Re: Low-Tech Missile Weapon Range and Accuracy
 

Interesting. I hadn't thought to vary draw weight multiplier with skill. Increasing ST is the functional equivalent at constant multiplier, however, although I suspect your numbers above have more granularity than just (say) +1ST at DX and +2ST at DX+2 or something.

If we "believe" (or really, we wish to stipulate) the equivalent of +4 to ST through skill - or if we say that you can pull, say +40% heavier bow with special exercises and +40% with technique, rather than +2ST for each, then you could easily, say, give +10% to allowable draw weight at DX, with a +10% more per point of skill higher, capping at +40% at DX+4 or DX+5 in realistic campaigns. Likewise, charge 4pts per +10% for "special exercises" or something. Easier would be allowable up to +2 arm ST with the special Exercises perk and +1 at DX and +1 more at DX+2 or something.

Net/net, though, once you've spent the points in archery, presumably that's worth something as you say.


It wasn't an "experiment." I took my stats from the very useful article "The Physics of Medieval Archery" [http://www.stortford-archers.org.uk/medieval.htm] which give physics-based estimates for the strength of bows of the period, as well as estimating the velocity and mass of the projectiles themselves.

From this, using bullet impact formulae I derived in my article on GURPS bullet damage in Pyramid, I can calculate the points of armor a projectile of certain cross section and energy would penetrate. For a "muzzle velocity" of 60m/s and a weight of 60g, and a 1cm diameter shaft, you get about 3.8pts (1d) calculated penetration. This is complicated by the arrowhead, which has a MUCH lower cross section than the shaft, but even a cross-sectional area more accurately calculated (say, a trapezoid 4mm at its thickest and 30mm wide as a broadhead point) won't be less than about half that of the shaft, which only changes damage by 10% higher. (3.8pts goes to 4.2pts). What MIGHT drive that number higher is if the arrowheads were hardened or forged or something much harder than the jacketed lead or mild steel my model was built around. That would usually add an armor divisor...with good steel (semi-armor piercing) usually being worth a 1.25 to 1.5 armor divisor. That would typically make an arrow from this bow penetrate like 1d+1 (4.5pts) to 2d-1 (6.3pts). Given how much oomph I think we can all agree is required for a draw of 180-200lbs, having THAT bow eke out no more than 2d damage as a "ST20 bow" upper end would be fairly OK. That's thr or thr+1 using the ST table AS IS. But, it also requires the assumption of hard arrowheads and smaller cross section...which frankly ain't that bad.

Crossbows, apparently, have the benefit of not requiring so many points to eke out that same damage.


My impression, mainly from this forum, is that arrows would rarely punch through metal armor.

Re: Low-Tech Missile Weapon Range and Accuracy
 

I thought Benjamin Franklin was the proponent for the Continental Army...googling.

Yep. Franklin, 1776.

Problems with bows --
 

GURPS should not give a heavy crossbow 25 shots per minute. A light crossbow (no more draw weight than a small bow) perhaps -- but there wouldn't be much aiming.

As a number of sources, including the Royal Ordnance Museum (IIRC -- it was British gov't facility) have noted, longbows will not penetrate decently-made plate armor from c. 1450 on. Said outfit made repops of both bow & armor, (actually, armour, being British) fired A at B at a range of less than 10 meters, and arrows bounced without so much as denting the surface. I've seen the film; plate existed for a reason.

Heavy crossbows could -- but they were problematic. If you're holding a 1500 pound draw weight any flaw in the metal can & will be fatal. At least one monarch, a king of Scotland, died in a hunting accident when his crossbow went SPROING! and inflicted heavy injury.

In some ways a heavy (c. 1500# draw) crossbow is a more difficult manufacturing task than a musket. While the latter has to survive more peak pressure, no part of it has to be terribly hard AND have great tensile strength. The tips of the crossbow and the faces of the trigger mechanism thereof do require this. If the tips are soft, the bow-wire will cut into them and (if you're lucky) disable the crossbow. If you're not lucky the tip will separate. Given the geometry of the crossbow, if you're aiming it at the time a wire lash will hit you driven by c. 750# (a single bow-limb). Not good.

And, as stated, it was easier to train a man to use a musket than a longbow.

As far as accuracy, the Knights of St. John at Malta (1565 CE) noted that Turkish musketeers were inflicting hits on single targets (human) at over 100 yards in the siege of Fort St. Elmo. While they may no have been accurate by our standards they were accurate enough to be a problem.

Re: Low-Tech Missile Weapon Range and Accuracy
 

Crossbows definitely held on longer than bows. Magellen's expedition used a number of crossbows alongside their firearms.

Re: Low-Tech Missile Weapon Range and Accuracy
 

Crossbows don't refuse to fire when wet, unlike black powder. So they might have had a certain attraction to a naval expedition. As well, the raw materials for additional quarrels could be reasonably be trusted to be found all over the world; I could see an expedition planner worried about easily obtaining the raw materials for black powder in Terra Incognita.

Re: Low-Tech Missile Weapon Range and Accuracy
 

I feel those stats are correct and accurate. In a game perspective a hero with a xbow will kick ass but, rarely are these weapons used by heroes.

I've read up and discussed with some friends the studies about the bow, the xbow and the muskets (even the handgonnes). A friend (who lurks these forums) as told me about some calculations made to see how these two technologies would interact.

From his anecdote a program running a simulation of 13C longbowmen of 5,000 against an equal no. of Napoleonic Riflemen. Depending on the circumstance they can defeat each other quite soundly. Bottomline is basically the morale, the first to receive a terrible loss would be the loser.

Stat-wise, I find them correct. It is the context of what happens when the typically bad circumstances in war that alter what is theoretically probably from what will happen.

Food for thought. My friend who is reading up on many Chinese texts about their combined arms tactics found that they employed the Rotating Massed Volley Fire with their Heavy Xbows (contrast to the squad firing as quickly as they can, continuously), similar to those employed with early slow loading rifles. Between volleys, they would have archers step up and, with rapid fire, fill in these crucial gaps. An amazing sight IMO, if xbows use matured fully and combined with archery.

Re: Low-Tech Missile Weapon Range and Accuracy
 

Bowstrings are useless when wet. English archers stored spares under their helmets. Composite crossbows delaminate when wet. All bows lose distance and power when wet.

Re: Low-Tech Missile Weapon Range and Accuracy
 

Which is what happened during the Wars of the Roses. Both sides started out with longbow volleys. Those on the losing side of such an exchange charged first and usually lost because the enemy was in a prepared position

Re: Low-Tech Missile Weapon Range and Accuracy
 

Well, that was the prestigious royal flagship.

Re: Low-Tech Missile Weapon Range and Accuracy
 

Which, apparently, is a point in favour of bows over crossbows. It's easier to keep your bowstring in a dry place and then string the weapon the moment you expect action than it is to keep a war crossbow's string dry.