Small Railgun fighter designs, Ion tech

[DeMatt (OP)]

So, I was spending some time designing some small (1HS engine out of 4HS total size) railgun fighters, came up with these designs, and decided I wanted to hear other players' opinions:

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Spitfire Ia class Light Fighter      200 tons       9 Crew       47.4 BP       TCS 4    TH 31    EM 0
7824 km/s      Armour 2-3       Shields 0-0       HTK 1      Sensors 0/0/0/0      DCR 0      PPV 0.98
Maint Life 28.50 Years     MSP 29    AFR 2%    IFR 0.0%    1YR 0    5YR 1    Max Repair 15.625 MSP
Lieutenant Commander    Control Rating 1   
Intended Deployment Time: 15 days    Morale Check Required   

Ion Drive  EP31.25 (1)    Power 31.2    Fuel Use 1875.00%    Signature 31.25    Explosion 25%
Fuel Capacity 13,000 Litres    Range 0.62 billion km (22 hours at full power)

10cm Railgun V50/C1/S1 (1)    Range 50,000km     TS: 7,824 km/s     Power 0.75-1     RM 50,000 km   ROF 5        1 1 1 1 1 0 0 0 0 0
Beam Fire Control R51-TS8000 (SW) (1)     Max Range: 51,200 km   TS: 8,000 km/s     80 61 41 22 2 0 0 0 0 0
Gas-Cooled Fast Reactor R1-PB60 (1)     Total Power Output 1    Exp 30%

Active Sensor AS3-R1 (1)     GPS 3     Range 3.5m km    MCR 317.9k km    Resolution 1A single-shot 10cm railgun is the most compact of the weapons I was looking at, which freed up space for more not-specifically-combat gear.  The active sensor is a mere 5 tons (and no crew requirement);  I suppose it could be discarded in favor of more fuel, but the change to active sensor range means these minimum-size sensors are more attractive than they used to be.

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Spitfire Ib class Light Fighter      200 tons       10 Crew       43.1 BP       TCS 4    TH 28    EM 0
7039 km/s      Armour 1-3       Shields 0-0       HTK 1      Sensors 0/0/0/0      DCR 0      PPV 1.65
Maint Life 14.75 Years     MSP 18    AFR 3%    IFR 0.0%    1YR 0    5YR 2    Max Repair 14.06 MSP
Lieutenant Commander    Control Rating 1   
Intended Deployment Time: 3 days    Morale Check Required   

Ion Drive  EP28.12 (1)    Power 28.1    Fuel Use 1976.42%    Signature 28.12    Explosion 25%
Fuel Capacity 11,000 Litres    Range 0.5 billion km (19 hours at full power)

10cm Railgun V50/C1.5/S2 (1x2)    Range 50,000km     TS: 7,039 km/s     Power 1.5-1.5     RM 50,000 km   ROF 5        1 1 1 1 1 0 0 0 0 0
Beam Fire Control R51-TS7200 (SW) (1)     Max Range: 51,200 km   TS: 7,200 km/s     80 61 41 22 2 0 0 0 0 0
Gas-Cooled Fast Reactor R2-PB60 (1)     Total Power Output 1.5    Exp 30%Double the shots, at the cost of reduced speed and endurance.  I'm not sure it's worth it - the railgun goes from 0.975 HS to 1.65 HS.

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Spitfire Ic class Light Fighter      220 tons       12 Crew       55 BP       TCS 4    TH 31    EM 0
7102 km/s      Armour 1-3       Shields 0-0       HTK 1      Sensors 0/0/0/0      DCR 0      PPV 1.63
Maint Life 11.94 Years     MSP 20    AFR 4%    IFR 0.1%    1YR 0    5YR 4    Max Repair 19.6 MSP
Lieutenant Commander    Control Rating 1   
Intended Deployment Time: 1.5 days    Morale Check Required   

Ion Drive  EP31.25 (1)    Power 31.2    Fuel Use 1875.00%    Signature 31.25    Explosion 25%
Fuel Capacity 5,000 Litres    Range 0.22 billion km (8 hours at full power)

12cm Railgun V50/C1.5/S1 (1)    Range 100,000km     TS: 7,102 km/s     Power 1.50-1.5     RM 50,000 km   ROF 5        2 2 2 2 2 1 1 1 1 1
Beam Fire Control R112-TS7200 (SW) (1)     Max Range: 112,000 km   TS: 7,200 km/s     91 82 73 64 55 46 38 29 20 11
Gas-Cooled Fast Reactor R2-PB60 (1)     Total Power Output 1.5    Exp 30%This goes for a single-shot 12cm railgun (1.625 HS) for double the range as well as (slightly) more gunpower at point blank.  The extra range is very tempting, but I needed to give up on the 200-ton limit in order to fit an appropriate fire control.

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Spitfire Id class Light Fighter      250 tons       15 Crew       63.3 BP       TCS 5    TH 38    EM 0
7502 km/s      Armour 1-3       Shields 0-0       HTK 1      Sensors 0/0/0/0      DCR 0      PPV 1.63
Maint Life 17.84 Years     MSP 36    AFR 2%    IFR 0.0%    1YR 0    5YR 3    Max Repair 22.4 MSP
Lieutenant Commander    Control Rating 1   
Intended Deployment Time: 6 days    Morale Check Required   

Ion Drive  EP37.50 (1)    Power 37.5    Fuel Use 1711.63%    Signature 37.50    Explosion 25%
Fuel Capacity 10,000 Litres    Range 0.42 billion km (15 hours at full power)

12cm Railgun V50/C1.5/S1 (1)    Range 100,000km     TS: 7,502 km/s     Power 1.50-1.5     RM 50,000 km   ROF 5        2 2 2 2 2 1 1 1 1 1
Beam Fire Control R112-TS8000 (SW) (1)     Max Range: 112,000 km   TS: 8,000 km/s     91 82 73 64 55 46 38 29 20 11
Gas-Cooled Fast Reactor R2-PB60 (1)     Total Power Output 1.5    Exp 30%Bulking the Ic variant up to 250 tons gave me this guy.  On the minus side, it fits four to a Hangar Deck compared to the Ia's five;  on the plus side, it does fully occupy a Boat Bay.

