Realism - Large & Small Ships

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utilae
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Realism - Large & Small Ships

#1 Post by utilae »

We may have discussed this before, but it has been on my mind. We know that there is no friction in space, so it is probably correct to say that a large ship could move equally as fast as a small ship. At least we will discuss these questions.


1)Would a large ship and a small ship move at equivelent speeds (eg we assume that a large ship will be slower, will it be just as fast) ?

2)If a ship has engines, does the mass of the ship affect the speed and manuerverability in any way?

3)If the above two questions result in the fact that large ships can move just as fast as the small ship (ie mass doesn't alter speed), then how should this affect game design?

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skdiw
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#2 Post by skdiw »

you forgot inertia so large ship = less agile, accelerates slower given the same thurst so the average velocity is lower.

1) under this universe, any objects can travel up to c if it was accelerated below c. However, warp engines are different. You have to ask the military for that information.

2) you can look up basic physics for moments of inertia. Qualitatively, mass does affect manuverability, but not as much as its geometry.

3) even if large can move just as "fast" as small ship, it should not affect what normal players are accustom to. Things that don't make sense creates psychological stress. This is a game, which is not meant to be stressful. It could be interesting, but if everybody wants large ship to move slower despite any physical realities, again gameply first, realism second.

This topic has already been discussed. you might want to look for it first.
:mrgreen:

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#3 Post by Sapphire Wyvern »

skdiw wrote:you forgot inertia so large ship = less agile, accelerates slower given the same thurst so the average velocity is lower.

1) under this universe, any objects can travel up to c if it was accelerated below c. However, warp engines are different. You have to ask the military for that information.

2) you can look up basic physics for moments of inertia. Qualitatively, mass does affect manuverability, but not as much as its geometry.
Geometry in friction-less movement affects only angular acceleration (the rate at which you can pivot about your center of mass); it has no effect on translational acceleration (the rate at which you can move from place to place). The equation for this is:

Angular acceleration = Force x Distance from point of application to center of mass / Moment of Inertia (which is dependant on mass & geometry).

Since maneuverability in space combat means changing your velocity vector to dodge missiles, other ships, move from place to place etc, angular acceleration is only really important if you have no source of vectored thrust.

For moving from place to place, only the familiar a = F/m form of Newton's Second Law applies. Note that this means that it's the power-to-weight ratio that determines acceleration, not the mass of the thing being accelerated.

Note that there is no upper cap on ship velocity under pure Newtonian mechanics; these equations become increasingly inaccurate as objects approach light speed and you need to use relativistic modelling for full accuracy.

Herendeth the lesson in mechanics. :)

Now, the question of what we do in FO is entirely open, as far as I'm concerned. Large ships should definitely be less maneuverable than smaller ones, because that's intuitive and accurate, and gives a useful bonus to smaller vessels. Using an acceleration-based model for movement would make for an intriguing game, but I expect people would find it difficult to grasp and we would probably need to display velocity vectors on screen. Therefore, it may be best if we go for the usual convention and simply say "maneuverability = speed", apply speed caps to ships, and don't bother tracking inertia and velocity vectors in a "realistic" sense.
3) even if large can move just as "fast" as small ship, it should not affect what normal players are accustom to. Things that don't make sense creates psychological stress. This is a game, which is not meant to be stressful. It could be interesting, but if everybody wants large ship to move slower despite any physical realities, again gameply first, realism second.

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#4 Post by Daveybaby »

Sapphire Wyvern is correct - if a ships engines scale in power linearly with its mass, then a large ship is every bit as fast and manoeverable as a small one. Thats assuming standard newtonian physics.

Right, thats realism out of the way. Kill it with guns and stamp on its head. Throw the bits in the bin. GAMEPLAY is the important issue.

The thing to decide is: should big ships be heavy and lumbering compared to small ships for gameplay purposes? I would say: yes. Give small ships the edge in speed and manouevrability to counter big ships heavy shields and armour. This will encourage diversity in gameplay and ship designs.

