Tuesday, September 13, 2011

Leonardo's Giant Crossbow Challenge - First Sketch

The "Da Vinci" project is slowly maturing.

The book about Leonardo's giant crossbow arrived,

See the book on Amazon

and also I found the original documentary from ITN Factual Television (2002), which was telecast in Germany by The Discovery Channel a few years back.

Very insightful. Turns out that da Vinci never built the thing, he only sketched it out for the Duke of Milan, Ludovico Sforza, sometime between 1482 and 1492. Interesting: He promised that it will shoot a 100 lbs (44kg) stone ball (roughly 12" or 31 cm diameter) 28 yards (25 meters) far, and a 10lbs (4,4kg) ball 280 yards (250 meters) far.

The ITN team had three months and probably more than 10 craftsmen to build the crossbow. I think they spent at least 100,000 Euros. A fail, in the end. The 20 lbs ball they used did not even fly 20 yards. Then the prod broke, so they gave up. Pathetic attempt, really.

Just for the fun of it, I ordered a 1:100 scale plastic model of the Giant Crossbow, can't wait.

Here it is on amazon

Anyway, I want to make a slingshot cannon that exceeds the ancient promise, and I want to do it in three WEEKS, not months. With hopefully just two assitants. For under 3,000 Euros.

This will be pretty much a variation of my previous slingshot cannon, with a few changes. I sketched it for the Tapefilm guys, who need to find a TV channel as a buyer (sorry for the German text).

- Length will be 7 meters total, 6 meters stretch.
- Four wheels
- 500 kg to 1000 kg draw weight (1,100 to 2,200 lbs)
- Adjustable shooting angle
- Ratchet like cocking mechanism (not enough room for a four arms "cross" winch)

If all goes well, this can be done before the winter kicks in (early November 2011).

My brother, who is a physicist, figured out that I will be able to shoot the 100lbs ball about 34 meters with 500kg draw. I absolutely can't wait to feel the earth shaking when that ball hits the ground!




 

69 comments:

  1. you sir, are officially....nutz...:D

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  2. Cant wait to see that giant slingshot :D

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  3. Great idea but
    wouldn´t the ´´schlitten´´ take to much force?

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  4. you are crazy... That is awesome

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  5. dude, i can see thats gonna be really fun to make, cant wait to see you try it out on Youtube!

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  6. If anyone can do it, it will be you Joerg! You never cease to amaze me with your answers to 'Now what do I do next?' Can we contribute to the building costs via PayPal or some other venue? No wonder you are my favorite YouTube channel. Leonardo would be proud! You are as entertaining, in your narrow field, as 'MythBusters' and are worthy of the same respect. All you need is a beret and a walrus mustache! Or better yet, they need to work out with weights to come up to you.

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  7. This is going to be amazing, please finish off that pesky little white car from the other cannon lol. 500kg draw thats 1,102.31 lbs. That sounds like it will be rather difficult to get cocked back. Can't wait to see this it is going to redefine the word epic.

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  8. By November! That's impressive, Good luck!

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  9. Do you know what kind of rubber you will be using?
    Have you used Bungee Jumping rubber yet?

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  10. Man, will I enjoy seeing it in action!
    Way to go, Joerg!

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  11. Are any of your friends willing to fly a plane over it it?
    It would make good target practice!

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  12. you can use me as ammo i love flying
    but first i have to get my insurance:)
    are u going to become joerg da vinci

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  13. It is cool that your brother is a physicist! Me too.

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  14. That is a big under taking, I wish you all the best with it!

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  15. oh yes, this one i have to see, good luck with the build

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  16. Is that close to any record or will it set a Guinness world record?

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  17. I don't think the Guinness record keepers do weapon based stuff. Anyway, I have never heard of a slingshot cannon that even outperforms my car sized beauty, so I think it is safe to say that the Da Vinci model will be a record attempt.

    By the way, Prof, Landrus, author of the book about the Giant Crossbow and probably THE expert on the topic, answered my email - he is willing to help! That's great news. He is a world renowned military historian, his CV is as extensive as it is impressive. I am excited to no end - the kind of people I meet just because of my humble little slingshot hobby.

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  18. Wow! That's cool so your build team is already starting to come together!

