The Utility of AKVs [Spaceships]

[AlexanderHowl]

AKVs (Autonomous Kill Vehicles) are probably the most effective weapons in the Spaceships series. Usually SM+4, they are generally cheaper than their weight in conventional shells, yet they are capable of dealing 6d×60 d-damage (× Velocity), making them more damaging that any conventional missile. Because they are autonomous, they can either be carried internally within hanger bays or externally with external clamps.

A simple TL9 AKV possesses the following components: 16 fuel tanks, 2 HEDM engines, 1 control room, and 1 front armor (usually AML). With eight tons of HEDM reaction mass, they cost less than $200,000 each. With 4gs of acceleration and 16 mps of delta-v, they are capable of dealing 6d×960 d-damage when they hit at full speed, allowing them to deal over 20,000 points of d-damage on average. Such an attack destroys any spacecraft of less than SM+19 and cripples any spacecraft of less than SM+23.

So, how do people use AKVs in your experience? Are they the weapon of terrorists or are they the standard weapon of space militaries in your settings? Since AKVs are so cheap, what type of defenses work against AKVs in your settings?

[Varyon]

As mentioned in the other thread, AKV's cheat by using their entire loaded mass even after they've thrown (in this case) 80% of it out into space behind them. Your 16 mps collision should really be with a dHP 6.7 or so vessel, not a dHP 15 one, for 6dx320 (also, even at full mass it should only do 6dx720, SM+4 has dHP 15, not 20). If you're ramming as a matter of course rather than as something that just happens sometimes, it's probably worthwhile to update the rules from the book; indeed, you may want to have a chart for your AKV, indicating what dHP it has when it has a certain amount of delta-v remaining. Here's an example; note I'm ignoring the complication of the rocket equation here, so most of these values are slightly high. dV stands for delta-v remaining in the tanks.

dV	dHP
16	15
15	14.6
14	14.2
13	13.8
12	13.4
11	13
10	12.5
9	12.1
8	11.6
7	11.1
6	10.6
5	10.1
4	9.5
3	8.9
2	8.2
1	7.5
0	6.7

Granted, that's still superior performance compared to a missile, but that's because missiles have decoys and all manner of other fun toys that aren't explicitly taken into account. However, they do have one notable effect - they make it much easier for the missile to actually hit its target. For a missile to hit, the gunner simply needs to roll against the Artillery (Guided Missile) with a bonus equal to sAcc (+2) and a penalty for speed (-2 for 2 mps), plus other modifiers that are equivalent between the two (but note it can give up its AD (2) - which the AKV lacks - for +4 to hit and the ability to score up to 10 hits at once with a proximity detonation), and the target must fail its Dodge and its single chance at PD fire. For the AKV, the remote (or AI) pilot needs to severely outmaneuver the target (winning by 10 in a quick contest of Piloting) first, then is able to make a ramming attempt, with a bonus equal to Hnd (+0) and a penalty based on speed (-8 for 16 mps), alongside modifiers it shares with the missile, leaving it at -8 relative to the missile (-12 relative to a missile using proximity detonation). While it's trying to achieve a collision course, it may be under fire by the target's point defense weapons (or other weapons). If it succeeds on that, it still has to contend with PD fire (although the PD needs to be larger than for the missile, as it doesn't have the benefit of "hit means automatic destruction," although against HEDM it doesn't need to be that much larger*) and the target's Dodge attempt. It could be at the same 2 mps as the missile, for only -2 to hit, but that will drop its damage down to 6dx85 (which is still exceptional compared to the missile).

*Assuming a streamlined AKV (which you probably want, to make it harder to hit) and Advanced Metallic Laminate, that's dDR 2. Assuming you put the armor and control station in the front (control station being hit is actually better than a fuel tank being hit, at least if your computer can handle a -1 to Complexity), a 300 kJ is roughly the minimum size laser that can take it out, while a 3 MJ is arguably preferred. There's a 4/6 chance of hitting a fuel tank, a 1/6 of hitting a control station. A hit to a fuel tank from the 300 kJ laser has a ~25% chance of causing the HEDM to explode at the end of next turn, while a second hit to the same system from the 300 kJ laser or a fresh one from the 3 MJ laser has a ~85% chance of doing the same. A hit to the Control room from the 300 kJ laser will disable it (which just drops Complexity by 1), while a second 300 kJ laser hit or a fresh 3 MJ laser hit will destroy it, leaving the AKV drifting. That's better survival than being taken out with a single hit by a 3 kJ laser, but not by a lot.


