What if medieval super cannon invented ?

Or WI fin stabilized smooth-bore cannon projectiles not forgotten ?

(I try to learn from my mistakes so this time no long technical title ;).)


Introduction of Concept

Okay, this idea obviously needs a bit of explaining. After browsing the google groups alternate history thread I came across this idea/thread by Alfred Montestruc :

In the 1960s smooth-bore tank guns were reintroduced by the USSR where some clever engineer figured out one could use fins to stabilize a projectile and have less loss of muzzle velocity. "To reliably penetrate the thick armor of modern armored vehicles, a very long, thin kinetic-energy projectile is required. The longer the projectile is in relation to its diameter, the higher the spin rate must be to provide stability. Practical rifling can only stabilize projectiles of a limited length-to-diameter ratio, and these modern rounds are simply too long. These rounds are instead formed into a dart shape, using fins for stabilization. With the fins for stability, rifling is no longer needed, and in fact the spin imparted by rifling would degrade the accuracy of a finned projectile.
The first tank with a smoothbore gun was the Soviet T-62, introduced into service in 1961; today all main battle tanks except the British Challenger 2 and Indian Arjun MBT use smoothbore guns. The Russian navy conducted experiments with large-caliber smoothbore naval guns, which were halted by budget cuts."
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Now the fascinating things is that the concept is pretty basic and could have revolutionized martime warfare whenver it is invented. As the thread in question already explored such rounds would be a lot more accurate and have a much higher range. The only question left is why nobody came up with this invention earlier. Curiosly they did, but then forgot about it for the next 700 years.

As explained here:

"The first projectiles in early gun systems dating from the 14th century were typically hand wrought iron flechettes wrapped in a leather sabot. However, due to the expense and trouble of making these darts in a pre-industrial society, they were soon replaced with the less accurate stone cannonball."
http://en.wikipedia.org/wiki/Needlegun

Though occasionally made with cast bronze, the pot-de-fer was essentially an iron bottle with a narrow neck. It was loaded with powder and an iron arrow-like bolt, feathered with iron. It is believed that the middle of the bolt was likely wrapped in leather for a snug fit, necessary to enhance the thrust from the gaseous pressure within the cannon. However, this feature is not shown in manuscript illuminations. The cannon was set off through a small-diameter touchhole, where a red-hot wire could be thrust to set off an explosion and fire the cannon
http://en.wikipedia.org/wiki/Pot-de-fer#Description

And for those not trusting wiki the weapon is also referenced in "Deadly Metal Rain: The Legality of Flechette Weapons in International Law" by Eitan Barak.


Further Speculation on Concept

Now to the actual question. How would world history change if people kept experimenting with these flechettes?

According to Alfred Montestruc:

1) Range and hitting power, arrow shot would more than double his effective range, while hitting the target at a large fraction of the muzzle velocity, and doing a large fraction of the damage round shot would do at point blank range. A long slender rod with fins on the back will have enormously less loss of speed by drag than a "bullet" or ball shape all else held equal. The same starting muzzle a long slender projectile of the same mass as a bullet shaped projectile, should fly many times further, and hit at a much higher velocity.

2) Accuracy, un-rifled round shot was notoriously inaccurate. The reason for this was the round shout would get random rotational vectors coming out the barrel as the ball touched the bore of the gun at random locations. Arrow shot would have fins and would fly straight as an arrow. Net effect, a much smaller ship, say a frigate, could fire devastating broadsides, that will do great damage on a ship of the line at ranges the SOL could not reply with any effect at using standard round shot.
 
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Or WI fin stabilized smooth-bore cannon projectiles not forgotten ?


Now the fascinating things is that the concept is pretty basic


"The first projectiles in early gun systems dating from the 14th century were typically hand wrought iron flechettes wrapped in a leather sabot. However, due to the expense and trouble of making these darts in a pre-industrial society, they were soon replaced with the less accurate stone cannonball."


1) Range and hitting power,

2) Accuracy

Heavily edited you will note but the key points are retained. Firstly while the concept of finned projectiles is simple in concept it is rather more difficult in executions.

The problem with the phrase 'as straight as an arrow' is that for much of history arrows would not count as straight according to the standards of modern engineering practices.

