The Chinese had been using large crossbows – akin to Greek and Roman ballistae – for warfare for many of the same reasons that European armies loved them. Their single, large arrow was effectively unstoppable, though this also was rather useless against large groups of infantry unless they were so kind to neatly line up. Old Chinese records mention a special kind of ammunition, called a cup arrow, or ‘storm of crows’, which involves launching many smaller arrows instead of a single large one, a feat that [Tod] really wanted to try and recreate.
In itself this doesn’t sound too complex: just grab some arrows, loosely tie them together in a bundle and slap them on the crossbow. Yet with the immense forces applied on this bundle it clearly turns out that the engineering challenge isn’t quite that straightforward, as the arrows love to scatter wildly in all directions or otherwise be rather unpredictable.
Although we can find historical references to multiple bolt siege crossbows being used, details are sparse on how the Chinese engineers addressed these aforementioned issues, so [Tod] tries a range of approaches to try and make it work on his own siege crossbow. Unfortunately he wasn’t able to make it work reliably, but he says he’ll be back with a range of improvements, with the community invited to pitch in their own ideas.
These type of weapons were very commonly used in China and surrounding nations from hundreds of years BCE to around the 16th century CE, when black powder was used to launch projectiles like fire arrows from a Huo Che or the Korean equivalent of the Hwacha, effectively multiple rocket launchers, not unlike the MLRS units seen in militaries today.
Really highlights how much frustrating fiddling and experimentation is required to keep an odd projectile from keyholing
Medieval siege weapons…truly what I was destined to work on, if I was born in the 1200s
Of course if scurvy or tetanus wouldn’t have taken me first.
Fun fact:
engineer(n.)
mid-14c., enginour, “constructor of military engines,” from Old French engigneor “engineer, architect, maker of war-engines; schemer” (12c.), from Late Latin ingeniare (see engine).
I don’t think scurvy or tetanus were the major killers.
On a related note, there are a lot of countries where people still never heard of tetanus shots. The population that is, obviously the doctors know about it, but it’s not given to everybody and people with wounds that warrant precaution would not think about getting a shot. And yet they don’t massively die, sporadically sure, but not in insane numbers because tetanus is a risk not a certainty.
And scurvy was mainly a thing with long period sea journeys I think right? Due to the limited diet enjoyed on ships.
Tetanus isn’t like rabies (mortality 99.9999%) or ebola (mortality 80%), it’s down in the 10-15% range. It’s very, very unpleasant, though. But it’s really rare. Smallpox, measles, mumps, plague, bacterial septicemia, amoebic dysentary, killed vastly more people than tetanus.
It’s a disease we’ve evolved with. 200 years ago people thought putting moss and dirt into a wound would heal it. Maybe that did something to control some bacteria, not so much the others.
I think the problems are weight of the sabot (cup) and the arrows. The sabot is too heavy, the arrows too light. It means that drag will affect the arrows more than the sabot, and so the sabot kind of ‘pushes’ the arrows out of it’s way in the first few meters. What if you make it so that the sabot doesn’t exit the bow but stays behind? Could be a simple as a rope.
Seems like you could cut a ton of weight, make it out of paper or idunno cane reeds, and have it go up over more of the length of the arrows. Heck just design a scaled-up shotgun shell wad
Paper would not be period-correct. But since it’s a Chinese thing hollowed bamboo might do?
not that he sticks to period-correct from seeing the image, perhaps I’m silly to expect that kind of effort
Idk I’m looking at the history of both and nearly all of the use of this weapon overlaps with Chinese paper, and if you use some estimates for when the earliest fiber-sheets were made it’s the entire lifetime of the weapon. Interesting.
But yeah, maybe grass mats, reeds, peeled veneers… Anything except a big carved bowl of 3-inch-thick solid wood right
Interesting to hear about that historical overlap with paper.
And as you say, there are alternatives too.
The most useful source is the Wujing Zongyao (武經總要), published in 1044 during the Song dynasty.
It contains illustrations of large siege crossbows and explicitly describes the Douzi Jian (斗子箭), also called Han Ya Jian (寒鴉箭), or Crow Arrows. The text says “an iron cup was attached to the bowstring and filled with dozens of arrows”
So looks like the cup was directly attached to the bow string. This should solve the seperation issue.
D’Alembert’s principle and a bit of inverse-pendulum thinking would find a lot of use in this.
https://en.wikipedia.org/wiki/D%27Alembert%27s_principle
That cup needs to stop at the end of the crossbow, it has done its work, from there it just adds extra instability. There needs to be guides on top and two sides to keep the arrows together, this way when they leave the bow, they are flying straight.
An arrow without fletching will never flight straight, it is just not stable, not sure why it wasn’t included. You want the arrows to impact tip first, the only way to do that is with fletching. Maybe one could figure a way to add spin to the arrows, now that would be really interesting.
Use a DEEP cup, maybe 30%± of arrow length.
Disengage cup from arrows at, or shortly after the end of the crossbow.
A mechanical stop, string, or elastic will hold the cup back from the arrows.
Fletching is a must. Flexible for fitting into the cup while attached to the arrows.
Fletch can be vanes, or trailing lightweight strings or ribbons.
( Ribbons flapping behind the arrows in flight might explain the appearance of “crows” approaching like a storm. )
So,
1. Arrow packet contained in a tubular ‘cup’ is accelerated to flight speed.
2. Tube/Cup is held back and disengaged from arrows right after launch.
3. Fletching stabilizes arrows on trajectory to target.
4. Arrows disperse somewhat due to individual aerodynamic variation.
5. Increase dispersion with spongy light material loaded between arrows.
6. Optimize each of the 5 factors above incrementally.
Has anyone fired a whole atlatl (or speargun) from a heavy crossbow? Like rocket staging.
An annular speargun would be surrounded by much lighter weight arrows each with rubber tubing. The central tube is quite heavy, perhaps with gunpowder in that barrel, small amount of high explosive in the rear.
Heavy crossbow fires the whole thing–the inner spear thrower shoots the lighter weight arrows and blows itself to bits mid flight.
Shrapnel everywhere
I don’t know, but the US has nuclear shells for howitzers. In case you need them.