Kinetic Kill Bombs

[xevus11]

Hello all, this is an idea i'v had for several years, and I finally found the time today to get it down on paper. For some context this is written for Mongoose V2, but I believe that with some modifications it could be converted to other editions.

I apologise if the order/formatting is a bit strange, this was copied out of my Realm Works page for the weapon.

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​The kinetic kill bomb (KKB) is an extremely simplistic, and extremely effective, weapon used by fighters to attack larger ships. KKBs are mounted outside of the hull of a fighter, which accelerates towards an oncoming target, before releasing the weapon and pulling away. The damage of this weapon is therefor based on the differential speed of the attacking and defending ships. However the rounds do tend to overpenetrate against sub-capital ships, and so the weapon is usually reserved for capital class targets.

There is no attack roll for this weapon, instead make a difficult (-2) pilot check. A result of 6+ results in a crit as per a normal weapon attack, failure results in 1d6 damage to the fighter per thrust point it expended in this attack, and half that to the target ship, as the ship scrapes along the hull of the target vessel.
Additionally, Point defense receives a +2 to hit fighters deploying KKBs


There are two types of mounts, the smaller (cheaper and lower capacity) mount is external, and can only be reloaded from outside the ship by a hanger crew, while the larger is a belly mounted bay, that can be closed and reloaded by the crew.

The bomb itself is usually half a meter long, and 120mm in diameter, and come in packs of 4 weighing 1 ton.​

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​TL: 7
Damage: 1d6*speed difference between attacker and defender. Limit 1d6 per 200 tons of hull
If damage dealt is greater than 10% of the targets remaining hull, deal an automatic critical hit.

Range: Adjacent
Capacity: 1 or 4 attacks
Mounting size: 2 or 8 tons
Cost: 400,000 Cr. or 2,00,000 Cr.​

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​Attack example:

Joe is attacking a 5000 Ton escort ship with a pair of standard kinetic kill bombs. His ship is moving towards the target at thrust 6, while the escort is moving towards joe at thrust 3. As such, joe will deal 9d6 damage, however first it must be compared to the ships size. The escorts size divided by 200 is 25, which is more than the 9d6 damage the KKB will do, so nothing will change.

Damage is then dealt as normal.​

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​​The KKB is not generally used by militaries due to the risk it poses to the fighter, however guerrilla forces, and wealthy forces with access to drones, do make use of it, as it is an extremely effective defensive weapon.​​ It is also used by some low-tech navies, as a large number of KKB equipped fighters can disable even high-tech capital ships.

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Ammunition:

Antimatter:
​Triple damage, no hull limitations

TL 16
8,000,000 Cr. for a pack of 4

additional -2 to pilot check to avoid damage​

​While the effect is similar to a Nuclear KKB, the antimatter version is functionally very different. Using a small capacitor to power the containment field, the antimatter is released about a tenth of a second after impact, creating a large explosion inside the target hull. This removes all the damage limitations from hull size, as the round rarely makes it more than a few dozen meters. Risk to the pilot is increased however.​

Fragmentation:
​Deals an automatic crit, increases damage by 3, unless the round overpenetrates.

TL 10

2,00,000 Cr. for a pack of 4​

​A common KKB round, this is a segmented crystaliron round with a small explosive along the core. Impact primes the explosive for detonation about a second later. Upon detonation, the round deals additional damage, both to the hull and system components, however does nothing (other than be an expensive waste) if it overpenetrates.​

Nuclear
​Deals radiation damage (no hull protection), deals an additional 3d6 damage, damage limit is increased to 1d6 per 500 tons.

TL 8

2,50,000 Cr. for a pack of 4​

​A nuclear warhead embedded in a tungsten shell, the Nuclear KKB detonates after penetrating the hull. However, the round is purely anti-capital, as the round must "stick" within the hull to deal any damage. If the round overpentrates, the nuclear weapon deals no radiation damage, and it looses the 3d6 bonus damage.