Now this is going to impact on accuracy, which is your point 2).

Not only that but as you note above being hand crafted it will be slower and harder to produce than equivalent roundshot.

So you want it to hit harder right?

The problem here is that highly velocity small bore shot does not transfer nearly as much of its energy to the target. This was true of the cannon used by the Elizabethans against the Armada, lots of long range shooting producing small holes in the target which did not really impact the function of the target vessels at all.

What you wanted in naval combat were projectiles that had a lot of surface area on the impact point in order to convert as much of the wooden hull of the target into man killing splinters. Vessels were by and large put out of action by degrading the crew.

Which is not to say long range shots were not tried throughout the Age of Sail but one problem is that you have an almost complete lack of range finding equipment so working out the range is a matter of guess work based on a vague idea of how big the target is(if you have one at all) and how big it looks like to the mark one eyeball, then of course it would be handy to know the speed of your own vessel and the target vessel, neither of which is possible until comparatively recently with any degree of accuracy.

So your desire for 1) range is hampered by your inability to achieve 2) accuracy at range. Which brings us back to 1) hitting power where the roundshot has the advantage and is cheaper to produce.

Of course you can try the French style of disabling the rigging but as experience taught the best kind of ammunition for that is bar shot and chain shot with has the greatest chance of snagging a significant portion of spars and lines rather than punching neat little holes in the sails.

The later anti-tank rounds were reliant on the nature of the materials they were made and how they interacted with the materials of the tank target given the truly enormous impact velocities. The HE-Frag rounds relied on explosively driven fragments for their anti-personnel effectiveness and so on.

The results of fin stabilised rounds in early modern warfare however were somewhat disappointing.
 
effect of fins

On a large shot at the relatively slow speeds that black powder shoots, would fins have enough surface area to produce stability? Area goes up much slower than mass, so the fins might be insufficient to inhibit tumbling.
 
On a large shot at the relatively slow speeds that black powder shoots, would fins have enough surface area to produce stability? Area goes up much slower than mass, so the fins might be insufficient to inhibit tumbling.

Stability is directly related to projectile speed; the faster the projectile, the more air flows over the fins and the more stable the projectile is. On the downside the fins increase the projectile's drag, thus slowing it down and making them less effective.

At the relatively low muzzle velocities of early guns the benefits are outweighed by the disadvantages; finned projectiles are more expensive, more time-consuming to make, and do less damage than round projectiles, and only offer a slight increase in accuracy. They're just not worth the trouble.

(For those of you with the image of Robin Hood splitting an arrow at three hundred paces with laser-like accuracy, that's BS. English longbowmen, and other archers as well, were trained to fire en-masse at large groups of opponents; rate of fire was far more important than individual accuracy under battlefield conditions. And as said above, the quality of the bows and arrows in use at the time would have horrified a modern archer.)
 
Finned does not have to mean high velocity sub-caliber.

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Finned does not have to mean high velocity sub-caliber.

<snip>

That's a different kettle of fish, but no easier for a late Renaissance craftsman to make. Add to that the touchiness of black powder and the generally unreliable fuses available and you have a weapon of dubious utility at best which is likely to be more dangerous to gunner than target.

That said, fins do make sense here, in that they keep the projectile properly oriented, so that the fuse will function properly, at least in theory.
 
That's a different kettle of fish, but no easier for a late Renaissance craftsman to make.

I'm not so sure. Remember, for a long time cannon balls were made of stone, not iron. Stone cannon balls were made by highly skilled stone carvers hand crafting spherical stone shot. That really only went away when the economic climate changed to make stone shot too expensive.

It shouldn't be too hard for a Renaissance craftsman to make something like the photo. Really it's just a matter of making a mold and pouring the iron into it. They could either cast it as a solid pice or as two separate ones that are screwed together. Casting as a single piece seems more likely and eminently doable by Renaissance craftsmen seeing as they were able to cast cannon.

Add to that the touchiness of black powder and the generally unreliable fuses available and you have a weapon of dubious utility at best which is likely to be more dangerous to gunner than target.
I'm not sure I understand your point. How is any of that different from standard round shot?

That said, fins do make sense here, in that they keep the projectile properly oriented, so that the fuse will function properly, at least in theory.
Do you mean the fuse to set of the charge in the cannon or a fuse in the shot itself? I don't see how the fins would affect the first.


