Don’t you just love Mercury Retrograde?

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5 Responses to “The worst of news.”

  1. Captn harpoon says:

    Ouch. Would I be correct in that the brass inserts on the stanchions have been removed? If so, I recall saying you would be hitting 400fps at around 65-75 degrees.

    A shorter limb would allow you to max at 5000lbs with less structural stress, as draw would climb as before. It would not need to be an excessive amount.

    An alternative allowing you the same dimensions of the arms would be metal plate reinforcing along each side of the arms before insertion into the bundle? the extra mass’s placement would minimalize effects of a couple of extra lbs.

    Excessive rotation past 75 degrees might require the bundle to kinda loose up front, and using those extra 15 degrees as “tightening” the bundle as opposed to raising the crosspiece.

    With the inserts out giving the extra rotation, not rotating the arms so they are horizontally opposed eliminates much of the unproductivity. It also gives you a lot more usable power where it makes a difference.

    Good luck on next limb build.

  2. Captn harpoon says:

    FYI – My prediction on arm construction back in mid March in comments section:

    “Since it appears the arms will retain original length thats okay too. By June or July and several rounds of testing perhaps you will come to the same conclusion about the arms as you did for the frame. Metal is inherently stronger.”

    – the “good” Capt’n….

  3. Samuli Seppänen says:


    There are lots of smart people (Nick, Pat B, Captn Harpoon) following this blog. We _could_ start working together to get the math and all that right here:

    There’s already lots of technical stuff (e.g. same static analysis Pat B was talking about) there, written and visualized by me.

    Hope you guys are interested in creating a pool of knowledge about ballistas, containing all the lessons we’ve learned so far. It’s difficult for any newcomer to join our community of ballista freaks, because the relevant information is “all over the place” in blogs, articles, forum posts etc.

    Anyways, just my 5 cents. I’ll be writing about my cheiroballistra reconstruction to the Wiki anyways, but I’d love to see you guys onboard, too.

  4. Pat B says:

    I took a quick look at your site. It looks quite promising in terms of its scientific approach. I’ll give it a longer look when I have time. Good luck with it anyway.

  5. Nick Watts says:

    Dear Samuli,

    At the risk of being considered a materialistic knave, I venture to ask: would this enterprise be calculated to earn some revenue?

    I expect to have some new, and perhaps interesting, video footage soon.

    Best regards, Nick.

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