Zep Rules Teaser, designer's notes in italics.
Zeppelin Construction Rules
I'm big on story, and integrating rules to story. For that reason, in addition to the rules, I like fluff pieces like the following. The 'raw' rules are all written out, but I figured this would be more entertaining to read. The focus of the rules was simplicity but not simplicity, and compromise. Thanks to Yahzuk for his cool zep rules pdf from which I drew inspiration.
Good Morning class, please be seated. I'm Engineer Neils Reimer, currently employed by the Empire State Zeppelin Company out at Lakehurst Naval Air Station. I've been invited to speak to you today about Zeppelins, airships, or rigids as we like to call them in the business. Specifically, I'm going to teach you the difference from what you've read in adventure serials and reality. Today we end the rumours and get down to the cold hard facts about airships.
Let's start with something simple, what is an airship? What's that? You'll have to speak up. No, I'm sorry, 'bags of gas' is not the correct answer, although that is what a lot of people think. Bags of gas could describe, a balloon, or a blimp. This is not what we are talking about. A rigid airship is a series of cells, held together by an aluminum or duralim internal construction, surrounded by an outer canvas layer and stabilized and counterbalanced by numerous cables. The number of internal gas cells determines the Airships size. To be more specific, a single cell ship is technically a blimp, a bag of air is a balloon, everything else is a rigid airship.
Most airships are three to five cells, although six and seven cell zeppelins are possible, but are prohibitively expensive to build and manufacture. In fact, there are currently only four airship hangars large enough to manufacture seven cell leviathans, the Goodyear facility in Akron, the Luft-Technik hangar in Germany, the Royal Airship Works in the United Kingdom, specifically in Cardington, Bedfordshire. The final location is right here in the Empire State, at Lakehurst, where if you remember last month's headlines, we successfully launched 'Son of Empire' our first seven cell rigid airship. Sorry, I really can't hear you at the back of the class, speak up please. Eight Cells? Well, I suppose it could technically be done, but let's think about the problems inherent. Chief in my mind would be torsional stress. I mean, we're pushing it at seven cells, that's 350 meters of aluminum stress beams and tensioned cables. Oh, sorry, just shy of 1150 feet long, I keep forgetting to not use metric when I teach. As it stands, we can barely keep that together, and you want to add another 170 feet to it? You'd be looking at stress fractures after every flight, constant tension cable adjustments in flight, and overall, prohibitive maintenance. Until we find a metal stronger than duralim, and lighter than aluminum, I doubt we'll see anything bigger than seven cells for a while. Titanium? Well yes, but let me clarify my prior statement, until we find a useable and easily workable metal, we won't see mega-ships bigger than 'Son of Empire'.
Ok, let's move on from simply size, let's talk performance. I'll be frank, most zeps don't have much. Sure, in a straight line most zeps can edge towards 100 miles per hour, and military class vessels can touch 150, but the moment you want to turn, you'd better have a lot of time, and a lot of room. But let's get back to straight line speed. An airship takes time to accelerate, but like an airplane, a captain can push her engines to get going a bit faster. What? Oh yes, military class, that's just a general term we toss around for overpowered zeps, your standard zep needs roughly two engines per gas cell, but for that extra edge, most military airships mount four engines per gas cell. There are some civilian high speed liners that also have this feature, but the prohibitive expense in both fuel and weight makes them very rare. It's a valid question, the slight speed increase doesn't seem worth the loss, I know, but that excess power makes them more survivable, and, if the captain and engineering crew are any good, more maneuverable.
