Here are some Orbital Weapons Platform designs I came up with. There are two of them, each with their own pros and cons. I think they can still be SMed in under the story that the aliens managed to damage the platforms somehow beforehand using electronic weapons, and it is only now that they are being repaired. Or possibly the platforms were completely caught off guard before activating, or they were decommissioned and it took time for the Sirian forces to get to the stations and then activate them. Either way, I think at least one of these designs should be SMed in for all colonies and Earth, as they serve to protect the colonies while also providing the protection value so that the colonies aren't hampered until they produce their first military ships. Even then, these stations won't cover the PPV required by any of the colonies by themselves.
Great Wall Mk.IR class Orbital Weapon Platform 10,000 tons 423 Crew 4458 BP TCS 200 TH 0 EM 0
1 km/s Armour 10-41 Shields 0-0 Sensors 1/1/0/0 Damage Control Rating 10 PPV 90
Maint Life 6.14 Years MSP 2786 AFR 80% IFR 1.1% 1YR 127 5YR 1901 Max Repair 720 MSP
Intended Deployment Time: 1 months Spare Berths 2
10cm Railgun V5/C3 (14x4) Range 50,000km TS: 10000 km/s Power 3-3 RM 5 ROF 5 1 1 1 1 1 0 0 0 0 0
25cm Railgun V5/C5 (6x4) Range 250,000km TS: 10000 km/s Power 15-5 RM 5 ROF 15 5 5 5 5 5 4 3 3 2 2
Anti-Missile Fire Control (3) Max Range: 240,000 km TS: 40000 km/s 96 92 88 83 79 75 71 67 62 58
Anti-Ship Fire Control (1) Max Range: 480,000 km TS: 10000 km/s 98 96 94 92 90 88 85 83 81 79
Gas-Cooled Fast Reactor Technology PB-4.5 (16) Total Power Output 72 Armour 0 Exp 5%
Active Search Sensor MR10-R1 (1) GPS 180 Range 10.8m km Resolution 1
This design is classed as a Military Vessel for maintenance purposes
Designated Mk.IR, because it relies entirely on Railguns which are generally effective. Although Gauss Cannons might be better in this situation given the tech, 10cm railguns still have a 10,000km range advantage. 14 10cm railguns firing every 5 second increment can take down some a good chunk of missiles, so long as they fall within 50,000km within a five second interval. Again, these have a 10,000km range advantage to any gauss cannons we design.
Six 25cm railguns firing every 15 seconds can help to soften up any incoming missile salvoes, as their range is 250,000km, meaning they will definitely get their shots in, so long as they aren't recharging. At the same time, it ensures that the station will be able to fight back if the enemy isn't using missiles and has beam weapons instead. 250,000km for a beam fight is pretty respectable.
10 layers of armor means it can take some serious punishment from any enemy weapon (except meson cannons. But again, the enemy would have to come very close for that, and by that time the 25cm railguns are breaking them down). Any leakers that break through the railguns can easily be absorbed. However, sacrificing 6 engineering spaces and 1 layer of armor allows for a CIWS unit to be placed onboard, meaning it has the chance to take out anything that slips by.
This station is meant to orbit population centers, given its deployment time. It has no engines, and would have to be towed if it needed to be moved. The only reason tehre are 10 engineering spaces is because it reduces maintenance costs and saves on some minerals while also making it exactly 10,000 tons. Taking a portion of those away might allow for an extra 10cm railgun and its power plant at a higher maintenance cost.
Great Wall Mk.IG class Orbital Weapon Platform 10,000 tons 180 Crew 2299 BP TCS 200 TH 0 EM 0
1 km/s Armour 10-41 Shields 0-0 Sensors 1/1/0/0 Damage Control Rating 4 PPV 136.8
Maint Life 0.97 Years MSP 575 AFR 200% IFR 2.8% 1YR 593 5YR 8901 Max Repair 720 MSP
Intended Deployment Time: 1 months Spare Berths 0
Quad Gauss Cannon R4-100 Turret (3x16) Range 40,000km TS: 40000 km/s Power 0-0 RM 4 ROF 5 1 1 1 1 0 0 0 0 0 0
Anti-Missile Fire Control (1) Max Range: 240,000 km TS: 40000 km/s 96 92 88 83 79 75 71 67 62 58
Active Search Sensor MR10-R1 (1) GPS 180 Range 10.8m km Resolution 1
This design is classed as a Military Vessel for maintenance purposes
This is the gauss cannon variant with 3 quad turrets that can pour out 48 shots every 5 seconds. This has 10,000km less range than 10cm railguns, but it makes up for it with firepower. These turrets are massive, meaning they were the only armament that could be fit on a 10,000 ton design. There is a variation that follows which combines the two.
The major disadvantage with this is that any enemy ship that doesn't rely on missiles can outrange these platforms and win on attrition. It would be a matter of time before the enemy ship landed enough shots to wear down the armor destroy the OWP.