So... thoughts?  Which would you build?  Would you try to change something, e.g. more fuel or armor?

Off-Topic: show

Techs used:
- Gas-cooled Fast Reactor, Power Plant Boost 60%
- Ion Drive Technology, Fuel Consumption: 0.6 L/EPH, Maximum Engine Power Modifier x2.5
- 12cm Railgun, Railgun Launch Velocity 50,000
- BFC Range 64,000 km, FC Speed Rating 4000 km/s
- Active Sensor Strength 28, EM Sensitivity 14, Thermal Sensitivity 14
- Ceramic Composite Armor

[BAGrimm]

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Circe class Fast Attack Craft (P)      250 tons       11 Crew       40.4 BP       TCS 5    TH 30    EM 0
6014 km/s      Armour 1-3       Shields 0-0       HTK 1      Sensors 0/0/0/0      DCR 0      PPV 1.63
Maint Life 5.18 Years     MSP 50    AFR 50%    IFR 0.7%    1YR 3    5YR 47    Max Repair 15 MSP
Captain (JG)    Control Rating 1   
Intended Deployment Time: 3 days    Morale Check Required   

Improved Nuclear Pulse Engine  EP30.00 (1)    Power 30    Fuel Use 1168.47%    Signature 30    Explosion 20%
Fuel Capacity 5,000 Litres    Range 0.31 billion km (14 hours at full power)

12cm Railgun 60k/R5/S1 (1)    Range 60,000km     TS: 6,014 km/s     Power 1-1.5     RM 30,000 km    ROF 5       
Beam Fire Control R60-TS6000 (SW) (1)     Max Range: 60,000 km   TS: 6,000 km/s     83 67 50 33 17 0 0 0 0 0
Improved Pebble Bed Reactor R1.5-PB10 (1)     Total Power Output 1.5    Exp 7%
Just recently designed this.  Using some slightly lower tech than you, but on the whole it appears that we have both ended up with similar specifications.  It seems to me that with these techs, and at this size, there isn't much else one can do to squeeze out any more performance.  But only time, and trial by fire, will tell for sure if they are of any real use!

[skoormit]

I'm always looking to squeeze more on a fighter by reducing range.
I don't use my fighters for independent operations of any duration, and I don't use them to chase things down.
To me, they are just cheap, portable, semi-disposable firepower, parked in a hangar that has a long deployment time.

So I'd take the extra fuel off of the Id and see what that would buy me--probably nothing but a tad longer deployment time, which isn't useful.
I'd rather be 249t with minimal fuel.

[nuclearslurpee]

With your listed technologies the following design is possible:

Example class Fighter (P)      500 tons       25 Crew       139.8 BP       TCS 10    TH 141    EM 0
14089 km/s      Armour 1-5       Shields 0-0       HTK 3      Sensors 0/0/0/0      DCR 0      PPV 3
Maint Life 0 Years     MSP 0    AFR 99%    IFR 1.4%    1YR 31    5YR 467    Max Repair 70.31 MSP
Lieutenant Commander    Control Rating 1   
Intended Deployment Time: 3 days    Morale Check Required   

Ion Drive  EP140.62 (1)    Power 140.6    Fuel Use 883.88%    Signature 140.62    Explosion 25%
Fuel Capacity 6,000 Litres    Range 0.24 billion km (4 hours at full power)

10cm Railgun V50/C3 (1x4)    Range 50,000km     TS: 14,089 km/s     Power 3-3     RM 50,000 km    ROF 5       
Beam Fire Control R64-TS14000 (SW) (1)     Max Range: 64,000 km   TS: 14,000 km/s     84 69 53 38 22 6 0 0 0 0
Gas-Cooled Fast Reactor R3-PB60 (1)     Total Power Output 3    Exp 30%

Active Search Sensor AS3-R1 (1)     GPS 3     Range 3.5m km    MCR 317.9k km    Resolution 1

Using a full-size 10 cm railgun allows you to build a fighter which has 4 shots instead of 1 or 2 and goes roughly twice as fast therefore having 2x the accuracy per shot against fast targets (i.e. missiles). This more than makes up for being 2.5x the size of either 200-ton design.

In general since the reduced-shot railguns do not scale efficiently with size, using the full-size railgun will remain always the most efficient use of tonnage for a railgun fighter. You have fewer of them but each one is much more effective. Also, note that you could use these 500 tons to mount three railguns on a ship which goes ~1/3 the speed and benefits from better armor and efficiency, so using railgun fighters is marginal in terms of pure performance (but beneficial in terms of logistics).

As a side note the build cost can be reduced by using the 10,000 km range to bring down the railgun cost by 80%, which saves about 21 BP. Any additional range is unnecessary for missile defense and minimally useful for other purposes as these are such quick fighters. However the PD efficiency on a per-ton basis is not harmed by using the longer range so I've left it as specified.

[Lord Solar]

I prefer shorter ranged fighters that move between 16-20k km/s at ion.