Let’s playtest everything again! We’ll use the same scenario as beforehand, and simply use the new rules. Actually, we’ll use the same rules but with two differences:

Even More New Rules

In addition to last post’s rules, I have added two more.

Railgun Targeting

As already mentioned in the forums, I’m testing a rule adapted from Tactical Shooting (although simplified compared to my first approach): For every 20-second-turn after the first your projectile needs to reach a randomly-dodging enemy, roll 1d-5 and apply this to your to-hit roll.

Proximity Detonation

Proximity detonation in 4e’s Spaceships system is quite good. You trade a +4 to hit for losing your (2) armour divisor (which, most of the time you won’t really need). For us, there’ll be a difference.

Specifically, +4 from a rapid-fire multiplier means 17-24 shots. If we assume that it’s better to point your gun at something and shoot multiple times instead of relying on explosives to generate an accurate shot, we can just say the railgun projectile is split into 25 parts (this fits roughly with the +4 you get). Each of these then does the same damage as a railgun of 1/3rd the calibre.

As an example, the AKVs have 12cm cannons. Each of these does 3dx2xRV damage. If we use proximity detonation, each of them will do 3dx0.06xRV damage. That’s… really not much. Let’s see how it works out in practice.

Calibre Railgun Damage Major Battery
2cm 3dx0.006  
2.5cm 3dx0.01  
3cm 3dx0.02  
3.5cm 3dx0.03  
4cm 3dx0.06  
5cm 3dx0.1  
6cm 3dx0.2  
7cm 3dx0.3  
8cm 3dx0.6 SM+4
10cm 3d SM+5
12cm 3dx2 SM+6
14cm 3dx3 SM+7
16cm 3dx6 SM+8
20cm 3dx10 SM+9
24cm 3dx20 SM+10
28cm 3dx35 SM+11
32cm 3dx60 SM+12
40cm 3dx100 SM+13
48cm 3dx200 SM+14
56cm 3dx350 SM+15

The Playtest

The Spacecraft

The AKV Modelled after the Predator AKV, it replaces the engine as in the previous playtest, for 4.5G acceleration at 30km/s dV. I’ll replace one armour system each in the sections with structural reinforcement. Armour is now 200d to the front, 5d to the side, and 100d to the rear. HP is 35x4, or 140. It is armed with a single 12cm major-battery EM gun which does 3dx2xRV damage.

Front Hull System
[1-4] Nanocomposite Armour (5d x 5 each)
[5] Structural Reinforcement
[6!] Major Battery
[core] Control Room
Centre Hull System
[1] Nanocomposite Armour (5d)
[3-6] Fuel Tank
Rear Hull System
[1-2] Nanocomposite Armour (5dx5 each)
[4-6] Water Fusion Torch (1.5g each)
[core!] Fission Reactor
TL Spacecraft dST/HP Hnd/SR HT Move LWt. Load SM Occ dDR FTL Cost
10^ Predator 140 -1/4 12 4.5g/30km/s 100t - +6 - 100d/5d/50d - -

The SDV Again using the Hermann Oberth-class, replacement of the drives gives us an acceleration of 3G and dV of 30km/s. We’ll have to replace a few systems again; delete one armour from the front and one fuel tank each from the other two sections. That’s already included in the dV above. HP is 200x4, or 800, with armour at 150d in the front, 10d to the side, and 50d to the rear.

It is armed with one 16cm railgun, doing 3dx6xRV damage, ten laser turrets

  • usually doing rapid fire, but I don’t yet have rules for that - doing 3dx6(2) damage with a half-damage range of 2000 kilometres.
Front Hull System
[1-3] Advanced Metallic Laminate Armour
[4] Structural Reinforcement
[5!] Smaller Systems: 16cm fixed EM gun, multipurpose array, external clamp
[6] Habitat
[core] Control Room
Centre Hull System
[1] Advanced Metallic Laminate Armour
[2!] Secondary Battery (ten UV lasers)
[3-4] Fuel Tank
[5] Structural Reinforcement
[6] 3x external clamps
Rear Hull System
[1-2] Advanced Metallic Laminate Armour
[2-3] Fuel Tank
[4] Structural Reinforcement
[5-6] Water Fusion Torch (1.5g each)
[core] Fusion Reactor
TL Spacecraft dST/HP Hnd/SR HT Move LWt. Load SM Occ dDR FTL Cost
10^ Oberth 800 -1/5 12 3g/30km/s 3,000t - +9 12ASV 150d/10d/50d - -

AKVs on Intercept

Again, we’re modelling our previous scenario: Four AKVs are burning towards the planet, and the engagement takes place at twenty kilometres per second relative velocity.