​Penetrator
​Reduce damage by 6, penetrates the number of damage dice it deals in armour.

TL 8
800,000 Cr. for a pack of 4​

​A common KKB round, this is a depleted uranium or osmium penetrator rod with a long, thin head designed punch through thick armour.

Range Boosted
​Reduces damage by 6

TL 6
600,000 Cr. for a pack of 4

+3 to pilot check​

​A common KKB round, this is a tungsten penetrator rod with a conical head, but with a rocket motor to increase range. The reduced weight reduces damage, but allows the pilot to pull out of the attack earlier, leading to increased accuracy and survivability.​

Standard
​No modifications to standard damage.

TL 6
400,000 Cr. for a pack of 4

Low grade (Steel) versions are available for 50,000 Cr.​

​A standard KKB round, this is a tungsten penetrator rod with a conical head designed to inflict damage on the cheap. Lower grade versions are availible made of iron, trading damage for cost and availability of materials.​


TL;DR: a fighter sized weapon that uses the speed of ships to push rods through capital class ships.

 

[Magnus von Thornwood]

Excellent!

For CT excellent, for T5 pretty much fall under Kinetic Kill Weapons, either way fun with simple tech.

Nice stuff. Like the variant rods and the tradeoffs. Really good work here.

 

[AnotherDilbert]

I like the concept, Stukas in space, but...

1) It is completely unbalanced. In MgT2 fighters can (and probably will) achieve 25G and capital ships 9G. If they close in with 34 G the KKBs will make much more damage than any bay weapon.

They are sized like torpedoes. A standard torpedo does 6D damage and cannot ignore armour. A torpedo has accelerated for up to an hour before impact so can have a very high closing speed.


2) "Thrust" is not speed, but acceleration. Speed is not something we keep track of in MgT2 rangeband combat. Speeds can be very high an hour or two into a combat.

 

[BlackBat242]

Antimissiles and Roundshot by Jefferson P. Swycaffer , Dragon Magazine #95 (March 1985)

Gives a short discussion on "solid shot" turret weapons for Traveller - the weapon would rapid-fire a "cloud" of solid projectiles at "several thousand kilometers per second".

 

[Whipsnade]

An old and silly, yet still interesting, idea.

While it couldn't work in any combat system using anything resembling vector movement, it would fit a cinematic/space opera game very well while also being a helluva a lot of fun.

Your treatment needs to be placed in the File Library before it gets "lost" in the forums. Please write it up and drop off a copy there so other people can find it in the future.

Thanks!

 

[kilemall]

I like the concept, Stukas in space, but...

1) It is completely unbalanced. In MgT2 fighters can (and probably will) achieve 25G and capital ships 9G. If they close in with 34 G the KKBs will make much more damage than any bay weapon.

They are sized like torpedoes. A standard torpedo does 6D damage and cannot ignore armour. A torpedo has accelerated for up to an hour before impact so can have a very high closing speed.


2) "Thrust" is not speed, but acceleration. Speed is not something we keep track of in MgT2 rangeband combat. Speeds can be very high an hour or two into a combat.

This is the central issue I am dealing with in my Mayday Guard version, I want the missiles to have vector impact damage which can go up to spinal weapon levels of damage.

Which is the effect I want, but messes something fierce with the movement and board/hex size mechanisms when some things will be going slower for heavier energy weapon passes and fighters/light ships come zooming through with their killer missile attacks.

 

[mike wightman]

So let's get this right - the fighter is accelerating hard to the target so the relative velocity is high.
How exactly does it 'pull away' as you describe?

By the way, why can't the target ship just fire a steel rod at the fighter and inflict a similar hit since it is relative velocity causing the damage?

 

[AnotherDilbert]

So let's get this right - the fighter is accelerating hard to the target so the relative velocity is high.
How exactly does it 'pull away' as you describe?

I can see it, you just have to change your vector enough to miss the target. Obviously you cannot pull up like an atmospheric dive bomber and change direction.

