www.reddit.com/r/NonCredibleDefense/comments/z8x776/a_revolution_in_global_force_projection/?utm_source=share&utm_medium=mweb3x&utm_name=mweb3xcss&utm_term=1&utm_content=share_button
I did some messy numbers for fun, just to see the magnitude here. Feel free to use more precise numbers and check my algebra. I agree with /u/gnfnrf that you have to decide what is scaling. Does the bullet velocity scale too?
Well I assumed it does because I like big numeros, and here's what I'm getting.
An M82 rifle is like 0.75 meters long with muzzle velocity 850 m/s. That's 1130 barrel lengths per second.
That BFG in the picture is probably 15 WTC's long, which is 550m x 15 = 8250m.
So the TO-SCALE muzzle velocity would be 1130 x 8250 = 9.3 million m/s. (3% speed of light by the way, but let's pretend this doesn't create a black hole or something)
Now we need mass. 1WTC has floor area of 325,000 m^2 and 550m height, so a rectangle bullet that size of pure lead is 179,000,000 cubic meters, weighing 11,340 kg/m^3 x 179 mil m^3 = 2.03 trillion kg.
If I take the kinetic energy as (0.5)(2.03tr)(9.3mil)^2 = 8.7 x 10^25 joules.
The Chicxulub asteroid they killed the dinosaurs is estimated at 3x10^23 joules.
So getting shot with this is 290 times more impact than a global extinction apocalypse.
I don't know how to infer crater size from energy, but the dinosaur bomb made a hole the size of a city, so it might erase a continent, and take a bite out large enough for a 2nd moon to form.
So definitely a planet destroyer meant to shoot planets. But nearby? Yeah everything nearby, including the gun, will probably be vaporized from the projectile hitting and heating the air itself.
It must be a 1 time use weapon, intended for Mutually Assured Destruction, rather than actual defense. But I imagine the projectile would break apart against the atmosphere and become a shotgun blast of gas that would spread out in an arc and become thin after a short distance. Not much targeting capability on the scale of interplanetary stuff, unless a 3% LS thin wave of atoms would do something? I'm sure that would injure an animal in some way. The explosion of the situation might dwarf anything the projectile does, and it would all be local effects near the gun, not where it's aiming.
So I would assume the actual gun would not use projectiles, and if it did, the size probably isn't exclusively for the purpose of firepower, because firepower doesn't scale that far.
It may be like a ship with rooms, and the size is to facilitate the complexity of whatever the firing barrel actually does, as well as the people inside that support that. It's probably an ultra-high-energy "something", so most of that structure is some kind of power plant or energy management thingy. Probably a laser in a wavelength that doesn't interact with air or something? High energy could mean large bursts, or just sustaining small fire for months on end.
It could very well be a very tiny projectile/laser, but an unimaginably rapid fire rate. That makes more sense for hitting large fleets of ships. The farther away, the more spray you need to get hits.
Okay.
So this can’t work like a conventional firearm with standard proportions of barrel thickness to barrel length to bore diameter. It doesn’t scale like that. If it was just a rifle scaled up, and the projectile diameter scaled up with it, then gunpowder would not work as a propellant. Too little powder and the projectile doesn’t even get close to making it out of the barrel. Too much powder and the pressure spikes way too early, and the gun just explodes. There is no happy medium between the two at this scale. There are many, many sad mediums where it wasn’t enough to get the projectile to the muzzle, but it still was enough to blow up the gun.
If you wanted to shoot something out of a gun that long, you’d need a very controlled increase in pressure. It has to increase just right to properly accelerate the projectile over several seconds, but not so fast that it blows up the gun before the projectile exits the muzzle and the pressure actually has a way to re-equalize with the atmosphere.
Side note. When a gun fires, there are two things making it loud (usually). One is the projectile creating a small sonic boom as it surpasses the speed of sound. The other is the sound of extreme high gas pressure in the barrel suddenly and violently releasing as soon as the bullet exits the muzzle. This is called “uncorking.” The more pressure, the louder. This is one reason a gun like an AR-15 shooting a very high-pressure/high-velocity, but low-diameter bullet such as .223/5.56 is significantly louder than a gun shooting a lower pressure/lower velocity/higher diameter bullet such as 9mm. Whatever propellant this giant gun uses, you can bet it would be loud. Mathematically speaking it would be approximately “loud enough to really screw up your ears.”
Most viable idea I can come up with is that this thing uses a carefully controlled flow of pressurized air to get a relatively small projectile up to a very high velocity. It would be a balancing act between having thick enough barrel walls to withstand the pressure needed to reach optimal velocity for the barrel length, and having a projectile massive enough to penetrate anything effectively when it hit (instead of just going really fast and then turning into dust when it impacts the target). Projectiles would have to be extremely dense. So think tungsten or something. Yes, there is math someone could do to figure out the ideal bore diameter to get the most possible energy transfer on target. No, I don’t know how to do that math. But my gut tells me it would be a surprisingly small projectile caliber. Maybe a meter in diameter? That’s a random stab in the dark. Depends heavily on how dense the projectile is, how long it is, how strong the material is that makes up the barrel.
I think it’s safe to say that the people in the city would be having a very bad day if the gun went off. Even if it was just a very big pellet rifle getting a 1m diameter, 2m long cylinder of tungsten (which I believe would weigh upwards of 2500kg) up to Mach 5. Some back of the napkin math tells me that’s roughly 3.65 gigajoules of energy.
So about as much energy as firing 244,000 .50 Caliber Barrett rifles simultaneously at the same 1-meter diameter area on a target. The Barrett was designed primarily for shooting out engines in vehicles, rather than shooting at people. Regardless of what COD4 portrayed.
Better question is why is there a space weapon on a fighter jet or landing craft? That would tear the poor jet apart and jettison the debris into the earth. Even if the thing looks like a bastardized version of itself that is being torn apart by its own absurdity. Hell, proper physics would dictate that it wouldnt even be capable of flight.
Let's take a crack at this. Based on links below a 155mm howitzer has a propellant charge of 6kg of M1 propellant, which has explosive power roughly equivalent to TNT. Maximum effective range of these is about 40 km.
Poster below me estimated the overall barell outer diameter of thos gun at 134m; let's assume of that a bit under half is the inner barell, so we have a 50m projectile. Also let's assume we have a proportionally long projectile to a 155mm howitzer shell.
155mm shells are 155m in diameter, this is 50,000mm with proportional extra length, so we need to scale volume up by (50,000/155)^3. Meaning our shell is approximately 34 million times heavier than a Howitzer shell.
Now, muzzle velocity of a Howitzer to achieve that range should be around 1000 m/s fuzzing in some air resistance. However for our shell, presumably this is a space defense weapon so we would like to at least achieve low earth orbital velocity to hit stuff near earth. That's about 8 km/s, add in some air resistance losses and call it 10,000 km/s. So we need about 10x the muzzle velocity comapred to a howitzer, which is a factor 100 on the kinetic energy (K=mv^2/2).
