Ever heard of a cannononball .. ovoid?

[Jim McDougall]

That is really fascinating information Mark!!! I had never heard of a shot tower, nor such a method of making shot and cannon balls. While you might come in late, you do so with a bang!!! great stuff!

Thanks for the links on the sites describing these towers too. It seems so odd to fabricate these with such an elaborate method...I always thought these were cast in molds, and it seems like dropping a blob of molten metal would produce all kinds of various shapes, like a rain or tear drop, who would have guessed this method would be effective. I cant get Galileo outa my head on this one
It seems odd in the note that the Baltimore tower was still producing shot until 1892, but although rifled guns had come in long before and were technically obsolete, I suppose the smoothbore cannon would have remained servicable ordnance as required and as on hand.

If a ball was indeed oblong or distorted in shape, how would that have effected its firing ? If the spherical shape maintained force and rotation to retain kinetic energy, would the distorted shape cause the shot to slow as discharged, and lessen its range or impact?

It really is fantastic to learn so much more on ballistics and artillery of these times, thank you guys for all this information, and please excuse my attempts at trying to describe my questions with the terminology which may or may not be correct, my exposure to physics and dynamics is limited at best!

All best regards,
Jim

[fernando]

Hi Mark, i'll be damned
I fully agree with Jim ... last but not least .
Hardly shot towers were implemented in Portugal: i am still trying to find out if hot shot was used here; not impossible, though.
Not wishing to go off topic, but something that fascinates me and which i have not been managing to spot where i have read it, is that the "pointed" bullet was idealized by Da Vinci in the XV-XVI century, although only implemented just the "other day".
The guy was simply unique.

[laEspadaAncha]

Originally Posted by Jim McDougall

If a ball was indeed oblong or distorted in shape, how would that have effected its firing ? If the spherical shape maintained force and rotation to retain kinetic energy, would the distorted shape cause the shot to slow as discharged, and lessen its range or impact?

Howdy Jim...

Given the limitations inherent to a smooth bore and the subsequent lack of rotational velocity (that would have otherwise been imparted by way of a rifled bore), I doubt small variations in (shot) shape would have much more than a nominal impact with regards to precision and accuracy - IMO such variation would likely have been taken into account in the application of artillery tactics at the time.

The "shot tower" method is new to me, and not only interesting but congruent with the deformation of my included example, which has a small and subtle (but noticeable) flat spot consistent with its bottom-biased distribution of mass. This has always given me the impression it either deformed upon impact (unlikely given it is doubtful it would reach a sufficiently high temperature to do so), or had been dropped before it had cooled sufficiently to harden to the point it would resist deformation, something I now realize is inherent to the "shot tower" manufacturing process.

[M ELEY]

The shot tower method was created in England at the end of the 18th century. The process was used in other countries, but quite popular here in the U.S. Jim, there's a shot tower in Virginia not far from me on the New River. It's a pretty cool site to see from the highway if you are ever passing this way, mate!

elEspadaAncha, your cannon balls could also be more primitively cast iron of the period. They resemble my Rev War American 2 pounders with their "off"- rounded shape.

Yes, Fernando, I definitely agree that hot shot is still in the running. I was unaware before I read this thread that it was ever used against anything but ships. I was going to suggest that a near-molten ball striking ocean water could deform this way, but I'm assuming we know for sure it was found buried on dry land? Likewise, IF it had been used against a ship, one could look for pick-marks to the hot shot where a naval crew would have been working double time with their spiked axes to dig it free from the decking and kick it over the side.( the only way to extinguish these monsters, as buckets of sea water were futile). Fascinating topic, folks.

[M ELEY]

A few other sites of interest. The first speaks of mill balls. The second shows a few oddly-shaped cannon balls-

http://angloboerwarmuseum.com/Boer12...nnonballs.html

http://www.goldiproductions.com/angl...cs_shells.html

[kronckew]

i've never heard of iron cannon shot being made in drop towers, the few references i've seen seem to be by people who assumed too much.

shot towers were for making lead spheres, from bird shot up to small arms sizes. the low melting point of lead and the surface tension of the metal does indeed form spheres, the tear-drop shape so popular in myth is just that, free falling rain drops are essentially spherical, tho easily deformed by external forces.

in a shot tower lead was poured into an appropriate sized sieve or array of funnels selected to provide the correct final diameter, the height of the tower was based on how long it took the lead to harden on the way down where it terminated in a tub of water for final cooling.

after cooling the lead shot was tested for roundness on a tilted table and any that failed returned to the melt. i would guess that large balls of lead intended for case shot and cannister may have lead to the assumption that cast iron could similarly make large cannon balls.

not so, the height of tower required for the higher temp. and larger sized cannon balls molten iron would have been beyond the capabilities of the period. dropping an 18 lb. blob of molten iron into a bath of water is not something i would attempt from any practical height. the 2in. oval grape shot mentioned in the ref. above may have been just small enough for a very high drop tower, but i'd expect a bit more variation.

anyway, one of a few quotes i found on line, it followed a post where drop tower made 'cannon balls' was mentioned:

Someone misled you. Shot (for shotguns) is made in freefall using a tower. And it basically does work the way you're thinking: it doesn't necessarily solidify all the way, but the outside does, and that's enough for it to retain its shape when it hits the water at the bottom of the tower.

