Monday, January 23, 2012

"Entropy Slayer 2000": A crossbow to defeat hysteresis

As announced.


  1. As usual, I enjoyed this video and your ingenuous innovations such as the nice 'nerdy' touch to add the switch with the safety cover over it topped off with a silencer. You also proved your point of re-kindling the available energy by the use of a heating element. You make fun videos, Joerg and I thank you for them. All the best to you and yours.

  2. Very interesting. It was for me a mystery up to now !
    thank you very much for your job.

  3. Thank you for your very entertaining post-apocalyptic weapons. The Zombie-Hammer with skull ejector is genius. I am your new fan. More please.

  4. Joerg, I recently found your blog and have to say I am inspired. We have copious amounts of dogwood and osage orange here in the Midwest, so I am hoping to try my hand at some of your more simple carved designs. Any tips for a beginner?


  5. Jesse, start with my six circles design!

  6. Hallo Jörg, I'm Mathieu from France. I've only discovered your work for a short time, but I do really think it's great ! You are a true inventor, Renaissance-style. I am at the moment considering the purchase of a slingshot, so if you don't mind I might just drop you a line for some advice. For the moment, keep up your interesting researches.
    Tchüss !

  7. Dear Jorg,
    Thanks for this latest report. It was great reading as usual. I have only just joined your blog, but have followed it for a long time, now. Sorry if this is slightly off topic or a repeat of my other post (wasn’t sure if you’d get it). I have been looking at the Liberty 1 for a long time before your review. I would like to get your honest assessment and opinion of the Liberty, since you've owned it (and I assume shot it ) quite a lot and have some more experience of it now since your original comparative review. I am seriously interested in this bow and really would like your thoughts on it and experience with it. Good points/negatives, how much tinkering does it require or is it tinker free? How reliable is it? Have you had any problems with it? I spend part of my year in the UK which is not weapons friendly-so I liked the fact that it is very compact and looks actually childlike. I will be able to play with it with my daughters and not scare people as much as with a big bad mean looking conventional compound bow. But reliability and trouble free operation are absolutely key for me...My email is
    Best regards,
    Anthony Banks,
    Sth Korea & UK

  8. Does that mean it's better to relase ur shot as quickly as possible after u draw? Before the band completes the cool down process?

  9. Hi Joerg,

    Living in Bavaria (as you?), a friend from Australia had to make me aware of your ingenious and fun channel :-)
    Your Entropy Slayer experiment eventually revealed to me, why scope adjustment never seemed to work in my childhood quest for a reasonable accurate sniper slingshot rifle. Thanks for that!

    May I please propose two ideas for improving your design:
    1. Use a Peltier element (like in those portable battery powered cooling/warming boxes). That heats on one side and cools at the other, depending on the polarity. In a two-barreled rifle you could alternatingly heat one and cool the other compartment.
    Load the cold rubber, which will then collect additional strain from the surrounding heat. Flipping the switch to heating before firing will give you even more power ... and at the same time cool the other string for loading.
    2. Couple the rubber with a spring (and possibly a damper), e.g. in the release, the front mountings of the rubber, or make the "barrel" itself a spring/damper element. Choose a rheological element (see e.g. that offsets changing temperatures in the rubber. That might require some research on the rheology of your rubber. The goal is to maintain constant force for the shot, keeping your sight adjustment valid all the time.

    Have fun!

    1. Sorry, "additional stress", not "additional strain".