Using the railgun designed in the last post, it’s now time to look at it in the space combat system. We’ll reuse the interception scenario yet again, equipping the AKVs with railguns. This requires more space - a slight increase in dimensions also increases loaded mass to about 140t. That’s close enough for me to simply reuse performance statistics from last turn.

Relevant Changes to Tactics

The primary difference is that AKVs now come with their own “suppressive fire” - four of these can fire eight bursts per turn. The SDV has eight lasers available, meaning that it can manage to defend itself - until you fail a PD roll. But during that time, it cannot attack the AKVs, which are arguably the greater threat.

The Encounter

As last time, we will start the engagement at 12,000km. At this distance, and with a closing speed of 20 km/s, the first projectiles will arrive during turn 6. Indeed, the first three salvoes will impact during that turn; the next four will impact in turn 7 - as will the AKVs.

Turn 1

Distance is 12,000km, for extreme range. At that range, only the heavy lasers can fire. Since distance is too great to damage the AKVs, the lasers fire at the projectiles instead. They roll against the gunner skill of 14; all rolls succeed and half of the first salvo is eliminated. Four shots in flight.

Turn 2

Distance is 10,000km. Still at extreme range. Repeating the exercise, the first salvo is now completely eliminated. Of course, this does not help against the second salvo now under way.

Turn 3

Distance closed to 8,000km. Now at long range, the heavy lasers can damage the AKVs. They switch targets to AKV A, and after a successful gunnery roll do 90, 50, 110, and 60 damage, for 120 injury after armour. This kills the AKV.

In the meantime, the light lasers fail with two rolls - four full bursts are remaining, and one each with one and two projectiles left. And the next salvo (but with only six bursts) is already underway.

Turn 4

Distance is 6,000km. Long-range, and the heavy lasers fire at AKV B. With a success rolled, 40 injury is inflicted. The drive and weapon are damaged. The fourth salvo (now with only four bursts) is launched. The light lasers eliminate the four remaining full bursts of the second salvo. Aside from the three projectiles of the second salvo, two more salvos (100 projectiles total) are still incoming.

Turn 5

Distance down to 4,000km. Last turn at long range. The heavy lasers now split their fire between AKV C and D for a better chance to knock out the weapons. That’s 80 injury for AKV C (knocked out), and 60 for AKV D (6 major damage rolls). AKV D has a drive damaged and the weapon knocked out.

This means that the two salvos currently incoming are all that remains. And the SDV even now goes on to eliminating more of those: Another four bursts are eliminated. Six remaining - but they will impact next turn.

Turn 6

Distance is now 2,000km. Heavy lasers split their fire between AKV B and D. 120 injury is inflicted on AKV B, which is disabled. AKV D is killed.

Light lasers fire yet again, this time in point defence mode. Three succeed, but one fails. Three full salvos and one with an after-armour modifier of 2 remain. And these hit now. Or at least the three full ones hit; the depleted one failed its gunnery roll.

The SDV attempts to dodge, accelerating at 0.65g (medium gear). That costs 65 burn points, multiplied by 5 for an effective 325BPs. 3,925BPs remaining. This gives +8 to the dodge roll, and -9 from SM. Two full salvos hit. Each of those does 1.12d(3) x V = 25d+2(3) cDam against the front armour of 70cDR (effective 23). 102 and 98 is rolled, for 79 and 75 penetrating damage. Multiplying that by 10 gives 790 and 750 damage. At cHP of 1600, that leaves only 60cHP, with the SDV badly damaged: sAccel is halved, and we roll 9 times on the major damage table. This is:

  1. 15: Spacedock damaged, converted to 25% of current cargo lost.
  2. 8: Surgery knocked out.
  3. 5: Drive damaged; sAccel halved yet again.
  4. 7: Sensor knocked out.
  5. 7: Another sensor knocked out.
  6. 5: Drive yet again damaged.
  7. 6: Cargo damaged.
  8. 15: Spacedock, converted to yet more cargo lost.
  9. 15: Yet more cargo lost.

In summary, acceleration has dropped significantly, surgery knocked out, half-blind; and actually lost all of the cargo. On the other hand: All weapons are still ready to fire.

Summary

Originally, I thought that the vehicle-built railgun would be significantly worse. After all, it has an extremely low muzzle velocity. On the other hand, it will hit at almost all ranges, which makes it quite powerful. And, for the SDV, its point defence was quite clearly inadequate.

On the other hand, that was arguably the best-case scenario: Unless there’s a closing speed of more than 3km/s, the average railgun hit cannot penetrate the SDVs frontal armour.