[Icelander]

Originally Posted by Nereidalbel

1. They actually make sling grenades for paintball. I imagine a similar design could work for explosives.

Historically, they did launch black powder grenades from slings. I just happen to lack GURPS stats for such things or even the sort of real life details one could use to extrapolate such stats.

I'm looking to figure out what clever PCs aided by some of the best TL4 (advanced) engineers could design, with the most important difference from the real world being that instead of explosive filler being cheap and plentiful, it costs more than custom-made casing from a good smith. So while real world designs might usefully try to keep the cost of casing casting and preparation down and go for volume (at $10 per, most of it in casing, you can afford that), this makes less sense when you're paying more than $12 per ounce of smokepowder.

So, some way to make a useful anti-personnel weapon while using as little powder as possible would be nice. If that's practical, that is. I'm not sure myself, hence the appeal to the Hivemind.

Originally Posted by Nereidalbel

2. Figure you need at least 4 ounces for the grenade itself to survive the launch, so whatever explosive damage you would expect with 12 ounces of powder. Also, figure on either cutting or piercing shrapnel, depending on the material used.

Judging by extant GURPS stats on grenades and bombs, you need a lot more than 4 ounces of cast iron or other fragmentation material to produce decent shrapnel damage.

I also have no conception of the relative difficulty of making shells of various sizes at pre-modern tech levels. What can most journeymen be taught to make with normal TL3 blacksmithing tools? What is extremely hard to make? What requires TL4 knowledge or tools?

Hollow lead or iron spheres the size of 1-pounder rocks would be useful, but are they substantially harder to make than the heavier shell casings used for historical grenades? Are they strong enough so that the powder actually explodes, instead of burning messily in all directions?

Originally Posted by Nereidalbel

3. Staff sling is probably the way to go for these. Roughly the same range, but easier to get a steeper angle for lobbing heavy projectiles. The current world record for such a weapon is 477 meters.

I was thinking that too. The current GURPS rules don't allow a staff sling to be of a heavy variety. Maybe adding some Cost and Weight to a Heavy Sling, adding +1 to damage and increasing the range to x6/x10 would do it.

Though a 3-lb version would be far superior as a grenade launcher. Any suggestions for the range? x2.5/x4?

Originally Posted by Nereidalbel

4. Assuming smokepowder creates enough heat to ignite alchemist's fire, you would probably want the magical fuze so you can have a small container of smokepowder within a larger container of alchemist's fire. If you just want to burn one target to death, you could make it a specialized tip for a bow/crossbow.

The point of using Alchemist's Fire is that it's slightly cheaper than smokepowder. Hence, it's a more economical, if less effective, weapon.

But I'm not sure if it would be effective at all, at least not unless it weighed a lot. How much oil can one fit in the volume of a hollow sphere similar to a 1-lb rock? Would that be any more effective than just lobbing a rock? Enough to justify the cost?

Originally Posted by Nereidalbel

The 2-3 pound version? You're basically making a napalm grenade there. The initial explosive damage is just a bonus on spreading burning death to whatever radius smokepowder can manage. A staff sling could still launch this into the middle of an army to not only get multiple kills, but also to demoralize the enemy. They can see a mage casting, their mages can counter fireballs, but how do the counter having an entire line of men launching explosive death?

One would hope badly. On the other hand, I don't know what the stats of a sling like that would be. It would need to launch a huge projectile that was substantially less dense than a rock.

Maybe a reasonable goal is an earthenware shell with a pint of alchemical über-oil, enough smokepowder to spread it and a basic TL4 burning fuse. Could weigh around 2-lb and be launched from a huge staff sling designed for 3-lb rocks. But what kind of range would that get?

Originally Posted by Nereidalbel

5. If you want to use non-magical means, the smaller container of smokepowder needs to be attached to the outer shell, with either a short fuze, or some form of impact detonation. Again, the minimum size is entirely dependent on the blast yield of smokepowder. If they use the cheap stuff, you'll need more than you would for something freshly made.

I wonder if there's any point in slinging a an earthenware shell the size of a 1-lb rock filled with smokepowder. How much can you fit in a shell that size?

What about a more reasonable sling bullet size? How small could you make this and still do more damage than just using traditional projectiles?