Balanced Starships

[LordQulex]

There are two challenges I would like to overcome before running a StarHero campaign.

The first is the constant wrestling match between the SciFi genre and Sir Isaac Newton. I like the realistic movement endurance rule and the realistic space acceleration rule, but I don't believe they combine logically enough for my taste. Sure, accelerating a big ship costs more endurance, but it still costs 15 points to buy 15m of flight. Combined with the maximum velocities per turn that the book suggests, there is no reason why a battleship wouldn't buy the same acceleration as a fighter. This makes interceptors unable to, well, intercept... I'm toying around with a few ideas to fix this, but maybe the community already has one? Right now my leading idea is to enforce an adder on the flight power somehow based on the vehicles size - that way flight costs more on bigger ships, and more endurance. This should artificially cause larger ships to accelerate slower than smaller ones. The reason I believe this works is due to the second rule I am toying around with:

Upper limit of vehicle cost based on size. I was talking to a USAF friend of mine about how modern military vehicles are designed. I summation, the #1 restraint of a modern military vehicle is size. Sure, you can make a battleship go 50 knots, but half of its space and displacement will be utilized by engines. If you want a fast ship with limited projection capabilities, great! But most modern militaries would choose a larger radius of efficacy over raw speed, so smaller engines and more space for guns and planes. I was crunching some numbers on the example vehicles, and saw that they all spent between 8 and 19 times more points on capabilities than size. So I set ship class sizes (DD 13, CR 16 etc...) and simply said a ship can only spend 15x more on powers than on size. I think this will adequately represent space limitations on ships. And the starter ship for my PCs it's only 5x or 10x to represent being a run down, old POS ship.

Does this approach make any sense? What other tools and mechanics have been used to balance and normalize ships?

 

Thanks!

[megaplayboy]

Another way to think about weapon systems is to simply scale up personal weapons by adding the "class size" to the DC of the equivalent personal weapon.  So if your blaster rifle does 3d6 KA, the main blast cannon on a Size 15 light cruiser do 8d6KA.  

[massey]

I wouldn't mess with point costs.  Instead I would pre-design a lot of the ships and just limit what the players can take.  Just because the game system would let someone buy something, that doesn't mean it's appropriate in the campaign setting.  For example, you can't normally be a starship commander in a D&D game.

 

Point costs aren't about how "realistic" something is.  It's about how useful it is in the game.  FTL speeds get very high for a tiny increase in points.  That's not realistic at all.  But remember, in the game, there's not much difference between 20 points of FTL travel and 50 points of it.  In both cases, you're traveling to a fictional location that is as far away as the gamemaster wants it to be, and it takes as long to get there as the gamemaster says.  It's a "scene change" power.  The GM says "Okay, you're traveling to the Andaarian Nebula.  You've been going there for the last 4 days.  You still have 2 more days to get there.  On the way, your trip is interrupted by this thing happening."  It doesn't matter if it's the Andaarian Nebula, or some other place he made up.  It doesn't matter if you've been traveling for 4 days, or 4 weeks, or 4 hours.  You've entered into the realm of GM narration.

 

It's perfectly fine to say that your big battleships can only go at X speed, while smaller interceptors can go faster.  If you want your game universe to work that way, that's fine.  But don't bother with changing the point costs.  It will give a false illusion that you've balanced it somehow, when in fact you haven't.

[Funk Thompson]

Keep in mind that in the real world, there are considerations to be made other than "point cost" when it comes to designing, well, just about anything.

 

The key is in setting up the rules and norms for your campaign.  Sure, mechanically, you can build a battleship that has the same acceleration as a fighter.  But, in the real world, this would mean your battleship is 90% engine - "All legs."  

 

So you set up the rules for acceleration by ship class, size, tonnage, whatever.  Based on the rules and norms of things in your campaign - not the HERO Rules and Norms, but how you see things working, which you then translate into HERO System rules via campaign limits and such.

[C-Note]

Have larger ships take the "Decreased Acceleration/Deceleration" Limitation on Flight.  There are two levels for a -1/4 or -1/2 limitation.  6E1 p158.

[Zeropoint]

You know, there's no inherent reason why larger space vessels should have lower acceleration. Let's try a thought experiment: Imagine a "small, fast" ship. It has a certain acceleration capability that you consider "fast". Now imagine two of these ships flying side by side. Obviously, they can accelerate just as fast as they can individually. Now, imagine those ships flying not just side by side, but touching. It should be clear that they can still accelerate just as well as an individual ship. Finally, imagine that they are not just touching but welded together. They've effectively become a ship with twice the mass as a single small ship, and yet they can still accelerate equally fast.