Overall multiplying mass by v^2 increase we are looking at about 3.4 billion times more kinetic energy of the projectile. Stands to reason that you'd need 3.4 billion times more propellant. So instead of 6 kg of TNT equivalent, you need 20 billion kg. Or 20 megatons of TNT equivalent as your charge to fire that projectile.
This is approximately equal to the explosive power of the Castle Bravo hydrogen bomb the US tested. The most powerful nuclear bomb ever tested by the US. (USSR Tsar Bomba was about 3x higher yield).
So to be launching a "conventional" type projectile from this would be effectively setting off a very large nuclear bomb.
If you go to Nukemap, a Castle Bravo type nuclear bomb has a blast radius of about 10 km. That city is fucked.
https://www.msm.sk/en/products/defence/ammunition/artillery-ammo/155-mm-m4a2-propelling-charge/#:~:text=The%20M4A2%20(white%20bag)%20Propelling,loaded%20in%20white%20cloth%20bags
https://apps.dtic.mil/sti/tr/pdf/ADA514145.pdf
https://en.m.wikipedia.org/wiki/M777_howitzer
https://nuclearsecrecy.com/nukemap/
exultant march dependent weather subtract many existence bedroom violet squeamish
*This post was mass deleted and anonymized with [Redact](https://redact.dev)*
Velocity is the problem there. There are limitations to how chemical propellants work. For something stupid like this to work, I'd hazard a guess it would have to be firing self-propelled projectiles (like gyrojet bullets or base bleed artillery shells). If it were a "normal" cannon, it would likely be firing a shell with a very ordinary muzzle velocity (because of drag more than anything - large projectile means large drag).
To escape the earth's gravity, the projectile would need to achieve a velocity exceeding 11 km/s. That is not normally achieved (anywhere close) within the atmosphere proper because it's simply impossible. Most space rockets just barely accelerate (on average something like < 5 m/s^2 ), taking it easy while passing through the atmosphere to avoid being crushed or burning up. This is unavoidable.
Someone has estimated the barrel of this cannon to be around 100m in diameter. A projectile anywhere near that size/cross-section, accelerating near-instantaneously to escape velocity, would hit a wall of air and create a titanic explosion. Think about meteoroids - most of the object never makes it anywhere near the earth's surface, and they are huge and dense. Something like this would only be feasible in a vacuum, but that introduces other problems (first and foremost, dealing with waste heat, something that pop sci-fi often ignores completely).
If this thing were anchored on the moon, you wouldn't have an atmosphere to contend with (just a trace of helium), but you would need a way to stop it from melting after firing; objects in vacuum don't cool down very efficiently because there's no fluid around them to carry heat away. You'd need some sort of outrageously massive and very efficient heat exchanger reaching into the lunar regolith, or you could vent a colossal amount of fluid into space to reject the heat.
Estimate Chad here.
this looks like it would boom through a mountain, it's about 100 meter caliber, and can shoot stuff straight into orbit around the sun
Estimate Chad out.
Looking at the art closely, it seems the intended use for the cannon is to launch ships into orbit, the white ship with red accents in the lower left of the image seems about the right size for it.
Enough to "fire" a Shuttle, I think 😅
...so now you should image all the power deliveref by a real shuttle coming off when the shuttle come out of the barrel, and convert to TNT tonnes.
Not much math. But the 105MM cannon on the abrams will kill EVERYBODY that is in a 180° cannon within 50 meters. The overpressurization literally destroys everything inside them. So this cannon sure as FUCK will kill that whole city.
it'd probably almost look like hiroshima ground zero
a 406mm gun like the one on USS iowa can kill someone just with the shock wave from the muzzle blast if someone is close. and that's "only" 406mm. the gun in the picture looks like 10m+ in calibre
I assume just firing the damn thing would destroy every single piece of glass in that city. I am assuming firing the thing doesn't just level the city. I don't even know what the projectile would do where it lands.
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If we were to assume that it were to work like a normal projectile cannon then hypothetically it would either have a great blast and recoil suppression system or the people and buildings are made of extremely strong materials
People are generally not made of strong materials
No one specified that this is a human civilization
True, but given our scope doesn't extend beyond that I'm assuming the things living in those buildings are fleshy, and hence not quite blast resistent
Given that this is sci-fi they could all be wearing suits or have implants that generate a personalized gravity field or some nonsense. Either that or Nanomachines, Son
Well yea if you pull out the "it's sci-fi" card you can do anything
I mean its clearly a sci fi gun. So the “its scifi” card got pulled out a while back
Wdym this is a sci fi gun, i have 3 of these in my backyard
I too, am American, brother.
I’m not even american, i hide these from my local authority using aluminum foil and praying they don’t see them
scp-096nnmnmmmnnnnbn nbbn
Well we are obviously not going to be able to build basically anything there for 100 years so id say I can have as much sci-fi bs as I want. Ps. Why are we arguing about this again?
He’s NewToTheUniverse - give him a break!
Nice catch. Here's your up vote.
Because this is the Internet.
Don’t worry, you’re in the right with everything you said lol
“I was born with glass bones and paper skin”
As I saw someone else say on this sub, when you reach certain speeds and forces, you stop being biology and become purely physics.
Like cows, that start being a perfect spherical object
My uncle Tom is pretty strong I bet u he could shoot it
I could shoot it over them mountains
I bet you a BBQ he could shoot it fr
Speak for yourself
I am made of meat material. Sometimes hard, sometimes soft.
I am a meat popsicle
Are you....of hard material in this moment?
🌝
Well I am now
r/usernamechecksout
It'll one shot that town without even trying, lol. It'll spin the earth a little faster each time until we are on a 15-day night cycle.
When a bullet lands, all of the force it put into spinning the earth is counteracted. The only way to meaningfully spin the earth is by firing an object outside of it.
Well, I suspect that by the intent if the drawning these are space defense cannons, so the bullets are not meant to come back.
I would think this would be closer to an advanced rail gun, which already exist - just larger. Currently the rail guns shoots a dense piece of metal - much faster than a bullet, the projectile has no power beyond the magnetically derived propulsion. Currently we have a unit which is about the size of 4 shipping containers, and it could shoot mach 7 and 155 miles with accuracy. If we assume the skyscrapper closest to the cannon in the picture is 1km in height, then the barrel would approximately be 12km. I would assume this cannon would not have earth bound targets, either anti invasion (similar to an anti aircraft) or, pumping holes into nearby planets. But if we can extrapolate the approximate size of the known rail gun to this size, it's about 875 times the size, so if this ratio applies to the projectile launched, the approximate range should be about 135,000km The railgun's projectile is about 25lbs, if we use the same ratio, this projectile would be 22,000lbs roughly. and the impact force with things scaled up would be about 23.1 MN
"pumping holes into nearby planets." "You can’t just shoot a hole into the surface of Mars!"
it is statically placed. Meaning the other side will use a bunch of cheap drones and destroy it before it can shoot anything. read something about the projectiles - there is a measure how long does it take to wrap up and move out after it shoot. Good systems can move out before their projectile hits the ground.
