by David Weber
“That does sound like him,” Sharleyan acknowledged. “And I have to admit, I’m definitely in favor of not missing our window on this one.”
“There are arguments in favor of delaying till tomorrow so we can launch even earlier in the day, when we’d have plenty of time to make adjustments,” Delthak pointed out, but it was obvious from his tone that he was only teasing her.
“Any more thoughts about using hydrogen in the production ships instead of kerosene?” Merlin asked before Sharleyan could respond in kind. At the moment, he and Nynian were in their comfortable cabin aboard the steamer returning them from a quick trip to Boisseau.
“We’re putting it on hold for now, at least in the experimental ships.” Delthak shrugged. He stood on an observation platform outside an enormous wooden shed at one of the Delthak Works’ several test tracks while a dozen blast furnaces produced their own fiery iteration of a sunset and the SNARC parked directly above Charis looked down upon him. “There’s a lot to be said for it, and we’ve had a lot of experience with gas jets and burners now, but the ducting could pose some problems. Increases the chances of a hydrogen leak, for one thing—not to mention providing a pathway for an unfortunate spark. At least for the moment we’ve decided it’s more important to keep the power plants completely separated from the gasbags as a precaution.” He shrugged again. “This is an experiment, after all. There are plenty of other ways we can wreck it if we really try, without adding any additional risk factors. If we do go to series production, we’ll look at the notion again, but for right now, safety’s our main concern.
“Probably not a bad idea,” Merlin conceded after a moment. “And it’s going to be a spectacular enough achievement even without that particular bell or whistle.”
“Yes, it is,” Admiral Rock Point put in across the com.
“As long as it works.” Delthak sounded like a man putting out a sheet anchor he didn’t really expect to need. “And, speaking of working.…”
His voice trailed off, and there was silence on the com. It was a tense, waiting, anticipatory silence, and then the huge shed’s enormous doors rolled fully open and a chuff of smoke went up from the steam-powered tractor which had been waiting for this moment. The tractor moved forward, pulling a thick towing hawser behind it, and a blunt, gray bullet of a nose poked itself through the doors.
It moved slowly but steadily, almost majestically, under the tractor’s urging, and as it emerged into the slanting late afternoon sunlight the watchers saw the scores of Delthak workmen coming with it, clinging to dozens of tethers as they guided it carefully forward.
As the nose completely cleared the doors they could see the rest of the vehicle coming along behind it. It was enormous—ten feet longer than the original River-class ironclads—and shaped like some huge version of the tethered observation balloons the Imperial Charisian Navy had deployed for the final campaigns of the Jihad. Not surprisingly, because that was precisely what it was, but with a few added features.
The most obvious of those added features were the cruciform stabilizers at the tail of the gasbag and the pair of podded engine nacelles thrusting out on either side of the thirty-foot-long control cabin nestled under the gasbag’s midpoint. The twin-bladed propellers were locked in the upright position; even so, they barely cleared the frame of the shed’s—no, the hangar’s—gaping doors.
It took the better part of fifteen minutes to tow it totally out of the hangar, and no one said a word as they watched its progress in rapt silence. Once it was completely clear, the workmen on the tethers moved carefully, using their weight as they allowed it to pivot until its rounded nose pointed into the gentle wind coming out of the west. The tractor’s massive weight provided a solid anchor as it pivoted, and they adjusted its position with finicky precision. Obviously, it was a task they had rehearsed carefully.
“It looks even bigger than I expected,” Sharleyan murmured finally.
“She, Sharley,” Delthak corrected. “She, not it, please!”
“Sexist!” Nimue shot back with something very like a giggle.
“Simply a traditionalist,” Delthak replied. “This is a ship, so she’s a she.”
“Well, she looks even bigger than I expected.”
“She’s thirty feet shorter than Sword of Charis-class was,” Cayleb pointed out. “That should have given you some kind of scale to prepare yourself.”
“If you’ll recall, galleons spend most of their time floating,” his wife replied tartly.
“Well, this is floating, too!” Cayleb told her with a chuckle.
“But not in water, clown!” She clouted him across the head and he laughed.
