[LT/ HT/ UT] Explosions

[jacobmuller]

A little topic drift in this thread has left me wondering what/ how is precisely RAW on dealing with the myriad variations possible in a GURPS explosion. I've not yet had the pleasure of dealing with them in a game:(.

Specifically-
Internal Frag hits: if your explosive device detonates inside someone/creature the frag hits are subsumed in the x3 Wound Modifier?

Internal Explosions versus Homogenous or IT: No Vitals: they do still get the x3 WM don't they?

Touching Frag hits: if the victim was lying down and a grenade landed on him, how many frag hits might he suffer?

Contact Frag Hits: tamped or "between hero and hard place" explosions do maximum damage; are frag subsumed as per internal explosion?

And I have an untried HouseRule for making frag hits vary with weapon size. Basically giving frag damage a RoF and adding that to frag's To Hit of 15 [table of baseline values below].
No change to incidental frag. Frag weapons are given a bonus to hit, eg [2d] becomes [2dx±#]; treat as if Rcl is 1; ½D range is the weapon’s explosive damage in yards. In Contact +6* to hit. To Hit with Frag = 15 + RoF bonus ± SM ± Posture ± Range – Dodge.
Is adding the RoF bonus to 15 total overkill? Should it be 10+To Hit x instead of 15?

Calibre	HT Dam	UT Dam	To Hit x	Calibre	HT Dam	UT Dam	To Hit x
10mm	-	[1d-2]	  +4		40mm	[1d+1]	[2d]	  +6
15mm	-	[1d-1]	  +5		64mm	[2d]	[3d]	  +7
18.5mm	[1d-1]	[1d]	  +5		100mm	[3d]	[5d]	  +7
25mm	[1d]	[1d+1]	  +6		150mm	[5d]	[7d]	  +8

*and now I'm wondering what I meant by "in contact": touching or tamped...

[vierasmarius]

As I recall, the basic rule for Frag hits is that Contact results in one automatic hit, though that's open to further interpretation: rolling frag hits and adding one, rolling frag hits with a minimum of one, or not rolling and just doing one hit. My preference is the first option.

EDIT: Actually, on rereading B415, the third option is almost certainly RAW: "A hit is automatic if the explosive attack actually strikes the target. The fragments attack everyone else in the area at skill 15." Which I think is a horrible rule, since it means direct contact almost always results in fewer frag hits than a hit nearby.

I would not subsume the Frag hits into the x3 Internal modifier, since that essentially penalizes shells with heavy fragmenting cases. At worst, I'd treat it like a Contact detonation. A further bonus to the roll for the number of frag hits could be in order.

[vierasmarius]

Originally Posted by jacobmuller

Is adding the RoF bonus to 15 total overkill? Should it be 10+To Hit x instead of 15?

The 15 base "skill" assumes a large number of fragments already. If you're basing your To-Hit bonus on the total fragments produced, I'd use a base number around 6-8 (akin to Suppression Fire).

Originally Posted by jacobmuller

*and now I'm wondering what I meant by "in contact": touching or tamped...

IIRC, "Touching" is what happens when a shell directly hits a target, but doesn't penetrate the exterior (whether fused to explode on contact, or simply failing to penetrate the DR). "Tamped" is used when the the explosion is contained and focused into the target, such as with properly placed demolition charges or someone throwing hirself on a grenade.

[the_matrix_walker]

Piggybacking your thread... Fire Arrows from Low Tech carry an explosive charge... if your arrow hits, is the resulting explosion considered a contact explosion?

[Ulzgoroth]

Originally Posted by vierasmarius

IIRC, "Touching" is what happens when a shell directly hits a target, but doesn't penetrate the exterior (whether fused to explode on contact, or simply failing to penetrate the DR). "Tamped" is used when the the explosion is contained and focused into the target, such as with properly placed demolition charges or someone throwing hirself on a grenade.

There's two different 'touching' examples that spring to mind, both on 415. One is in the left column, in relation to fragmentation hits if the projectile hit the target. The other is "Contact Explosions" in the box (just above internal explosions), which is for throwing yourself on grenades.

Tamped explosions aren't in the Basic Set that I'm aware of. Aren't they from High Tech on demolitions?

An explosion in contact with the enemy can result from shooting them with an HE round (which doesn't penetrate). An explosion using the "Contact Explosions" rule pretty much can't.

[jacobmuller]

Originally Posted by the_matrix_walker

Piggybacking your thread... Fire Arrows from Low Tech carry an explosive charge... if your arrow hits, is the resulting explosion considered a contact explosion?

No. The Maximum Damage from Contact is meant to apply to tamped explosions or equivalent, eg the heroic diving on a grenade example - you in contact and the explosion has nowhere else to go. eg a 6d grenade would then do 36 damage.
Being hit by an explosive is when you use the value given. eg that 6d grenade landing on you/ detonating on impact would average 21 damage.

So, if you where to throw yourself on top of the fire arrow, then it would be maximum damage.

[jacobmuller]

Originally Posted by vierasmarius

The 15 base "skill" assumes a large number of fragments already. If you're basing your To-Hit bonus on the total fragments produced, I'd use a base number around 6-8 (akin to Suppression Fire).

Doh! Obvious when it's pointed out to me:)