By the way, why can't the target ship just fire a steel rod at the fighter and inflict a similar hit since it is relative velocity causing the damage?

The target doesn't even have to shoot it, just release some mass in the fighters path. If the fighter is not heavily armoured a bit of sand or gravel should be dangerous enough.

 

[AnotherDilbert]

This is the central issue I am dealing with in my Mayday Guard version, I want the missiles to have vector impact damage which can go up to spinal weapon levels of damage.

Which is the effect I want, but messes something fierce with the movement and board/hex size mechanisms when some things will be going slower for heavier energy weapon passes and fighters/light ships come zooming through with their killer missile attacks.

Mayday keeps track of ships velocity vectors, right?

If you don't keep track of each missile's vector, you have to approximate it with the launching ship's vector plus full acceleration towards the target during the missile's flight time?

Then it's just some vector math or geometry to find the closing speed?

A distant launch from a slow ship, or a close launch from a fast fighter should lead to similar results?

 

[xevus11]

Thanks for all the feedback so far, i'v never really paid much attention to the movement system (always just used an approximate version for space combat), so I never really thought about how Gs being acceleration rather than speed would effect it. I'm going to rewrite (and repost) this at some point over the weekend.

I'm thinking of changing the "hull size damage limit" to a flat 10% of hull point damage cap for starters, and changing the damage calculation to be based on number of relative kilometers moved per turn. While this will require you to keep track of how fast which ships are moving in which direction, this shouldn't be a huge issue if you already play with a battle-map rather than an abstraction.

 

[mike wightman]

I can see it, you just have to change your vector enough to miss the target. Obviously you cannot pull up like an atmospheric dive bomber and change direction.

In which case you are flying by your target and then overshooting, plenty of opportunity for the target ship to toast you.

The target doesn't even have to shoot it, just release some mass in the fighters path. If the fighter is not heavily armoured a bit of sand or gravel should be dangerous enough.

A sandcaster canister perhaps...

 

[Whipsnade]

I'm going to rewrite (and repost) this at some point over the weekend.

Please don't do that.

As it stands now your "kinetic kill bombs" is a delightful piece of physics-ignoring silliness which is perfect for cinematic/space opera games where the players want the "realism dial" pointed right at Star Wars and it's ilk.

If you try to make the idea work with even partially realistic 2D vector movement you'll fail because the idea is wholly unrealistic. In fact, it's those very physics-ignoring and scientifically-illiterate characteristics which make the idea so much fun in the first place.

Don't try to explain it because you can't. Don't try to make it more realistic because you can't. Just clean up the text and present it as is. People will use it because it is fun and not because it in any way is possible.

 

[AnotherDilbert]

In which case you are flying by your target and then overshooting, plety of opportunity for the target ship to toast you.

Flying in on a predictable course should be the most dangerous part. Once you dropped the KKB you can start evasive manoeuvres. When you pass the target ship you should have a very high speed, and you pass at a very short distance, meaning that your angular speed will be extremely high, limiting the ability of enemy weapons to track you.

A sandcaster canister perhaps...

Exactly...


A quick estimate: If you accelerate at 6 G for 1 h you have travelled 388000 km (~1,3 ls) and reached a speed of 216 km/s. A 1 tonne mass with that speed would have a kinetic energy of 1000 × 216000² / 2 ≈ 2,3 × 10¹³ J or about 5,5 kt_TNT (a very small nuke). Need more speed...

 

[McPerth]

This is the central issue I am dealing with in my Mayday Guard version, I want the missiles to have vector impact damage which can go up to spinal weapon levels of damage.

Assuming Mayday comes directly from LBB2 Ship Combat System (or more exactly my reference will be from TTB, page 76), see that (underscoring is mine):

Missile Detonation: Ordnance which impacts a target in a movement phase, and which then survives anti-missile fire, detonates in the ordnance launch phase. This detonation will inflict 1 to 6 hits depending on the range at detonation

As I understand it, this hints that the missiles are proximity fuses detonated, not really coming to true contact with the target before exploding (as explosive anti-air projectiles ,that fill the area with shrapnel instead of expecting to explode in contact with the airplane). I'm not an expert with explosives or missiles (to say the least), but I guess if the missiles are not contact fused the relative speed is irrelevant, or at least its effect severely reduced.

