More on Catapults & Giants

In the past few weeks I was looking closely at the mechanics for OD&D catapults, giant stone-throwing, and fireball spells, which really all share the same single mechanic originating in Chainmail. If you recall how catapult-like-attacks function in Chainmail, they land at some declared range by the attacker, killing everything within an area-of-effect diameter of 2" or 3.5" (depending on light/heavy category; some survival allowed for heroic-type targets; but otherwise ignoring any armor considerations). Particularly with catapults, you then get into questions of what scale this is intended to be -- I argued that they're best understood at Siege/Man-to-Man scale, and somewhat accidentally shoved into the mass combat section.

As usual, Gygax's Swords & Spells book (which counts as being in the OD&D line) gives some nice additional perspective if you hunt around in it enough. In these 1:10 mass-combat rules, catapults are explicitly said to be 1:1 scale, which I think bolsters my previous argument:

Artillery: As the various artillery pieces represent but a single scale engine, only a single figure is needed to represent crew for each... [S&S, p. 10]

Catapults (both light & heavy) have decreased rate-of-fire from 1/2 or 1/3 [CM, p. 12] to 1/4 here [S&S, p. 9]. Meanwhile, bow archery has increased rate-of-fire from 2 per turn [CM, p. 11] to 3 per turn [S&S, p. 9]. And as far as giants go:

Giants act as 20" range -- light catapults with a fire arc of 45% [sic] left or right, but they must stand one-half move to fire. [S&S, p. 10]

That's an oddball rate-of-fire: sort of between the allowances for ROF 1 or 2 [S&S, p. 9], now much more potent than a mundane light catapult (by a factor of 4), similar to the description in Chainmail but without following the Swords & Spells reduction to catapult speed. This is backed up by the Example of Game Play at the back of the book which features giants throwing rocks on each of subsequent turns [S&S, p. 38].

Now, the thing I thought particularly interesting is that the result of catapult/giant fire is already no longer an area-of-effect. And I think this is particularly reasonable if we're interfacing between scale 1:1 throwers and 1:10 targets. The effect is now simply an application of a certain number of hit points damage to the target unit [S&S, p. 26]:

STONE CASTERS	Target About Man-sized	Larger
Small Catapult	30	15
Large Catapult	40	20
Trebuchet	50	25

Consider: The effect of the small catapult (i.e., giants) in these rules is to kill 30/4.5 = 6.7 normal men. That's actually very close to the number of men you'd kill if the Chainmail/OD&D area-of-effect was applied over man-to-man figure bases areas: Pi*r^2/Fig^2 = 3.14*1^2/(0.75)^2 = 3.14/0.5625 = 5.6 normal men. The large catapult kills 40/4.5 = 8.9 normal men, compared to Chainmail's heavy catapult which at man-to-man scale would kill at most Pi*r^2/Fig^2 = 3.14*1.75^2/(0.75)^2 = 9.62/0.5625 = 17.1 normal men (i.e., about twice as many).