Jonathan_S wrote:JimHacker wrote:Also, if I had to choose between giving the navy shells and giving a portion of my army shells, I would go with the navy as I think shells are a bigger force multiplyer in naval combat than they are on land. I may be wrong about that though?
I think that's correct, at least for field artillery.
Exploding shells before reliable time fuses (or VT fuses) were very tricky to get to explode reliably midair over the enemy formation. But my understanding is that that's when they're most deadly against troops in the open. Contact fuses (which I'm not sure if either side has) or unreliable time fuses (like fuse cord lit from the cannon firing) are far less effective. They tend to blow up after the shell is on the ground (or even buried itself somewhat) which drastically limits the shrapnel damage, or they blow up early, before they reach the enemy.
Now large explosive shells, even with imprecise time fuses, are good against fortifications that will shrug off prolonged solid shot bombardment (packed earthen or brick forts). So if the Army of God is expecting siege operations some explosive shells for their heavy artillery would be useful.
But a naval engagement is more like attacking a fort than a field formation. The shell is likely to lodge in the enemy ship, so having a time fuse that runs a bit long is still pretty effective, and ship hulls are far less resilient than forts, so the shells do proportionally more damage.
And since the Charisan Navy has explosive shells, and the CoGA knows it, their naval forces will certainly need shells of their own before being in a position to contemplate going on the offensive.
One bit of good news is that naval artillery tends to be in what would be considered siege artillery size for army use. So the CoGA could focus on shells for one or two types of heavy cannon and distribute them to the army for siege work and the navy for normal use. That should both cut back on the number of rounds the army needs and simplify manufacturing, rather than trying to make lots of the smaller shells that field artillery would need.
Couple of points (and I’m not saying how or even
if these figure in
MT&T):
(1) Overhead air bursts
are deadly, but they are scarcely the only way in which shells can be lethal. The shrapnel shell was also designed for airbursts, but it was supposed to burst in horizontal flight before it reached its actual target, spraying shrapnel balls against its target in a continuation of its flight path. Think of it as grapeshot or cannister, but instead of the “sub-projectiles” beginning to disperse (losing density) and shed velocity (and hence energy) the moment they leave the muzzle of the gun, they continue onward with the momentum of a substantially larger projectile, then scatter and
begin their dispersal when the bursting charge fires. This throws a much denser pattern of balls with a higher velocity at very long ranges, rather than restricting the “shotgun” effect of artillery to the 4-500 yards of cannister or grapeshot.
(2) The American Civil War (to use but one example) used remarkably accurate fuses which depended on combustion of fine-grained powder at a predictable, consistent rate. Because quality control was less than perfect, samples from each lot of fuse compound were tested when that lot was made. If results were too far outside specs, the lot was rejected; if the results were outside the exact specs but within acceptable limits of deviation, the amount of deviation was noted to that it could be taken into account by the fusemaker and/or gunners. As such, reliable bursting ranges for shrapnel shells were quite common using what we might consider to be very crude fuses today. And, yes, the fuses were ignited by the flash when the gun fired.
The USN used standard fuse settings of 5, 10, and 15 seconds, and Army fuses were similar in performance. The gunner estimated the range, cut (or set) the fuse to the desired bracket (against infantry, to the longest bracket short of the time of flight at that range so they would burst the shrapnel shell as close as possible to the target), loaded, and fired. For the USN, ranges for the standard fuses were: 5-second fuse = up to 1,320 yards; 10-second = 1,320-2,400 yards for the 8” and 32-pounder or up 2,000 yards for the 9”; 15-second = up to 3,080 yards. USN shells were filled and fused before they arrived aboard ship and stored in boxes which were labelled with the fuse burn time. The standard for heavy shells was for 50% of the ship's total shells to be fused for 5 seconds, 25% for 10 seconds, and 25% for 15 seconds. Field artillery tended to have fuses cut (or set) in the field, and the Shenkl percussion fuse (used by both Navy and Army gunners) worked quite well for contact fusing.
As far as airbursts are concerned, if the time of flight for a howitzer or mortar shell can be properly estimated, it can be made to detonate above the target reliably even with ACW-era fuses. It’s more a matter of the trajectory — flat for a field gun, high and arcing for the howitzer or mortar — than a difference in the fusing. If you know it will take 12 seconds for your shell to reach the target and you cut the fuse for 10 seconds, then you have an excellent chance of dispersing your shrapnel balls with an extensive lethal radius.
(3) Smoothbore shells are actually pretty darned
ineffective against solid masonry defenses until you start getting into some really massive gun bores. Smoothbore
roundshot are effective at shattering masony with repeated impacts, but they usually have to be fired from fairly short range because, among other things, their veolcity drops fairly rapidly, which causes them to bleed energy.