Personally, I think AKV's shine when given weapons of their own that are able to harass their target, allowing them to engage while trying to set up to ram. The missiles in my Harpyias setting are going to be designed as small spaceships, however, as they don't have the same assumptions as Spaceships (in fact, they have fairly poor performance compared to SS missiles, but space combat in Harpyias occurs at distances more reminiscent of air combat in WWII). Those lack the weapons I'd prefer on a "proper" AKV, largely due to quirks of the setting's tech (basically, remote-piloted ramming missiles are doable, but automated ones aren't, and if they were armed their blasters would have no chance of getting through an enemy's shields).

[Celjabba]

I didn't check the stats, not a "G:Spaceship" expert, but generally speaking :

In any space game that sit high in the Mohs scale (no forcefield, no pseudo-velocity drive, no "submarines in space" physics ...)
and
allow high-performance engines,

you have the obvious problem : E = .5*m*v^2 .

Any spaceship (or in fact any rock with an engine bolted on) is a weapon of mass destruction, and you need to have arbitrary restriction to handwave that away.

That said, in a setting with kinetic killer AKV :

-remember that space is big. Your AKV have to hit the target.

-don't travel alone (or deploy a cloud of autonomous weapon platforms)
If caught in a PDS crossfire so that you can avoid the front armor, the AKVs will hopefully go boom easily (especially with 16 HEDM tanks ...).
This is what I used in the one game I ran with AKV (a variation on THS).
A significant plot point was swarms of rogue AKVs left behind after a war (and in violation of law that prohibited such weapon being used), and waiting dormant in deep space. Nobody had the FoF code anymore, so they were a navigation hasard.

[AlexanderHowl]

That is right, it is 15dHP, my apologies. Still, 6d×720 d-damage is an average of ~15,000 d-damage, which kills most ships straight out.

In TL10^ settings, reactionless AKVs are possible. With 1 Control Room, 1 External Clamp, 3 MHD Turbines, 3 Defensive ECMs, 6 Hot Reactionless Drives, and 6 Front Armor (nanocomposite), you get a more expensive AKV, but a much more effective one. With 6gs acceleration, it is capable of achieving massive velocities before hitting its target. It is also capable of attaching itself to any spaceship, allowing for easy transportation.

[Rupert]

Originally Posted by AlexanderHowl

That is right, it is 15dHP, my apologies. Still, 6d×720 d-damage is an average of ~15,000 d-damage, which kills most ships straight out.

In TL10^ settings, reactionless AKVs are possible. With 1 Control Room, 1 External Clamp, 3 MHD Turbines, 3 Defensive ECMs, 6 Hot Reactionless Drives, and 6 Front Armor (nanocomposite), you get a more expensive AKV, but a much more effective one. With 6gs acceleration, it is capable of achieving massive velocities before hitting its target. It is also capable of attaching itself to any spaceship, allowing for easy transportation.

There is no way I'd be allowing you to just clamp AKVs (or anything else, for that matter) onto any old spaceship, and certainly not in quantity. If it's a thing in a particular setting, then within limits it's reasonable, but in general it's not.

Another thing - that AKVs are so cheap compared to missiles, means that either they must be much less effective, or missiles are badly over-priced because they'd just be built like an AKV and thus cost the same. Varyon's point about AKVs having to severely out-manoeuvre their target might be why, especially as it's assumed in the non-tactical combat rules that missiles can't be outrun, whereas AKVs can (in theory).

[AlexanderHowl]

Since AKVs are spaceships rather than munitions, they require a lot more damage from beam weapons to cripple or destroy, and they can dodge before they make their ramming attack. For example, a TL9 AKV requires one of its fuel tanks to be disabled before possibly exploding (roll against HT 12) and, even if it explodes, it does so at the end of its next turn (after the attempted ramming attack if it is hit by point defense).

As for clamping onto other spaceships, external clamps allow small spaceships to attach to other objects, so I am confused about the issue. A dozen AKVs attached to a SM+10 merchant ship could be an effective way to deter commerce raiding, though authorities would likely require any such equipped spaceship to disarm a light-second away from their jurisdiction. The AKVs would just wait for recovery, or the merchant ship could sell them and purchase a reload if it was a bother.