Still, she had a point, Merlin reflected. True, the airship turning to point its—her—nose into the wind was actually shorter than the shuttles squirreled away in Nimue’s Cave. But while Sharleyan had seen those shuttles, even walked under the shadow of their wings, she’d never seen them actually fly. And what they were looking at, at this moment, was something totally new in Safehold’s experience.
The airship stopped, bobbing ever so gently, tugging against its tethers. Shouted commands rang out, too distant for Delthak’s com to pick up and relay. And then the workmen released the tethers. They disappeared, reeled up into the structure under the long, stretched oval of the gasbag, and the locked propellers began to turn. Slowly, at first, then with gathering speed, until they vanished into a blur of motion and the entire craft moved slowly forward. It drifted towards the tractor, and the towing hawser drooped as the tension came off it.
And then the moment they’d been awaiting came. The airship released the towing hawser. It fell away, ballast bags thudded down from the airship’s keel, it bobbed as its buoyancy increased with the lost weight, and then the nose tilted upward. It climbed into the wind, propeller blades a throbbing blur, curving into the west as it climbed in obedience to the rudder and elevators on its stabilizers. It swept upward with majestic grace, its haze-gray envelope, the same color as the Navy’s warships, gleaming in the mellow light of the westering sun. They’d chosen to make the maiden flight largely in darkness because no one really knew how even Charisians would respond to the sight of something half the length of a soccer pitch soaring overhead.
“God, that’s beautiful,” a momentarily subdued Cayleb murmured as the airship swept steadily higher, shrinking as it went.
“Hear, hear,” Rock Point said, his voice almost equally soft. “I only wish Ahlfryd was here to see it.”
“So do I—so do all of us, Domynyk,” Sharleyan said with a sad smile. “At least he got to learn the truth before we lost him, though.”
“I know,” Maikel Staynair’s brother said. “And God knows he died doing what he loved to do. I always teased him about that. I told him anybody who played with explosives as much as he did was bound to blow himself up eventually.” He shook his head sadly. “I just wish I’d been wrong.”
“It wasn’t the explosives, it was the breech failure,” Delthak said, never looking away from the ascending airship. “And, no, I’m not going to beat myself up over it again. It looked good on every inspection—including Owl’s. Just one of those things we all wish to hell had never happened.”
“Yes, it was, and I didn’t mean to be a wet blanket,” Rock Point said. “He really would have loved this, though!”
“If we hadn’t already named the Ahlfryd for him, I’d’ve named this one in his honor, female pronouns or not,” Delthak said. “Because you’re right. If he were still here, he’d be dancing on top of the gasbag!”
Fond, bittersweet laughter muttered across the com, because Delthak had a point, Merlin reflected, and not just about Sir Ahlfryd Hyndryk or how much they all missed him. Baron Seamount really would have been ready to dance at the mere thought of the Delthak Works’ newest brainchild. Although he probably would have disapproved of the notion of naming it after him. In fact, he probably would have disapproved of Sharleyan’s determination to name the imperial yacht after him.<
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Fortunately for his sense of propriety, assuming he was keeping an eye on them from wherever he was now (and rather to Zhain Howsmyn’s chagrin), the first powered airship in Safeholdian history had been christened Duchess of Delthak, instead. Despite her size, she was actually on the small size for a powered airship. And, as Delthak had said, she was a purely experimental vessel, but that made her no less impressive as an achievement. And in time, if all went well, she would serve as the official inspiration for much more substantial designs farther down the line.
Unlike a dirigible like the ill-fated Hindenburg, with its aerodynamic external aluminum shell, or a simple blimp, with no true support structure for its gasbag, Duchess of Delthak was a semi-rigid design. Her keel of high-tensile steel and blue spruce—a native Safeholdian tree very similar in many respects to its Old Terran namesake—stabilized and supported the lower half of her gasbag, which otherwise held its aerodynamic shape only when its gas cells were inflated. It also provided more structural strength than a blimp would have had, as well as anchorage for her control cabin and the nacelles for her Praigyr steam engines, but at a far lower weight penalty than a rigid design.