Let's move on to components. I've touched on the subject of weight a few times, but now you're going to discover the headaches of any modern airship engineer. Weight is your enemy, and you will fight a constant battle against it. Every component you put on an airship adds weight, and you can't have everything, you have to compromise. Yes, go ahead, you with the red tie. Total weight? Well, we're talking thousands of pounds, determined by total lifitng capacity of the Helium in the cells, and I could go into a very long and boring explanation, but for simplicity let me tell you about the little engineering shortcut we call the rule of ten. Every cell on an airship has a lifting value of ten. For every component you put on it, subtract one. When you arrive at zero, you cannot add anything else to that particular cell location. Now of course, you'll need engines, so really it's more like the rule of eight, but I like the sound of the former. Pardon me, stockpiling? No, of course you can't stockpile, think about the torsion effect of not putting any components under one lifting cell, and concentrating them all in another, not to mention how you'd destroy the Zep's balance. No, every cell can accommodate up to ten components or enhancements. Additional lift that you don't use for that cell is lost, and is usually indicative of sloppy design. This isn't a feel good lecture, it's about the realities of physics. My assistants are handing out a small list of components for the rule of ten. I can see your frowns, and I feel your frustration. Yes, extra armour would be nice, but are you sacrificing defensive armament, hangar and cargo space?
Yes, I can see your hand waving at me frantically, go ahead ask. Hydrogen cells? Yes I know the lift characteristics of Hydrogen, but I also know the chemical properties. While lift with hydrogen is better, and it is cheaper than Helium, the spark proofing required on a Hydrogen zep cuts into the benefits. Not to mention the disaster that would occur if only one of the bags caught fire. However, if you insist on using it, if as I suspect, you end up at a third world airship plant in Bolivia, you can change your rule of ten to a rule of thirteen. Likewise, a super-expensive alloy structured duralim zeppelin would make it a rule of twelve. I see a few hands, and let me pre-empt you, the rule has already taken care of all those secondary concerns, such as ammunition storage, part storage, and other incidental weight concerns. I admit, it is a bit abstracted, but it works, you can quickly plot out a zeppelin schematic using the methodology. A note on zep hook and launch bays. The amount of locations for them is determined by taking the number of cells and subtracting one. Thus, blimps cannot recover aircraft, and the smallest airships have only one ingress/egress location. Most modern combat zeps have one launch bay, and one zep hook, in separate locations, to permit flight ops. Dedicated Carrier Zeppelins, like the Texan's Wildcat class, generally have multiple launch bays, to speed up aircraft deployment.
In the Rulebook, this will be overlayed on a piece of notepaper, like a student handout.
Zeppelin Gas Cell Components
10 pts max (Duralim Structure gets +2 pts, Hydrogen cells get +3 points)
Docking Clamp - 1 (Must be placed in Cell 1, required)
Control Cabin - 1 (Required)
Directional control surfaces - 2 (Must be placed in last cell, required)
Engines – 2
Military Engines – 4
Zep Hook or Launch Bay – 1
Aircraft Hangar (4 Planes) – 1 (Maximum 1 per cell)
Guns Light – 1
Guns Heavy – 2
Broadside Naval Class Cannon – 2
Flak Cannons – 1
Armour – 1
Heavy Armour – 2
Anti Fighter Line – 1
Cargo – 1
Passenger/Crew/Aircrew Cabins – 1
I suppose we may as well move on to destruction of cells, since we've covered hydrogen already. We have three states for gas cells, intact, ruptured, and destroyed. For a blimp, a ruptured cell will cause a descent, and a destroyed one, well, let's just hope the crew has parachutes. A two cell airship will descend on one cell destroyed, and crash if the other bag is ruptured. For every class greater than that, the ship will descend on the loss of cells equal to half it's starting cell count, plus one. So, four cells will descend on two and half, sorry, two destroyed one ruptured, and crash on three. Seven cells would descend on four bags lost, and crash on four and half. Now, there is one exception to this rule, if all the cells required for a descent are in a line, and destroyed, the zeppelin will lose structural integrity and crash. What? No, lifting power doesn't stay the same, don't be silly. Crews who lose cells immediately begin dumping ballast, generally whatever didn't fall off when the cell was destroyed. For your purposes, you can assume that any component located in that cell location is lost with the cell, with a few notable exceptions.
We'll talk about the second limiting factor, cost, in tommorows lesson. Tonight, as review, I want you to construct a zeppelin, and bring it in for review tomorrow.
That's it for now. As always, this is an early alpha draft, as the project advances, it will be cleaned, expanded, and formatted. Oh yeah, Diagrams are being produced as well. Comments appreciated