Midst Toil And Tribulation – Snippet 39
Merlin’s expression was admirably grave. He, too, was sure they’d be able to make it work, especially since Howsmyn had access to detailed plans of de Bange’s original design, including the “mushroom,” the rounded “nose cone” at the head of the breech block. It was actually the most ingenious part of the entire concept in many ways, because when the gun fired, the mushroom was driven to the rear, compressing the asbestos “washer,” squeezing it so that it expanded outward to seal the breech completely. And because the mushroom was driven by the firing chamber pressure, the tightness of the seal automatically adjusted to different weights of charge. Merlin had no doubt that when Howsmyn sat down with Saigyl to look at his drawings, the industrialist would experience another of those intuitive inspirations for which he had become known and start enthusiastically sketching in ideas of his own.
“All right, now that that’s out of the way, what about this other problem you wanted to discuss?” the high admiral continued. “Something about bore pressures and combustion rates?”
“Yes, Sir,” Seamount replied in a distinctly less cheerful tone. “I’m afraid we won’t be able to get as much benefit out of some of the new advances as I’d hoped.”
“Well, Ahldahs and Commander Malkaihy and I have been going back over the results of Urvyn’s artillery tests. We’ve repeated several of his firings using the new crush gauges to measure bore pressures and the pendulum to measure velocities, and they’ve confirmed something we already suspected. We’d hoped we could increase shot velocities by increasing barrel length, but it turns out we can’t.”
“Why not?” Rock Point repeated.
“Essentially, My Lord, the powder burns too quickly,” Rahzwail said. “It gives all its propulsive power in a single, sharp kick the instant that the charge fires; with a longer barrel, we actually start losing some of that initial velocity due to friction between the projectile and the inside of the gun tube. Looking at the pressure gauges, we’ve concluded that a great deal of the powder is transformed into smoke — solid particles and soot — rather than the combustion gases that actually drive the projectile. Corning the powder clearly helps in that regard, given how the particulate mass is reduced and how much more of the powder is actually burned before it’s ejected from the muzzle, but there are still limits, and we seem to’ve reached them . . . for the moment, at least.
“Of course, that’s only part of the problem. The rifled pieces’ shells are much tighter fitting, which means they rub against the walls of the bore more than roundshot do. That increases friction still further, which costs us even more velocity, and the rifling studs only make it worse. Frankly, I suspect the new ‘driving bands’ Master Howsmyn’s experimenting with will be even worse than the studded shells in that respect. I still think the advantages outweigh the problems, mind you, but there’s no denying there’ll be more than enough problems to keep us busy.”
“And that’s not the only difficulty we’re experiencing,” Seamount put in. “Among other things, Master Howsmyn’s new steels, especially now that he’s tried adding nickel to them, are even tougher and stronger than we expected. That’s wonderful news in most ways, but, unfortunately, it also means we can’t produce satisfactory armor and stone-piercing shells out of them, after all. The shell walls will be too strong for gunpowder bursting charges to shatter properly if we make them out his new steels. At the moment, it looks like it’ll be wiser to restrict ourselves to cast iron shells for the smoothbores and the wrought iron shells he’s already developed for the rifled pieces.”
“They seem to’ve worked quite well in the Gulf of Tarot and at Iythria,” Rock Point said dryly.
“That they did, Sir. And they should still be quite effective against wooden ships and light shore structures. But it’s only going to be a matter of time — and probably not a lot of it — before people begin designing shell-proof magazines for their fortresses, for example. Ten or twelve feet of earth, reinforced by a few feet of solid masonry, would most probably stop any of our present shells from penetrating, even from the angle guns, and overhead protection for the batteries is also going to be high on fortress designers’ list of priorities once they begin to recognize the threat’s parameters. That’s why we’ve been concentrating on producing shells heavy enough to do what the bombardment ships did at Iythria to the next generation of forts. Or even, eventually, to penetrate someone else’s ironclad. Wrought iron isn’t going to be as effective for those uses, and it’s more likely to break up or shatter on impact than Master Howsmyn’s steel, especially with the quenching processes he’s been developing to harden the new shells’ noses. But if we can’t find some way to improve our gunpowder, there won’t be any point putting a bursting charge inside those shells. Basically, we’d be restricted to essentially the same solid shot we’ve always used — heavier, with better penetration qualities, but still a solid projectile rather than an exploding shell.”
“And have you and Captain Rahzwail had any thoughts about how that might be accomplished?” Rock Point asked.
“At the moment, all we’ve really come up with is the idea that we should find a way to increase the uniformity of the powder grains, My Lord,” Rahzwail replied. “It seems to me that if we could . . . compress the powder, make the individual grains denser, and possibly produce it in shapes that would increase the surface area, we ought to be able to retard the burning rate at least somewhat. That would mean combustion would take longer, and the projectile would be accelerated for a longer period, rather than beginning to lose velocity from friction. For that matter, if the grains were all a uniform size, we ought to get a more uniform burn rate from powder lot to powder lot, which would make for much more consistent ranges and trajectories for a given charge of powder. I suspect that pelletizing the powder we’re using in the new Mahndrayns would improve their muzzle velocity measurably, as well. And Commander Malkaihy’s also suggested we might find some ingredient or adulterant that could slow the combustion rate for artillery propellants still further. Since it’s the charcoal in the gunpowder that provides the actual fuel, we’re considering alternative types of charcoal that would burn more slowly, but we haven’t found one that would do the job yet.”
Merlin managed to keep his expression blank, but it was harder than usual. Admittedly, Rahzwail had certain advantages, given the significant boost one Merlin Athrawes and his friend Owl had provided to the Safeholdian science of pyrotechnics. And the resources of the “archangels'” allowable technology gave Safeholdians a much broader base of capabilities to build upon than their pre-Merlin artillery and explosives might have led most people to expect. Still, the captain’s summary had been almost breathtaking, carrying him — conceptually, at least — all the way from the corned powder of the seventeenth century through Thomas Rodman’s prismatic powder in mid-nineteenth century to the German “cocoa powder” of the 1890s in no more than a handful of sentences.
And he doesn’t even know about Sahndrah’s little discovery yet! Dear Lord, what are these people going to come up with
He didn’t have a clue, but as he sat at that conference table, looking back and forth between Sir Ahlfryd Hyndryk and Ahldahs Rahzwail, he suddenly felt far less concerned about how they were going to react when he had to get around to telling them about the information the traitor in Hairatha had sent to Zhaspahr Clyntahn.
The bastard can steal whatever “secrets” he wants, and he’s still going to fall further and further behind,
Merlin thought with grim, harsh satisfaction. He can’t begin to match what our people can come up with, even without me standing in the corner handing out ideas. And that’s why the son-of-a-bitch is going to lose. I don’t care how many men he can put into the field, our people — my people — are going to kick their sorry arses all the way back to the Temple, and then that bastard is going to pay the price for Gwylym Manthyr and everybody else his sick, sadistic butchers have tortured and killed.
“That sounds like a very interesting idea, Captain,” he said out loud, his voice calm, his expression intent. “Have you given any thought to how you might do that? It occurs to me, that if you were to manufacture a form — a nozzle, perhaps — of the right shape, then force a gunpowder paste through it under heavy pressure using one of Master Howsmyn’s hydraulic presses, what you’d get would be –”