Here is a real time video of today’s test recorded by using the new radio control unit for the camera.  It was able to trigger the camera to capture the bolt plunging through the same target as yesterday.  The only purpose of this remote set up is to save on the wear, tear, and possible perforation of the cameraman.   Like yesterday, range is 50 yards.  20100306160111(1)

Before its saunter downrange,  here is what today’s 33 1/2 ” long bolt looked like.

After the bolt’s momentary disagreement with the archery backstop,  here’s how the fins faired.

Velocity of this shot was down from yesterday as the bundles are still normalizing themselves to the new torque setting.  Stats are:  draw weight 4700 lbs., draw length 42″, bolt weight 6929 grains, velocity 310.6 fps,   energy 1484  foot lbs.

Some disturbance in the bolt flight was still visible.  The tale end appeared to spiral around the central axis a bit.  Tomorrow we will try bigger fins.  How retro.

2 Responses to “First long range remote vid.”

  1. 5:19 pm, 7 March, 2010 р.
    Samuli Seppänen says:

    Hi,

    I posted a few suggestions on how to further improve your ballista performance here:

    http://www.romanarmytalk.com/rat/viewtopic.php?f=17&t=25970&start=20

    Don’t hesitate to contact me if you need any help with your project. Keep up the great work!

  2. 6:51 pm, 7 March, 2010 р.
    Captn Harpoon says:

    HEY…nice shooting. Loved the stats. It appears to me like you are in a nice position to challenge laws of physics, and also help me with the theory that perhaps 90 degrees was the outside range used. More likely 70 degrees of rotation like you shot!

    If you were to tighten those bundles so that 4700lbs of pull occurred at 60 degrees of rotation (limb arc) or earlier Im thinkin that a further increase in velocity might be had.

    If you look at the data I sent you there a column that deals with degrees of lever arc to draw in inches. Its actually an effeciency study. It shows you where in-effeciency is put into the equation. Its hard data.

    The hard data puts me at odds with the laws of physics that says the more limb arc the higher energy potential. None the less the data intrigues me. I’ve always suspected a small lever movement was made when the machine is at its most effecient in converting energy to velocity.

    The string must double its speed during the last 32 degrees right? So where does it make sense to apply the most power to? Consider giving it a try. Hitting 4700lbs pull at 60 degrees or less would increase the amount of power available
    by at least 15% during the last 32 degrees where a lot of acceleration MUST take place.

    Call me nuts but it wont hurt to try. Beating the laws of physics aint for the faint hearted.LOL.

    By the way, I have just to congratulate you on your build. I dont know how much those limbs weigh, but the forces your machine must absorb is tremoundous. You do fine work.

    Joel.

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