Note the first paragraph. Note, in fact, the first word. A ship's engines do not have to scale linearly in power with its mass. For a start, we probably arent dealing with newtonian physics, thats assuming you dont want to wait 100 turns to get halfway across the map. This is sci-fi. we can have warp drives, gravity drives, jump drives, infinite improbability drives, whatever we want. There is no reason thay the power output of this mythical engine technology has to scale linearly with size. Make big engines less efficient, so big ships go more slowly than small ships. Make big shields more efficient, so big ships are tougher, to compensate.

Or whatever. Do the exact opposite if thats what we like. Its easy to justify it using sci-fi technobabble. Dont get bogged down in real world physics, because real world physics makes for really boring scifi games.
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#5 Post by Dreamer »

This is like disccusing "can a carrier move as fast as my speedboat on the water?" And the answer is the same. It could, if you use enought muscle for it. But then again... why whould you like that? The basic purpose of both is completely different. As I se it. Big ships are more war platforms for support, command, repair and heavy weaponry than a big version of a figther.

On the other hand. Moo2 had very fast doomstars in fact.

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#6 Post by skdiw »

Sapphire Wyvern wrote:
skdiw wrote:you forgot inertia so large ship = less agile, accelerates slower given the same thurst so the average velocity is lower.

1) under this universe, any objects can travel up to c if it was accelerated below c. However, warp engines are different. You have to ask the military for that information.

2) you can look up basic physics for moments of inertia. Qualitatively, mass does affect manuverability, but not as much as its geometry.
Geometry in friction-less movement affects only angular acceleration (the rate at which you can pivot about your center of mass); it has no effect on translational acceleration (the rate at which you can move from place to place). The equation for this is:

Angular acceleration = Force x Distance from point of application to center of mass / Moment of Inertia (which is dependant on mass & geometry).

Since maneuverability in space combat means changing your velocity vector to dodge missiles, other ships, move from place to place etc, angular acceleration is only really important if you have no source of vectored thrust.
Hence I said manuverability, didn't say linear acceleration.
For moving from place to place, only the familiar a = F/m form of Newton's Second Law applies. Note that this means that it's the power-to-weight ratio that determines acceleration, not the mass of the thing being accelerated.
If you are gonna be all technical like that, FYI, objects in space is weightless? It actally the mass that is being accelerated. F=ma, not F=mga=Wa. And if you want to be even more techical, F=dp/dt, then you throw in gamma for relativity, and that applies for objects at sub c.


I am in favor with everyone here. I think large ship should be less manuverable. And it so happens that it makes sense :).
:mrgreen:

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#7 Post by utilae »

I also think big ships should act like big trucks (slow and slow turning), while small ships are fast and manueverable, like a car.

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#8 Post by Magus »

One way to do this would be via Inertial Compensation systems. Basically, you can accelerate instantaneously to c at high tech levels. Your ship will just be turned into a fine mist. Compensators magically reduce the forces acting on a vessel and its occupants, so higher compensator tech (and if you can automate the vessel...) = better achievable acceleration. We can then say that the efficency of an inertial compensator is proportional to the inverse of the volume of the field, resulting in smaller ships being able to mount smaller and better compensators, while larger ship either have to do without or make room for massive compensators.

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#9 Post by Sapphire Wyvern »

Meh. Fluff can be written to justify any arbitrary game design decision. Besides, this is Space Opera. No-one's ever bothered to explain to me why my TIE Fighter or X-Wing coast to a stop when the engines get damaged, so I don't see why we need to explain to a player why we're ignoring physics. :)

So why don't we see some gameplay-based arguments for or against?

Personally I'm liking Big = Slow, because it is intuitive, even if it's somewhat hackneyed.