To the best of Owl’s knowledge, no one had ever powered an Old Terran dirigible with steam. Then again, no one on Old Terra had ever had to worry about a cosmic bombardment for fooling about with electricity. And, Merlin acknowledged, watching Duchess of Delthak dwindle with altitude and distance, most people would have had the odd qualm or three about hanging a boiler on a bag full of hydrogen. By far the most common source of disaster for Old Terra’s airships had been fire or explosion.
But while the Praigyr’s operating temperature might be well above seven hundred degrees, those were Fahrenheit degrees, another legacy of Eric Langhorne’s deliberate suppression of the metric system, and seven hundred degrees was actually only about eighty percent of the compression temperature of the air in a diesel. And it wasn’t as if the Praigyr had an exposed firebox. The combustion chamber was sealed and heavily insulated, and its kerosene fuel burned at such a high temperature that the exhaust was little more than water vapor. Coupled with the fact that any hydrogen which escaped the gasbag would be enthusiastically racing towards the edge of space and away from the engines, the likelihood of an engine-induced catastrophe was minute.
Duchess of Delthak was unbelievably light for something her size. Her gasbag was 18 percent as long (and 83 percent as wide) as Hindenburg’s had been, yet her gross weight came to just over 4,800 pounds, only about 3 percent that of the ancient dirigible. The 123,000 cubic feet of hydrogen in her gas cells produced 8,360 pounds of lift … which, after allowing a ton and a half for fuel, feed water, and ballast would let her lift her three-man crew to her designed altitude of 9,000 feet with a 500-pound safety margin for cargo.
Producing all that hydrogen presented its own challenges. During the Jihad, all of the Balloon Corps’ hydrogen had been generated by reacting zinc in hydrochloric acid, which had been possible only because the Lizard Range in eastern Old Charis contained large deposits of what had once been known as calamine (or, more properly, zinc silicate) on Old Terra. It had been mined, in rather smaller quantities, for over a hundred years to support the production of brass, although demand had risen sharply as the scale of Charisian manufactories skyrocketed. On the other hand, the miners had never before had the tools and explosives Delthak Enterprises had made available, so it had been relatively straightforward to mine and smelt the zinc in the needed quantities. But transporting that much hydrochloric acid and controlling the reaction had been logistically difficult. It had also been dangerous. Delthak’s personnel had gained a great deal of expertise in the management of explosive gases from handling the coal gas his blast furnaces had been producing for years now, but “safe” was an elastic term when applied to producing hydrogen in such quantities, and transporting liquid acid in bulk was always risky.
Since the Jihad, however, Sahndrah Lywys had “discovered” that hydrogen could also be liberated, albeit at a small loss in efficiency, from ferrosilicon dissolved in a heated sodium hydroxide solution made with old-fashioned lye. Safehold was well accustomed to producing lye in large quantities, given its many uses in textiles and cleaning generally, and ramping it up further had presented little problem. Well, little in the way of technical problems; producing it with a pre-electric tech base significantly increased the environmental impact, but that was true of a lot of the workarounds the inner circle had been forced to adopt. All they could do was hold those impacts to the minimum possible and adopt less destructive techniques the instant they could.
The good thing about ferrosilicon was that the Delthak Works’ blast furnaces could produce it in industrial quantities by firing charges of crushed quartz and iron ore, which had led to its Safeholdian name: ironquartz. The highest silicon concentration Duke Delthak could achieve with a coke-fired blast furnace was only about fifteen percent, but that was workable, and he’d developed a more efficient—well, safer, anyway—portable hydrogen generator for the Balloon Corps. It consisted primarily of a sealed steel vessel, small enough to load into a dragon-drawn freight wagon, in which ironquartz and the sodium hydroxide solution were combined. The reaction was exothermic and heated the solution to about two hundred degrees, starting the process, but the vessel could be heated externally to jumpstart gas production. Every pound of ironquartz yielded about 3.4 cubic feet of the gas, and Delthak Aircraft, the newest subsidiary of Delthak Enterprises, was in the process of designing a permanent, high-capacity ironquartz hydrogen generation plant which would be safely located underground to minimize explosion risks and generate somewhere around 840,000 cubic feet of hydrogen a day.
