And since you mentioned the give/take of weight vs armor vs speed, etc, and since it's about time I started writing it up anyway, Here's a very basic look at the airship building rules:
You start by trying to figure out what you want it to do. Usually I find it helpful to pick one or two variables I want to meet. (I want this ship to be under $150,000)(I want this ship to go at least 80 Kph)
Then you set up your compartment layout.
An airship HAS to have at least 4 compartments:
• Bridge
• Pressure Tank
• Boiler
• Engine
There are a few simple restrictions on where you can put things. For instance:
• Bridges have to be the forwardmost compartment on the deck they're on (so you can see out. Durr.)
• Engines have to be within 4 compartments of a pressure tank.
• Pressure tanks and Boilers must be horizontally or vertically adjacent to each other (though you can daisy-chain Boilers)
• Engines must be evenly spaced to front and back or on the centerline (this is measured form the outermost compartments of the airship)
The way you arrange your compartments will impact you ship's overall performance, especially it's Flight rolls.
Shorter ships will be able to turn a little better, but tall ships won't be as stable at high speed.
Long thin ships might be a little easier to pilot at speed, but they won't turn as easily.
When you have your layout, you figure out the stats of your compartments.
The 'power' of your compartments is determined by it's Rating. Ratings go from 1000 to 5000. In SP! the rating is a little more important than in SA, as high-rating compartments are more expensive and more difficult to fix/finds parts for. In SA it's not an issue, though higher-rating compartments are still more expensive, and contribute to the cost of upkeep.
Basically the Rating is a multiplier by which you find the values for your compartment's stats.
Before you do that though, you set a Priority for each stat the compartment has. Priorities are A, B, C, and D. This is due to the fact that in ship design you can't always get all of what you want. You can have a powerful engine at the cost of weight. if you want a light engine, it'll cost you some power, If you want a durable engine, maybe it'll cost more. Basically you can indicate what you want to sacrifice for what by putting in your Priorities.
You get one A, one B, and one C, and the rest are filled in with 'D's automatically.
Engines have these stats you can set Priority for
Weight: (How much the compartment weighs. Higher priority lowers weight)
Cost: (How much it costs: Higher priority lowers cost)
Power: (How much power it puts out. Higher priority increases power)
Stats: (What bonus stats the compartment gives it's user. Higher priority increases the amount of stats, a D rating means no stats.)
Durability: (Determines how hard the compartment is to destroy, and the chance of generating a malfunction when damaged or destroyed.)
I want a cheap, fast ship (not easy to achieve) so for my engine so I assign:
SUPER AWESOME ENGINE DELUXE
Rating: 2000 (<--decent for a mid/small sized ship)
Weight: C
Cost: A
Power: B
Stats: D
Durability: D
Now I use the Shipbuilding Calc sheet (Which will be posted when I open up shipbuilding) to figure out what that translates to. Each stat has a chart that shows how to get the result, by compartment. Here's Weight for Engines, for instance:
Weight:
A Priority: [10% Rating] /10
B Priority: [15% Rating] /10
C Priority: [20% Rating] /10
D Priority: [25% Rating] /10
I gave Weight a C Priority, so the formula becomes
C Priority: [20% of 2000] /10 = 40
So the Engine's weight is 40.
Doing this for all the stats gives me the result of:
SUPER AWESOME ENGINE DELUXE
Weight: 40
Cost: $6,000
Power: 1,600
Stats: -none-
Durability: 20
((the Durability priority also tells me what the Malfunction and Destroyed effect lists will be))
Malfunction-
D:[10-29: Nothing][30-49 :Steamline Rupture][50-59: Fire!][60-69: Explosion!][70-79: FIRE!!][80-89: Disabled][90-100: EXPLOSION!!]
Destroyed-
D: [1-19: Nothing][20-39: Fire! ][40-59: Explosion!][FIRE!!: 60-79][80-100: EXPLOSION!!]
...basically... don't shake this engine too hard...... D Durability stuff tends to be a bit fragile.
So I take a look at the stats and decide it's nice and cheap. but... I don't think that's going to be enough power... So after some thought I rearrange my Stat Priorities to sacrifice a little cost for some power. (Can't make a brawny engine on the cheap, you know!)