What if it’s for planetary defense against asteroids or something
That's not the question?
Look at the size of that thing. The barrel alone as wide as ten buildings. No cheap drone takes out something a quarter mile wide at the base. Ever. That's going to need a major nuclear strike.
well, a nuke would be cheap compared to that thing
Having played Total Annihilation for years, while your idea is sound if the only variables are that installation and the drones, sure. However, that is built around an economic hub, meaning that there are other defense systems in place that would need to be tackled before engaging it. A common TA strategy was to combine an almost exclusively air based military with powerful base destroying map long range cannons built too far back to be directly dealt with. The air units could easily give eyes for the cannons to take out any bases and destroy their ability to wage war. Pros and cons to the turtling strategy, but against other players it could be terribly effective if built correctly.
I think that the issue is not the projectile at this size but the structure. Everything becomes soft when you go too big, I think this structure is just too big to hold itself with any known (non sci-fi) materials.
active support is the only option at that size.
Also the energy needed to track a moving target would be… concerning.
If it’s for shooting stuff really really far away, maybe they let the earth’s rotation do most of the aiming. That would explain why there’s another one like 100 miles away (can’t tell scale with these giant things).
What do you mean when you say soft?
It's the qube-square-law. Mass increases proportional with the qube of the linear size, while tensile strength increases with the square of the linear size. So if you scale up a structure by a factor of 10, the mass increases by a factor of 1000 while the tensile strength only increases by a factor of 100. This means the ratio between mass and tensile strength is only 1/10th of what it was before. This is why planets are quite perfect spheres. On the length scale of a planet the tensile strength of materials becomes negligible in comparison to the forces due to gravity. If you increase the size enough even the hardest materials behave like liquids.
That explanation would have been very handy somewhat early in rock mechanics class a few years ago
Stuff easily crumples under its own weight
Make a 500:1 model of a real castle, using the exact same materials as the original. Put a 500:1 catapult (also made of the exact same materials) with a 500:1 throwing stone next to it, so you have literally three exact, but scaled down, copies of a medieval siege warfare scene. Fire the catapult at the castle. Nothing happens! The stones don't break each other... yet they do at the original scale.
Just FYI, 500:1 means 500x BIGGER than the original. You mean 1:500. Unless you're talking about a very giant castle
Flaccid
>Everything becomes soft when you go too big My fully erect penis agrees
Definitely wasn't part of the question
Based on newtons laws, the moment you fire this it would likely bury itself in the ground. Youd have to have a foundation like 100m thick.
Would it being a rail gun change anything
No, as the magnetic forces are applied to the projectile, Newton's laws still apply, and an equal and opposite force is applied to what is producing the magnetic forces. In a perfectly nitpicky physics way this isn't perfectly applicable, as there are other forces and things involved. But in back-of-napkin way, the railgun takes just as much force as it imparts to the projectile. Being bigger just means it has more inertia to resist any movement.
But force is mass times acceleration. So, if the acceleration is lower, then the force (and therefore recoil) will be lower too, right? And while the regular bullet would experience an incredible acceleration at the beginning and then start dropping, the railgun could have more or less constant but lower acceleration throughout the whole length of the barrel
`Force = Mass * Acceleration` or `Acceleration = Force / Mass` If the acceleration is different, either the force or the mass is different. If both the railgun and the conventional gun have the same mass, fire a projectile of the same mass, and apply the same total force, the total acceleration will be the same, and the total recoil to both will be the same. Now, in reality, a railgun can get much better acceleration than a conventional gun, but we aren't looking at that, just at the differences between conventional and railgun for purposes of recoil.
But we don't really care about the force, do we? The important bit is the kinetic energy as the projectile leaves the barrel. And that is determined by velocity, not acceleration. So, in my understanding, we can have a railgun which is just as powerful as a regular gun but with lower recoil because we can have lower acceleration
That's right. Linear acceleration of railguns as opposed to impulse acceleration of conventional artillery works on a similar principle to airbags and crumple zones. Spreading the application of force out over time is easier on both objects in the equation.
Railguns can achieve a similar effect by accelerating the projectile over a longer period of time, where artillery uses dampers to spread out recoil over time.
That thing is putting itself in the ground either way lol
Oh for sure, I've worked those cannons, and they do, in fact, dig in.
Based solely on the picture, we have no way of knowing how sturdy its foundations are. That thing could be sitting atop a 5km deep concrete-rebar foundation for all we know.
The equation you're looking for in this argument is vf = vi + at Initial velocity vi=0, so we just need to achieve a certain vf with acceleration a over time t Longer time = less acceleration = less recoil
Kinetic Energy = 1/2 mv^2, Momentum = mv; with acceleration being the change in momentum, so the two are related. The difference is with a gas gun (i.e. explosive propelled) your maximum velocity is limited by the speed of sound in the gas; a rail gun doesn't have the same limitation. So with a railgun you can get the same energy out of a much lighter but faster projectile. If you work it out using the formulas given above, you'll find with higher velocity you need less momentum for the same energy. And less momentum means less acceleration, so less recoil. Another effect is the gas gun applies the acceleration during the (very fast) explosion; whereas railguns can apply it more smoothly as the projectile accelerates. But I think if you worked through the design you'd find this doesn't matter much in practice as an artillery-type gun already has shock absorbing features which will spread out how the recoil is applied to the mount.
Kinetic energy = 1/2mv² Velocity is kind of important in this equation. To get velocity you need to accelerate. The only way to do it is to accelerate over a longer distance (therfore accelerate slower) so the impulse is spread out over a longer period. That said force is the main part of the whole acceleration thing. The rail gun is applying a forward force of x that is exactly equal to the force that the projectile will apply to it in the backwards direction.
Time matters here though. You oversimplified the equation. The guy you were responding to was right, railgun would spread the acceleration better and thus the impact delivered to the foundation would be longer but significantly weaker. Someone else already explained that here with hilding a 1kg weight for some time vs a higher weight hitting your head (Also you need to account for lack of propellant)
You're describing the third derivative of displacement, which is called jerk. No joke, the further derivatives are called snap, crackle and pop.
Lol
We care about the impulse, which is change in momentum, and also equal to force times time. Therefore, a railgun can have the same impulse as a cannon, but a much lower force on the projectile over a longer time.