There’s just one problem: The Oberth cannot actually damage the AKVs except by railgun, since the laser will only do 18d of damage against an effective 50d of armour. Ahem.

Even replacing the railgun on the Oberth with an SM+8 particle beam (which does 3dx6 (5) damage with a half-damage range of 2000 kilometres), it still cannot damage the AKVs from the front - clearly, armour is too effective.

We’ll therefore add two adjustments: First, we decrease the multiplier for front armour to 3, and second we switch all armour one line down in the SM/Armour chart. This changes the chart as follows:

SM Steel Light Alloy Metallic Laminate Advanced ML Nanocomposite Diamondoid
SM+5 0.5 1 2 1d 2d 3d
SM+6 1 2 1d 2d 3d 5d
SM+7 2 1d 2d 3d 5d 7d
SM+8 1d 2d 3d 5d 7d 10d
SM+9 2d 3d 5d 7d 10d 15d
SM+10 3d 5d 7d 10d 15d 20d
SM+11 5d 7d 10d 15d 20d 30d
SM+12 7d 10d 15d 20d 30d 50d
SM+13 10d 15d 20d 30d 50d 70d
SM+14 15d 20d 30d 50d 70d 100d
SM+15 20d 30d 50d 70d 100d 150d

This means our AKVs now have armour of 36d/3d/18d (which still makes them invulnerable to the lasers above from the front, if only slightly) while our SDV has 63d/7d/21d.

Since the UV lasers are useless, I’ll replace them with particle beams, which do 3dx6 (5) damage at a half-damage range of 2000 kilometres. This means it does 3dx3 (5) damage out to 4000km and lastly 4d (5) out to 8000km. This is against an effective DR of 7d+1 for the AKVs.

Restarting our scenario, the Oberth now opens fire at its half-damage range of 4000 kilometres. The particle beams do 9d (5) damage there, against an effective armour of 7d+1. Each hit therefore does 2d-1 of damage. The zone lasts for 2000 kilometres, which the AKVs cross in just 100 seconds (or five turns).

