Commercial engines and military ships

[jseah (OP)]

After looking around on ship design, I have noticed that commercial engines have half the power to weight ratio of military engines. 
This isn't quite too bad and I looked around to check how much the engine ratio affected speed and various other stuff. 

All this leads me to conclude that putting commercial engines on military ships is actually a viable strategy. 

Proposed fleet doctrine modification:
per 5ktons -> 2x commercial engines = 50% engines = effective 25% military engine space

Space penalty on ships = 25/75 = 1/3 less *stuff* compared to military engined ships. 
Hence 50% commercial engined ships will require a 1/3 increase in size for the same payload. 

Advantages:
Commercial engines are super cheap! 
You can seriously inflate the size of your ships and the engine cost (which is really high for military ships) is still reasonable. 
And given that engines can go up to 30-40% of a ship's cost depending on design, you make your ships cost alot less. 

No need to use military jumpdrives! 
Military jumpdrives are notoriously expensive.  Commercial jumpdrives can jump ships 3 to 4 times the size of military drives and still cost less. 

Fuel efficiency! 
With 10x more fuel efficient engines, you can kiss all your fuel problems goodbye.  No need to stuff 20 fuel tanks onto ships anymore!  (but see maintenance below)
TF train your ships all day long and never bat an eyelid at your fuel consumption. 

Explosion chance is massively reduced.  You can push the power efficiency tech to it's limits and have little fear of chain explosions. 
And your engines WILL get hit.  If they take up to 50% of your ship, the chance of a shot hitting your engines is incredibly high. 

Disadvantages:
Maintenance. 
Super big ships are incredibly hard to maintain.  And while commercial engines cost little and need little maintenance supplies to repair them per ton, they do require quite alot apiece.  This makes your maintenance lifetime drop like a rock.  The space you save in fuel tanks is eaten up by engineering spaces. 
But which would you rather save on, fuel or maintenance supplies?  Maintenance supplies aren't required too much if you overhaul regularly, while fuel is eaten on every trip you make.  Also watch that damage control rating shoot sky high, you might not even need damage control components!

Needs BIG shipyards. 
Big ships = big shipyards.  But assuming you have them, this strategy is actually possible. 

Slow speed.  =(
You can't feasibly do higher than effective 25% military engines (50% space in commercial engines) without turning your ships into giant balls of nothing but armour. 
This is a problem of course and fleet strategy must be arranged around large and slow ships.  Which affects missile design, which affects their use on the faster military ships who rocket around. 
Of course, large ships gives you an advantage in armour since sandpapering your armour will take forever but that's pretty minor. 

--------------------------------------------------------

So, comments?  Think it's possible / worthwhile?

I might try it, once I get some shipyards up to scratch.  Perhaps I shall redesign my cruiser to use commercial engines and have the loadout of a destroyer. 

[Erik L]

I think your last line summarizes it perfectly. "A cruiser with the firepower of a destroyer."

[Brian Neumann]

A second problem of using civilian jump drives is that they have a much longer sensor down time.  This will leave you defensless in a jump point assault for much longer than with a military jump drive.

Brian

[jseah (OP)]

I think your last line summarizes it perfectly. "A cruiser with the firepower of a destroyer."

But costs less than a destroyer and has easier logistics. 

The main thing is that it costs less than the destroyer, has a much cheaper jumpengine, and requires far less fuel. 

Sure, it's bigger, but you can have more of them.  It's not like 10ktons vs 15ktons will make much of a difference wrt to sensors. 

Code: [Select]

EttinB class Destroyer    10,000 tons     611 Crew     2125.96 BP      TCS 200  TH 1562  EM 0
7810 km/s     Armour 4-41     Shields 0-0     Sensors 1/1/0/0     Damage Control Rating 16     PPV 75.9
Annual Failure Rate: 133%    IFR: 1.9%    Maint Capacity 797 MSP    Max Repair 78 MSP    Est Time: 3.42 Years
Magazine 710   

Magnetic Confinement Fusion Drive E7.5 (10)    Power 156.25    Fuel Use 75%    Signature 156.25    Armour 0    Exp 20%
Fuel Capacity 355,000 Litres    Range 85.2 billion km   (126 days at full power)

Size 5 Missile Launcher (33% Reduction) (46)    Missile Size 5    Rate of Fire 500
Missile Fire Control FC83-R16 (1)     Range 83.2m km    Resolution 16
'Gawain' Size 5 Anti-ship Missile (142)  Speed: 55,200 km/s   End: 18.2m    Range: 60.4m km   WH: 6    Size: 5    TH: 202 / 121 / 60

ECCM-4 (1)         Missile to hit chances are vs targets moving at 3000 km/s, 5000 km/s and 10,000 km/s

This design is classed as a Military Vessel for maintenance purposes

Code: [Select]