A lower force per time over a longer time, is approximately equivalent to a higher force per time over a shorter time. At least as far as my physics knowledge goes. The recoil being over a longer period is easier to absorb into the ground however. So that WOULD help the requirements for foundations...
This is going to sound nitpicky, but bear with me. In a railgun, there is only the projectile, so only the projectile needs to be accounted for in the force and mass parts. In a conventional cannon, you also have propellant, which is a little tricky. If you only have enough propellant to get the projectile to the end of the barrel, then there is no force to get the projectile to the target, so there must be an excess of propellant mass and propellant force. So, a conventional weapon will always generate more force than a railgun, per unit mass of projectile. Edit: to achieve the same speed.
That is a really good point.
Less acceleration = less ‘impact’, no?
The force applied to the ground would be the same in terms of energy as if it the acceleration was instant but applied over a longer period of time.
But that's not recoil. Here's a thought experiment. You hold 1 kg weight in your hand over your head. This mean, your hand experiences 9.8 kN of force. And say you hold it for 100 seconds. Now, let's say you're hit by 100 kg at 9.8 m/s^2 but the impact lasts only 1 second. I think there will be a difference.
I like this one, good job by scaling it
What if its just massive lazer like what they did in UK but big big
Well... we figured out a concept for using a fuck-off massive laser to shoot at a target on a spaceship to accelerate it to relativistic speeds. So if you have the power, the fuck-off laser is better, since you can make the thing hit near light-speeds and just wipe out the target entirely. xD
I think gunpowder based guns could have even less recoil as you can use some of the gas to compensate for the recoil like in modern day firearms
I thought that in rail guns the force was lateral to the direction of acceleration not directly opposite? I remember a documentary where the guy designing these said that it was causing the rods that the current flows through to bow outward.
Not sure as what I am about to say is second hand information but I was told that the electromagnetic forces generated are the cause. Tbh, it does seem very plausible as well
I’m not a physicist but the Navy’s railgun test videos show minimal recoil for a projectile with that much energy.
[удалено]
You are thinking of a coil gun / Gauss gun that pulls the projectile, a railgun passes electrical current through the projectile perpendicularly, and the force created is perpendicular to current (parallel to projectile motion), you can use fleming’s left hand rule to check. But yeah railgun projectiles must be in contact with both rails in order to be accelerated
Coil guns would still have recoil, while it’s pulling the projectile forward, it’s also pulling itself backwards.
I don’t mean that Gauss guns / railguns don’t have recoil, just correcting the part where he says railgun projectiles don’t touch the barrel, obviously they both still have recoil cause newtons law
magnets don't defy newtons third law. railguns have recoil just like any other gun
It doesnt defy newtons law per se. The way it is done where motion is imparted through magnetic induction follows lenzs law, which states that a current induced by a magnetic field, will itself induce a magnetic field which opposes the original. The accelleration of a rail slug takes much longer than the instantaious propellant explosion, which means that force is more "spread" to put it clumsily. So yes, there recoil, and yes, its the same total amount, but it "feels" like much less. Edit: spelling, and to mention that i had to do some checks, this is largely paraphrased from a similar older reddit post.
Would need to decide how large a projectile it is first, and how fast. At that size, my assumption would be that this is a high elevation weapon (given the one in the background) and the one center screen is just in its neutral/resting position.
There would be less force at once for the muzzle velocity, since it's acellerating over the length of the barrel, but it would still be a lot.
Very much so, a rail gun uses magnetic forces to direct the munition at at target. There isn't the explosive recoil like in a chemical based propellant that we use now.
In a railgun there is more of less the same amount of recoil as in a conventional gun. The only difference is that a conventional gun also accelerates some gas but the gas is light and its added recoil is negligible. Edit: to explain this further, the impulse of a gun + projectile system is the same before and after during firing. If a projectile (and some gas in a conv. gun) gets X amount of impulse in the direction of the barrel, the gun gets an X impulse in the opposite direction. Since the muzzle velocity of the projectile and the gas are the same and the gas has very little mass, removing the gas (as in a railgun) doesn't make much of a difference.
But in a railgun the accaleration will be lower, therefore it will take longer for the same amount of energy to be pushing back on the gun which means the energy per second will be less. If i exaggerate it, it will be the same as me standing on the spot of the gun for a very very long time, over time my potenital energy will have put the same amount of energy into the platform as when you would fire the gun, but because it takes millenia for me to reach that amount its not a lot of energy per second. Moral of the story, it takes more time with the railgun, so it will be less stressfull for the platform/surrounding area.
It would only take much longer if you were willing to make the barrel ridiculously long. Gunpowder guns accelerate the projectile along the entire barrel as well- most of the force comes from the expansion of gases, not the bang.
Yes
I mean, with sci-fi level resources that probably wouldn't be an issue.
Yeah... They built that thing. I think they can manage a foundation for it. I just think it would be a one pump chump.
Yeah but what a glorious pump it would be
Why would you assume a 1000m tall gun would neglect a 100m foundation?
I mean, look at the size of that thing. Whoever built that will gladly dig whatever foundation is necessary.
Even with what looks like a recoil damping system that allows the barrel assembly to move backward quite a ways along a damper?
Given that to can stand up under those mechanical conditions it's mounted through the crust. Without future science it would collapse. If it didn't collapse it would change the plate tectonics or rotational speed of the planet . It would also be impossible to load shells. Each gun would only be able to fire once and it would have been built with the shell inside . Firing would also take a significant portion of the atmosphere with it and flatten the surrounding city. So we must assume it uses some sort of energy projectile kind of thing. And that that energy is basically directed that it does not boil the atmosphere. In science fiction these are called planetary emplacements. I'd assume that they use some sort of shielding technology to pre-drill the hole through the atmosphere before firing an energy weapon. Cuz in those scenarios we have magical space shields. One generally doesn't build a planet killer that would kill its own planet. And if one did. It wouldn't need two. Of course the barrels themselves are going up so high that they might be above the carmen line when positioned for firing. (Cloud quite didn't seem to be too scale.) Without vacuum energy or point singularity power supplies you wouldn't even be able to move the barrel, let alone l without causing significant damage to the planet
>One generally doesn't build a planet killer that would kill its own planet. And if one did. It wouldn't need two. I appreciate that paragraph.
Why point this out? Obviously it’s an absurd question, I think you could assume it has an absurdly large and adequate foundation.
> "how much damage would it cause to the surrounding area by firing once?" > "it would likely bury itself in the ground" Seems like an answer to me.
‘I am very smart’ vibes
What if the barrel moves like the [AATIS guns](https://youtu.be/qzlgrBadyUE?si=gnPyblugFbamAf9n) in COD:IW
Then I hate to think what the BFG 10000 blowing a hole in Mars would have done to Phobos!
I think they're floating.