  • Turn 1 Oberth opens fire, shooting at Aggressive Armadillo. Ten particle beams impact the AKV, doing a total of 56 damage. 84 HP left. The four AKVs fire Salvo 1, which will impact on turn 6. Oberth answers with one shot.
  • Turn 2 Second salvo. Another ten particle beams impact the AKV, doing a total of 61 damage. 23 HP left. Salvo 2 is fired by both sides, impacting on turn 7.
  • Turn 3 Third salvo. Yet another ten particle beams impact the AKV, doing a total of 79 damage. Armadillo is at -56 HP. Salvo 3 is fired, also impacting on turn 7.
  • Turn 4 Oberth continues to melt Armadillo into slag. The next shots do 64 damage; -110HP. Salvo 4 for turn 8.
  • Turn 5 Last turn in the half-damage zone. Next impact does 52 damage, bringing Armadillo to -162HP. Armadillo rolls 9 and survives for now. Salvo 5 is fired, turn 8.
  • Turn 6 Now, the particle beams do 11d-1 damage. Each. Accordingly, Oberth spreads fire, targeting the three undamaged AKVs with three particle beams each and Armadillo with one beam. Armadillo takes 30 damage, for -192HP, which also disables the EM gun. Beaver takes 120 damage and is reduced to 20 HP. Each of those three hits disables one system, in this case just the armour (I’m ignoring DR reduction caused by this). Curious Crow takes 126 damage (14 HP left, EM gun disabled), Dangerous Dalmatian 115 damage (25 HP left, EM gun disabled). The AKVs (or “steel chunks formerly known as AKVs”) are only 1600 kilometres away now. And while this turn’s salvo is the last with four shots, it will impact on turn 8. Now - first turn with kinetics arriving! The AKVs roll against 15 + 9 (SM) - 7 (sAcc) + 4 (proximity det) - 9 (relative velocity) = 12. As another malus, there’s the modifier from flight time, which is 5d-25 for five turns. As an example, Armadillo’s shot rolls -11 on the modifier roll, bringing its target to 1, which cannot be achieved. Similar for the other AKVs, though two could actually hit with a critical success. They don’t, though. Oberth’s shot also rolls 5d-25; it rolls -9 on the modifier and also cannot reach its target (goal number is 9 due to different SM).
  • Turn 7 We’ll repeat last turn’s attacks again: Armadillo takes 36 damage, bringing it to -228 HP. Beaver takes 108 damage (another disabled EM gun), for -88HP, Crow 113 damage for -99 HP. Lastly, Dalmatian takes 128 damage and is brought to -103HP. The last salvo from the AKVs (arriving on turn 9) consits of just one projectile. Next impact phase, now with two salvos of four shots each. One has a 5d-25 malus, the other 4d-20. Incredibly, two of the first salvo (rolling -2 and 2 on the malus) actually manage to hit! Oberth rolls against 8 to dodge and succeeds once. The last projectile hits, doing 3dx0.06xR = 3dx2 damage, which doesn’t even come close to damaging the SDV. Since proximity detonation clearly is useless, every other attack will use the full projectile and therefore roll against 8. Accordingly, none of the other projectiles from the second salvo hits. It counter-strike does not hit.
  • Turn 8 Repeat everything: The AKVs are brought down to -273, -189, -200, and -219 respectively. The latter three have to roll their first HT check; all make it. Next shot from the Oberth at Curious Crow. And, similarly, three salvoes are incoming, rolling against 4d-20, 3d-15, and 2d-10 respectively. Oberth rolls against 8 to dodge the single successful shot and fails. One shot from the last salvo hits, doing 3dx2xRV = 3dx70 damage, reduced to 3dx49 by the armour. These do 637 damage, battering Oberth down to 163HP. This also destroys the EM gun and tactical array are destroyed. Oberth’s salvoes miss.
  • Turn 9 And again. Down to -316, -299, -311, and -321HP respectively, which means everyone makes their second health check. Curious Crow fails and is finally disabled. The next (and last!) incoming salvo contains just one projectile. We roll a -4 on the modification and a critical failure on the attack itself. Safe! Oberth’s strike hits Armadillo, vapourizing it.
  • Turn 10 This one’ll be difficult. Let’s therefore do everything step-by-step:
    • Beaver is attacked by five particle beams. 169 damage gets it to -468HP. It also makes its death check. A last kinetic shot arrives, rolling -3 for modifier but failing to hit.
    • Dalmatian takes 111 damage (-507HP). It also succeeds, if just. Those are some tenacious AKVs. Of course, they only roll against their HT, not modified by how much damage they took (-1 for -1xHP, -2 for -2xHP, etc - might be better that way).
    • Ramming AKVs Two AKVs are on a collision course now. The to-hit target is 15, and the AKVs make it with a 10 and an 11. Damage is 3dx35x20 (we discount the structural reinforcement for this), reduced to slightly above 2000d damage by the armour. The Oberth, together with Dalmatian and Beaver, is vapourized.

Victory… huh. AKVs, probably, since they invested less money and personnel. But it’s been a pretty gritty fight. And not only has it been gritty, the last twenty seconds were harrowing. And, in fact, the narrative is quite gripping: Four AKVs in a diamond formation coasting towards the Oberth, which fires its particle beams at them. First, only at one of them then, once they’re close enough spreading out the damage. All the while, Oberth’s vectors are constrained more and more, finally leading to multiple hits. Then, it goes faster: Another AKV is hit a few hundred kilometres out. And, lastly, nothing was sufficient to stop the third and fourth AKV, which ram the Oberth at 20km/s speed difference, punching a hole through the whole craft. About five metres wide at the front, spalling and expansion soon shred everything and so the only remains of the Oberth bigger than a few centimetres are some of the front section’s armour plates.

Yup, liked it.

Well, there are a few things I did dislike: Railguns still seem to be extremely deadly (maybe decrease damage by 1/2?), although the elimination of proximity detonations seems to have fixed the chance-to-hit issue I had in an earlier playtest. However, they cannot really hit AKVs from far-off.

Also, and this should be stressed, turreted particle beams might not be available (SS7:22). And I’d actually like to keep them as dedicated anti-capital craft weaponry, not as point defense. But we’ll see about that.