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  19. That's even crazier than the last one. But can't wait till you make it.

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  20. I am certain you can complete this task. But, it looks quite dangerous. Do take care.

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  21. I went out and found some good natural Y shaped hardwood to make my first slingshot with, for the first I picked this one:

    http://i162.photobucket.com/albums/t267/Busted11290/SD534259.jpg

    It has a nice size handle to it, I just need some bands and a pouch for it. Oh and it is made from Mountain Laurel I think is the type of Laurel it is.

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  22. gratz to your first natural fork :)
    i can show my collection from last week (and yesterday) also if you like :)

    jörg have you already calculated how many meters or theraband-gold you will need?
    or do you plan to contact them to make you a special, extra thick and wide one :P

    congratulation that the author offered help, i´m really surprised how fast your evolution pace is.

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  23. oh btw, i don´t see how this is a "da vince" katapult...i mean, da vinci just wanted to bild a giant crossbow right?
    like those ones used in medival wars...scorpions and stuff...just bigger.
    i don´t think he already knew rubber....so how s that a da vinci crossbow, isn´t it just an even bigger version of your last rubber-katapult?

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  24. Your biggest project yet! I like it!

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  25. what about using two well placed trees for you forks and attaching your "schlitten" (i refer to it as an ammo block) to the trailer hitch of your truck and let fly.

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  26. man, that is going to be one of the most amazing slingshots i have ever seen(or ever will see)(lol)

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  27. Again, the challenge is to deliver Leonardo's ancient promise to the Duke of Milan... shooting a 44 kg (100lbs) stone ball 25 meters far, with muscle power. That is the same performance as a siege cannon of that time, but silent, cheap and safe.

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  28. Jord, the weapon must be portable (= on a carriage that has wheels), otherwise it does not qualify as a siege engine.

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  29. Well i cant tell if i remeber right but i think i saw a show on DMAX where they construct old Leonardos inventions and if my memorys dont fool me they build one giant "crossbow" with historical acurate materials.
    So if you can find the video you are maybe able to get some ideas!
    I whish u best of luck.

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  30. Hey i love your designs. Are you still giving out slingshots?

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  31. I think you should use a tank to cock it.

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  32. http://www.maniacworld.com/greatest-sling-shot-man-ever.html



    ran across this and thought of you!

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  33. Fantastic, Joerge!!!
    I love seeing Leonardos designs, even if they were simply sketches, being brought to life. My anticipation is like a fully drawn cougar waiting to be released for the sight of this behemoth laying waste to all in its path...
    Good luck, bud!!!
    Dalbergian

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  34. I'm sure you will surpass the 34 meters!

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  35. This is where i see Jörg in 2 years:

    http://www.youtube.com/watch?v=-wVADKznOhY

    (i like how he "drills" the holes)


    Btw: Congratualtion and greetings to your wife! A man can only make his crazy wishes come true if he has an understandable women behind him, that supports his work!That cannot be assumed!

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  36. Good luck Jorg!
    How much rubber are you using for that and what kind do you think you will go with?

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  37. and i thought the cannon was a sweetly insane idea!!!! this thing is gunna be AWESOME!!! how many hours are u guessing it will take u to make it?

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  38. That will be German engineering at its finest!

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  39. That draw weight is ridiculous!
    I think a ton of force might be too much for a winch.
    Or do you think it will hold with that much weight?

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  40. I was very impressed by the slingshot cannon, I wish you would have shot the car's headlights!

    Good luck in this next project. I can't wait to see the result, all of your builds are quite impressive.

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  41. This is Madness! just call me crazy!

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  42. And I thought you couldn't top the canon.... Wrong! LOL!

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  43. I figured I will need about 34 meters of TB Gold (500kg), twice that (68 meters) for 1000 kg.

    The winch will have to have a much thicker axis and also a longer lever. It will work like a ratchet, not enough room for a wheel.

    The making of the documentary was witnessed by Prof. Landrus, who covers it in his great book. I found it online somewhere and watched it (again). It was a huge fail, the ball simply dropped from the crossbow and kept on rolling for a few meters. Pathetic.

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  44. d00d, you are now approaching artillery machines, I hope I can get my youtube back up and running to see this lol. You, sir, are an honorary 13Banger for this .

