Re: Vector Movement

On 9/2/2003 Oerjan Ohlson wrote:

> Jared Hilal wrote:
>
>> 1) At the risk of picking nits; the problem is not rotate-burn-fire, 
>> but rather rotate-burn-ROTATE-fire.
>
> This is the *esthetic* problem Jared has with the current Vector 
> rules. Unfortunately neither it isn't the *game balance* problem he 
> intended his proposal to solve

Actually, this is the root cause of the problems (symptoms) that I am 
trying to solve, namely that AGD does not give enough extra benefit in 
Vector to justify its higher cost and that multi-arc weapons are also 
not useful enough to justify the extra cost.  By allowing ships to 
rotate twice in a game turn, it makes them much more maneuverable and 
reduces the long term (multi-turn) tactical planning necessary to be 
successful in the encounter.

>> A T4 human ship in this situation could, under the current RAW, 
>> rotate to heading 12, burn MD, then rotate back to facing 9 (R12, 
>> MD2, R9).  Or, using a loophole, simply thruster push with the port 
>> thrusters (PS2).
>
> In the FB2 Vector rules a "PS2" order is illegal for Standard-engined 
> drives, since the side and retro thrusters are only allowed a single 
> 1-pt push each per turn. 

Upon rereading the rules, you are right, I originally misread the rules 
addendum.  However, the human ship could rotate to facing 6, retro 
thruster 1, rotate back to facing 9 and then thruster push with the port

thrusters (R6, PA1, R9, PS1).

Anyways, for ships with low thrust (which happen to be the larger 
ships), this means that the single-side thrusters are often close to 
half as powerful as the main drive.  Huh?

Further,

On 8/28/2003 Oerjan Ohlson wrote:

> Unfortunately for your suggestion, you haven't correctly identified 
> the problem. (Unfortunately for GZG, neither did we playtesters during

> the FB1 and FB2 development :-/ )

Then what is the root cause of the problem?

> What your suggestion does is to prevent the narrow-arc ships from 
> keeping the enemy under continuous fire (ie. shooting at him every 
> turn) *while accelerating away from him*. Trouble is, this is merely a

> special case of the real problem - and removing this special case 
> while leaving the real problem unsolved won't make wide-arc weapons 
> any more useful.
>
> The real problem is that the narrow-arc ships can keep the enemy under

> continuous fire *at all*, as opposed to Cinematic where narrow-arc 
> ships tend to make an attack run and then spend several turns during 
> which they can't fire on lining up for their next attack run (or else 
> come to a full stop, in which case they can rotate freely but make 
> themselves very easy missile targets and also allow the enemy to 
> control the range).

But in vector, narrow arc standard drive ships should be able to keep 
the enemy under continuous fire if they forego accelerating in any 
direction except towards the enemy.  I.e. the ship is sliding "sideways"

and remains pointed at the target.  The whole point is that the current 
rules allow the player (the "captain") to rotate the ship 60-120 
degrees, burn the MD on a parallel course for 1/2 to 1 minute and then 
rotate back to bring the target under fire again.  This, combined with 
your "while accelerating away from him" results in the majority of 
cases, rather than the "special case", as you said.  Accelerating toward

the enemy and then rotating (once) to keep him under fire is reasonable 
to me.

> The reason why wide-arc weapons cost more than narrow-arc weapons is 
> that the wide-arc weapons *in Cinematic* have a much better chance of 
> having a target in arc and thus on average get to fire more shots each

> over the course of a (Cinematic) battle than narrow-arc weapons do. 
> Fewer weapons firing more shots each per battle give about the same 
> damage-dealing capability as more numerous weapons firing fewer shots 
> each, so for a given amount of points you get fewer wide-arc weapons 
> than you could've gotten narrow-arc weapons of the same type and class

And the same should be true for vector, where, if a target passes your 
ship obliquely, you can track it with your gun turrets while continuing 
to accelerate on your desired heading or you can rotate to track him 
with your main (forward) gun(s), but not both.

> (Kra'Vak pay the extra points for better engines instead of for extra 
> fire arcs, but the end result is the same: they get fewer guns which 
> get to fire more shots each than the same points value of single-arc 
> human weapons on human-engined ships.)
>
> However, if 1 thrust point in Vector is sufficient to rotate the ship 
> to any facing it likes - and in the FB Vector rules it is - then you 
> can almost always rotate the ship to point your single-arc guns at 
> where the target will be after movement.

However, on the turn after you have pointed your ship at the target, you

should have to make a choice between keeping the target in the 
engagement basket or continuing your acceleration, rather than being 
able to do both.

