What makes a good point defense platform

[Thiosk (OP)]

I'm prepping a laser-based point defender.  The concept is 4 twin turrets, each slaved to a small beam FC.

It needs to be fast, because it flies along side a main line beam brawler designed to punch through missile screens-- it would be nice if the defender could keep a reasonable number of incoming ordinance off to allow it to punch in.

It has a very limited sensing platform, but primary tracking comes from a dedicated sensor vessel that remains with the bulk of the task group.

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Point Defender class Cruiser    12,150 tons     1195 Crew     2529 BP      TCS 243  TH 2200  EM 540
9053 km/s     Armour 6-47     Shields 18-240     Sensors 1/1/0/0     Damage Control Rating 15     PPV 43.4
Maint Life 2.86 Years     MSP 650    AFR 236%    IFR 3.3%    1YR 116    5YR 1746    Max Repair 78 MSP

ICF Drive (22)    Power 100    Fuel Use 60%    Signature 100    Armour 0    Exp 5%
Fuel Capacity 500,000 Litres    Range 123.5 billion km   (157 days at full power)
Gamma R240/12 Shields (9)   Total Fuel Cost  108 Litres per day

Twin 12cm C4 Ultraviolet Laser Turret (4x2)    Range 64,000km     TS: 15000 km/s     Power 8-8     RM 4    ROF 5        4 4 4 4 3 2 0 0 0 0
PD Beam FC Short Range (4)    Max Range: 64,000 km   TS: 16000 km/s     84 69 53 37 22 6 0 0 0 0
Tokamak Fusion Reactor Technology PB-1 (2)     Total Power Output 32    Armour 0    Exp 5%

Small AMM Scanner (1)     GPS 60     Range 4.8m km    Resolution 1

ECCM-1 (2)         ECM 10

This design is classed as a Military Vessel for maintenance purposes

Is this... enough beam?  Did I do the energy math right? 

[Andrew]

The only thing I would change is the turret tracking speed I would make it at least 16000 to match your fire control I often prefer to have turrets with a higher Tracking speed than my initial FC as that way when I get better FC it is a simpler upgrade to just add a new FC without changing the turrets over. In general I would want higher tracking speeds for Fire control and turrets given your engine technology but that could be a limit in your available tech.

I may drop the ECCM unless you are planning on having these ships have a dual purpose against ships

[Panopticon]

At the ranges you will be engaging you won't really need the ECCM I think, even if you use them against ships. I have always had difficulty getting laser weapons to be useful in an antimissile role, the multiple shots provided by railguns or gauss weapons seems more efficient to me.

My laser AMM ships always end up being anti ship, particularly they are murder on FACs. I would note that with four twin turrets these guys seem to be pretty decent main line beam brawlers all by themselves, you might consider just using them rather than building two different classes.

The other thing I noticed was the shields, not sure they will be worth their weight at Gamma, might be better off with more armor or just a lighter ship. Your mileage may vary of course on that.

[Charlie Beeler]

Here are some things to consider when designing a beam based missile defense ship/system.

Do you have the tech that will supply a beam fire control that can engage missiles at a range of over 5 seconds (10 seconds is better) flight time from the mounting ship with a 50% chance to hit?  If you do, do you have a beam weapon that can also do damage at the same range?  

If both answers are yes then you may consider fielding a system that is intended for area defense.  Odds are that at least the fire control answer is no, which means your efforts will be better spent fielding a system that is intended for final defense.  

The reasoning behind the two different systems has to do with the sequence of play and how point defense functions within it.  Area defensive fire occurs during normal weapons fire which happens after all movement has been resolved, while final defense occurs during movement triggered by missiles who's movement will result in attacks.  The +5 second range break for area defense is because missiles that are at a shorter range will resolve their attacks before normal weapons fire meaning the area defense beam will have no shot.

In both cases the beam fire control should be 4x range and 4x tracking speed.  Yes this is a massive BFC, but this is supposed be your best point defense platform.  Also in both cases match to turret tracking speed to the BFC tracking speed.

Beams intended for area defense should be the largest that you can turret mount and can cycle every 5 seconds.

For final defense the beams need only be able to cycle every 5 seconds.  The caliber only needs to increased when you start seeing armored missiles with more protection than a single beam can handle.  Do not use the range modifier for beam weapons intended for final defense.  Ignore this advice if the ship has intended to have a dual anti-ship role.

Build quad turrets and match 1:1 with the BFC.  This gives you the maximum flexability against multiple salvos.

Unless your seeing ECM equipped missiles forget the ECCM for this ship class.

Area defense PD TG's should be deployed with escort orders where they can get 2 cycles of fire against missile targeting the ships they are defending.

Final defense PD ships should be integrated in the TG's they are defending and set to range 1 (but not self defense).

Keep in mind that the best single system missile defense is another missile.  