Rifled projectiles (shot or shell) tend to drill into masonry more efficiently because their shape retains velocity better and they have a much smaller cross section than a round shot of the same weight, which gives them better penetration. This means a rifled shell is far more likely to be
inside the masonry of its target when it explodes, however it happens to be fused, and it will also usually have a larger bursting charge than a shell of the same disameter. Spherical shell, on the other hand, tends to ricochet off of masonry or even to break up instead of penetrating. It’s more effective against earthworks than stonework, but even there without very large bursting charges (or high-explosive fillers) it tends more to rearrange the earthwork than to batter it down. Rifled shells, with heavier bursting charges and more penetration, are more effective even there.
During the ACW, the standard rule of thumb was that a rifled projectile weighed twice as much as a smoothbore’s spherical shot. (They could have been made even heavier by the simple expedient of making them longer, but then you started getting into issues of just how heavy a shell even the brawniest gunner was going to be able to handle, especially when you took rate of fire into consideration.) Thus the 12-pounder smoothbore and the 24-pounder rifle both had a bore of around 4.5” or so. (I’d have to look it up to be certain.)
Despite the rifled shell’s greater bursting charge, the USN generally favored really
big smoothbores rather than rifles for use against ironclads, hence the 15” Dahlgren and the enormous 20” Dahlgren/Rodman (don't even get me started on the controversy of whether Dahlgren or Rodman deserved credit for their design) which was cast at the very end of the war. The reason was that black powder placed an absolute limit of only around 1,500 fps on attainable shot/shell muzzle velocities. Since they couldn’t push velocity higher (and because naval engagements of the time were fought at close ranges, where the velocity drop of a spherical projectile wasn’t much of an issue), they went for the greatest mass they could generate, and their approach was based on “racking” or battering the armor until it broke up rather than trying to punch through it.
That isn’t to say smoothbore shells
couldn’t be driven through armor. The shell from the 11” Dahlgren could be driven through 4.5” of iron plate backed by 20 inches of solid oak, and the same gun was capable of firing 160-pound steel-cored shot (or “bolts”) in “racking” attacks on armor too thick for the shell to pierce (like the 10-19" armor of a monitor's turret, for example). By comparison, the 20” Dahlgren fired a 1,080-pound cored shot. (Of course, the 20” also weighed 50 tons and was a
tad impractical for shipboard use! On the other hand, according to at least one authority the main reason no more than a dozen or so shots were ever fired from either of the only two 20” cast was that no one could find a target which couldn’t be destroyed with a single hit.)
(4) There are actually significant arguments
against adopting rifled guns for shipboard use, given the current state of Safeholdian ship design. There are also significant arguments in favor of adopting the largest guns possible, but there are countervailing considerations, as well.
Even a 6” (30-pounder) smoothbore shell will pierce most wooden hulls at short or medium range. The bursting charges are small compared to larger smoothbore shells, but their incendiary effect is significant and they will shatter wooden hull timbers more effectively than solid shot many times their size and weight. Obviously, the larger the shell, the better. Dahlgren’s tests suggested that a single 9” shot did more damage to the fabric of a wooden ship than 3 32-pounder (roughly 5.5”) shot, and that a single 9”
shell did six times the damage of the 3 32-pounder roundshot. The 11” did roughly twice the damage of the 9”, and I hate to think of what a single hit with a 20” Dahlgren’s shell would have been like. On the other hand, firing time for the 15" was over 6 minutes per round in a monitor's turret, whereas
New Ironsides could fire her broadside mounted 11" every 108 seconds or so. In other words, especially with muscle-powered loading, you have to choose between rate of fire and size of shell, and the disparity is much worse for muzzleloaders than for breechloaders.
Given that rifled shells are more accurate, carry larger bursting charges for a given bore diameter, and are more aerodynamically efficient (and hence maintain velocity farther and better than spherical projectiles), one would think that rifled guns would be a no-brainer for naval use. The problem is that — as Dahlgren pointed out in the late 1850s — 6,000 yards of range was pretty much useless in a naval engagement. The target was moving, the firing platform was moving, lock time on the gun wasn’t fully consistent, each gun was individually aimed — there were lots of reasons, but the result was that at a range of much more than 1,500 yards, hits were almost impossible to obtain, whether the gun was rifled or not. In fact, you were more likely to score a hit with a
smoothbore at extended ranges, because a roundshot could be “skipped” or ricocheted across the water and a rifled projectile couldn’t. (It either "nosed in" and drove deep or else ricocheted in a completely unpredictable direction because of the spin which had been imparted to it.) If the water was smooth enough to permit “skipping,” a spherical shot from a smoothbore which was on for deflection but off for elevation might well hit short and “skip” into the target, whereas a cylindrical rifled projectile wouldn’t. And since ships tended to roll, elevation was more likely to be off than deflection at the moment the gun fired.
Edited to clean up some fatuigue-induced ambiguities.