 

You can keep welding "small, fast" ships onto this combination until you reach any arbitrarily large volume or mass, and the resulting abomination will STILL be able to accelerate just as fast as a single small ship did in the first place.

 

In fact, there are reasons to believe that a larger ship would be able to accelerate even faster: First and most obviously, a single large ship will benefit from the square/cube law regarding its pressure hull and/or armor. It will be able to have the same protection for a smaller relative fraction of its weight. Second, it seems likely that there would be an economy of scale on the ship's engines--that is, that a single large engine would have a better thrust to mass ratio than a collection of small engines. I don't know enough about rocketry to be certain of this, however.

 

As I see it, most of the popular belief that big means slow comes from comparing things of different sizes but unlike natures. Comparing a speedboat to a cargo ship isn't fair, because one of them is designed to maximize performance, and the other is designed to maximize efficiency . . . and neither of them operate in space. Comparing a carrier to a fighter is even worse, because the fighter operates in the air, while the carrier operates in the water. If I compared civilian light aircraft to commercial airliners, I'd come to the conclusion that larger vehicles go FASTER.

[C-Note]

17 hours ago, Zeropoint said:

You know, there's no inherent reason why larger space vessels should have lower acceleration.

                                    Force

Acceleration   =    ----------

                                    Mass

 

In your multiple "small, fast" ship thought experiment, you are increasing the Mass, but you are also increasing the "Force" (each ship also has its own engine).  It takes a lot less Force to accelerate a 50-ton fighter at 5 Gs that it does to accelerate million-ton dreadnought at 5 Gs.

[massey]

In real life, larger naval vessels can go faster than smaller ones.  According to my Navy buddies, an aircraft carrier would leave everything else in the dust if it wanted to.

[C-Note]

13 hours ago, massey said:

In real life, larger naval vessels can go faster than smaller ones.  According to my Navy buddies, an aircraft carrier would leave everything else in the dust if it wanted to.

 

Absolutely.  Their engines generate an incredible amount of power, but don't confuse Velocity with Acceleration.  In a half-mile race, I'll take the speedboat.  In a 50-mile race, my money's on the aircraft carrier.

[dmjalund]

 

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[Cantriped]

This is a genre simulation problem, and such problems are often more easily fixed with design conceit than by changing the rules (in other words... just change how you use the mechanics, not the mechanics themselves. Remember that you have final say on anything players might want to build, and a responsibility to audit such material to ensure it is appropriate to your campaign. No amount of rules-text can prevent abuse and user error.

 

Sure... 15m of Flight has the same cost regardless of user size... except that a vehicle has already paid for its Size as a characteristic, making it pay an added fee based on size for movement powers is double-dipping and contrary to system principles. Given two otherwise identical vehicles the larger (or faster) one should be the more expensive one, and amongst two "equal vehicles" one migut be larger and slower than the other (as points spent on Size don't improve Flight).

 

As for the reason why one ship may buy more less movement than another, there is only one reason that actually matters. Because you said so (and/or because that is what is appropriate to the campaign). If you need your Carriers to be slower than your Fighters, simply don't let the Carrier buy more flight than you let Fighters have.

[Zeropoint]

21 hours ago, C-Note said:

                                    Force

Acceleration   =    ----------

                                    Mass

 

In your multiple "small, fast" ship thought experiment, you are increasing the Mass, but you are also increasing the "Force" (each ship also has its own engine).  It takes a lot less Force to accelerate a 50-ton fighter at 5 Gs that it does to accelerate million-ton dreadnought at 5 Gs.

Yes, I'm perfectly familiar with such basic principles of physics. I'm also perfectly aware that I was increasing the force in proportion to the mass in my thought experiment. That was actually the entire point. The million ton dreadnought masses as much as 20,000 fighters . . . and if it's equipped with 20,000 fighter engines, it will accelerate just as fast as they do, despite being larger and more massive. If the million ton dreadnought has 20,001 fighter engines on it, it will accelerate FASTER than the fighters.

 

21 hours ago, massey said:

In real life, larger naval vessels can go faster than smaller ones.  According to my Navy buddies, an aircraft carrier would leave everything else in the dust if it wanted to.

I can confirm that a Nimitz-class carrier can go far faster than what seems appropriate for something that big. It's a little unnerving.

[Christougher]

On 4/1/2018 at 1:27 PM, LordQulex said:

There are two challenges I would like to overcome before running a StarHero campaign.