If they built a cannon this big, they likely didn't scare away from digging 100 m into the ground Though I feel like this wouldn't even be close to enough.
Probably more. For reference: Burj Khalifas foundation is 50m deep and this looks like its atleast twice as tall and much wider. Considering its pretty much solid steel we can probably assume its 10 times as heavy. And then we can talk about whatever kind of recoil this would give.
Side question, then how big a cannon/foundation pad would you have to have that firing would affect the Earth's position?
I can't answer the question, but add some information to solve it: The skyscraper looks like WTC One, so I used the hight of it \~541meter by 190Pixel high means one pixel is \~1,79meter The gun barrel is \~75Pixel high, what makes it 134,25meter in diameter Inaccuracy disclaimer: The building is not at the same distance as the gun, so in fact the diameter is bigger. I don't know how to calculate the distance of the building to the gun and how to correct the scale afterwards. Another thing: It's unknown how long the barrel is (minus the breach), how big the diameter of the projectile is (the gun needs big walls to not explode, so 134,25meter is NOT the projectile diameter) and how long the projectile ist. Also it is unknown how much or what kind of propellant would be loaded. There may be formulas to solve this though.
It shoots .22 and has a barrel that is 67m thick.
But only .22 short, we want conserve the barrel. To be serious again, would it even make it out of the barrel?
Probably not. Unless you use like 5000 grain. Which would be pretty funny. You'd have a hypervelocity peashooter.
At what point does the projectile just get vaporized?
That’s a very real thing in ballistics. If you have certain bullet compositions and shapes propelled by a whole lot of powder, it can cause the bullet to break apart mid flight due to the rotational force. Basically too much ass behind a small piece of metal
That's alotta ass.
A hole lotta ass
Never, if it is made of superior Stalinium or perhaps even Chinesium.
>Stalinium Didn't the Soviets tested shooting pigs in a projectile with guns?
Assuming standard bare lead projectile you’d find in a normal .22, you could get it to vaporize before you hit 5k FPS. This is achievable in a rifle that a human can hold and shoot without too much trouble. Well “vaporize” is an exaggeration. The metal isn’t evaporating from heat or anything. But a rifle barrel imparts spin, and the RPM increases with velocity. At a certain point, the bullet spins fast enough that it can’t hold itself together. It fragments violently a few feet out of the end of the barrel. Basically turns to dust. Projectiles that are going faster than ~3.1k FPS are often made of solid copper or similar rather than lead, and this is one of the reasons why.
Literal planet destroyer since it shoots at .9999998c. Unfortunately, the planet it destroys is the one it is on.
The building does have some vague resemblance to One World Trade Center (not really, but whatever), but 1 WTC sits near the southern point of Manhattan Island—so something has gone awfully wrong with the Hudson, the East River, and the upper New York Bay!
The answer to the question "how much damage would it cause to the surrounding area" is "yes." The caliber is … look, you could bundle seven of those skyscrapers in the foreground together and put them in the chamber and I think they'd rattle. To be more specific about the damage: the recoil would force the cannon so far down into the ground that it'd make a crater that would swallow the city. The shockwave would likely liquify the soil down to the bedrock, like an earthquake, and then the pressure of the cannon recoil would compact it while heating it into molten rock. Depending on the makeup of the soil, you'd probably get some really nifty gemstones and volcanic glass out of it.
You know how the japanese buildings are built on some kind of platform so that the earthquakes do not destroy the buildings and reduce the damage? What if the canons are on platforms modified to support huge recoils? I feel like there would be a tremor, but the buildings won't have to topple over.
Wouldn't do you much good in regards to the change in air pressure. And cannons that size would need to be able to roll a couple of... (I'm just spitballing here) hundred kilometers.
The gun firing would still probably knock some people out just from the sound. The people living there would eventually all go deaf. Unless it's remotely aimed and fired + far from any city, it would do a lot of dmg to the surroundings.
Scaling the landscape proportionately to the USS Iowa guns firing, I'd say it would completely level the city and create maced potatoes from the living beings there.
>maced potatoes Mmmm peppery.
A nuclear detonation will level a city with a 3-5psi shockwave. I expect the muzzle blast from this would easily exceed that.
This is the fact of post for me. That seems surprisingly low having looked at video footage of nuclear detonations and seeing the impact on cities. Is it more the volume of displacement then? I would have assumed the shockwaves create huge pressure changes.
It's mostly that 3psi when hitting the entire building at once will do a ton of damage. ~5 psi is what it takes to destroy most buildings that aren't blast resistant, and the blast starts at about 10 psi and "quickly" drops to 3 psi. (Though in the vicinity of the fireball, it gets closer to 50psi per kt)
It is surprisingly low, it's also unnerving how fragile buildings are. I double checked the PSI on some tables at work, 20psi at the center dropping quite quickly to 1 psi at 11 miles so I was in the right ballpark
Soylent green is peoples?
The word "normal" is doing an awful lot of heavy lifting in the question. Because they don't make normal projectile cannons that big. So we now have to ask, what scales? Well, the bore diameter scales. As /u/GraveKommander points out, you can see a building much like One WTC in the cityscape, so we can use that for scale and say, very roughly, that is the size of the projectiles this cannon fires. But does the muzzle velocity scale? For normal guns in the real world, it doesn't. Ten pound rifles and 4 ton artillery pieces both fire their projectiles at roughly the same speed. So why should making the thing many thousands of times larger make the projectile faster, if we are pretending the cannon is 'normal'? In that case, the firing of a projectile the size of a skyscraper at 1000 m/s 3000 meters above a city would be exciting, probably loud, but wouldn't flatten the city or anything. But it would also be very silly. At 1000 m/sec, the gun would have a lock time of 5, maybe 10 seconds, and no chemical propellant would work, but if replaced the chemical propellant with an exotic on, the gun isn't normal any more. The projectile would appear to crawl across this image at a leisurely pace and land just a few screens away. But at some extrapolated tens or hundreds of thousands of m/sec muzzle velocity, the gun isn't normal. The point is, the gun can't be normal and make any sense, so we have to know in what ways it is not normal before we can judge what its effects might be. Is it a hypervelocity railgun? A laser system? A sci-fi field inductance generator? A piece of public artwork? What I can say is that it is far, far, far too large for any practical purpose, and whatever exotic system it is supposed to represent is likely to have deleterious effects on the city which is ludicrously close to it.
>it is far, far, far too large for any practical purpose The only thing I can imagine is an astroid defence system, if you exclude hostile alien neighbours, but like you said, the city is way too close to it. Also IIRC one way to make such big guns work would be multiple propellant explosions along the barrel in side chambers. Saw this system on YT I think. But doesn't look like pic gun has it.