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#10 Post by Geoff the Medio »

Assuming combat is real time, and on the scale of anything reasonably large compared to a solar system or planet, then ships or weapons in combat will have to be moving faster than light... otherwise combat would take hours (or weeks) to play out... not minutes. So a sensical fluff justification can be given due to how FTL works in FO for just about any dependence of speed or manoevrability on ship size. So yes... gameplay reasons please.

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#11 Post by skdiw »

Well, gameplay reason isn't necessary if everyone wants big = slow, and small = fast.

Even if the battle takes place in a system, it's the beams weapons and missiles that doing the damage. The ships don't have to move at speeds greater or around light. Of course, that's realism.

As for gameplay, aside from intuition, which again I stressed my first post that if something is too weird, it creates stress in players and that's bad. And if everybody wants the same thing, that is reason enough to do it. Secondly, I envision a ship size role. The smaller ships are cheaper and can be more roles specific because of their smaller capacity. Since they are cheaper, you can more easily build a variety of different roles to make more interesting gameplay. A faster speed for smaller ships will help smaller ships accomplish there roles better by reaching their position faster. The large ships are usually slow, but are more balance (because they are expensive so you only have a few so you don't want them completely weak against something) and carries specials. Because large are powerful ships, they could be a target for enemies attack, but to make then vulnerable, they should be slow. For example, heavy bomber should be slow so defending fighters have a change to shoot them down. In another example, the game is borken if a large ship can use powerful specials then retreat out and never gets damage. Then I envision unique wonders more as defensive ship with supportive role for the fleet (to prevent WC3 arguement that the whole battle turns into hero vs. hero).
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#12 Post by Dreamer »

Wow. First discussion ever to find concensuss so quickly. Fast = slow. Period.

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#13 Post by utilae »

Dreamer wrote:Wow. First discussion ever to find concensuss so quickly. Fast = slow. Period.
Well, that's how it usually turns out isn't it. Moo2 had it so that big ships and small ships move at equal speeds. You didn't get the chance to customize your engines either.


What I am wondering though, if we want to make big ships slow, and small ships fast, we could do it by using the ships mass to determine how many enigines are ship needs to reach a certain speed.

So a small ship needs 1 engine to reach FTLx4, while a big ship needs 4 engines. What do you think. Would people just say that this is not realistic, as mass doesn't matter?

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#14 Post by Dreamer »

utilae wrote:What I am wondering though, if we want to make big ships slow, and small ships fast, we could do it by using the ships mass to determine how many enigines are ship needs to reach a certain speed.

So a small ship needs 1 engine to reach FTLx4, while a big ship needs 4 engines. What do you think. Would people just say that this is not realistic, as mass doesn't matter?
Well, it all depends on what fluff we use to explain FTL travel. But anyway, I would indeed use mass/propusion proportion for speed, at least in combat (between stars I would obviously want my carriers to move equaly fast). It's simple, it's intuitive and it's also realistic to some extent. Big ships wont be slow because of size, but because you really don't (or shouldn't) want half of your doomstar to be a propulsion system (as it happens on small figthers).

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#15 Post by Geoff the Medio »

Dreamer wrote:But anyway, I would indeed use mass/propusion proportion for speed, at least in combat (between stars I would obviously want my carriers to move equaly fast).
Assuming you've put all your ships into a fleet, in which they'd all move together at the speed of the slowest ship, what is the disadvantage to having big ships (generally) move slower than small ones on the galaxy map?

The (potential) advantages would be more distinctions between small and large ships... specifically the ability for smaller ships to outrun and outmaneouvre (on the map) the big ships. This lets the small ships cut of supplies to the big ship, or any nontraditional ways of knocking out a big ship (say destroying a starlane with the ship on it...) get set up in time to take effect, or lets wherever the big ship is going see it coming well ahead of time in order to evacute or make preparations for the attack. Conversely smaller ships could zip in quick, faster than the defender could react. This would also make big ships less useful for force projection, as it'd take forever for them to get where they're going... so you'd want some medium ships as well to actually go out and shoot stuff most of the time, and you'd only move your big ships around for important things. In theory anyway...

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