The first is the constant wrestling match between the SciFi genre and Sir Isaac Newton. I like the realistic movement endurance rule and the realistic space acceleration rule, but I don't believe they combine logically enough for my taste. Sure, accelerating a big ship costs more endurance, but it still costs 15 points to buy 15m of flight. Combined with the maximum velocities per turn that the book suggests, there is no reason why a battleship wouldn't buy the same acceleration as a fighter. This makes interceptors unable to, well, intercept... I'm toying around with a few ideas to fix this, but maybe the community already has one? Right now my leading idea is to enforce an adder on the flight power somehow based on the vehicles size - that way flight costs more on bigger ships, and more endurance. This should artificially cause larger ships to accelerate slower than smaller ones. The reason I believe this works is due to the second rule I am toying around with:

Upper limit of vehicle cost based on size. I was talking to a USAF friend of mine about how modern military vehicles are designed. I summation, the #1 restraint of a modern military vehicle is size. Sure, you can make a battleship go 50 knots, but half of its space and displacement will be utilized by engines. If you want a fast ship with limited projection capabilities, great! But most modern militaries would choose a larger radius of efficacy over raw speed, so smaller engines and more space for guns and planes. I was crunching some numbers on the example vehicles, and saw that they all spent between 8 and 19 times more points on capabilities than size. So I set ship class sizes (DD 13, CR 16 etc...) and simply said a ship can only spend 15x more on powers than on size. I think this will adequately represent space limitations on ships. And the starter ship for my PCs it's only 5x or 10x to represent being a run down, old POS ship.

Does this approach make any sense? What other tools and mechanics have been used to balance and normalize ships?

 

Thanks!

 

Where are these rules for realistic movement endurance and realistic space acceleration?

 

I have previously posted some of my design rules for a Master of Orion space game, where starship design can play a significant part.  I'm still monkeying around with this particular issue, but have some thoughts on engine mass as percentage of ship size, and dividing maximum flight by vehicle size to asjust results more than just "no more than X flight" rules.  

 

Chris.

[C-Note]

4 hours ago, Zeropoint said:

Yes, I'm perfectly familiar with such basic principles of physics. I'm also perfectly aware that I was increasing the force in proportion to the mass in my thought experiment. That was actually the entire point. The million ton dreadnought masses as much as 20,000 fighters . . . and if it's equipped with 20,000 fighter engines, it will accelerate just as fast as they do, despite being larger and more massive. If the million ton dreadnought has 20,001 fighter engines on it, it will accelerate FASTER than the fighters.

 

Sorry, misread your economies-of-scale example.

[Funk Thompson]

For my Star HERO campaign, I use the cumulative advantage on flight.

 

Smaller ships have more meters of base movement, but lower cumulative totals.  30m x256 vs. 20m x512, for instance.  So smaller ships accelerate faster (less mass to throw around, higher thrust-to-mass ratio) while larger ships have higher top speeds (WAY more mass and lower thrust-to-mass ratio, but far more fuel reserves - and they almost all act as carriers for the smaller ships.)

[Cantriped]

Cumulative isn't applicable to movement powers, as they do not apply a dice roll against a defense to determine whether or not a threshold of effect is met (Dispel and Mind Control for example)...

 

The legal way to manipulate a vehicle's acceleration per turn versus maximum velocity is to use Increased Noncombat Movement (which is an Adder instead of a Modifier) and the modifiers related specifically to accelleration and decelleration. You can give the vehicle Movement Skill Levels to fine-tune its performance further.

Almost all vehicles are assumed to be traveling at Noncombat Velocities at all times.

 

Ships that accelerate faster would genrally have a higher ratio of Combat Movement to Noncombat Movement, or MSLs.

[Funk Thompson]

2 hours ago, Cantriped said:

Cumulative isn't applicable to movement powers, as they do not apply a dice roll against a defense to determine whether or not a threshold of effect is met (Dispel and Mind Control for example)...

 

The legal way to manipulate a vehicle's acceleration per turn versus maximum velocity is to use Increased Noncombat Movement (which is an Adder instead of a Modifier) and the modifiers related specifically to accelleration and decelleration. You can give the vehicle Movement Skill Levels to fine-tune its performance further.

Almost all vehicles are assumed to be traveling at Noncombat Velocities at all times.

 

Ships that accelerate faster would genrally have a higher ratio of Combat Movement to Noncombat Movement, or MSLs.

 

I forget which book, but yes, you can use cumulative on flight - just dug it up, Star HERO 6E pg. 219.

 

Using x8 noncombat means (without other mods) that acceleration goes up and it is hard to balance if you want bigger ships to have higher max speeds but slower accelerations.

