Tank vs. Cannon

[The Colonel]

Bit of a sanity check - is it reasonable for a low grade, early WW2 tank (say, a Japanese I-Go) to be successfully killed by a Napoleonic style cannon, possibly scared up by some Chinese soldiers?

Hi-tech gives the Bourges Mle 1853 12lber (presumably a pretty typical Napoleonic style field gun) a damage of 6dx5 (mean 105) and the FT-17 45/20 dr (and given that the FT-17 has, according to Wikipedia 8-22mm of armour against the I-Go's 6-17mm that should be representative) … which makes it look doable, but is it sane?

[malloyd]

Originally Posted by The Colonel

Hi-tech gives the Bourges Mle 1853 12lber (presumably a pretty typical Napoleonic style field gun) a damage of 6dx5 (mean 105) and the FT-17 45/20 dr (and given that the FT-17 has, according to Wikipedia 8-22mm of armour against the I-Go's 6-17mm that should be representative) … which makes it look doable, but is it sane?

I expect it is. That cannon ball has 2 to 5 times the muzzle energy of anti-tank rifles that continued in service up into the 1950s. Admittedly it's also got like 5 times the caliber, and isn't as pointy so the pressure at the point of impact is presumably not as great, but it's certainly not hopelessly outclassed. Mind you a single solid shot has to get really lucky to [blow up] a tank, but a mission kill hit smashing up a tread or taking out an engine seems quite plausible.

[smurf]

Armour vs, IIRC, subsonic projectiles get at least twice the DR (not sure if it is 10x armour).

Not forgetting that gun laying a 12lber is going to take ages, and there is a maximum firing 13/14 skill. Therefore, after deducting distance, speed and adding size the net result is going to be miserable.

[Anthony]

22mm of WWII armor steel should be around DR 60 (penetration is normalized for RHA being DR 70/inch, and I would expect early tanks to be comparable to RHA).

Not sure about the penetration of the 12 lb gun, though. You can essentially view it as a 144 weight (5.24*scale) 12 gauge shotgun (12 gauge means a spherical lead ball would be 1/12 lb, 12 lb means a spherical lead ball would be 12 lb), and 12 gauge slugs are generally stopped by level IIIa armor (DR 12), so I'd be tempted to assign a (0.5) armor divisor.

[Rupert]

Originally Posted by Anthony

22mm of WWII armor steel should be around DR 60 (penetration is normalized for RHA being DR 70/inch, and I would expect early tanks to be comparable to RHA).

Not sure about the penetration of the 12 lb gun, though. You can essentially view it as a 144 weight (5.24*scale) 12 gauge shotgun (12 gauge means a spherical lead ball would be 1/12 lb, 12 lb means a spherical lead ball would be 12 lb), and 12 gauge slugs are generally stopped by level IIIa armor (DR 12), so I'd be tempted to assign a (0.5) armor divisor.

I'd be concerned about spalling, rivets, and from the shock of impact. Getting hit by a 12 pound ball of iron moving at high sub-sonic speeds is going to make quite a bang. The armour plates might also simply get bent and deformed to the point where they fall off.

On the other hand, if the ball hits at an oblique angle, it's probably just going to bounce off and do nothing other than make a loud clang!

[Sam Cade]

One thing to consider is that everyone in the vicinity is going to know *exactly* where the cannon is emplaced as the huge plume of white smoke billows forth.
The crew better shoot then scoot with haste.

[copeab]

Originally Posted by Sam Cade

One thing to consider is that everyone in the vicinity is going to know *exactly* where the cannon is emplaced as the huge plume of white smoke billows forth.
The crew better shoot then scoot with haste.

It sounds like the tank is not supported by infantry, so the overworked TC is unlikely to notice anything after his tank rings like a gong.

[Rupert]

Originally Posted by Sam Cade

One thing to consider is that everyone in the vicinity is going to know *exactly* where the cannon is emplaced as the huge plume of white smoke billows forth.
The crew better shoot then scoot with haste.

Another thing to consider it that guns were usually used in pairs or units of four, so if they are set up down a side street in ambush at short range, the tank could well get hit by 2-3 balls from the side, which would be pretty exciting for the crew. I would expect a ball that hits the tracks or track skirts to be stopped by them, but to jam the track in the process. A ball that hits those thin vertical plates is probably going to go through, and if not smash the plate. Either way most crews would be out of the tank quick-smart.

[smurf]

Would the Merrimack vs Monitor battle be any help?

Most Cannon at that time were firing 1200fps/366mps. Shot was a ball and not a ballistic round designed to travel at supersonic speeds.

[Ulzgoroth]

Originally Posted by The Colonel

Bit of a sanity check - is it reasonable for a low grade, early WW2 tank (say, a Japanese I-Go) to be successfully killed by a Napoleonic style cannon, possibly scared up by some Chinese soldiers?

Hi-tech gives the Bourges Mle 1853 12lber (presumably a pretty typical Napoleonic style field gun) a damage of 6dx5 (mean 105) and the FT-17 45/20 dr (and given that the FT-17 has, according to Wikipedia 8-22mm of armour against the I-Go's 6-17mm that should be representative) … which makes it look doable, but is it sane?

I'd believe it. It's really thin armor on those pieces of junk. A heavy machine gun or antitank rifle would have no problem going through them. I'd believe a black-powder cannon could do the job.

That said it would be a really impressive shot. Napoleonic-style cannons aren't very well suited to tracking a moving target. And are going to be trickier to conceal that a modern AT gun too. You probably need to lure the tank into a really narrow ambush spot so that you can aim the gun long before it arrives and just touch it off at the right time.