EttinB - Copy class Destroyer    15,000 tons     530 Crew     1933.76 BP      TCS 300  TH 2344  EM 0
7813 km/s     Armour 4-54     Shields 0-0     Sensors 1/1/0/0     Damage Control Rating 13     PPV 72.6
Annual Failure Rate: 138%    IFR: 1.9%    Maint Capacity 1047 MSP    Max Repair 98 MSP    Est Time: 3.43 Years
Magazine 700   

Magnetic Confinement Fusion Drive E0.75 (6)    Power 390.625    Fuel Use 7.5%    Signature 390.625    Armour 0    Exp 4%
Fuel Capacity 55,000 Litres    Range 88.0 billion km   (130 days at full power)

Size 5 Missile Launcher (33% Reduction) (44)    Missile Size 5    Rate of Fire 500
Missile Fire Control FC83-R16 (1)     Range 83.2m km    Resolution 16
'Gawain' Size 5 Anti-ship Missile (142)  Speed: 55,200 km/s   End: 18.2m    Range: 60.4m km   WH: 6    Size: 5    TH: 202 / 121 / 60

ECCM-4 (1)         Missile to hit chances are vs targets moving at 3000 km/s, 5000 km/s and 10,000 km/s

This design is classed as a Military Vessel for maintenance purposes
Commercial engine design has:
Same speed, same maintenance, same fuel.  (0.4HS spare space, which could easily increase fuel by 40% or maintenance by a bit)
2 less launchers (-5%), 10% less cost. 
Same armour thickness, +13 columns of armour area. 

IE. in terms of how useful it is in firepower, it's equal to a destroyer with a slight advantage in the amount of damage it can soak. 


Out of combat wise:
It is easier to keep in the field, requiring less tankers for the same size fleet.  And tankers take *forever* to build since planets can't build fuel tanks. 

Jumpships are far far cheaper, allowing the design to scale up to humongous ships and still have them be jump capable. 

In fact, if you have enough maintenance facilities, a one-off (but large) investment, you could build fleets of really huge ships, all of which were jump capable. 
It's is feasible to build a commercial jumpship rated for 39ktons by efficiency 4. 

If you really need the speed, you could use a commercial engine Carrier to ferry FACs and fighters as your main force. 

Code: [Select]

EttinB - Copy - Copy class Carrier    25,000 tons     836 Crew     2641 BP      TCS 500  TH 3906  EM 0
7812 km/s     Armour 4-76     Shields 0-0     Sensors 1/1/0/0     Damage Control Rating 26     PPV 0
Annual Failure Rate: 191%    IFR: 2.7%    Maint Capacity 1723 MSP    Max Repair 98 MSP    Est Time: 3.79 Years
Hangar Deck Capacity 6000 tons     Magazine 640   

Magnetic Confinement Fusion Drive E0.75 (10)    Power 390.625    Fuel Use 7.5%    Signature 390.625    Armour 0    Exp 4%
Fuel Capacity 1,150,000 Litres    Range 1104.0 billion km   (1635 days at full power)

'Gawain' Size 5 Anti-ship Missile (128)  Speed: 55,200 km/s   End: 18.2m    Range: 60.4m km   WH: 6    Size: 5    TH: 202 / 121 / 60

Missile to hit chances are vs targets moving at 3000 km/s, 5000 km/s and 10,000 km/s

This design is classed as a Military Vessel for maintenance purposes
And this could be moved with an incredibly cheap jumpdrive.  (at jump efficiency 6, it's a size 11 jumpdrive costing 300 RP; vs a size 50 jumpdrive costing 6250 RP for the equivalent 15kton military ship)

Brian:
Did not know that. 

What's the difference in sensor blindness time?

[Erik L]

The size doesn't make much of a difference, but the civ engines have over 2x the signature. Makes it much easier to find (and avoid). Those are also fairly advanced drives also.

[Brian Neumann]

Brian:
Did not know that.  

What's the difference in sensor blindness time?

A military jump ship has a sensor blind time of up to 30 seconds.  A civilian jump ship or a jump gate has a sensor blind time of up to 3 minutes (iirc).  My numbers may be off a bit, but not by much unless there has been a change without documentation.  In this case I doubt it would happen.  The sensor blindness is one of the reasons that civilian jump engines are so much cheaper.  They also can take 1 fewer ships with them for any given tech.  For example if your military ship could handle a total of 4 ships then the same civilian drive would handle only 3 ships total.  At low tech levels this is very important, at high tech it becomes less so.  Having 7 vs 8 ships in a jump group is a smaller difference than having 2 vs 3 that starting tech would give you.  The big up side to civilian jump engines is the low cost, and much bigger hull you can use.

Here is a link to the discussion with the code at the bottom of the thread
http://aurora2.pentarch.org/index.php/topic,2480.0.html

Brian

[dooots]

If fuel is the limiting factor for you it looks like it can work but larger ships make it harder to setup a outpost and the maintenance clock is the limiting factor in how far you can expand.

Is it worth it to make the same sized ships?