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  45. Yellow :)
    You should already have a pretty nice discount at www.thera-band.de
    Maybe a factory sponsorship ore something like that? :)
    Does the model from amazon shoot? Of course a 100times smaller objects that Leonardo promised :)
    Cheers
    Rafal

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  46. Joerg, having had my sub-concious deal with this overnight, I've awakened to some doubts. I've been a fan long enough to know what you can and have done, but somehow, I have reservations that you can launch a 100 lb. ball at all. I really hope I'm very wrong, but I've got a bad feeling about this project. The best of luck on this, nonetheless.

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  47. porcelanowy, the amazon model does not shoot "out of the box". But I will see if I can modify it a bit. This is The Slingshot Channel, after all.

    Tosh Togo, thanks for your concerns, but I believe I CAN shoot a 44 kg stone just fine. My brother (the physicist) thinks so too. But in any case, worst thing that can happen is that the stone drops down. So what?

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  48. Why do you still calculate in "Thera Band"?
    Why don´t you buy that Stuff for Bungee Jumps and those Human-Catapults the use on Oktoberfest etc.?

    i bet you would onl need one or 2 of them.

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  49. Bungee cord is useless, far too weak. I tested it and it is ridiculous. The Mythbusters came to the same conclusion, by the way ("border slingshot").

    Thera Band remains the best rubber I tested so far. It is as stretchy and fast as natural gum rubber, but lasts longer and is less sensitive against sunlight.

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  50. Because he is paid by Theraband big-time... :D

    Well they actually should, the promotional effect of such a machine really shows the capabilities of their products. I've actually never heard of theraband before I had to make a slingshot, and then found Jörgs how-to movies on youtube.

    I think the biggest concern will be making a stable solid construction because of the immense stress on it and the shock after release. And there will be a lot of friction on the axis, so maybe bearings are needed, or perhaps waxing is also enough. Or maybe heavy ´tie down straps´ instead of a wood mechanism. That avoids one of the complex parts and less complexity is often better.

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  51. I plan on using thick wooden beams from roof construction suppliers.

    I think I can avoid bearings by using a larger diameter axis and lots of grease. I really don't want to use too many parts that weren't available in Leonardo's time. Ideally, it is just the rubber that makes the difference.

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  52. Too weak? really?
    Got to watch that mythbusters episode.

    i´m not talking about that usual bungee stuff tho, that is used to slow a falling human down, i´m talking about the other way:

    http://www.youtube.com/watch?v=rOvzkXDYSRc
    http://www.youtube.com/watch?v=2W43qK0vETI

    i bet those ball is calculated with 300kg, if not more.

    andreas you are right btw, i bet 1/3 of theraband is sold for slingshot use only...i haven´t heard of it before too, just saw it in a nivea commercial once.

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  53. The bungee stuff needs really long stretching.

    In my cannon, 1,10 meter of theband is stretched to roughly 6 meters. If you take 1,10 of the bungee cord, the power is very limited.

    It is the rubber in the bungee cord that delivers the energy. But there are textile components in it, too. These slow down the shot. The more pure the latex, the faster the shot. For bungee, you don't want ultra fast speed (because of the dangers). You want a nice, slow swinging motion.

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  54. If only I had a large workshop space to build things like this! But will it toss a 45lb Olympic plate 100 yards or more? Let's hope so.

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  55. this will be a great thing, but you need to consider the mechanism of sorting out, for the transport of

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  56. What's your cost estimate on rubber?
    How much do you think you will need?

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  57. soon youll have enough slingshot rifles crossbows and now artillery to make your own army! it won't be long now before you have your own tank!

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  58. soon youll have enough slingshot rifles crossbows and now artillery to make your own army! it won't be long now before you have your own tank!

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  59. Biggest project yet I like it!

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  60. Cant wait for this 1 to be finished :D

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  61. I have to agree to anthraxx: You ARE nuts....I love it!!

    Wow. Last year You fired 8cm steelballs at small white cars. This year it's gonna be a 33cm stone! I guess next year You will fire small white cars from a giant trebuchet with half a mile of Theraband instead of the weights :D

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  62. Jörg?.....You know that trebuchet/car idea was a joke right?....


    ...stupid me, what have I done??

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  63. Love this new project man..greetings from Brazil!

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