GURPS Explosives: Custom Shrapnel and other ways to deal more damage

[Anthony]

Originally Posted by Fred Brackin

The weight of comventional artillery shells before filler may have more to do with firing stresses than design for fragmentation.

Density is likely a factor as well. Typical explosive filler is about a fifth the density of the shell casing, so a shell that's 10% explosive by weight is 35% by volume. Double the amount of explosive and you reduce overall shell weight by 40%, which will substantially reduce ballistic range.

[Rupert]

Originally Posted by Fred Brackin

The weight of comventional artillery shells before filler may have more to do with firing stresses than design for fragmentation. Or aror pentration for the big APEX.

A rule of thumb for aerial bombs and mortar rounds is that casing is 50% of total weight while you're looking at c. 90% for artillery shells and 95% for APEX.

The latest 5" gun used by the US navy has a burster charge of 11% of its mass. The WWII 5/38 gun's HE shell had about 13%.

The famous heavy 15" shells of the USN's WWII-era 16" guns had 1.5% buster in the AP shells (technically APEX in GURPS terms), unusually low even for battleship AP shells, and 8% burster in the HE shells. Another well-known battleship gun, the British 15/42 gun, in WWII used AP shells with 2.5% busters, and HE with 6.7% bursters.

A 155mm howitzer shell manages about 16% burster.

At the other end of the scale you get the 4,000-12,000 pound 'blockbuster' or 'cookie' bombs used by the RAF in WWII, with about 75% burster. Those weren't designed for fragmentation at all, but to blow the roofs of houses so incendiary bombs could ignite them more effectively.

The Mk82 "500lb" general purpose bomb of the USAF (and others) has a burster of about 38% of its weight. The Mk83 "1000lb" GP bomb has a burster of about 45%.

So, APEX shells have 1.5-2.5%, semi-AP and HE shells intended to have some penetration 5-10%, and HE-frag shells intended for AA and contact or airbursts vs infantry 10-15% or even slightly more.

Meanwhile Frag bombs have 35-45%, and blast bombs up around 75%.

FWIW, VE2 for GURPS 3e assumed ~14% burster for HE-frag and SAP, ~19% for HEC, and ~9% for APEX

[fula farbrorn]

Originally Posted by Rupert

Because your average piece of shell casing or random junk thrown by an explosion tends to be a twisted and jagged object spinning around some random axis.
That seems unnecessary, given that you then also need to give them an effective skill. Currently they are effectively Skill-15, Rcl 3, RoF ∞. Aside from giving bonuses to bigger shells/bombs, I'm okay with that. What value do you get from giving them a RoF stat, etc.?

I gave them a skill and ROF based on their supposed Average frag throw and i did it because i could, not recommending others do it too