Ever heard of a cannononball .. ovoid?

[fernando]

Fascinating thread!
How would i guess that the posting of my atypical ball would result in such a treatise on cannonballs.
Hot shot and shot towers would certainly never dream of making part of my vocabulary!
I finally located some data on the use of hot shot in old Portuguese (and Brazilian) coast forts. It was a question of having not browsed with the right term; here they call it bala ardente (burning bullet).
Considering Fearn's reasonable suggestion that this ball was not even fired, having been discarded due to its faulty construction, one question arises: why then wasn't it discarded right after casting inspection, instead of going to take a risky chance to be used in campaign?

[fearn]

I was thinking of a field modification: what do you do when the cannonball is too big for your cannon, and you really need to fire that projectile? "You men, take these hammers and chisels....followed hours later by colorful invectives and a "that didn't work!" Then you leave your failure on the battlefield, to mess with the minds of those who come after you.

Anyway, I was reading a little about hot shot, and the one thing I'm pretty sure about is that they weren't heating the balls enough to deform them. It's hard to do that without a formed air draft and a much hotter fire than they describe.

Best,

F

[fernando]

You will forgive me Fearn but, resizing cannonballs on the battlefield, sounds pretty fictional to me, even assuming the artillery officer had flour in his head, instead of brains.
Even if the issue were to adjust only one ball, which seems rather insolit, it would have to be a sculptor's work, to reshape the thing with the necessary profile ... not a task for rank and file .
More plausibly i would accept this is not an actual cannonball.

[fearn]

Could be, Fernando.

You know how this is going to end, right? Someone's going to have to make a modern cannonball of that particular shape and fire it, just to see if it will fly.

Volunteers?

[fernando]

Originally Posted by fearn

Could be, Fernando.

You know how this is going to end, right? Someone's going to have to make a modern cannonball of that particular shape and fire it, just to see if it will fly.

Volunteers?

That´s what i call a brilliant idea .

Say, you know english better than me; have a look to these extracts:

... The interior of the furnace is lined with fire brick and contains a set of sloping iron rails to hold rows of cannonballs. Rows of iron rods pass through the furnace from one side to the other and are fitted on each end with bolts and "star" braces to support the weight of the shot rails and roof. Cold cannonballs are placed in the furnace and allowed to roll down the inclined rails in rows. The first halls are directly over the firebox at the low end and are heated "cherry red." As they are removed, the next balls roll down into their place and are likewise heated ...

Couldn't the balls prior to the one being heated, start deforming while waiting for their turn, getting the cylindrical shape due to their rolling on the rails ... this assuming that, if the ball being heated reaches "cherry red" temperature, the next ones in the queue must already be half way to it.

... does the cool air tend to reduce the temperature of the cannonball as it flies through the air to the target after it is fired? No. In fact the air friction caused by the cannonball speeding through the air adds to the temperature ...

Something i wouldn't guess!

... The cannonball can even be made to ricochet upon the surface of the water several times without losing enough heat to ignite wood ...

A bit off topic, but this reminds me that, such ricochet method was also used with cold balls, right after portholes were invented and naval artillery could be placed inside the ships decks at sea level. This system brought remarkable advantages for the Portuguese, in naval battles during the discoveries period.

-

[fearn]

re heating cherry red: the thing about these balls is that they're thick. If it's hot on the outside, it almost certainly won't be that hot on the inside.

If it was hot enough to deform, it would droop, not turn egg-shaped. You can run this experiment yourself with a candle, a ball of wax, and something to roll the ball of wax over the flame.

You can also try rolling an egg down a rail, with the long ends on the rails. The egg is going to "want" to spin the long axis, so it's going to twist as it rolls to roll on the short axis. In doing this, it will probably get stuck. So having an oval design isn't going to keep a cannonball on the rails. Round would be simpler.

The thickness of the cannonball will affect how it ignites. For example, if it skips across the water (another place where a spinning round shape works well--see the dam busters), only the part that touches the water will cool, and the heat from the inside will move to the outside. You could get the interesting situation of a cannonball with a cool outer skin hitting a piece of wood, then getting hot enough on the surface to ignite the wood (and this assumes the wood was dry).

Best,

F

[kronckew]

just found this manual: (pdf format)

Gibbon Artillery Manual 2nd ed. 1863

rather extensive tome covering gunpowder and how to make it, artillery history,theory, construction in bronze and cast iron for coastal defence, naval and field artillery, alloys used, casting methods, bore turning, fittings, fixtures, tools, methods of employment, loading, firing, cleaning, spiking, unspiking, testing, etc. etc. also includes use with hot shot, heating shot in furnaces, how use of hot shot varied in differnt countries (french used wet hay wadding) use of sabots, rifling, elongated shot, shells, and even mentions electrical measurements of velocity (odd for 1863) as well as the development of gun cotton in 1846 which proved too strong for the guns and small arms of the time so was abandoned in spite of it's smokelessness...