A Mythbuster’s ™ Guide To Cannon Ballistics

“Don’t try this at home,” Jamie Hyneman and Adam Savage solemnly warn us at the intro to each episode of Mythbusters. “We’re what you call ‘experts’.”  Sometimes it’s a good idea to heed your own advice, especially when 1) your advice is not to play with cannons, and 2) you’re actually playing with cannons. Muzzleloading bronze cannon have really impressive ballistics, especially monsters like the 30-pounder the Mythbusters apprentices were playing with.

Muzzleloading cannon were not rated by caliber, but by the weight of their spherical shot. A 30-pound bronze cannonball (that’s 210,000 grains to us gun guys) is almost 6 inches in diameter, and a ‘Long 32’ (a slightly larger cannon with a bore of approximately 16 calibers, or 8 feet) uses 11 pounds of gunpowder to launch it downrange at about 1600 fps.

This generates 1.2 million concrete-crushing, dirt-throwing, hill-hopping, house-smashing, window-breaking pound-feet.  Give or take a few hundred thousand.

I always love those Mythbusters ‘Blowing Shit Up’ episodes, but then again I don’t live in Alameda County.

While Savage and his team are still investigating the incident, he said the cannon involved in the experiment was aimed too high.

Yeah, that would probably do it. The Mythbusters were actually damned lucky, because the slightly larger 32-pounder cannon at 8 degrees elevation has a range of more than 1.5 miles. 1.2 million foot-pounds is what ballistics wonks technically call a ‘Shitload’ (or maybe 1.2 ‘Shitloads’) of energy, and it can do all sorts of interesting things.

(As a historical aside, the Master and Commander and Horatio Hornblower books tell us that 30-pounder muzzleloading cannon are enormous guns even by the standards of their day.  HMS Victory’s heaviest standard guns in the battle of Trafalgar were long-barreled 24-pounder cannon and short-barreled 32-pounders known as carronades.  Two monstrous 68-pound carronades were installed just before the battle.)

comments

  1. avatar Joe nobody says:

    They were under the supervision of actual explosives professionals.

  2. avatar Redleg says:

    “All ranges the is Range Control. Cease fire, cease fire. Lock and Clear all weapons. We have a round out of impact. Artillery -freeze all guns in place. Acknowledge. Over”.

    “Umm, Smoke? Was that supposed to be Red Bag or White Bag?”

  3. avatar BLAMMO says:

    “We’re whatchya call EXPERTS!!

  4. avatar caffeinated says:

    Chrono measurements and simple physics could have prevented this. They are just lucky no one got hurt.

  5. avatar Ross says:

    Hey ya’ll watch this!

    1. avatar Richard W. says:

      Prefix that with, “Hold my beer, ” and I think you got it.

  6. avatar Tom says:

    You would think somebody might have had some sort of ballistic tables for this play toy before they fired it.
    The 30 pound cannon is quite a weapon system.

  7. avatar Lemming says:

    Still, I want to see Box O’ Truth try this.

    1. avatar Chris Dumm says:

      They’ll have to use something a little thicker than ballistics gelatin. The 32-pounder was rated to penetrate more than 40 inches thickness of solid oak, from a range of 400 yards. At 1000 yards, penetration was down to only about 32 inches of solid oak.

      1. avatar Casey1911 says:

        only

      2. avatar Pete says:

        Did you see the opening scenes in the movie “Master and Commander”, with a broadside fired down the length of the British ship? When you read about “splinter wounds” during the era of wooden ships and muzzleloading cannon, think “six foot long chunks of oak flying through the air at several hundred feet per second”. The term “loose cannon” takes on new meaning when you realize it refers to a 2-ton cannon with wheeled carriage breaking loose on the deck of a ship during a storm, rolling around the deck, crushing sailors who didn’t dodge it, and likely breaking through a hatch cover – through the decks and out through the hull. Tends to sink your ship.

        If you want to understand the carnage inflicted on infantry attacking in a nice line into the face of muzzleloading cannon, read about Pickett’s charge on the last day of battle at Gettysburg (1863). The cannon involved were “only” 12-pounders. The solid shot was fired to graze the ground, bouncing through the ranks of infantry. When the infantry got to within about 200-300 yards, the artillery would switch to canister (tin cans fill of 3/4″ lead balls). Of Pickett’s 15,000 men attacking the Union lines, about 7,000 made it back to the Confederate side.

        All of the men involved in the Civil War battles knew exactly what they were facing in an attack, but they went ahead anyway. Union troops attacking Marye’s heights at Fredricksburg pinned their names on pieces of paper attached to their coats, so their bodies could be identified. “Uncommon valor was common.”

  8. avatar Don says:

    While it makes a better story to say it’s their fault, when they do explosion or ballistics related myths they put themselves and the experiment in the complete control and mercy of LEO bomb and ballistics experts. This screw up is on the “LEO experts”.

    When they almost killed themselves with the pneumatic grappling hook ricochet, and when they shot a gas cylinder through the wall of their shop, and when they lit the shop on fire doing a test inside of a shipping container inside their building… those screw ups were on them.

    Still the best show on TV, and I would contend they’ve done more than anyone to demystify and normalize guns in pop culture for what they are… fun (but powerful) technology.

    -D

    1. avatar Guywithagun says:

      +1

      Well said. Throughout history, the quest for scientific truths have yielded many disasterous mistakes. It’s not like Adam and Jaime are out on this range alone with a camera. They’re just the “personality”. This is a show with many people involved and they are almost always supervised by a safety crew of some kind. Please, make jokes. They’re funny. But don’t even think about solely blaming these two scientists simply because they get all the face time on the show.

