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    1000 lb. plus crossbow...

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    olrono
    Techno Weeny

    Lets put a laser on it!!!


    Techno WeenyLets put a laser on it!!!

    Posts : 54
    Join date : 2011-05-11

    1000 lb. plus crossbow...

    Post by olrono on Thu Oct 18, 2012 7:30 pm

    First topic message reminder :

    I don't want to make the same old stuff
    again that every one here has made before. So, what is it that none
    of you guy's has ever made or even seen? A 1000 lb. PLUS crossbow!

    I intend to have the spring made for me
    by a spring fabricator that makes and repairs heavy equipment. I
    am thinking the bow stave will be over all length 40” and 3”
    wide and ½ inch thick! The tiller will be made as a platform to
    accommodate this bow and not necessary pretty. I will use a


    4 x 6 Douglas fir with 1/4” steel
    plate on the sides from the 'bow notch' up to the lock. The 'roller
    lock' will be made from steel. I am thinking the socket will have to
    be made from a solid metal block with a hole in front of and behind
    the socket to be mounted between the side plates with bolts to hold
    this tremendous force. Even the axle for the tickler will have to go
    through these heavy side plates.

    The bow it self will be attached to the
    front of the tiller with the same size U-bolts that hold them on an
    axle of a semi trailer. A 2” pipe will go through the tiller and
    side plates about 10 inches from the bow notch and the 'round' part
    of the U-bolts will be held on the pipe there. A steel plate or
    saddle will hold the bow stave on front with four holes that the
    U-bolts pass through and can be 'torqued' to this arrangement and
    'checked' at anytime.

    The only area that I am not that sure
    of is the size of the roller and the tickler were the sear and
    release take place? Every thing else is very solid and I don't want
    this monster to explode in this weak area.

    I want this thing when it is fired to
    make a very loud bang and see a little 'smoke' come off it. If you
    know what I mean? Can't wait to read your comments on this one...
    Rolling Eyes

    JoergS
    Tinkerer

    If there is a will, there is a way.


    TinkererIf there is a will, there  is a way.

    Posts : 69
    Join date : 2011-09-07

    Re: 1000 lb. plus crossbow...

    Post by JoergS on Wed Oct 24, 2012 9:20 pm

    If you want to shoot ANYTHING 1,000 yards far, you will need to shoot it with very high speed.

    I guess that you will have to achieve at least 750 to 1000 fps to get to that distance - if you use a very streamlined projectile (like a non tumbling bolt).

    I see no way how you can possibly achieve that with a crossbow. As Geezer said, you CAN shoot very heavy objects at 200 fps if you use a powerful spring (which will send your bolt easily 250 yards far). But you won't see 750 fps.

    I use rubber as a power storage/conversion media, which allows a far, far longer draw at much lower draw weights. I just came home from a TV job in South Carolina, where I made a 15 ft long brick launcher. It shoots a 4.4 lb brick at 164 fps. Draw weight is 475 lb. Power stroke is 100".

    http://www.zombiehunters.org/forum/viewtopic.php?f=33&t=101021

    If you can achieve a similar result with a 1,000 lb steel spring at 14" power stroke, you would be very lucky.

    It is as Geezer said - for performance in the dimension you are looking for, you need expanding gas.

    But anyway, your project sounds like a LOT of fun, and by all means go ahead with it. It will be mighty, even if you won't reach your lofty performance goals!

    MRobin
    Tinkerer

    If there is a will, there is a way.


    TinkererIf there is a will, there  is a way.

    Posts : 67
    Join date : 2012-09-01
    Age : 28
    Location : Paris, France

    Re: 1000 lb. plus crossbow...

    Post by MRobin on Thu Oct 25, 2012 1:02 am

    1000 yards may be possible with very thick bow limbs, either made from spring steel or composite, and a compound system that allows huge powerstroke (like 30") for minimal bow deformation. Won't be easy though, and you will have to be very careful with the strenght of your design, a crash would be harmful.

    This guy is very close to the 1000 yard range :
    http://wattsunique.com/blog/?paged=1 Not hand-held, though. And this is a scorpio, no bow technology here
    avatar
    Geezer
    Master Crossbowyer
    Master Crossbowyer

    Posts : 1013
    Join date : 2010-01-12
    Age : 70
    Location : Austin, Texas, USA

    Re: 1000 lb. plus crossbow...

    Post by Geezer on Thu Oct 25, 2012 7:32 am

    This guy's 'Scorpion' (ballista) is pretty durned impressive. He's getting @ 400 fps and ranges of 890 yards. Note his bolts are the correct Roman pattern, with laminar-flow along their wedge-spindle shape and correct balance. Good work from a well engineered torsion-bundle machine! Geezer.
    http://wattsunique.com/blog/?paged=1

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