[Thiosk (OP)]

I;m planning gauss turrets for final defensive fire AMM escorts.  Do you use full size gauss for that?  Or do you take the accuracy penalties?  6 HS per gun seems excessive.

[Brian Neumann]

I;m planning gauss turrets for final defensive fire AMM escorts.  Do you use full size gauss for that?  Or do you take the accuracy penalties?  6 HS per gun seems excessive.

6 HS is bulky, but you need to figure in the power plants when comparing to other weapon systems.  I usually find the gauss cannon gets better results when I have a rate of fire of 4.  At a rof of 3 it is a roughly the same as than two 10cm railguns would be.  (6 shots but not turreted vs 3 shots turreted).  The other side to think about however is if you want to use the same ship/weapons in an offensive role for beam combat.  I often favor mesons over gauss cannon even though they are no where near as effective in missile defense because they will tear up a warship that gets in close.  And in close is where the other beam weapons are generally most effective.  If my mesons keep the enemy out of their most effective beam range, or do major damage when they come in then that is usually worth the somewhat weaker point defense.

Brian

[Charlie Beeler]

I'll stipulate that I have a very high bias where Gauss Cannon are concerned. 

For a final defense point defense turret do not chose the reduced size versions if you have at least ROF 2 and the missiles that you need to intercept will force at least at 25% accuracy penalty vs your best ship speed.  The full size turreted single GC actually has a slight mass to performance advantage against both twin laser and meson cannon installations because of the lack of a reactor requirement. 

I believe, though I haven't run the numbers to prove, that the single turreted ROF 2 GC has a slight effectiveness advantage against 2 10cm railguns as well.  Yes the railguns will have 8 shots vs 2 but the accuracy degradation from the mismatch between ship speed and missile speed offsets the railguns ROF advantage significantly.

As soon as you compromise and use the reduced size GC and accept the accuracy reduction you need much more that a ROF of 4 to regain the GC's advantages.

[Ashery]

I;m planning gauss turrets for final defensive fire AMM escorts.  Do you use full size gauss for that?  Or do you take the accuracy penalties?  6 HS per gun seems excessive.

Effective PD relies on consistency, so I'd be weary of using anything smaller than the 5HC/85% to hit GC. Theoretically, you'd have a greater expected hit rate when using quad 3HS/50% GCs than twin 6HS/100% GCs thanks to the reduced turret gear size for quads, but consistency is key for PD.

[Charlie Beeler]

While a quad mount of 3hs 50% accuracy GC's generates twice as many shots to resolve as twin mount of 6hs 100% accuracy GC's the probably number of hits are functionally the same. 

[Brian Neumann]

While a quad mount of 3hs 50% accuracy GC's generates twice as many shots to resolve as twin mount of 6hs 100% accuracy GC's the probably number of hits are functionally the same. 

Not quite as missile ecm vs shipboard eccm can become a factor.  The big difference here is that 10% off from a 40% hit chance gives you a 36% chance while 10% from the 20% base gives you 14%.  The ew modifier is calculated before the size modifier but from I have been seeing is the same regardless of the size modifier. This means that your effective hit chance would be 36% for the full up system while only 28% with the half size version on a per hull space basis.  The other side of this however is that crew grade is also factored in after everything and is a straight addition.  If you have a significant crew grade advantage then the extra shots can make a big difference.

Brian

[Charlie Beeler]

Except that 10% reduced from 20% leaves you 18% not 14%.  And 4 shots at 18% should average the same number of hits as 2 shots at 36%.

But I think Brian is also stating that there is no net benefit to using the reduced Gauss Cannons when the same mass/hull space is used.

[UnLimiTeD]

What is is stating, however, is that the change in accuracy is not always relative.
I've already had tests more than a half year ago where I had 50% accuracy Gauss turrets with weak ECCM target missiles with around ECm 5 and a decent speed advantage, and the accuracy of the beam weapons turned negative and crashed the game.
Int he same vein, I've managed to get my Full HS gauss cannons up to 117% accuracy, which expectedly did not make them hit twice.
The latter might have been a fluke of sorts, but the first I could reliably reproduce.
As he said, if your crew has a 30% accuracy bionus, this might (not sure about current version) result in a bonus on reduced size weapons that is relatively far higher than 30%.

[Charlie Beeler]

As long as the only things that change are size and number of GC's then it is just a wash.  As in, if you replace 1 6hs/100%/rof 3 GC with 2 3hs/50%/rof 3 GC's (and all other modifiers apply equally to both), then the probably results are the same.  Yes there will be occasional aberrant variations, but not enough to give an advantage to either. 

I'll grant that I'm no statistician.  So if someone can produce a mathematical model that proves otherwise I'm all ears. 

[Father Tim]

Sorry Charlie, but while your math is right, Brian is right about what actually happens in the game because of the manner in which various bonuses and penalties are applied.  They're not all just multiplied together like they (probably) should be - some are added or subtracted.