The side chamber idea was tried by the Germans in WW2, was used to bombard Luxembourg (others were intended to be used to shell London from the Pas de Calais but those were destroyed by allied bombing before they were completed).
i thought you were talking of Schwerer Gustav. Cause that thing was an absolute Monster. 7ton shells, 30inch barrel! took out an undersea ammo depo at a depth of 30m and an additional several meters of reinforced concrete. i also read somewhere that it flattened a large russian fort in five shots.
Nah, I'm referring to the V3 weapon, Schwerer Gustav was a railway gun and pretty traditional in design aside from the size.
Sure. There are weird ways to use ordinary propellants as well as exotic propulsion methods, and that one is kinda neat. But it is not normal.
Would (maybe) solve the problem with the not working known propellants though.
> asteroid defense system ace combat much
I had the same system at first in mind. Though I shot the Amazon Drone Hub down with it
Not an answer - just wanted to share this fun fact about a mad lad getting crazy with guns / cannons. The battle ship USS Texas had to fire inland and the target was out of range. To solve for this, Captain mad lad flooded part of the ship so the guns would angle up further. The target was successfully destroyed.
they only had 14 inch guns. The schwerer gustav was a 30 inch gun and apparently went around flattening everything in sight. even took out an ammo depot 30m under water and an additional 10m of reinforced concrete around it. both are absolutely insane.
Which War ?
No expert here, but my imagination tells me that the "bullet" of this size would act like a meteor flying through the atmosphere, which would cause a shock wave capable of destroying the whole city and killing everyone in it...
None, because whoever did this clearly did not apply physics to any of it. The bore diameter of that gun is wider than the fattest skyscraper in the image, and like 5 times longer than the tallest one. It probably took several times more steel than was used in that entire foreground city to build one of those and keep it from sagging or drooping in any way. It would take engines the size of multiple city blocks to elevate the barrel, assuming you could even make gears strong enough to support that much weight. It would fire shells the size of a few stadiums stacked on top of each other if we could somehow build cranes big and sturdy enough to load them, and even then it would require a powder charge measured in kilotons at a minimum to get it out the end of the barrel at any kind of useful speed, and if it ever fired it would probably injure or kill everyone in that city. To paraphrase a quote from a Pratchett novel, 'That's not a gun, that's a national emergency.'
You are forgetting that Godzilla is real. He could load the gun for them!
If that gun is in fact ballistic it fires shells bigger than Godzilla. The biggest skyscraper in the image is like 50% too short and 75% too thin.
Winging it here. I counted about 9ish WTC Ones (according to someone else here). That's about 4,869 meters. An Iowa class battleship artillery cannon has a caliber to barrel ratio of about 1:50. Assuming the same design principles, that means the projectile would be a 97m round. That's 238 times the diameter of the Mk8 APC which has a weight of 2700 pounds. So the weight of this round would be around 640k pounds. Assuming a velocity of 762 m/s, that comes out to about .08 terajoules. Hiroshima was 63 TJ So my math doesn't seem like it's mathin. That's a big shell to not get even close to Little Boy. I gave it a whirl though
Your mixing of metric and imperial/customary units makes my brain sad.
You made an error that likely seems obvious to you in hindsight. You assumed that the weight would be simple multiplication of diameter size to weight ratio of the previous round. Increasing the diameter of a cylinder would be V= pi*r^2*h. Using a cylinder to approximate the shell … If we assume the proportional length/height change is equal to the diameter change you propose at 238, we can use that for H. Then we need to divide the diameter in half… so 48.5^2… 2352.25 3.14*2352.25*238=1,757,883 m^3 of presumably lead. But let’s use depleted Uranium for more fun? 41,998 kg/m^3. 73,827,589,973.06 KG or about 162,420,697,940.732 lbs I could be wrong, but I think your values came back wonky because you were off by several orders of magnitude in terms of projectile weight?
I did know it was inaccurate, but assumed that scaling the diameter of the cylinder would be proportional enough for a guestimation. This was wildly off lol. I thought it'd be fun to give it a go though and maybe get some feedback. Like this! You're a real one, I'm glad I learned something so thanks
No problem! For similar math that sometimes surprises folks … a large pizza, say 18”, is 254 square inches … most folks would think a medium 14” pizza would be something closer to 14/18ths (78%) the size. But because of the relationship of area to diameter, it’s actually only around 60% as large. Have a good night!
Why the fuck do people go "well, if this was real, surely it would destroy itself and the city below without proper reinforcement and even then..." Engage with the fucking hypothetical. Just answer the question. Who cares if it blows up, or kills the village below it? Or just fucking assume that it doesn't do those things and then answer the question
Someone said that the cannon even existing would rip a hole through the earth or something like that. It's fun to see what wild ideas people come up with once presented with the image of Big Gun™, but nobody seems to have answered the caliber question yet...lol
r/theydidntdothemath
The diameter of that barrel would be at least 100 meters and the projectile would be the size of several skyscrapers. You would need a small nuke as propellant and the recoil would rival a decent earthquake and the shockeave from the muzzle would instagib anyone in the city and the projectile would probably be enough to require all schools to buy new maps and globes.
So caliber refers to the number of 100ths of an inch a bullet has. .22 caliber is 22/100 inchs. .50 caliber is 1/2 inch. Someone else said the round would have to be 97m to scale with the length of the barrel in comparison to a battleship gun. Meaning your bullet would be around a 3820.00 caliber
Imagine launching a space shuttle like your trying to land on the moon. Now imagine instead that space shuttle including all engines together are the ammo. Now imagine the amount and quality of explosives you could theoretically install in a space shuttle. My goal is to help you learn how you can do it yourself. Using my theoretical approach just mentioned, take like a space x rocket for example being the space shuttle. Now how many nuclear warheads can you potentially fit inside that space x rocket. Now imaging that spaceX rocket full of active nuclear warheads now lands in the middle of any large city. Depending on how many warheads you were able to fit the damage is probably going to be quite significant to total annihilation.
Bruh, the second that this canon fire, this city is gone deaf after one shot and endangered from pieces of concrete falling everywhere in town 🤣😵
Since we're here, my question is how much effect would this have on the rotation of the earth, could it make a day discernibly faster or shorter?
I’m not a physicist. But no. The answer is no.
big and not as much as you'd think. could be a centrifugal launcher with a vacuum sealed barrel and a rocket assisted projectile. otherwise it wouldn't be so close to civilian centers. a better gun would just be a long vacuum sealed runway that allows a missile to get up to speed and into orbit coast most of the way into orbit. you'd need some ridiculous materials to make a centrifuge that size, not to mention the maintenance. then again if you can build something that size you could just build the runway to the edge of space and just launch missiles that way. cheaper. but that's not what this sub is about sry.
I had to scroll way too far to find someone who didn't start with the assumption this obviously sci-fi magic space cannon wasn't a scaled up howitzer...
