It is probably a good job that we are located out in the boonies and have miles of wilderness to cavort in.  Firefly  managed to chuck the last of my old Gallwey bolts a bare inch over the top of the backstop today.  That worthy projectile shattered itself into pieces as it’s blunt tip ploughed 3 inches deep into a pine tree.   The Becky is dangerously protective of her trees.   Fortunately for me,  the pine in question had sustained heavy damage from a windstorm and was slated to be cut down for firewood anyway.   The chron0graph showed that this 5,000 grain bolt was trundling along at 245.5  fps.  That kind of speed is pretty low.    On the other hand,  I had only increased the washer rotation by 7 1/2 degrees from the 220 fps achieved on Sunday,  for a net increase of 25 fps.   Yesterday’s prediction on where the Wheatie meter would be after another 7 1/2 degrees of  rotation, was off a bit.   I am still able to shift the limbs away from the stanchions by 3/4″.   This is good.   Very good.   It means I haven’t entered the serious power zone for these new springs and yet we are still churning out over 669 foot pounds of energy.  None of my previous testing has shown anywhere near this much promise at this early stage of tuning.

Further testing will have to wait until I make up some more bolts.   Also,  a new synthetic winch cable has been ordered.  The old one made from wire rope jabbed my hand pretty deeply today,  so I will back off more testing until next week when the new cable arrives.

One Response to “The wild, wild West.”

  1. Joel Maki says:

    I would love to see more data from testing. Instead or spring rotation, see draw length, pull in lbs, and resulting speed. It would also be very helpful to give limb arc in degrees as well.

    I anxiously visit and read your site almost everyday. Here is a link to a blog page that I did in the hope you would read it and think about it. It concerns limb length and spacing, pointing out some very interesting data for you to use.

    I really really admire your work and wish you were the one to build my prototypes. There is so much you would learn by doing that, and easily break that 400fps barrier with a fraction of the power you currently use.

    It be cool if you were at least polite enough to acknowledge reciept of my posts or emails, even if you just wrote to tell to **** – off and stop writing.

    On the link I provided, I also included data from a compound design so you would be able to judge for yourself whether you need a compounding design to break 500fps or whether it is even possible.

    Im getting great results from a 1800 grain arrow and 25 lbs of pull on a little hand held inswinger ballista bow.

    Good luck NIck, I hope you attain your goal of 400fps. With 4000lbs pull and 5000grain durabolt it works out to 1.25 grains per lbs of thrust. Your previous 394fps at 3600 lbs thrust worked out to 1.2 grains per lbs of thrust.

    I still say you need a much heavier projectile 10,000 to 20,000 grains to gain benefit from those monster limbs and rope bundle spacing, which IMHO is a rock hurling set up.

    Good luck and I will be following!

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