As for missiles, I totally agree that they are overpriced, which is why few militaries use them in my settings. Militaries tend to use AKVs against space targets and bombs against ground targets. Warships tend to use beam weapons for long distance combat and conventional guns for point defense. Even small caliber shells are capable of destroying AKVs because the AKVs velocity adds to the shells velocity, meaning that 2cm shell hitting an AKV going 16 mps deals 3d×17 damage.

[Ulzgoroth]

Originally Posted by Rupert

There is no way I'd be allowing you to just clamp AKVs (or anything else, for that matter) onto any old spaceship, and certainly not in quantity. If it's a thing in a particular setting, then within limits it's reasonable, but in general it's not.

...Why not? It's not like spaceships have aerodynamics to worry about.

Well, unless you try to fly into an atmosphere with a bunch of AKVs clamped on. Don't do that, obviously.

Originally Posted by Rupert

Another thing - that AKVs are so cheap compared to missiles, means that either they must be much less effective, or missiles are badly over-priced because they'd just be built like an AKV and thus cost the same. Varyon's point about AKVs having to severely out-manoeuvre their target might be why, especially as it's assumed in the non-tactical combat rules that missiles can't be outrun, whereas AKVs can (in theory).

Yeah, with normal levels of piloting skill it's nearly impossible to actually pull off a ram with the rules. Even if the target isn't making any effort to evade you have to succeed on piloting by 10+ just to achieve a collision course, and that's before you actually try to make the attack.

Originally Posted by AlexanderHowl

Since AKVs are spaceships rather than munitions, they require a lot more damage from beam weapons to cripple or destroy, and they can dodge before they make their ramming attack. For example, a TL9 AKV requires one of its fuel tanks to be disabled before possibly exploding (roll against HT 12) and, even if it explodes, it does so at the end of its next turn (after the attempted ramming attack if it is hit by point defense).

If an AKV take a hit from a regular or decent-sized RF beam, it's almost certainly going to have the hit system instantly destroyed (for a -5 on the roll to not blow up if it's a volatile fuel tank) and is not unlikely to be instantly at zero-or-less HP which will further tank its chances of actually hitting the target.

[RogerBW]

Originally Posted by Ulzgoroth

...Why not? It's not like spaceships have aerodynamics to worry about.

Stress loading.

Say the mothership accelerates at half a G. That SM+7 AKV clamped onto it is 150 tons-weight. With a designed-in bracing point, sure, you can do that. Hanging off a random part of the structure?

[AlexanderHowl]

That does not make much sense though. A SM+8 spacecraft accelerating at 2g will experience the same amount of stress as a SM+8 spacecraft towing a SM+7 spacecraft at 1.5g. Of course, I do not allow spacecraft to attach to hull sections without armor, external clamps, or robot arms, as they have to attach to something that can take the stress.

[Kale]

Originally Posted by Ulzgoroth

Yeah, with normal levels of piloting skill it's nearly impossible to actually pull off a ram with the rules. Even if the target isn't making any effort to evade you have to succeed on piloting by 10+ just to achieve a collision course, and that's before you actually try to make the attack.

I suggest a house rule giving a bonus to the attacker equal to the size modifier difference. So an SM5 AKV attacking an SM10 cruiser would get +5 to its ram attempt. This makes them more effective at attacking larger vessels, giving them more a 'capital torpedo' flavor.

Originally Posted by RogerBW

Stress loading. Say the mothership accelerates at half a G. That SM+7 AKV clamped onto it is 150 tons-weight. With a designed-in bracing point, sure, you can do that. Hanging off a random part of the structure?

Originally Posted by AlexanderHowl

That does not make much sense though. A SM+8 spacecraft accelerating at 2g will experience the same amount of stress as a SM+8 spacecraft towing a SM+7 spacecraft at 1.5g. Of course, I do not allow spacecraft to attach to hull sections without armor, external clamps, or robot arms, as they have to attach to something that can take the stress.

It's not the overall stress, but the localized point stress on the hull. The AKV has to be anchored to something, and if that something is not reinforced for the job then the AKV will end up ripping off a hull plate if the ship accelerates too much. External docking clamps represent measures to strengthen the attachment area to prevent this in addition to the clamps themselves. I'd rule that any ship with something mag clamped to the outside skin could suffer damage if it attempts more than a very small acceleration. Something like the 0.001 G cruising drives would be OK, but a 1G torch is going to cause the mag clamped object to tear free messily if it has a significant mass compared to the host ship.