I think Venice is the most likely place for this sort of finned projectile to take hold. The advantages offered by the fins are quite well suited to the Venetian style of naval warfare and Venice has the expertise in metal working, specifically metal casting of cannon, to be able to make the finned shot.
 
I'm not so sure. Remember, for a long time cannon balls were made of stone, not iron. Stone cannon balls were made by highly skilled stone carvers hand crafting spherical stone shot. That really only went away when the economic climate changed to make stone shot too expensive.

It shouldn't be too hard for a Renaissance craftsman to make something like the photo. Really it's just a matter of making a mold and pouring the iron into it. They could either cast it as a solid pice or as two separate ones that are screwed together. Casting as a single piece seems more likely and eminently doable by Renaissance craftsmen seeing as they were able to cast cannon.


I'm not sure I understand your point. How is any of that different from standard round shot?


Do you mean the fuse to set of the charge in the cannon or a fuse in the shot itself? I don't see how the fins would affect the first.


I think Venice is the most likely place for this sort of finned projectile to take hold. The advantages offered by the fins are quite well suited to the Venetian style of naval warfare and Venice has the expertise in metal working, specifically metal casting of cannon, to be able to make the finned shot.

I was referring specifically to the projectiles in the picture, which are hollow and filled with gunpowder, as evidenced by the impact fuse on the nose of each projectile.

In the case of solid projectiles, the accuracy gain is minimal, so round shot offer more bang for the buck, so to speak. Until rifled guns appear, round shot offer the highest average damage per unit of money spent of all types of ammunition, so are standard issue.
 
I was referring specifically to the projectiles in the picture, which are hollow and filled with gunpowder, as evidenced by the impact fuse on the nose of each projectile.
Ah, that makes sense. My apologies, I thought you were making a general comment about finned. With respect to the specific rounds in the picture I agree with you, the fins are only useful for orientation if there is a fuse in the shot. And if that's the justification, easier to just flatten out the shot.

I think that kind of explosive shot is a stretch for Renaissance manufacturing. They could probably make it, but not on the scale necessary for widespread use.


In the case of solid projectiles, the accuracy gain is minimal, so round shot offer more bang for the buck, so to speak. Until rifled guns appear, round shot offer the highest average damage per unit of money spent of all types of ammunition, so are standard issue.
Why is the accuracy gain minimal? I'd guess it's the issue of the projectile bouncing along the barrel and getting a random deflection when it bounces on the muzzle. Is that correct? If it is I can't see much of a way around it. Perhaps angling the fins to rotate the projectile? It was an established practice among fletchers so it wouldn't be a stretch to apply it to cannon balls.
 
Why is the accuracy gain minimal? I'd guess it's the issue of the projectile bouncing along the barrel and getting a random deflection when it bounces on the muzzle. Is that correct? If it is I can't see much of a way around it. Perhaps angling the fins to rotate the projectile? It was an established practice among fletchers so it wouldn't be a stretch to apply it to cannon balls.

First, round shot is not as inaccurate as most think; a skilled gunner could reliably hit a ship or large building at ranges up to several hundred meters with most of his shots. So the potential gain in accuracy is not as great as one might think.

Second, adding fins to the projectile increases both weight and drag, resulting in lower muzzle velocity and greater loss of velocity during flight. The lower the velocity, the less accurate the projectile. So the actual gain in accuracy is much less than the potential gain.

Third, windage (the difference between the bore diameter of the weapon and the diameter of the projectile) is going to reduce the accuracy of both the normal and the finned projectiles, so is not really a determining factor. And that windage is necessary for safe operation of the gun, because of residue buildup from the black powder. Too little windage and you risk having the projectile getting stuck in the barrel, which will put the gun out of action until it is removed, or even having the gun burst from excessive pressure. Both of which were not rare occurences.

Curving the fins to spin the projectile will help somewhat, but the rate of spin needs to be fairly high to really increase accuracy, and high rates of spin are really only possible with conical projectiles, rifled guns, and much higher muzzle velocities. OTL this was only achieved in the mid nineteenth century by Mssrs. Armstrong, Whitworth, et al.
 
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