An Ancient Discoveries documentary I recently saw claimed on several occasions that the Ottoman bombard (a big cannon) used in the siege of Constantinople in 1453 could propel a stone ball weighing 1500 lbs. to a distance of one mile. I find this utterly unbelievable, due to the humonguous amount of energy needed (scientific, yeah). Could any engineers here offer proof either way?
Maybe they’re counting the distance that the ball rolled after hitting the ground.
Ignoring air resistance, you need to accelerate a body to ~280 mph in order to get it to travel 1 mile. This requires ~10 MJ for an object weighing 1,500 lbs, which according to wikipedia is the kind of energy released by about 20 lbs of gunpowder.
So, theoretically, a “tiny” amount of black powder is all it takes - ignorance fought!
I guess air resistance is a big hindrance here? Also, isn’t maximum projectile range achieved with a roughly 45 degree “launch angle”? In practice, the largest cannon ever built (in the 15th century) would shoot roughly horizontally. Also, stone cannon balls didn’t fit very precisely into the cast cannon muzzles - some leakage of explosive energy surely results from this.
Guess I hoped for an estimate of how far would a 1500 lbs. ball fly from a bombard under real-life 15th century battlefield conditions. The myriad variables combined with little real data probably make any estimate little more than an educated guess.
Here’s what the thing looked like. The two halves screwed together. Total weight around 17000 kg.
I’ve seen that one - Fort Nelson is only a few miles from here - it’s enormously impressive - (note the wooden bench seat at the far end, for an impression of the size.
Yes, the “280 mph” calculation assumes a 45 deg angle. The ball wouldn’t fly very far if it was shot horizontally. For example, if it was shot horizontally from 10 feet off the ground, a 4600 mph initial velocity would be required to reach a mile.
Yes as Iambatman says this assumes the ball is fired at a 45 degree angle which is always the maximum when air resistance is ignored (and other factors such obstacles). Whilst most of the factors that have been ignore (e.g. air resistance) will tend to decrease the range of the cannon, firing it from high ground to low ground would increase the range.
I can’t say I know a lot about cannons, but I would’ve thought that a siege cannon would generally fired at some angle to the horizontal. I think those operating the cannons would’ve almost certainly been aware that 45 degrees was approximatley the optimum angle for distance.
A 1500# granite shere will be on the order of 32" in diameter. Way too big for me to lift, but not some gigantic 10’ thing that would take all the king’s horses & all the king’s men to move.
As to launch angle, what are you trying to hit? If you are seiging a stone castle or walled city defended by archers, you want to set up just outside arrow range (200 yards?, 300?) and fire more or less horizontally to breach the walls.
if I had to aim a seige cannon at a wall from close up in cannon-range terms, I’d sight the bore to just graze the top of the wall, knowing I’d get some projectile drop enroute.
The plunging high angle fire commonly used with modern artillery is based on explosive shells and the need to be well back out of range from the enemy artillery counterfire.
In modern naval gunfire, they tend to shoot much flatter trajectories than land-based artillery. Why? There are no obstacles over the water enroute to the target, and the thing they’re trying to hit resembles a wall. i.e. getting the range right to within 100’ at most (the target ship’s beam) is tough, but since it exposes vertical development you can shoot into the side of it as long as your shell passes that range above the waterline and below the mast-top.
Maximum range is a nice sound-bite number to throw around, but isn’t really the main measure of merit for artillery, modern or ancient.
iirc from a bygone hw problem, at 1atm, the optimal launch angle is around 30 degrees.
4600 mph, hmmm.
That will take more powder.
Heh, heh.
Maybe in the specific homework problem you did, but it’ll depend on the shape, size, and density of the projectile and on the muzzle speed of the gun. There’s no one single answer.
Plus if you want the projectile to go REALLY far, you put enough charge in it to launch it into the stratosphere where there is less air resistance. So you sight your gun at more than 45 degrees in order to get it into the stratosphere faster so it will experience less air resistance in the troposphere.
I think you’re joking, but in case you’re not, this would be a huge waste. You’d end up with the projectile going through much more air unless you’re talking about shooting half way around the world with a missile or the like.
The Paris Gun had an elevation of 55 degrees and reached the stratosphere. I assume that if the Germans could have gotten an increased distance by lowering the elevation, they would have.
According to the text under that picture,
300 kg is around 660 lbm, not 1500 lbm. If that’s correct it changes the sum considerably and may make the 1-mile range more believable to the OP.
Why? Paris was what they wanted to hit, not empty fields on the far side of Paris. What it lacked wasn’t range, but payload and accuracy.
It didn’t lack payload OR accuracy. The goal wasn’t to hit specific targets. Quite the contrary, the goal was to be as indiscriminate as possible. It was a psychological weapon, and it worked in that nobody ever knew where or when it would hit. Living in a nonstop heightened state of tension is extremely demoralizing.
Hitting Paris, anywhere in Paris, was perfect for Germany’s purposes.
If they could have gotten increased range, they would have, so that they could set the behemoth up further behind the lines.
Which corresponds to a granite sphere some 57cm or 1’10" in diameter. Still much too heavy for a person to lift, but not so large that you couldn’t get your arms around it easily. The *World’s Strongest Man *competition World's Strongest Man - Wikipedia has competitors lifting similar though smaller spherical stones up to 160kg = ~350lbs.