Great Wall Mk.IRG class Orbital Weapon Platform 10,000 tons 266 Crew 2861 BP TCS 200 TH 0 EM 0
1 km/s Armour 10-41 Shields 0-0 Sensors 1/1/0/0 Damage Control Rating 7 PPV 123.2
Maint Life 2.51 Years MSP 1252 AFR 114% IFR 1.6% 1YR 276 5YR 4136 Max Repair 720 MSP
Intended Deployment Time: 1 months Spare Berths 4
Quad Gauss Cannon R4-100 Turret (2x16) Range 40,000km TS: 40000 km/s Power 0-0 RM 4 ROF 5 1 1 1 1 0 0 0 0 0 0
25cm Railgun V5/C5 (4x4) Range 250,000km TS: 10000 km/s Power 15-5 RM 5 ROF 15 5 5 5 5 5 4 3 3 2 2
Anti-Ship Fire Control (1) Max Range: 480,000 km TS: 10000 km/s 98 96 94 92 90 88 85 83 81 79
Anti-Missile Fire Control (1) Max Range: 240,000 km TS: 40000 km/s 96 92 88 83 79 75 71 67 62 58
Gas-Cooled Fast Reactor Technology PB-4.5 (5) Total Power Output 22.5 Armour 0 Exp 5%
Active Search Sensor MR10-R1 (1) GPS 180 Range 10.8m km Resolution 1
This design is classed as a Military Vessel for maintenance purposes
Best of both worlds. 32 shots fired from gauss turrets every five seconds along with 4 25cm railguns to help reduce incoming number of missiles while allowing the station to hit back against enemy beam ships.
What follows is a list of components, starting with those that are needed by all three designs:
Great Wall OWP Components
All Three Designs
Active Search Sensor MR10-R1
Active Sensor Strength: 180 Sensitivity Modifier: 60%
Sensor Size: 5 HS Sensor HTK: 1
Resolution: 1 Maximum Range vs 50 ton object (or larger): 10,800,000 km
Range vs Size 6 Missile (or smaller): 1,176,120 km
Range vs Size 8 Missile: 1,728,000 km
Range vs Size 12 Missile: 3,888,000 km
Chance of destruction by electronic damage: 100%
Cost: 180 Crew: 10
Materials Required: 12.2x Duranium 180x Uridium
Development Cost for Project: 1800RP
Anti-Missile Fire Control
50% Accuracy at Range: 120,000 km Tracking Speed: 40000 km/s
Size: 8 HS HTK: 1 Cost: 720 Crew: 16
Chance of destruction by electronic damage: 100%
Materials Required: 5x Duranium 720x Uridium
Development Cost for Project: 7200RP
Great Wall Mk.IG and Mk.IRG
Gauss Cannon R4-100
Damage Output 1 Rate of Fire: 4 shots every 5 seconds Range Modifier: 4
Max Range 40,000 km Size: 6 HTK: 2
Cost: 48 Crew: 12
Materials Required: 48x Vendarite
Development Cost for Project: 480RP
Quad Gauss Cannon R4-100 Turret
Damage Output 1x16 Rate of Fire: 5 seconds Range Modifier: 4
Max Range 40,000 km Turret Size: 45.6 SPW: 11.4 Turret HTK: 8
Cost: 300 Crew: 43
Maximum Tracking Speed: 40000km/s
Materials Required: 108x Duranium 192x Vendarite
Development Cost for Project: 3000RP
Great Wall Mk.IR and Mk.IRG
25cm Railgun V5/C5
Damage Per Shot (4): 5 Rate of Fire: 15 seconds Range Modifier: 5
Max Range 250,000 km Railgun Size: 8 HS Railgun HTK: 4
Power Requirement: 15 Power Recharge per 5 Secs: 5
Cost: 96 Crew: 24
Materials Required: 19.2x Duranium 19.2x Boronide 57.6x Neutronium
Development Cost for Project: 2000RP
Anti-Ship Fire Control
50% Accuracy at Range: 240,000 km Tracking Speed: 10000 km/s
Size: 4 HS HTK: 1 Cost: 360 Crew: 8
Chance of destruction by electronic damage: 100%
Materials Required: 5x Duranium 360x Uridium
Development Cost for Project: 3600RP
Gas-Cooled Fast Reactor Technology PB-4.5
Power Output: 4.5 Explosion Chance: 5
Reactor Size: 1 HS Reactor HTK: 1
Cost: 14 Crew: 2
Materials Required: 12.2x Duranium 36.6x Neutronium 14x Boronide
Development Cost for Project: 140RP
Great Wall Mk.IR
10cm Railgun V5/C3
Damage Per Shot (4): 1 Rate of Fire: 5 seconds Range Modifier: 5
Max Range 50,000 km Railgun Size: 3 HS Railgun HTK: 1
Power Requirement: 3 Power Recharge per 5 Secs: 3
Cost: 25 Crew: 9
Materials Required: 5x Duranium 5x Boronide 15x Neutronium
Development Cost for Project: 1000RP