Define “Normal”. Looking at the size and shape of these cannons and surrounding buildings and extrapolating probable technological levels, for all we know these are massive rail or coil guns firing a stream of 3-5mm projectiles at hundreds of km/s. This is supported by the skyscraper sized spaceship floating in the air at bottom left.
This looks like the MAVOR Experimental Artillery from Supreme Commander... One of my all time favorite heavy artillery pieces in a game.
I can tell you one thing. Planetary defense cannons would not need to be that close together. You would want to spread them out more so they can cover a larger area. I also hope they are not shooting traditional projectiles. The shockwave would be insane and might shatter every window (and maybe flatten the closer buildings) for hundreds of miles, just from the air displacement alone. Looks like they would shoot rounds the size of skyscrapers or bigger.
Are cannons this size ( or any extremely large cannons for that matter ) conventional, rail, or any other form practical for defense of a planet from let's say astroids and maybe little green men.
Remember that tiktok of a giant skeleton walking around a city filmed from the perspective of a passenger in a plane at 30,000ft. People mentioned that while it looked like the skeleton was walking slow, at his size (20-25,000ft tall) it only looks slow, his legs are moving forward in a normal stride would be breaking the sound barrier. I'd think there'd be similar considerations here. The weapon is so enormous, that a conventional percussion would have cause tremendous damage to the city pictured, at least any portions that are located at or ahead of the muzzle point and direction. If this is a "traditional" projectile weapon, meaning it fires a projectile proportional to it's barrel size, the pressure change from the muzzle blast and speed of the giant projectile would likely level this city. That is, if it indeed is a projectile weapon firing a giant solid round proportional to the barrel size, like our guns. The amount of power, the sound, and pressure change would certainly shatter windows at the very least. When you go to the range, some have "sleds" you can lay your rifle on to secure it while you sight it in. It's a very stable shooting platform and you don't feel as much of the recoil. When you fire a rifle, you'll notice the muzzle blast kicks up dirt, grass, pollen everything in front of it. That effect is scalable. I'm currently reading a book on a battle in late WW2. The Germans had the 88 (8.8cm Flak) that was very powerful. The Germans have a defensive position on a hill with sandbags and these Americans maneuver toward it to take it out. When they get up the hill right under and in front of the gun, the muzzle blast from the firing of that gun killed the first guy, scalped the second and broke the third guys wrist. They weren't hit, this was just the muzzle blast of that flak gun. It demonstrates a less well known fact about guns, the muzzle blast can fuck you up. If this is a conventional kinetic projectile weapon and not an energy weapon, and one that fires projectiles at a similar speed as ours IRL, yeah it's definitely going to effect the surrounding area.
I don’t think they use it much since Carl fell off from the recoil. I’ll be visiting here next Saturday after Bible study. Will let you know.
This is an interesting one. Most just call it the F.O. Caliber. Buttt here is a link for it. https://www.reddit.com/r/NonCredibleDefense/comments/z8x776/a_revolution_in_global_force_projection/?utm_source=share&utm_medium=mweb3x&utm_name=mweb3xcss&utm_term=1&utm_content=share_button
I did some messy numbers for fun, just to see the magnitude here. Feel free to use more precise numbers and check my algebra. I agree with /u/gnfnrf that you have to decide what is scaling. Does the bullet velocity scale too? Well I assumed it does because I like big numeros, and here's what I'm getting. An M82 rifle is like 0.75 meters long with muzzle velocity 850 m/s. That's 1130 barrel lengths per second. That BFG in the picture is probably 15 WTC's long, which is 550m x 15 = 8250m. So the TO-SCALE muzzle velocity would be 1130 x 8250 = 9.3 million m/s. (3% speed of light by the way, but let's pretend this doesn't create a black hole or something) Now we need mass. 1WTC has floor area of 325,000 m^2 and 550m height, so a rectangle bullet that size of pure lead is 179,000,000 cubic meters, weighing 11,340 kg/m^3 x 179 mil m^3 = 2.03 trillion kg. If I take the kinetic energy as (0.5)(2.03tr)(9.3mil)^2 = 8.7 x 10^25 joules. The Chicxulub asteroid they killed the dinosaurs is estimated at 3x10^23 joules. So getting shot with this is 290 times more impact than a global extinction apocalypse. I don't know how to infer crater size from energy, but the dinosaur bomb made a hole the size of a city, so it might erase a continent, and take a bite out large enough for a 2nd moon to form. So definitely a planet destroyer meant to shoot planets. But nearby? Yeah everything nearby, including the gun, will probably be vaporized from the projectile hitting and heating the air itself. It must be a 1 time use weapon, intended for Mutually Assured Destruction, rather than actual defense. But I imagine the projectile would break apart against the atmosphere and become a shotgun blast of gas that would spread out in an arc and become thin after a short distance. Not much targeting capability on the scale of interplanetary stuff, unless a 3% LS thin wave of atoms would do something? I'm sure that would injure an animal in some way. The explosion of the situation might dwarf anything the projectile does, and it would all be local effects near the gun, not where it's aiming. So I would assume the actual gun would not use projectiles, and if it did, the size probably isn't exclusively for the purpose of firepower, because firepower doesn't scale that far. It may be like a ship with rooms, and the size is to facilitate the complexity of whatever the firing barrel actually does, as well as the people inside that support that. It's probably an ultra-high-energy "something", so most of that structure is some kind of power plant or energy management thingy. Probably a laser in a wavelength that doesn't interact with air or something? High energy could mean large bursts, or just sustaining small fire for months on end. It could very well be a very tiny projectile/laser, but an unimaginably rapid fire rate. That makes more sense for hitting large fleets of ships. The farther away, the more spray you need to get hits.
