Re: Low Tech cannons mortars and shells
 

Yeah I'm not seeing it. Maybe break down an example like the Mk I 2.5" mountain gun on High-Tech p. 138 firing shrapnel?

Re: Low Tech cannons mortars and shells
 

See "Airburst" under Projectile Upgrades on HT174. This directs you to Attacking an Area (B414). It also notes that shrapnel, beehive, and ABF already include this option. (In HT, shrapnel = canister = case shot.)

The Airburst rule says the area is "typically a cone", but I'm not sure where you get the dimensions (length, spread rate) of the cone for the projectile contents.

Re: Low Tech cannons mortars and shells
 

Which doesn't answer any of the actual question, since all Attacking and Area (B414) tells you about is whether you hit or miss an area. (Also, it rather seems to assume the area must be a single hex, but that's not the important problem here.)

Whereas the question is what effects the attack has on individuals, and which individuals it has effects on. B414, reasonably, assumes that that will be explained by the attack. (Explosive, area effect, what-have-you.) Unfortunately, shrapnel isn't providing that explanation. (Cannister, I think, has the same problem. There are no general rules for a shotgun-like blast sweeping an area, except maybe something in Gun-Fu for cinematically doing that with small arms.)

Re: Low Tech cannons mortars and shells
 

And that is a big problem right! As is the fact that most of these projectiles don't have the Airburst option. But the whole point of canister from a 37 mm tank gun, or indirect machine-gun fire, is to hit anyone or anything in an area.

Re: Low Tech cannons mortars and shells
 

For shrapnel it was an elliptical sheaf.

But yes, that's what I'm asking. Where does it give the size of thr area of effecr?

Re: Low Tech cannons mortars and shells
 

Let's try for the 2.5" RML, starting with the Shrapnel round. That throws 88 fragments doing 2d+1 pi+ each, with Max 3,300. You treat it like a shotgun blast, so you get +6 for the high RoF.

The thing that seems to be missing is the cone angle. That's specified for the Claymore, but not other forms of many-projectile attacks. If Hans put it into High-Tech, I can't find it.

I resorted to historical research*, and found that the base of a shrapnel code should be about one-third of its length, a 30° cone, and that the burst should be within 100 yards of the target.

To make an attack, you pick a point where you want the shell to burst, fire at that, and determine how much you've missed by. If you're close enough, each relevant target in the cone gets attacked at 9, +6 for RoF, less range penalties from the burst, like the Claymore.

Canister will work the same way, but starts dispersing at the gun muzzle.

Beehive would be similar, but would its cone be narrower?




* Treatise on Ammunition, War Office, United Kingdom, 1874.

Re: Low Tech cannons mortars and shells
 

Realistically, the odds of a projectile hitting a target in an area is (target size) / (size of area), and human cross-section probably averages around 5 square feet if standing. If the height of the pattern is less than 6', you should probably treat it as 6'.

For any large number of projectiles, the expected number of hits is (target size) * (number of projectiles) / (size of area), and the odds of at least one hit can be approximated as 1-e^(-expected hits) (which, for small expected hits, will be pretty much the same as expected hits)

For a pattern 30 yards (90') across, total area of the pattern is around 6400 square feet if the pattern is circular, and expected hits is ~0.07, with about the same hit chance. You can increase the number of expected hits by producing a flat spread, but I very much doubt that dumb projectiles are able to do that.

Note that a 7% hit probability, while not much on an individual, is plenty to be disruptive on a unit of troops, and than 30 yard pattern is noted as outer limits of effective.

Re: Low Tech cannons mortars and shells
 

This is, in fact, the problem. Your post earlier seemed to say this wasn't the case.

Re: Low Tech cannons mortars and shells
 

Also, that's for a shrapnel shell from a very small artillery piece - the 75mm Mle 1897's Shrapnel shell contained 270 balls.

Re: Low Tech cannons mortars and shells
 

I had failed to realise it was missing for the general case.