Chapter 86: Royal Engineers Part 3

***
Over the following weeks, Cesare and his team used carefully constructed balloons to measure the lift of hot air versus hydrogen. They quickly determined hot air wouldn't be enough to float the airship. Even with hydrogen, they needed an enormous volume to lift a small weight. Armed with that information, Cal worked through her plans, cutting weight everywhere she could.
The boiler would be the biggest challenge. Train engines operated at much higher pressures than steamships, but to drive the airship any distance even they would be too heavy. The team struggled with spherical tanks as flaws in the shape became catastrophic much quicker than with cylinders. Cal started every time a boiler blew. Even the small prototypes made a considerable bang. She finally asked them to give her a five-minute warning so she wouldn't spoil so many drawings. Since her work paused for the time of the test, she began watching from the gallery. Even as her team's manufacturing skills improved, the balls failed where the two hemispheres joined. Cal headed down to listen in on their evaluation.
"Don't matter what we do with the flange, it blows. We can't tighten it enough."
"What about putting a lip inside the flange on one side?"
"Could do, I guess. I still think the issue is the join."
"We tried welds and we've tried bolting it, don't think a bit of a lip will help."
"What if you nested spheres, and staggered where the joins were?" Cal scratched her head. Then used a bit of chalk to illustrate on a convenient patch of blank wall. "See? Each layer reinforces the others. If we wrap in between layers with something with no give it would even out any spaces between the layers. We might be able to use a smaller amount of steel in total as a result."
"Hmmm," Digney peered at her scratches on the wall. "Worth trying. We'd want to set the fittings in each layer, or they'll blow. Need a new design for valves to handle the pressure. If we set the valve in the boiler, we won't have to fuss with the output pipe."
The others nodded and started discussing details and how to test them. Cal winked at Digney and went back to work.
She passed the room where Landers and his group had set up fans with different shaped blades to measure which was most efficient.
"Commander?" The old engineer called Cal in. "We're leaning toward this design. We have doubled up two oak props. Need a lot more surface than the water propellers to push the air. We found longer was better than wider. Four blades work best."
"Good work. I'm thinking you'll need the engine to test how fast they can spin before failing."
"That would be our next step. We'll start with a standard engine, least we know how to build 'em. A couple of us are working on something which will spin the shaft directly."
"Interesting. How do they plan on doing that?"
"Patrick wondered if a fan could push air if air could push a fan. Not as simple as all that, but he's been lying awake at night thinking about it."
"I'd like to hear more about his ideas." Cal closed her eyes to picture how it might work. It would take a lot of work to make it efficient.
"Commander?" A young man stood at attention in front of her, his knees visibly shaking.
"Sorry, Patrick. I was envisioning your concept." She smiled. "Do you have any drawings?"
"Let me fetch them."
"Bring them to my office, I'll put on tea. Anyone else who wants to kick it around can join us."
In the end Patrick, Landers and Cal sat at a table, tea cups holding his drawing open on the table.
"I see you have the blades enclosed, that's good, but a cylinder might not be the best shape. Remember the steam is under pressure, so it expands as it moves."
"Of course, that's the point."
Landers glared at the young man, but Cal shook her head and he didn't say anything.
"What if we used the expansion to push the fan faster?" Cal sketched a cone with a series of ever larger fans.
"The steam will blow past and we won't get much push." Landers peered at the drawing.
"What if the only path for the steam was past the blades?" Patrick drew a spiral shape with the blades growing larger, set with the cone. "We'll need to figure what shape cone is best and how many blades, but there is no reason we can't drive a shaft with this."
"Okay, Patrick what do you need to build this thing?" The young man looked at Landers, who laughed and slapped the younger man's shoulder.
"It's your project, you do the thinking." Landers nodded at Cal. "We'll need more people, and specialized fabricators would help. I can throw something together, but this will require accuracy beyond my talent."
"Bring me a plan by morning." Cal took a sip of her tea, then pushed the paper back into place. "My gut is telling me this could be a huge jump forward if we can make it work." She met Patrick and Landers' eyes. "Don't talk about this outside of the teams. I've never heard of anything like this, so as of this moment it is secret."
"Aye, Commander." The two men looked at Patrick's drawing with new respect.
***
Outside the Shed, Cal met Commander McAllen riding a horse, holding the reins of a second.
"The climbing wall is a fair distance, don't want you too tired to climb, and coming back here will be worse."
"I used to ride a little with my governess." Cal introduced herself to the horse. "Come on handsome, let's see how much I remember." Mounting in her pants and blouse was much easier than the riding dress her governess insisted she wore. She settled herself in the saddle and picked up the reins.