Rating: 2000
Weight: C
Cost: B
Power: A
Stats: D
Durability: D
which gives me:
SUPER AWESOME ENGINE DELUXE CHAMPIONSHIP EDITION
Rating: 2000
Weight: 40
Cost: $10,000
Power: 2000
Stats: -None-
Durability: 20
Which looks like it'll do the job.
I finish off calculating the other compartment stats I have and finish up the rest of the ship.
Once I'm done with the compartments I add the little finishing touches like cargo hatches, gunports (them's new) decks, stairwells, escape hatches, etc. These don't have a Priority list, they're just added in at a standard cost and weight.
I also need to add armor. Armor makes up as much at 40-50% of the craft's total weight in many cases, and since it's such a big part of the structure I sometimes lay out the armor before I do my compartment stats. It all depends on where my priorities lie.
Since I want a fast ship in this case I'm doing armor second. I know my ship's total horsepower and the weight of it's other compartments so I can figure out how much armor I can add while maintaining a max speed I think is acceptable. (For a fast ship I want it doing at least 70-80 kph)
Armor also increases the ship's Overspeed rating, so it's important to add at least a certain amount. Ships can be 'balanced' to have the exact same maximum speed and Overspeed, which is efficient though it shows it's limitations when you consider engine Overcharging can push it over it's Overspeed limit very easily. Most ships can handle a square or two of Overspeed though, unless they are damaged.
Anyway. Once we are at this point, we can figure out the overall performance of the ship and it's flight characteristics.
Again, this is done through a series of simple formulas. As a quick sample:
POWER COSTS
========================================
Flight: [100% Weight]
Move forward [50% weight]
Move Backward: [75% Weight]
Turn Left or Right: [20% Weight for 45° turn]
Move laterally: (90% Weight)
Ascend (150% weight)
Descend (20% weight per Vert for 1 Vert. Descends vertically)
Dive: (25% weight, moves forward 1 space and down 1 vert)
===========================================
((All values are rounded off to the nearest 10.))
And here an airship has to pass it's one major hurdle. It MUST have enough base horsepower to ascend at least 1 vert using un-overcharged engines. (Basically it needs to be able to generate 2.5x it's Weight in Power)
If it can't do that then it cant really fly, and it's back to the drawing board.... But so long as it can get off the ground it's good to go, no matter how terrible it's performance may be otherwise.
Next we move on to finding the flight rolls:
====================================
Forward: [#decks] + [#engines]
Backward: [Forward diff x2]
Base Turn Diff = Bulk/#decks + [#Engines]
45° Turn: [Base Turn Diff]
90° Turn: [Base Turn Diff x3]
135° Turn: [Base turn Diff x5]
180° Turn: [Base Turn Diff x12]
Lateral: [Bulk] + [#engines]
Ascent/Descent Diff: [[Weight/Power] x 50]] [ / 2] + [#Engines]
Dive: [Asc/Desc Diff] + [#Decks]
===========================================
Which again are pretty simple. Most of this depends on how you arranged your ship's compartments. In short, longer vessels are easier to fly forward but harder to turn, and shorter, taller vessels turn a little easier but aren't as easy to push through the air. Ships with lots of engines are harder to control overall. (This means that many larger ships have higher piloting rolls by default, since they usually rely on multiple engines)
Once all that is done they you move on to generating a hit table, which isn't particularly difficult but since I'm still considering exactly how I want to to be done (wavering on 1 minor point) I won't explain this just yet. =P But basically you figure each deck's chance of taking a bit based on it's size. So Larger decks are more likely to be hit, and shorter ones less likely.
And with that you're done, more or less.. The last major step it to codify the info. (I've got a specific way to do this that lets you recreate a ship from a text file, basically. It also makes it easier to make changes to a ship's design later.) and make the ship's diagram. I use Illustrator for this, but I imagine if you have a lot of patience and graph paper you could do it that way, too.. For the time being if anyone designs a ship I'll take it upon myself to set it up, or just give out my illustrator file base. Either way I'll ask for the text file so I can check the calcs and make sure everything was done to spec.
So yeah. That's how it works. :3 This week I'm going to (hopefully) be making some progress on the vehicle and updated ground combat rules, I had a lot of time to think about 'em this last week. But soon after that I hope to start writing up a formalized shipbuilding FAQ.