 

Don't get me wrong, you can do it that way (using mods that reduce acceleration on the higher noncombat movement power) but cumulative does the same with fewer mods - since acceleration never goes above the x2 noncombat speed, but higher cumulative modifier = higher top speed.  You can also combine it with higher noncombat speed multiplier for ships (or drive systems or whatever) where that is appropriate.

[Cantriped]

Ahh yes... a niche optional rule from a genre book that isn't used in any of that book's builds, and cannot be used in most vehicles because it explicitly only works in the vacuum of space...

 

1 hour ago, Funk Thompson said:

Using x8 noncombat means (without other mods) that acceleration goes up...

No, this is so very incorrect.

"A character [or vehicle] can accelerate at a rate of 5m per meter, up to his maximum normal Combat Movement in meters per Phase." (CC 131)

Your Noncombat Multiplier has no effect on your ability to accelerate (unless you take Noncombat Acceleration). It only affects your maximum velocity and the number of phases taken to reach it. Or in the case of Leaping... the total distance of the leap.

 

Functionally both methods limit the Character to an amount of acceleration per phase equal to their Combat Velocity, and a multiplier of that as their maximum velocity.

[Zeropoint]

I might consider just saying that all craft operating in space have infinite Noncombat Multiplier for free. This means that how much Flight a ship has effectively becomes its acceleration rating. Even the most sluggish ship with 2 SPD and one meter of Flight can still get up to any arbitrarily high velocity, but an agile ship with 4 SPD and 50 meters of Flight will run circles around it. Sane pilots will obviously keep their ship within its Combat speed while operating in areas that have collision hazards.

 

I don't remember the rules for turn radius, but obviously a ship's available acceleration relative to its speed will affect how tightly it can turn, and things will look odd on a hex grid. You might have a ship travel in a straight line for multiple turns and then suddenly make a sharp 60-degree corner. Well, that's what you get when you quantize movement.

[Funk Thompson]

I've found ship-to-ship combat using anything remotely close to "realistic" movement or weapon ranges is impossible to do on a map or with minis.

 

I've been tinkering with using the chase / follow rules for aerial combat (piloting skill vs. skill rolls) and some combat maneuvers, things like "Evasive Maneuvers" as dodge, "Plot Firing Solution" as set / brace, "Overtake" or "Strafe" or the like all as martial maneuvers that affect the ships OCV / DCV and modify the piloting roll, but haven't had a lot of chance to test or finalize it.

 

The idea was that I would compare the speed / acceleration of the involved ships, and whoever was faster had a bonus to the piloting roll (+1 per 10m or so difference.)  Each participating ship would declare its intent, its planned maneuver, and roll piloting.  Winner had "advantage" over the loser(s) and could fire first on their next phase, similar to block / counterstrike mechanics.  So long as your piloting roll succeeded (vs. your own target number, not that you won the skill vs. skill part) your planned maneuver worked and you got whatever CV bonus.  Tactics was a complimentary skill so long as the person rolling tactics was directing / controlling more than one ship (coordinating ship positioning to maximize firepower, or to cut off escape, etc.)

 

Then I would note current distance and vector for ships, and adjust the numbers accordingly, but that gets crazy complicated if you are doing anything more than chase / follow or jousting

 

I only got to really do one ship-to-ship combat with this, via an RPOL.net campaign I was running, and it "worked" but was hard to tell if the players really thought the same, and involved a whole lot of hand-waving so far as how ships were moving relative to each other.

 

I'd love to do some real play-testing and theory-crafting with this, if I ever find time.

[knasser2]

Just wanted to say that whilst the model of a big ship being many smaller ships wielded together is correct in simple terms, there's a practical difficulty with it. Force and mass may be increased proportionately to produce the same acceleration, but increased Force brings its own difficulty. Namely, stress on the ship itself. A thousand fighter engines on a thousand fighters, means each fighter gets its little bit of force on its structure. But a thousand fighter engines on a large ship that merely has the mass of a thousand fighters... Well unless it's built like a line of fighters glued together and it only flies in a straight line, parts of it are going to be subjected to drastically more absolute force than would ever be the case in one of those fighters alone. Which requires greater structural strength, which requires more mass. And that increases significantly the more you expect it to be able to pull off the same manoeuvres. Zeropoint makes a good point, but there's more to it. Try to turn a star destroyer like you turn a tie fighter and it doesn't matter if the engine power and mass are in exactly the same proportions as the tie-fighter: It's going to snap in half.

 

An ant can lift 50 times its body weight. Make a 2m tall ant and it will snap its own legs trying to walk.

