A glans funk is the worst kind of funk to be in if you are a catapult maker. Slow velocities in the mid to low 200’s (fps) does nothing to lighten the mood. True, these were some extra light pills we were tossing out there, but you’d think that would make them faster, if anything.

It started out with a 55 gram speck of steel bar rocketing along at (sarcasm alert) 242 feet per second (fps), for a yawning 110 foot pounds of energy (fpe).

Just knowing the bark on this tree was all wrong, I bit back my skepticism. However, I remained true to our methodology by making only an incremental increase in the mass of the projectile for the next shot. With this, a 133 gram slug made it up to 354 fps, for a titilating 571 fpe.

After this a duo of 155 gram steel slugs dawdled on the chrono readout for an average speed of 225 fps. WTF! How did that make many sense? Was this going to get really depressing, really fast? As it turned out these last two shots were an anomaly, and things were going to get really interesting, really fast! …..

Next a 270 gram piece of 1 1/4″ dia. X 1.44″ long steel bar hit 284 fps, energy 746 fpe. Yum! at this rate we were getting into the upper echelon of what the best Balearic hand slingers could do. 813 foot pounds (3.62 kilo Newtons) was achieved by, the very athletic, Mr. Luis Pons Livermore. He is a native of the Balearic Islands and is a recent world champion hand slinger. This data on his slinging prowess was taken from his appearance in an episode titled, Lost Science of the Bible on a show called, Ancient Discoveries. (Yes Egor! I know! It’s “Ancient Discoveries”. Now, do piss-off!, there’s a good chap. ……Sorry about that….. Egor can be such a snob sometimes.) Anyway, a quick Google can get you the whole story of this modern day David. He is a Cool Dude.

But, I digress…..

It seems that part of the trend in this string of shots from Firefly is for the velocity to increase as the weight of the projectile goes up. While this pattern may be enough to make high school physics teachers wince, that is what the measurements indicate.

Yes, I know! this doesn’t make any sense. Raise the payload weight, while keeping all the other factors the same, and the velocity should go down. Tell that to Firefly. Right now, she’s grinning all the way to the bank.

The above velocities were carefully measured with a doppler chronograpth. This device has been giving us highly consistent and accurate readings ever since it was installed on a longer bayonet mount. I check its accuracy by using a match grade, spring piston air rifle and comparing test shots between it and two other chronograpths. I am confident that all my readings with it are accurate.

But again, I diress…..

Feeling a sense of renewed optimism, I decided to boost the projectile weight back to our old standby from two years ago: a 400 gram lead glans. Actually the one we used in this test weighed 398 grams.

At the moment of firing the sound of the machine had a lower tone to it than in the previous shots. And the flight of that 398 gram glans….you should have seen it! Dead center over the groove, no sideways drift at all out to the 100 yard tree line. I observed that it was not tumbling, but moving through the air sideways, just as it had been when ejected from the pouch.

Hurrah! ….. Yipee-kay-yeh! ….. multiple Hosannas, etc.

This worthy 398 gram lead glans had put us into the zone we were at two years ago, clocking in at 290 fps, with an energy of 1,146 fpe. We’re back baby! The reprising was over.

…..As the imaginary applause dies down, a moment of somber reflection ensues…..

Even granting the prodigious surge of talent that might arise in an ancient, Golden Age of handslinging, Firefly was clearly exceeding the upper limits of what a human athlete could achieve. No surprise there. She is a big and heavy machine. A handsling is not much more sophisticated than the belt I use to hold up my trousers. All kudos to such a simple and effective device. But in this discussion, that is hardly the point. We are speaking strictly about the absolutes of power generation, not the perceived efficiency thereof.

And so, if a handslinger of Mr. Livermore’s caliber, can generate 813 foot pounds of energy, it seems fair to say that, even granting the ambient conditions of an adrenaline fueled martial moment, the rank and file ancient handslingers were probably not kicking out much more than this modern day world champion. Luis’s record breaking achievement of 813 foot pounds has given us a handle on what ancient slingers could have achieved with a handsling. I would suggest that any glans projection that tops an 800 foot pounds threshold with a 100-300 gram (or heavier) glans, is likely the work of a catapult rather than a human slinger.

In contrast, Firefly is still nosing the bottom of the tent at 1,146 foot pounds. She also has a provisional 1400 foot pounds and 320 fps with a 400 gram glans from a previous experiment. Who knows what breakthrough we’ll discover with more development? For the time being, we will explore what a series of progressiverly heavier glandes can do; at least untill some break-over point is reached and the good stats start to dwindle. After that it will be up to the Mk. IX limbs to “up the ante”.

Again, this comparison is not meant to discount the many obvious advantages of a handsling, but in a game of absolutes it is clear that ballista discharged glandes would have a utility at least equal to the expense of the special slingstring it took to fire them. If nothing else they might be used to convince the enemy they were up against some truly superhuman handslingers.

I digress…

The important thing here is: this is how my funk ended. With a 290 foot per second, 400 gram, ovoid chunk of lead.

Also: here is a pic of the two oak speaders that were added to keep the strings an inch and a half apart. They are working better than expected. No signs of shifting whatever.

One Response to “Sufficient unto the day is the snivelling thereof.”


  1. Andrew says:

    I know that I am no expert nor am I very familiar with your project, but I have built a ballista before for school. I used golf clubs, pieces of a flowery kids bike and didn’t hone it too much (it was a one weekend thing). The thing that I found was that throwing a ballish thing with a ballista is a mug’s game. These machines were made to “throw” arrows or things very much like them. I hear balistas still find a use in the navy bashing down doors on enemy ships when coming for close quarters work. The whole idea behind a ballista is not to cause rampant and indiscriminate destruction, but rather to secure tactical advantages with precision and power. I hope any of this was helpful and admire your work so far. Thanks

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