[jseah (OP)]

doots: same sized ships but with commercial engines, at 25% in military engines, will have commercial engine ships carrying 2/3 the tonnage of stuff compared to the same military ship. 

They will cost quite a lot less however, since a commercial engined ship in my examples above costs 10% less to carry 5% less stuff.  If you're going to carry 2/3 the stuff, I expect 90% of 2/3 the cost?  Around there anyway. 

But yes, if you want anything faster than 25% engine speed, you'll be better off with military engines. 


Brian:
According to the thread you linked:

Code: [Select]

    Bonus = 1 - (Int(Sqr(GradePoints) - 10) / 100)
   
    If Squadron Transit then
        Delay = (10 + Random Number(20)) * Bonus
    Else
        Delay = (120 + Random Number(60)) * Bonus
    EndThis only shows for squadron transit. 

Which means that a squadron transit will cause blindness for 11-30 seconds and a regular or jump gate transit will cause blindness for 121-180 seconds.

IIRC, commercial jumpdrives *can* squadron transit, just with one less ship per squad. 

[Brian Neumann]

For the sensor blindness.  At the time of the original post there was no distinction between military and civilian jump drives they were the same thing.  When Steve changed the size of cargo bays on ships he also had to introduce the civilian jump drive.  This was because of the drastic size increase in civilian ships.  He carried over the sensor blindness from the jump gate to the civilian jump drive.  The formula does work the same, and it can be reduced by the crew grade which will make a big difference, but it will still leave you blind for at least 1 minute even with exeptional crews and the minimum time rolled.  A minute is a long time in Aurora combat and your ships will be hurting for at least 1 missile salvo, probably two and with lots of shots from beam weapons.  In addition you will not have  your ecm to help protect the ship.

Brian

[jseah (OP)]

Ah, I see. 

Well, I tend to favour a direct obvious approach, have ECM 1 and ECCM4.  ^^

Plus my fleet still has no thermal sensor, actives are *always* on.  >.>
It just tends to be, mass ships, scout a bit, find a weakness or two, hit it with a missile salvo the likes of which have never been seen. 

I could probably work with commercial engine fleets under this doctrine. 
In fact, fuel is starting to be a problem.  Having 36 FACs and 464 military engines in my fleet is straining my 600 fuel refineries.  It's all fine when I park them at a planet, but any fleet action, even one in the neighbouring system like those precursors consumes millions of litres. 
And that's not counting the surveys and commercial freighters. 

On the other hand, I've not yet needed to build any maintenance supplies, being that I overhaul the moment anything breaks. 



Although, like you say, jumppoint assaults are going to be hell.  Perhaps mix in a mass of short range beam FACs in commercial carriers + a small military jumpship.  At the rate I'm building my fleet, I could chuck out over 30 facs a year (more if I bothered expanding Fac shipyards), limited only by fuel and carrier space. 

Massing "decoys" could also work, being frigate sized jumpships with nothing but humongous balls of armour.  Draws an incredible amount of missile fire so the FACs survive to shoot. 

[Brian Neumann]

You have a good idea, see how it works and let us know.

Brian

[jseah (OP)]

Yeah, I'll try that next game.  Still want to see how my current fleet will handle the wormhole aliens. 

Perhaps I could sacrifice fuel refineries for more ordnance factories. 

Of course, since it's a very slow fleet, long range missiles seems like the way to go.  In fact, apart from the beam FACs idea, it might be a good idea to specialize totally into missiles. 

FACs jump through the warppoint, launch off a bunch of specially built warppoint assault missiles (short range, super high speed, high warhead), one jumpship on the other end allows them to standard transit back when done or taking damage. 

How often do warppoint assaults happen?  I haven't actually been through one yet, on either side. 

[nafaho7]

I think I will have to try this.   Except without missiles.   I intend to put very heavy energy armaments on my vessels, in the vein of "Go big or go home. "  My goal is to outlast any missile armed opponent with sufficient point defence.   Then, advance like an unstoppable agent of Doom upon their now helpless worlds.   Bwa ha ha ha!

[Vanigo]

I think I will have to try this.   Except without missiles.   I intend to put very heavy energy armaments on my vessels, in the vein of "Go big or go home. "  My goal is to outlast any missile armed opponent with sufficient point defence.   Then, advance like an unstoppable agent of Doom upon their now helpless worlds.   Bwa ha ha ha!

Hmm. Low speed and beam weapons is generally a recipe for defeat, unfortunately.

[Brian Neumann]

I have managed a couple of games where my ships were slow moving and beam armed.  The only way that I got it to work was with massive fleets to soak up their missile attacks and big enough ships to survive without getting blown away when the missiles did get through.  It has been a while but I think I was flying mostly 30,000 ton ships with lots of dual purpose laser turrets.  They maxed out my fire control range and fired every 5 seconds.  Enough of the lasers would really thin out the missile salvo's and then it was up to the heavy shields and armor for the ship to survive.  Not an easy game at all but it was a lot of fun.

Brian