[Zeropoint]

All of that is true, but to some extent (just how much, I can't say) the need for an increased proportion of structural mass will be offset by the reduced surface area, and also by mass savings through economy of scale on various ship's systems.

 

The real problem that large ships face isn't linear acceleration, but rotational acceleration, i.e. turning. Winchell Chung, our very own Nyrath, describes the problems here.

[knasser2]

On ‎6‎/‎17‎/‎2018 at 12:54 AM, Zeropoint said:

All of that is true, but to some extent (just how much, I can't say) the need for an increased proportion of structural mass will be offset by the reduced surface area, and also by mass savings through economy of scale on various ship's systems.

 

The real problem that large ships face isn't linear acceleration, but rotational acceleration, i.e. turning. Winchell Chung, our very own Nyrath, describes the problems here.

 

Rotation is what I referred to when I talked about the Star Destroyer snapping itself in half trying to turn like an X-Wing. Actually, we can run some rought numbers to see how things are affected. Firstly for linear acceleration we can say that if you double the mass, you need double the Force to produce the same acceleration. Which, because this is linear, means double the Compressive Stress. Compressive Stress is Force / Area. Let's say our big space ship has a central spine the engines are on the back of that in simplified terms is 7m in diameter. Double the Force you need double the cross-sectional area so we can work that out to be a shade under 10m in diameter. Doubling our mass means we need to increase the cross-sectional area of our big ship (those parts that play a role in handing bow to stern pressure, that is) by 40%. As you can see, even for simply going in one direction, it's not a linear relationship. Only in the scenario where the ship length doesn't increase at all but the "fighters" are wielded together side by side, are there not increased mass requirements.

 

And when we come to turning, it becomes a great deal more problematic. Your link is interesting, but it's focus is solely on the force required to achieve speeds. Which is relevant but doesn't touch on structural integrity. It's a short step to calculate it though. Moment of Inertia (l) is mass multiplied by the (distance between axis and rotational mass)². I.e. l = mr². I.e. it increases at a square of the increase in length of the ship. Taking a simplistic example of needing proportional structural mass increases to the increase in moment of inertia you wish to handle (but which is nonetheless a reasonable assumption for purposes of argument), you're going to need exponentially (I don't mean that figuratively) more mass the longer you want your space ship to be but still be able to manoeuvre the same.

 

I think all this is a valuable example to the OP that whilst sometimes science shows our instincts to be wrong, when our instincts say something should be so it's good to check if the science which disagrees is right. OP is right in thinking that a larger ship should be less manoeuvrable and accelerate with more difficulty than a small one. It is not simply a convention of Sci-Fi or assumptions that you would design a big ship for different purposes than a small one (though that latter is true). Just calling a big ship a collection of small fighters stuck together doesn't work. Not unless they're all lined up in parallel like a ruler and only go forwards. Even tilting them up or down changes things.

 

Economies of Scale is really a cost question and based on too many setting assumptions to really be considered, imo. You can't say the Burj Khalifa costs are proportional to a thousand homes that provide equivalent internal space, even if that may be true. Economies of scale typically apply to quantity of unit produced, not relative size of units to each other. You might get a better rate on steel if you're buying 40,000 tonnes than 500 tonnes, but that can only be compared to overall output. If you had a shipyard that could build a thousand fighters or one capital ship in a year and it required the same amount of steel for both, the larger ship would not be cheaper because of "economies of scale". Savings per unit (i.e. capital ships are cheaper per unit if you build a twenty rather than one) are not the same as savings between units (i.e. we need a thousand windows for a thousand fighters, or a thousand windows for one capital ship).

[pinecone]

Yeah, space craft are differant to planetary craft. Some things will work out the same, and some will be "strange". Basicly a large ship can be just as "fast" as a small ship, in fact depending on how it is propelled it can, or should be faster. But a small craft is still going to be able to overcome it's inertia with less energy, and that May equal superior acceleration and manuver.  The main reason to use small intercepters might be simple cost, it is a smaller risk to send a small intercepter than a cruiser in a battle space that includes fusion weapons, etc...

[Asperion]

There really is only one concept that I follow when building vehicles:  all vehicles in that class must be balanced.  By this I mean that all fighters must be within a reasonable spread of each other.  However, if that fighter chooses to go against a battleship, then the comparative greater points in the battleship will almost guarantee a victory for the battleship.  (There can be situational deals that alter the picture, but it will be extremely lucky shots from fighter to have any possibility.  That is why there generally many fighters against one battleship - it increases the odds of fighter victory and destroying the battleship.)