The Exiled Duke's Lottery system

Chapter 260: Chapter 253:The jet engine

Three days later, the three of them came up to the office together.

"Whatever this is," Ironbreaker said, dropping into a chair, "you’ve asked for both mages and me in the same room, which you’ve done exactly twice before, and both times it cost Lucas a year’s revenue."

"Three times," Gandalf said.

"Twice that mattered."

"Then I’ll start with a question instead of an order." Lucien pushed his work aside. "The Stormwing flew. Everyone’s pleased. So tell me — how much faster can she get?"

"With a better engine," Ironbreaker said carefully, "a little. With a cleaner airframe, a little more. Shave the drag, tidy the joints—"

"How much is a little?"

"Not much," Maerath said.

"Say it properly."

Maerath put his hands on his knees. "She’s close to as fast as she will ever be, my lord. Not because of the engine. Because of the propeller."

"Go on."

"A propeller is a blade going round in a circle. The further out from the hub, the faster that part of the blade is travelling — the tips move far quicker than the roots." Maerath turned a hand over. "Past a certain point the tips outrun the air they’re working in. The blade stops biting and starts fighting. It shakes, it heats, and it hands you back noise instead of speed."

"And you can’t slow the tips down."

"Only by shortening the blades, which costs bite, or turning them slower, which costs everything. It’s a box with no door." He shrugged. "Put ten times the power into that nose and she’d fly no faster. She’d simply come apart more impressively."

"So it isn’t a power problem."

"It isn’t," Ironbreaker said, "and that’s what I’ve been chewing on since the flight, which is why I’ve been poor company. I could hand her twice the engine and get almost nothing back." He grimaced. "Every aircraft on this continent has the same wall in front of it and nobody’s noticed it, because nobody’s got close enough to touch it. We have. That’s what winning gets you. You find the ceiling first."

"And there’s no way past it."

"None I can see. Not while there’s a propeller on the front — and there is, my lord. On everything. On every flying machine anyone has ever built."

Lucien let that sit for a moment.

"Then take it off," he said.

"Take it off." Ironbreaker’s voice went flat. "And what pulls the aircraft?"

"Nothing pulls it. Something pushes it."

He drew it badly, which he always did and which they had all learned to read past. A tube. A wide mouth at the front, a chamber in the middle, a narrow opening at the back.

"Air comes in at the front and gets squeezed — packed into a smaller space than it wants to be. In that chamber the core dumps everything it has into the air itself. Heats it. Drives it. Makes it violent. And all that air has nowhere to go except out the back, through a hole much smaller than the one it came in by." He tapped the narrow end. "It leaves there very fast. Throw enough of anything backward, hard enough, and you go forward. That’s the engine. There’s no propeller. There’s nothing spinning outside the machine at all."

Everyone was silent for a moment.

"It shoves itself along on air it’s angry at," Gandalf said.

"That’s better than my version."

Maerath had gone very still. "There’s no blade," he said. "No blade, no tip. No tip, no tip speed."

"It has blades but not like propeller," Lucien said. "And though it find another ceiling eventually — everything does. But the wall you just spent five minutes explaining to me isn’t in front of it."

"How fast," Ironbreaker said.

"At least about four times what she does now."

The room stopped.

"Four," Maerath said.

"Roughly. Don’t hold me to the last mile of it." Lucien tapped the tube. "The Stormwing is the fastest thing on this continent and she will never be much faster than she was on Tuesday. This is four times that. It isn’t the next aircraft after her. It’s the aircraft that makes her, and everything any kingdom on this continent owns, turns into an antique in a single afternoon."

Ironbreaker sat back and said nothing for a while, which from him was practically a religious experience.

"Four times," he said eventually. "You said that very calmly."

"I’ve had longer to be calm about it than you have."

"Then I’ve a difficulty," Maerath said. "A practical one, and it’s going to bite us on the first day."

"Say it."

"How do I measure it?" He gestured at the drawing. "Every engine we own, we rate by turning. How hard it twists a shaft. That’s the number in every report I’ve ever written, it’s the number in Ironbreaker’s tables, it’s how we compare one core to another." He spread his hands. "That tube doesn’t twist anything. There’s no shaft. There’s no wheel. It has no turning force at all — it simply pushes. And I have no number for pushing."

