How did they reach that figure?

Alot of history shows are interesting, but when they recreate something they miss out on some important details and make alot of sweeping conclusions.

The probably reached those numbers with a chronograph, and that does sound about right. The thing you have to take into account is arrow weight. You could shoot a very light arrow and it would go faster. That is why when people test longbows and recurves now to review their performance, they list the weight.

Normally the rule of thumb is 10 grains of weight per pound of draw weight. For example 500grains for a 50# bow. That way if you have two similar bows, differing only in draw weight you can compare them. They are usually about the same.

Some typical speeds are 150-180 fps for most modern composite recurves and longbows, 200 fps for some expensive composites recurves and longbows using carbon fiber layers, 200-300 fps for some super high tech compound bows, and lastly 120-150 fps for older wooden bows.

There are exceptions, english longbows made from yew have similar properties to composite bows because of the wood, so they have about the same performance 180 fps or so.

That all said speed isn't everything, it has been proven time and again that with bows, the weight of the arrow, and the arrow head are what dictate penetration, not speed. For example I hunt with either a 65# recurve or a 70# longbow, so I make wooden arrows that are about 600 grains plus a 150 grain two-blade broadhead. I'm pretty sure they are only getting about 150 fps, if that, but they will pass-thru a deer or a bear, half the time and always kill if they hit close to the target zone.

If I shoot 200 grain carbon fiber arrows with 100 grain tips they must be much, much faster, at least 200 fps, but they will bounce right off a deer and not even hurt it.

I'm not sure but I think slings work the same way, we worked about the approx speed of a 3 oz projectile from my 55 inch sling, about 215 fps, but I'm certain that the regular size rocks I use (about 6oz) have much more power. I've killed some geese and racoons with bigger rocks, but had smaller ones do nothing.

Anyway, just my view, I could be wrong.

sounds about right - a clothyard arrow didn't have to be that fast.

It does happen, and ruining two arrows is no fun! I've never seen one done on purpose, but I do have a method for preventing it: when I practice with broadheads (they seem to always wreck the arrows compared to field tips) I put up six little targets spaced out, that way it can't happen.

But it is good for your condition. (I often have do it when slinging.)

Willeke

Mike_R
You are right. Velocity is not all. They showed that an arrow with this velocity of 50m/s went easily through a coat of chain mail.
I believe they measured the velocity with some infrared device. By the way it's a pity I don't understand the technical terminology (grains of weight...).

Makes sense to me that immediate effect on the target depends on speed, weight, shape of the projectile, and it's composition, because these determine how much energy (foot/lbs, Newton/Meters, etc) is put into the target upon impact. 

Seems like ideally you'd want an arrow to stop with it's head still (barely) inside the target, and a sling glande to impact, perhaps penetrate some, but never bounce.

So, once you've specified your "launcher", pick a projectile weight that launches with maximum foot/lbs available, then shape it to stay in the target, ....assuming that aerodynamics can be held constant all the while.

Does this make sense??