Okay, this is weird.  The blog post that follows just popped itself out of the archives and redated itself to the present.  Probably my fat fingers teasing me again.  I’ll not correct the error and just figure providence gets a say here too.  Here it is, ancient in it’s own right:


— I have been guilty of certain apriori approaches in the development of Firefly that have caused a lot of unnecessary effort.  Perhaps the greatest of these has been my fixation on protecting the field frames and the kamarion from the shock of the limbs crashing home.  Originally I had assumed that leather buffers would be a good idea to prevent damage to the machine from so much energy having  to be absorbed by the framework.  Great idea, until the leather buffers broke down and caused endless problems with bowstrings breaking as they absorbed all the shock.

After the buffers I moved on to heavy bronze hardstops intended to spread the load over a greater area of the stanchion,  I really thought I was on to something because now the limbs had a positive stopping point and the bowstrings were well protected from the limb shock by simply adjusting their length so that they were just long enough not to be over stressed.  The frames showed no damage with these bronze hardstops, so obviously this approach was working.

This phase with the bronze hardstops lasted quite a while.  Eventually my  desire to increase the limb rotation past 90 degrees caused the removal of these  pretty bronze parts, and with it (for reasons I don’t remember) my concerns about frame damage.

When we have experienced the pain of all the things that didn’t work we are ready to learn. —


Increasing limb rotation beyond 90 degrees?  Because, you know, back then I’d dreamed there were fabulous kinetic riches to be had with an extra long power stroke.  Oh! the innocence of the young!

2 Responses to “A priori. (An unintended reprint.)”

  1. Charles W. Fink says:

    Our computer was down for a while and was replaced. I have been rereading a lot of your blogs and am now able to see most of your videos (not all). The Phoenix is a work of art and it really does have some bird like qualities. The bat fin shoulder sighting rests are a nice touch.
    On this pages line of reasoning, what final conclusions did you come to on hardstops? I assume the limbs and the string are the weakest link. The photo from Wed. November 28 post shows a metal socket in the torsion bundle with a rope bridge brace. Are you still planning to use anything like that, or has that idea evolved beyond? The rope seems like a valuable safety in case of limb failure, so parts are held from flying too far. This post talks about frame damage , but the kamarions seem so strong compared to the limbs. It seems like you wouldn’t have reposted it if you weren’t still thinking about it.
    I am heading to Tx in a few days so if you have any new thoughts on Bois’Darc procurement let me know soon. As I said , when I’m there I’m off grid, I will catch up with what you have done sometime next month. I am fascinated by what you are building, so many people seem just a little bit too average to me.

  2. nick says:

    Charles, I am tardy in my response. Only just saw your comment. Apologies.

    I have been thinking about the osage orange for the limbs and have come to the conclusion that it may not be ideal for authentic ballista limbs. For the time being I think I will stick with the white ash and concentrate on how it is reinforced with a steel tension rod. Your offer is very kind and I only hope this belated response reaches you in time.

    You can email me at: nick@wattsunique.com if that helps.

    The hardstops have been relegated to the dustbin of catapult-dom. Anything that impedes the high level of bowstring tension at the end of the powerstroke seems to degrade velocity. Maximum bowstring snap is what we are after.

    I will certainly continue with the safety strap in some form or another, but I will be attempting to transfer the tension load into a steel rod of some kind in the interest of authenticity. The Elenovo horde has an iron rod that Mr.Kayumov speculates is just such a component. I’m not fond of the idea of self-decapitation, so this will all require great care. Probably a protective shield to stand behind will be used when I start to explore the very high draw weights.

    You may have noticed that people rarely take the time to comment on this blog and the work I’m doing. Can’t say I blame them, it does go on a bit. In some ways it is a relief as I don’t have to spend time fielding questions. However, you should know that I value your contributions. They are a reflective surface that allows me to cherish the illusion that someone, somewhere is reading all of this.

    In this game, motivation is everything.

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