"He’s right," Ironbreaker said, and looked genuinely bothered. "That’s not a small thing, my lord. I can’t build what I can’t compare. If I make a second one next year, I need to know whether it’s better than the first, and ’it seemed to go quite fast’ isn’t engineering."

"Then we’ll need a new unit," Lucien said.

"For pushing."

"For pushing. It’s a different quantity — you can’t measure it in the old one, and you’ll go mad trying." He pulled a fresh sheet over. "We’ll call it a kilonewton."

Gandalf’s eyebrows went up. "A what?"

"A kilonewton. The name doesn’t matter; it’s a name, and it’ll be in your tables by winter and nobody will think about it again." Lucien wrote it down. "What matters is what it measures. One kilonewton is roughly the push you’d need to hold a hundred kilos off the ground. That’s the whole of it. It’s a measure of shove, and nothing else."

"So a hundred of them—"

"Would hold ten thousand kilos against the earth, yes. And that’s exactly the sum you’ll want to be able to do, and you can’t do it at all with a turning number." Lucien set the pencil down. "Every engine of this kind gets rated in kilonewtons of thrust. Write it on the first drawing and never write anything else. If you let two units into a programme, somebody eventually adds one to the other and a pilot dies for it."

Ironbreaker was already writing.

"Kilonewtons," he muttered. "And how many does the fighter want?"

"That’s your first real question, and I don’t know the answer. Work out what the machine weighs, work out how hard the air pushes back at that speed, and the thrust you need falls out of it. But you’ll be able to ask the question now, which you couldn’t ten minutes ago."

"That’s the second time you’ve handed me a word and made a year’s work out of it."

"It’s the same trick as the calipers."

"It’s the same trick as the calipers," Ironbreaker agreed sourly, "and it worked then, so I’ll shut up about it."

"Right." He stood, which meant he had begun taking it seriously. "Then I do what I always do and list the ways it kills someone. Heat."

"Heat. First and worst." Lucien nodded. "You’re building a chamber whose entire purpose is to make air as violent as it can be, then asking the walls around it to survive that, continuously, for hours, with a man sitting a few feet away."

"Every alloy we own softens."

"Then that’s what you solve first. The shape is easy — it’s a tube. It’s the materials." He glanced at Gandalf. "And it may not be a metal problem alone. It might want a metal with a working in it."

"Now that is interesting," Gandalf said, in the voice of a man handed something to be rude to people about for a month.

"Second — it will be thirsty. That much violence, continuously, out of a mana core. It’s a sprinter, not a plough horse. Don’t design it into a machine that has to loiter."

"Third," Maerath said, "none of this lifts anything. It’s speed, not lift. Point that tube forward and you’ve a very quick aircraft that still needs a field to get off."

"A long one. Say that out loud now, because Skyforge’s strip won’t do and somebody will have to pay for a longer one."

"Lucas will be thrilled."

"Lucas will be inconsolable."

Ironbreaker had stopped writing, and was looking at the drawing with his head slightly on one side.

"It doesn’t care which way it’s pointed," he said.

"Say that again."

"Your tube." He turned the sheet around. "A propeller is a propeller. It pulls forward, and that’s the only thing it will ever do, because that’s the direction the shaft is facing and the whole aircraft is built around the shaft. But this—" he tapped the narrow end, "—all this does is shove. It doesn’t turn anything. It doesn’t drive anything. It throws air out of a hole." He looked up. "So point the hole at the ground."

Nobody said anything.

"That’s Arven’s machine," Ironbreaker said. "That’s the thing I stood on my own field and told twenty-five knights couldn’t be built. No rotor. No blades. No tail fighting for its life every second of the flight. The same tube, turned."

"That’s the road, yes."

"Then why do you look like a man about to spoil something?"

"Because it’s the road," Lucien said, "and it isn’t the destination, and we should do the arithmetic before you go and tell Arven he’s getting his aircraft." He pulled the sheet back across the desk. "Sit down. There’s a second half to this and you’re not going to enjoy it."

Ironbreaker sat.