Despite her diminutive size compared to the Hindenburg, Delthak’s new brainchild was still far larger than the Wyvern-class observation balloons of the Jihad. The Duchess’ gas cells held over four times as much as a Wyvern’s, and she could carry enough fuel for an endurance of seventeen and a half hours, which gave her a range of seven hundred miles at her forty-mile-per-hour cruising speed. In theory, at any rate; headwinds or tailwinds could change that number drastically. During that time, her Praigyrs would burn off enough kerosene (and lose enough feedwater, despite their closed condensers) to reduce her gross weight by three thousand pounds, so to maintain her altitude, her crew would be forced to vent sufficient hydrogen to compensate for the weight loss.
That hydrogen—all 44,000 cubic feet of it—would have to be replaced before Duchess Delthak could take to the air once again. Delthak’s portable generators made replacement reasonably practical, so that wasn’t a huge problem. But if they could burn that gas as fuel, instead of kerosene, they’d quadruple their cargo capacity—or gain a significant increase in range—using hydrogen they’d only have thrown away anyway.
Not even an unlimited supply of hydrogen could have overcome the explosive nature of the gas itself, however. Airships were undeniably fragile and hydrogen was dangerous, which was why it had been used on Old Terra only until helium became available in sufficient quantities. But while helium was far safer, it was also far rarer and impossible to refine in industrial quantities without electricity. It also offered less lift—only about half as much, given the practical design and operational differences between hydrogen- and helium-filled airships—so even if they could have obtained it in sufficient volumes, using it would curtail both weight and range significantly.
Airships would be another of the inner circle’s “technology demonstrators”—and damned impressive ones—and their enormous range and endurance would be extremely valuable, but the future almost certainly lay with fixed-wing aircraft, just as it had back on Old Terra.
The proscription of electricity created problems even there, since it ruled out spark plugs or even glow plugs for gasoline-powered engines. The current generation Praigyr produced about 0.13 Old Terran horsepower per pound, whereas Hindenburg’s diesels had produced 0.3 horsepower per pound. Despite that, Owl had already produced
a Praigyr-engined biplane design that was well within Safehold’s capabilities. But while there was ample room for Owl’s design to be tweaked as Praigyr improved the engines named for him, they would never really be able to get past the unfortunate fact that a steam engine—even a Praigyr—had to weigh about twice as much as any internal combustion engine of comparable output built with the same technology.
On the other hand, diesel aircraft engines were a distinct possibility. Even they would have a poorer power-to-weight ratio than a gasoline-powered engine could have attained. They would, however, be lighter than Praigyrs and fully capable of powering practical aircraft.
“Too bad she doesn’t have the range to overfly Desnair or South Harchong,” Merlin said out loud after a moment or two. “Assuming Zhyou-Zhwo didn’t drop dead of a heart attack—admittedly, the best outcome—he and Mahrys would both at least froth at the mouth nicely.”
“They would, wouldn’t they?” Delthak said wistfully. “And I’d love to see Showail explaining to Mahrys why he couldn’t build one of his own.”
“You’re a bad man, Ehdwyrd,” Sharleyan chuckled. “Besides, much as I may dislike Showail, we need him doing what he’s doing. For that matter, I like Mahrys even less, but we really don’t want to lose him at this point, either.”
“True, unfortunately,” Merlin conceded.
Symyn Gahrnet’s first “five-year plan” was actually going rather better than the inner circle had hoped. Which wasn’t to say it was going as well as they might have liked. Or remotely as well as industrialization was proceeding in some of the other Mainland realms, like Silkiah and Dohlar, for that matter. The Kingdom of Dohlar, especially, with little more than half Desnair’s population, was streaking ahead of the empire in terms of infrastructure.
Probably because Desnair had no Earl Thirsk, he reflected.
Never had a conversation that worked out better, he thought, remembering a long-ago stormy night in the earl’s library. Except, possibly, that first one with Haarahld!