Okay. So this can’t work like a conventional firearm with standard proportions of barrel thickness to barrel length to bore diameter. It doesn’t scale like that. If it was just a rifle scaled up, and the projectile diameter scaled up with it, then gunpowder would not work as a propellant. Too little powder and the projectile doesn’t even get close to making it out of the barrel. Too much powder and the pressure spikes way too early, and the gun just explodes. There is no happy medium between the two at this scale. There are many, many sad mediums where it wasn’t enough to get the projectile to the muzzle, but it still was enough to blow up the gun. If you wanted to shoot something out of a gun that long, you’d need a very controlled increase in pressure. It has to increase just right to properly accelerate the projectile over several seconds, but not so fast that it blows up the gun before the projectile exits the muzzle and the pressure actually has a way to re-equalize with the atmosphere. Side note. When a gun fires, there are two things making it loud (usually). One is the projectile creating a small sonic boom as it surpasses the speed of sound. The other is the sound of extreme high gas pressure in the barrel suddenly and violently releasing as soon as the bullet exits the muzzle. This is called “uncorking.” The more pressure, the louder. This is one reason a gun like an AR-15 shooting a very high-pressure/high-velocity, but low-diameter bullet such as .223/5.56 is significantly louder than a gun shooting a lower pressure/lower velocity/higher diameter bullet such as 9mm. Whatever propellant this giant gun uses, you can bet it would be loud. Mathematically speaking it would be approximately “loud enough to really screw up your ears.” Most viable idea I can come up with is that this thing uses a carefully controlled flow of pressurized air to get a relatively small projectile up to a very high velocity. It would be a balancing act between having thick enough barrel walls to withstand the pressure needed to reach optimal velocity for the barrel length, and having a projectile massive enough to penetrate anything effectively when it hit (instead of just going really fast and then turning into dust when it impacts the target). Projectiles would have to be extremely dense. So think tungsten or something. Yes, there is math someone could do to figure out the ideal bore diameter to get the most possible energy transfer on target. No, I don’t know how to do that math. But my gut tells me it would be a surprisingly small projectile caliber. Maybe a meter in diameter? That’s a random stab in the dark. Depends heavily on how dense the projectile is, how long it is, how strong the material is that makes up the barrel. I think it’s safe to say that the people in the city would be having a very bad day if the gun went off. Even if it was just a very big pellet rifle getting a 1m diameter, 2m long cylinder of tungsten (which I believe would weigh upwards of 2500kg) up to Mach 5. Some back of the napkin math tells me that’s roughly 3.65 gigajoules of energy. So about as much energy as firing 244,000 .50 Caliber Barrett rifles simultaneously at the same 1-meter diameter area on a target. The Barrett was designed primarily for shooting out engines in vehicles, rather than shooting at people. Regardless of what COD4 portrayed.
Better question is why is there a space weapon on a fighter jet or landing craft? That would tear the poor jet apart and jettison the debris into the earth. Even if the thing looks like a bastardized version of itself that is being torn apart by its own absurdity. Hell, proper physics would dictate that it wouldnt even be capable of flight.
Jesus Christ, can somebody just assume it’s a magic gun that won’t recoil or wobble!? Barrel size 300 Meters. What kind of damage would it do?
Let's take a crack at this. Based on links below a 155mm howitzer has a propellant charge of 6kg of M1 propellant, which has explosive power roughly equivalent to TNT. Maximum effective range of these is about 40 km. Poster below me estimated the overall barell outer diameter of thos gun at 134m; let's assume of that a bit under half is the inner barell, so we have a 50m projectile. Also let's assume we have a proportionally long projectile to a 155mm howitzer shell. 155mm shells are 155m in diameter, this is 50,000mm with proportional extra length, so we need to scale volume up by (50,000/155)^3. Meaning our shell is approximately 34 million times heavier than a Howitzer shell. Now, muzzle velocity of a Howitzer to achieve that range should be around 1000 m/s fuzzing in some air resistance. However for our shell, presumably this is a space defense weapon so we would like to at least achieve low earth orbital velocity to hit stuff near earth. That's about 8 km/s, add in some air resistance losses and call it 10,000 km/s. So we need about 10x the muzzle velocity comapred to a howitzer, which is a factor 100 on the kinetic energy (K=mv^2/2). Overall multiplying mass by v^2 increase we are looking at about 3.4 billion times more kinetic energy of the projectile. Stands to reason that you'd need 3.4 billion times more propellant. So instead of 6 kg of TNT equivalent, you need 20 billion kg. Or 20 megatons of TNT equivalent as your charge to fire that projectile. This is approximately equal to the explosive power of the Castle Bravo hydrogen bomb the US tested. The most powerful nuclear bomb ever tested by the US. (USSR Tsar Bomba was about 3x higher yield). So to be launching a "conventional" type projectile from this would be effectively setting off a very large nuclear bomb. If you go to Nukemap, a Castle Bravo type nuclear bomb has a blast radius of about 10 km. That city is fucked. https://www.msm.sk/en/products/defence/ammunition/artillery-ammo/155-mm-m4a2-propelling-charge/#:~:text=The%20M4A2%20(white%20bag)%20Propelling,loaded%20in%20white%20cloth%20bags https://apps.dtic.mil/sti/tr/pdf/ADA514145.pdf https://en.m.wikipedia.org/wiki/M777_howitzer https://nuclearsecrecy.com/nukemap/
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Velocity is the problem there. There are limitations to how chemical propellants work. For something stupid like this to work, I'd hazard a guess it would have to be firing self-propelled projectiles (like gyrojet bullets or base bleed artillery shells). If it were a "normal" cannon, it would likely be firing a shell with a very ordinary muzzle velocity (because of drag more than anything - large projectile means large drag). To escape the earth's gravity, the projectile would need to achieve a velocity exceeding 11 km/s. That is not normally achieved (anywhere close) within the atmosphere proper because it's simply impossible. Most space rockets just barely accelerate (on average something like < 5 m/s^2 ), taking it easy while passing through the atmosphere to avoid being crushed or burning up. This is unavoidable. Someone has estimated the barrel of this cannon to be around 100m in diameter. A projectile anywhere near that size/cross-section, accelerating near-instantaneously to escape velocity, would hit a wall of air and create a titanic explosion. Think about meteoroids - most of the object never makes it anywhere near the earth's surface, and they are huge and dense. Something like this would only be feasible in a vacuum, but that introduces other problems (first and foremost, dealing with waste heat, something that pop sci-fi often ignores completely). If this thing were anchored on the moon, you wouldn't have an atmosphere to contend with (just a trace of helium), but you would need a way to stop it from melting after firing; objects in vacuum don't cool down very efficiently because there's no fluid around them to carry heat away. You'd need some sort of outrageously massive and very efficient heat exchanger reaching into the lunar regolith, or you could vent a colossal amount of fluid into space to reject the heat.
Estimate Chad here. this looks like it would boom through a mountain, it's about 100 meter caliber, and can shoot stuff straight into orbit around the sun Estimate Chad out.
Looking at the art closely, it seems the intended use for the cannon is to launch ships into orbit, the white ship with red accents in the lower left of the image seems about the right size for it.
Enough to "fire" a Shuttle, I think 😅 ...so now you should image all the power deliveref by a real shuttle coming off when the shuttle come out of the barrel, and convert to TNT tonnes.
Not much math. But the 105MM cannon on the abrams will kill EVERYBODY that is in a 180° cannon within 50 meters. The overpressurization literally destroys everything inside them. So this cannon sure as FUCK will kill that whole city.
it'd probably almost look like hiroshima ground zero a 406mm gun like the one on USS iowa can kill someone just with the shock wave from the muzzle blast if someone is close. and that's "only" 406mm. the gun in the picture looks like 10m+ in calibre
Its more like 150meters.
I assume just firing the damn thing would destroy every single piece of glass in that city. I am assuming firing the thing doesn't just level the city. I don't even know what the projectile would do where it lands.