 

[mike wightman]

The Missiles special supplement introduced the rules for relative vector adding to the damage of a contact hit.

 

[kilemall]

Mayday keeps track of ships velocity vectors, right?

Yes, like CT movement does.

If you don't keep track of each missile's vector, you have to approximate it with the launching ship's vector plus full acceleration towards the target during the missile's flight time?

You have to have the missile vee plus target vee to add to the potential damage level yes.

Having say a missile attack rated F doesn't mean increased to hit, just more damage if it does hit.

Then it's just some vector math or geometry to find the closing speed?

A distant launch from a slow ship, or a close launch from a fast fighter should lead to similar results?

Well, a distant launch COULD be similar to a fast fighter up close, highly depends on how much vee the missile can build up with it's G vs. fuel vs. how many Gs the fighter could pile on in a short run. If the combined vees and base missile factor are the same and I wasn't doing some fancy different warhead type, I would rule the damage is the same, in general.

 

[kilemall]

The Missiles special supplement introduced the rules for relative vector adding to the damage of a contact hit.

Ya, that's what I am seeking to put into HG terms, in actual maneuver. Really changes maneuver as there is a reason to have high-G weapons on fighters be a thing. Messes with hex and time scale something fierce though.

SS3 also has 'bomb run' rules for unpowered missiles, which is what this is effectively. The OP might profit by a looksee.

 

[jcrocker]

A quick estimate: If you accelerate at 6 G for 1 h you have travelled 388000 km (~1,3 ls) and reached a speed of 216 km/s. A 1 tonne mass with that speed would have a kinetic energy of 1000 × 216000² / 2 ≈ 2,3 × 10¹³ J or about 5,5 kt_TNT (a very small nuke). Need more speed...

If they are true 'kinetic kill' weapons, anything like the fragmentation warheads probably wouldn't survive anyway. Any conventional fragmentation blast wouldn't even be noticed if the actual collision has the power of even a small nuke.

 

[AnotherDilbert]

The Missiles special supplement introduced the rules for relative vector adding to the damage of a contact hit.

Yes, but that is just silly...

Velocity Vector: If a missile contacts its target and the sum of the vectors of the missile and the target is greater than 300 millimeters, then one extra hit on the hit location table is allowed for each 300 millimeters of vector length. Ignore fractions remaining when dividing the vector by 300 millimeters.

So if the ship is moving away from the missile, more hits.
If the ship is moving towards the missile, damage is reduced, contrary to any logic.
Example: The target ship is moving at 1000 mm/turn at 0°. The missile is approaching from behind at 1100 mm/turn at 0°. Real relative speed is 100 mm/turn. Calculated impact speed is 1000 + 1100 = 2100 mm/turn. Silly.


Better would be to do something like Impact speed = |V_missile| + |V_target| × cos φ, where φ is the angle between the vectors.

Or at least Impact speed = |V_missile - V_target|

 

[AnotherDilbert]

If they are true 'kinetic kill' weapons, anything like the fragmentation warheads probably wouldn't survive anyway. Any conventional fragmentation blast wouldn't even be noticed if the actual collision has the power of even a small nuke.

Quite.

I overestimated what a regular nuke should yield. According to SS3 a 5.5 kt contact nuke would do ~1100 hits, destroying any LBB2 starship instantly.

In LBB2 terms a 1 tonne mass accelerated at 6G for 1 turn (1000 s) would be ~0,4 kt, doing 80 hits, killing any small ship immediately.

Or alternatively a mass of 50 kg accelerated at 6G for 1 turn (1000 s) would have a vector of 600 mm, doing 2 hits on impact. 20 times the mass, 1 tonne, would reasonably do 20 times the damage or 40 hits.