> Apart from the player screwing up the exception is if the ship's 
> no-thrust end locations - ie. where they'll end the movement if they 
> apply no thrust in any direction - are less than twice the target's 
> thrust rating apart... and even then you usually have a pretty good 
> chance of predicting where he'll end up and rotate your ship
accordingly.
>
> IOW, instead of single-arc weapons firing every other turn at best, 
> they now get to fire virtually *every* turn; and since no weapon is 
> allowed to fire more than once per turn the advantage a wider-arc 
> weapon can gain (ie. the ability to get more shots off during the 
> battle than narrow-arc weapons) becomes very small indeed. Taking 
> 3-arc weapons as an example, IME they only get 5-10% more shots per 
> weapon per battle in Vector, compared to the 50-60% more they get in 
> Cinematic - but they still have to *pay* 50% extra even when you play 
> in Vector.

But, if the player (ship captain) had to chose between pointing at the 
target and turning to accelerate in a direction 60 degrees or more from 
the target, then the ability to, for example, travel course 12 with a 
target at bearing 3, face heading 5 to both decelerate and converge on 
the target (bearing 3) and still be able to fire at that target with 
batteries that bear into your port broadside is worth the additional 
points and mass.

> Because of all this limiting the ship to one single rotation per game 
> turn in Vector does virtually nothing to solve the Vector fire-arc 
> balance problems. As long as one single rotation is enough to give the

> ship a close-to-100% probability of acquiring a target for its 
> single-arc weapons each turn, and your suggestion doesn't do anything 
> to change this, the narrow-arc weapons will remain underpriced in the 
> current FB ("Cinematic") design system. 

The problem is not that the single rotation can acquire the target once 
, or even continuously, the problem is that multiple uses of rotations 
allow the ship to keep the target engaged while simultaneously pulsing 
the MD for brief bursts of acceleration.

If the ship coasts while pointed at the target, then he has given up the

maneuver initiative in favor of an attempt at overwhelming (with his 
maximum firepower) the target before the target can redefine the 
maneuver situation, while the opposite is then also true (giving up 
firepower in order to maneuver).

> Since we'd very much prefer to use the same design system for Vector 
> and Cinematic, the only effective option that remains is to reduce the

> ability to point single-arc weapons in any direction you like in 
> Vector to  somethingsimilar to what it is in Cinematic... and that 
> means restricting the *angle* through which a ship can rotate in one 
> turn.
>
> (Which is of course the way the original (ie., EFSB) Vector rules 
> worked, and I'm acutely aware that I was one of the main proponents 
> for changing it to the FB1 system back in 1997/98 :-( In hindsight I'd

> rate that screw-up right down there with the FB2 Sa'Vasku... <sigh>)

Actually, I think the FB1 rules work well, with the provision that the 
effect of thruster pushes should be reduced considerably, i.e. to 1/2 or

1/4.  I think that the problem lies in the FB2 change to allow multiple 
rotations in exchange for maneuvering thrust (of all types) to be taken 
from the same "pool" of points as MD.

> >...what this comes down to is how long a turn represents.  In several
> >places I have seen this as high as 10 or 20 minutes.
>
> The current "standard GZGverse" FT time/distance scales use turn 
> lengths of 1.67 minutes and 5.32 minutes respectively (100 s and 319 
> s). The corresponding distance scales are 100 km/mu and 1000 km/mu; in

> either case thrust-1 is ~1 g.
>
> Once upon a time Steve Pugh used the MT orbital movement rules to 
> calculate a game scale where thrust-1 = 1/8 g, 1 mu ~ 1000 km and 1 
> turn = 19 minutes. The main problem with this scale is the very low 
> thrust level - even the fastest Sa'Vasku ships in both of the Fleet 
> Books couldn't manage accelerations over about 1.5 g, and no human 
> ships could do more than 1 g! This doesn't go too well together with 
> the GZGverse canon saying that the invention of gravitic compensators 
> was a major breakthrough in warship design (since it allowed ships to 
> make far more radical manoeuvres without crushing the crew), so at 
> least in the GZGverse thrust-1 must be rather higher than 1/8 g. Of 
> course you can use 20-minute turns and keep thrust-1 = 1 g, but then 
> an Earth-sized planet would be less than 1 mu in diameter. This look 
> rather silly compared to the ship models, and it also makes using the 
> orbital movement rule difficult to use... so the "1/8 g, 19 minutes" 
> scale has pretty much fallen out of favour. 

I had only seen the ~20 minute figure, but I am fine with the shorter 
game turn.
 
