Saturday, January 24, 2015

Shooting Speed of Longbow and Crossbow

This video suggests that with a belt hook, the disparity in shooting speed was not as great as commonly supposed: four shots in 30 seconds for the crossbow vs. nine for the longbow. Of course, a windlass crossbow would be much slower.

Leo "Tod" Todeschini was present at the shoot, and reports that the crossbow had a draw weight of 150 lbs, far too light for a war weapon. He reckons that a belt and claw can span a crossbow up to about 350 lbs in draw, at a rate of about six shots a minute. This agrees with the contemporary Florentine chronicler Villani's account of Crecy that the English shot three times in the time it took the Genoese crossbowmen to fire once.

Before about 1390,  minutes and seconds were things known only by the very learned. A first person portrayal of an English bowman from before then might  say " I can shoot six times in the time it takes to say the Lord's Prayer, three times the speed of a crossbowman spanning from the belt."

"But, if I shoot as fast as I can, I'll use a whole sheaf of 24 arrows before French men-at-arms on foot, starting 200 yards out, are still more than 60 yards out. And this is not to be thought on, since everyone knows that an archer does the greatest injury at close range.  So I will shoot more deliberately at long range, especially since there is much advantage to marking where your first shot falls before firing the second, which can scarcely be  done if you shoot when your first shot is still in the air."

An English bowman who shoots his arrows wisely will shoot his last arrow only a few seconds before he drops his bow and takes up another weapon.

In these videos Tod Todeschini shoots heavy crossbows spanned with a belt and pulley and a goat's foot lever, getting off about three and five shots a minute respectively.  I don't think he's trying to shoot as fast as he possibly can. The belt and pulley is, of course, somewhat more cumbersome than a simple belt hook, but allows a heavier draw.

Note Tod's superior biomechanics compare to the first video: he presses downward with one leg rather than lifting his entire body as he spans the bow. The downward leg press is often visible in medieval images of crossbowmen spanning from a belt.

In comments, Jason Daub says that he can get off six shots in 34 seconds with a 240 lb. bow using a simple belt hook. It is well to know that the draw weights of crossbows and hand bows are not directly comparable, since the crossbow generally has a much shorter power stroke. A 240 lb. composite crossbow might put no more energy into the missile than an 80 lb. hand bow. And crossbows with steel prods suffer further  in comparison, because much of the stored energy goes into accelerating the relatively heavy prod.


Jason Daub said...

I understand you are looking for information on ROF on heavier draw crossbows. The 4/30sec is the best I can manage with a 400lbs, but it is spanned with a compound pulley and belt rather than a simple belt hook due to the weight. I have achieved 6 in 34 seconds using a 240lbs and simple belt hook.

Oscar Taylor said...

You can build your own medieval crossbow at your home using your backyard's garage.
Medieval Crossbow