      Now if only they used a little more powder and aimed toward Sacramento…

    2. avatar Leo Atrox says:

      Exactly how many LEO bomb and ballistics experts are there for 32-pound cannons? (I’m just kidding. Every single one of them should have known that a cinder block wall or an angled berm wouldn’t stop a rolling 32-pound metal ball. I wonder what other safety measures were in place … How do you stop a sphere with that much energy?)

      1. avatar Moonshine7102 says:

        Several feet of steel-reinforced concrete would do the trick.

  9. avatar scott says:

    I’d love to see their insurance policy.

  10. avatar Brice says:

    The story proves but two things to me.

    1. I want to work there.
    2. I want to own one of these cannons.

    1. avatar Pauley says:

      1. I want to own one of those cannons, too.
      2. They should have test fired it at the Occupy Oakland encampment instead of the Alameda County bomb range.

  11. avatar GS650G says:

    I want to know what they said when it sailed through the cinder block wall and left the range, probably “wow, where did it go?” Then a few minutes of looking around and suddenly realizing it’s not to be found. I bet that phone call was a interesting one.

    If Kari comes over, climbs up a ladder and patches the hole in the wall I’d forgive it. As long as she takes her time with the repair.

    1. avatar Pete says:

      “Oops”.

  12. avatar Ralph says:

    I can’t wait for the Glock version. In polymer.

  13. avatar Matt in AZ says:

    Failure of epic proportions. What surprised me was the energy generated by a 30 lb gun and the bonehead mistake of not using a literal mountain as the back-stop. Someone screwed the pooch and I have a feeling that the range master is taking early retirement. Glad nobody was hurt and someday we will all laugh about this, in the mean time it really puts into perspective the depth of my Schadenfreude.

  14. avatar brad says:

    This is gonna play HELL with their ins.

    1. avatar Mr. Lion says:

      Discovery picks up the tab. Stuff like this is barely a blip on the radar for any large production insurance coverage. Third party property is actually some of the cheapest insurance related to stuff like this– the big price tags are generally concerning talent getting hurt and equipment that runs in the millions of bucks getting trashed.

      It would not surprise me that their coverage for this sort of thing is significantly cheaper than, say, rigging pyro on a building or famous landmark.

  15. avatar Robert says:

    What I can’t even begin to imagine is what it sounded like below decks when the Victory (or any other first-rate) opened up with a broadside.

    If wiki’s right (and I think it is), this was the ship’s long-gun armament at Trafalgar:
    lower gun deck: thirty 32-pounders, each gun on its carriage weighing 2.75 tons
    middle gun deck: twenty-eight 24-pounders, 2.5 tons each
    upper gun deck: thirty 12-pounders, 1.7 tons each
    quarterdeck: twelve 12-pounders, 1.7 tons each
    forecastle: two 12-pounders and two 68-pounder carronades

    As the numbers above are for both sides of the ship, a broadside meant half these numbers, firing at once.

    1. avatar Chris Dumm says:

      Almost 1200 pounds of projectiles, being fired from sixty enormous fire-belching cannon, all in the space of five or ten seconds? This was more firepower than any six or seven WWI British Artillery Brigades *combined,* all being fired off in a space the size of a movie theater.

      Absolute pandemonium.

      1. avatar Moonshine7102 says:

        If you’ve ever fired a large-bore magnum at an indoor range, multiply that noise by a factor of 100. Ouch.

      2. avatar Robert says:

        Accounts from the period talk about the gun crews tying rags around their heads to cover their ears. Still and all, it must have been deafening, at least temporarily.

        One possible mitigation: the gun carriages were run forward all the way, placing the muzzles outside the ship. Thus pushing the barrel out the gunport helped in a small way to suppress some of the blast noise.

      3. avatar Robert says:

        Added thought. That first broadside in an engagement didn’t fire over a space of five to 10 seconds, at least not if the crews were trained right. Remember, before the broadside, everybody still has functioning hearing. Crews were drilled to make that first blast go off simultaneously, all guns on the side, all at once.

        After that, keeping gun crews coordinated was the job of the officer in charge of the several guns in his division. Each gun crew had a captain who pulled the lanyard on the flintlock the primer that touched off the shot. He did that under visual control of the officer in charge — at least until the firing became general, and the enemy’s shots took their toll of the crews and officers.

        (Crews could use slow-matches to fire the primer, but flintlocks were preferred as faster and more reliable.)

  16. avatar DrewR55 says:

    In their defense; I spent several years at Ft. Sill in Lawton, Ok. Ft. Sill is the US Army Artillery School. I mention this because every year or so a shell would land off range in some poor sob’s back forty. It would plow a field or take out a cow and the Army would shell out big bucks. The locals in Lawton made a large amount of money of these ‘impact fees’.

    This happens… Alot. But it’s still funny!

  17. avatar JohnB says:

    You all need to do a little research. And without solid information from the Mythbusters, there is a lot of room for speculation. I know of no 30# bronze guns, 32# and 36#, even a 33#, but no 30# bronze guns.

    The only 30# gun I know of is a 30# Parrot RIFLED Muzzle Loader. If they were firing a round ball out of a RML, no wonder it went wild.

    If it was a 32# Smooth Bore and they were firing a 30# ball, no telling where it was going to go. One word, windage.

    You can try either experiment. Try shooting a round ball, without a patch, from you rifled muzzle loader. Try shooting a 20 gage slug from a 12 gage. Accuracy is best obtained by going inside the barn first.

    Oh, BTW, the projectile weight is for a cast iron ball. NOT bronze. Bronze was used for guns.

    A 30# Parrot had a range of 6,700 yards ar 25 degrees elevation.

    A 32# Seacoast Gun, cast iron, had a rage of 1,922 yards at 5 degrees elevation.

  18. avatar John Fritz says:

    Thought about this at work today but couldn’t post the linky because I gotta use a proxy to view evil firearms websites at work.

    Cannonball

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