<snip  catastrophic failure discussion>

> (FWIW quite a few of the larger ships destroyed in B5, particularly in

> the Narn-Centauri conflict, blow up as a result of secondary 
> explosions rather than as an immediate effect of the incoming fire. 
> The only way this can happen in FT is if the Power Core fails 
> catastrophically.) 

Unless you consider rerolls to represent those secondary explosions. :)

> Of course, in films and TV shows there's also the problem with time 
> compression; eg., JMS has repeatedly stated that B5 battles are often 
> speeded up in order to fit inside the fixed episode length :-/

Yep, so that each 5-10 second exchange of volleys on-screen could be 
considered to represent one 2-6 minute FT game turn.  So the 
Narn-Centuari single ship duel in "A Day in the Strife" (for example) 
lasts several FT turns.  Sounds good to me.

<snip more game turn length discussion>

> I once calculated how long it'd take for a Renegade Legion [Leviathan]

> Shiva-class battleship (IIRC 2.5 km long, and rather slow - in FT I'd 
> rate it as "thrust-2") to turn 180 degrees given Full Thrust Vector 
> manoeuvre thrusters strengths (which are capable of pushing the ship 
> sideways at thrust-1) and thrust-1 ~ 1/8 g (since that's what the 
> then-current "standard GZGverse" scale used).
>
> Turned out that it'd take *less than one minute* - re-running the 
> calculation I get 46 seconds - for the Shiva to reverse its facing. Of

> course the transverse stresses on its bow section would be quite 
> considerable, but the thruster power is there. It could rotate 180 
> degrees, stop to fire (eg. its huge spinal gun), and rotate another 
> 180 degrees within an 100-second game turn. (Being thrust-2 it 
> wouldn't have any thrust left to spend on a main drive burn though
<g>)
>
> Smaller ships or higher values of "thrust-1" reduce the time it takes 
> to spin around even further. Eg., combining your 'side thruster pushes

> at quarter strength' concept with the 'in the GZGverse thrust-1 ~ 1 g'

> scale you still get twice the effective thrust to spin the ship with 
> than I used in the above example (ie. 1/4 g instead of 1/8 g), 
> allowing the Shiva to do an 180 turn in a mere 33 seconds or an 
> 1714-meter EarthForce Omega-class ship to turn around in 27 seconds; 
> and the comparatively small warships used in the GZGverse (where even 
> an SDN is only 2-30000 tons) could literally twist around in seconds.

 From FB1, pg. 3, right hand column, "Rotation" section, 1st para.:
"...(the only difference between rotating 30 degrees and rotating 180 
degrees is simply that, once the thrusters have started the ship 
spinning, the ship is allowed to rotate for [a] longer [period of time] 
before the thrusters burn again to cancel the spin)..."

So, IIUC, FT thrusters are probably more than 1/4 g, probably closer to 
1 g, but only on for a brief burst, then 0 g coast, then short ~ 1 g 
counter-burn.

Further, if I understand the assumptions behind your math, you are 
assuming MD1 ~ 1g over a full game turn, but if you rotate twice, taking

1/2 of the game turn (total of 2x Rotate), then MD1 ~ 2g because the 
time that the drive is on is much less.

> When even huge ships like an Omega or a Shiva could potentially rotate

> this fast, even the fastest "GZGverse scale" with its 100-second game 
> turns clearly allows a ship to make two 180-degree facing changes in a

> single turn and still leave time for a main drive burn and/or firing 
> weapons :-7

But I would not want to be in a DCP, or a SBA, or etc. (and therefor not

strapped into a shock couch) when the ship makes a 1g rotate burn, 0g 
coast, 1g counter-burn, (total 30 sec) 2-4 g MD burn (40 sec) (could be 
as high as 8-12g on a destroyer or corvette), 1g rotate burn, 0g coast, 
and 1g counter-burn (another 30 sec), all in a 100s game turn.

BTW, ships in backgrounds where ships are not as tiny as the GZG-verse 
(like a star destroyer, battlestar or EA Omega/Nova classes), the 
capital ships are probably mass 100,000+ compared to the FB ships, which

are all smaller than the 1920s "treaty battleships" (capped at 35,000 t 
"standard load", which worked to 40-45,000 t full load).  The smallest 
would be the ST:movies Enterprise at TMF c. 2,000 (ST:TNG Ambassador 
class Ent-C TMF 37,000+, Ent-D 60,000+).  Even the Space Battleship 
Yamato ("Starblazers") would be c. TMF 700+ (built on the hull of HIJMS 
Yamato)

J