Cannonballs were generally made out of cast iron. If you look at an authentic one that's in good shape, you can usually see the mold lines and sprue marks where it was poured. They were usually poured into sand molds that were then knocked away after they cooled.

Some very old cannon balls (prior to the 18th century at least) were cast bronze or cut stone rather than iron, but most people switched to iron as soon as they were able to because it's a harder, cheaper material than bronze, and easier to work with and more effective than stone. (Bronze remained as a material for the cannons themselves well into the 19th century, though, since it has greater tensile strength than cast iron and is less likely to shatter.)

Also, if you think about pouring large quantities of viscous liquid, you'd realize that "dropping" a cannonball wouldn't work... Forming spheres via freefall cooling is only practical (in normal Earth gravity) for rather small parts, where the surface area to mass ratio is low.

oddly enough, on a science forum discussing the making of tiny silicon balls for solar cells...

i've owned and fired muzzle loading small arms (pistols/rifled muskets) and cast my own projectiles.

in the pistols (.36 and .44 calibre) i used commercially made shot that was swaged from lead wire or cast, 000 buck (0.36" nominal) from drop towers can also normally be used as the loading process for revolvers usually will trim off any slight oversize, and the forcing cone in the barrel will swage the ball to fit the rifling. rifles would take a cloth patched ball which allowed for some variation in diameter.

the .58 cal rifled musket took a .58 calibre minie ball. one of the shot tower blurbs i read about an american civil war shot tower that mentioned it being used to make cannon balls also said it made minie balls. i tend to doubt that, having cast my own for years.

minie ball.

note the deep recess in the base, propellant gas pressure would expand the base, forcing the raised portion by the grooves into the rifling. this not only provided for the rotation, but provided a gas tight seal that allowed for more efficient use of the propellant, increasing range. they could be made a bit smaller than the bore, allowing more rapid reloading as opposed to previous round ball/patch combos that required more effort to seat the ball which was engaged in the rifling from top to bottom & thus not only had more friction, but got worse as each shot further fouled the barrel. soldiers were known to pee down the barrels of their rifles in battle to clear the fouling so they could reload.

[M ELEY]

Well...that shoots that theory down. I assumed that some of the info I had read was correct that cannon balls were made in this way (included in the tour guide's speal about a local tower I have visited). If the issue is height, some of these structures were massively tall while others weren't. In any case, back to possible hot shot, I guess.

Here's what wikipedia had to say and a list of shot towers around the world, many of them dating to the 1780's-

http://en.wikipedia.org/wiki/Shot_tower

[kronckew]

another interesting ref. site:

Solid shot essentials

i noted in there that grapeshot was frequently cast in gangs, ie. like pearls on a string, rather than individually, thus no sprue, and ordinance regs required them to be tumble finished which would have reduced or removed any mould marks and obscured the end details where the individual balls had been broken apart. the oval grape could easily have been produced this way. as it notes, grape did not come into contact with the bore and so could be quite irregular, where odd shaped round shot could scrape or lodge in the bore, damaging it. grapeshot was required to be made from cast iron, tho lead was an accepted alternate. canister, which later replaced grape, used lead musket balls.

[fearn]

Darn, Kronck beat me to the point about the shot tower. I'd also point out that a heated cannon ball, if it was hot enough to deform that much, also wouldn't have an elongated oval shape. It would get flattened by the power of the explosion behind it. More to the point, if it was soft enough to deform that much, it would probably weld itself to the inside of the gun and cause the gun to explode when fired.

I keep looking at the dented surface of the thing. I suppose that could be corrosion that was cleaned off, but I keep thinking that some poor blacksmith got the job of trying to hammer a sub-par cannonball (or a too-big cannonball) into a diameter narrow enough for them to use it with the gun they had. It could also have been a really ugly cannonball that was discarded as too crappy/dangerous to fire.

After all, we've been assuming that it was fired, and I don't see that anyone has presented evidence to support this idea.

Best,

F