Speargun Tip Testing in Air

  • Ok,


    I need some help from the experts. I'm a polespear and pneumatic gun guy. I do have my bluewater Koah gun, I've never shot a band gun in the back yard.


    Anyway. I got this beater speargun US-Diver I got off of ebay for like $20 . It's like 2 foot long. Anyway it can handle 3 bands.


    My goal was to collect some data on a new spear point that can crack rocks. Been doing to much metallurgy reading at night and get too many new ideas...


    Back to topic, I got rid of the line, I made a new fitting that fit on the shaft that sits in the muzzle. Made a quick part to hold the tricut point material I want to test.


    I started with one band and was like 20 foot back from 2' x 3' 1/8" thick Steel plate. 1st shot dropped into the dirt. Anyway I added second band and got closer. some of the shots the shaft hit the plate sideways.


    Shots were all over the place, I got a couple hits, but nothing consistent Like I wanted. I finally went to 3 bands.


    The spear shaft was totally bend at the 3rd notch closest to the tip. I'm not sure if it was from the exit from the gun, or the bounce off the ground. My Son said the shaft was crazy looking in flight, meaning it was worse than the other ones.


    At this Point I went for Pole spear and piledrived the Steel plate and the tip did really good. Going to shoot some hard rocks later in the week for a better test.


    Any thoughts on what I was doing wrong using the speargun. I can't be the 1st to shoot one out of the water. The lack of line and drag must have changed the dynamics of the flight, the bent shaft, not sure.


    The gun and shaft and outside in the dirt. I'll retrieve and post pictures if that will help.

  • Lot that can go wrong with your experiment. I'll assume you know the risks and dangers and not try to convince you it is a bad idea


    I think that the spear behaves differently out of water due to the reduced density. Like an arrow with no flights, it has a hard time tracking

    i like to spear fish

  • I was way back in beginning, plywood barriers, Safety glasses and the such. metal fragments flying was my biggest concern.


    The Pole spear worked great, I had control of it's flight, I just had to be closer.... Why I went for beater speargun first.

  • Maybe you could mount the speartip with a vice or "C" clamp and launch the rocks at it via a pendulum...


    That was talked about, I wanted higher contact speed.


    I was going to do that to test the 12 gauge bang stick I got, using a 1 gal jug of water. I never did run that test.

  • Linghunt--First is would suggest that you do your R/D in a water environment to more accurately simulate real life spear gun/shaft conditions.
    Next I might suggest using an underwater camera to record your spear flight. Playing back your spear flight video in slow motion to truelly be able to visualize what your spear flight looks like would be a HUGE asset.
    Hope this helps

  • Here is the gun. Maybe the two rear bands bent the shaft before it left gun. Maybe it bent bouncing off the ground.


    It left the gun all crazy like, makes me think something went wrong before it left gun. Gun is old US Diver beater gun called a Sea Hunter.


  • If you only testing the tips then clamp down the gun a little more than a shaft length from your steel plate and use a long rope around the trigger so you can be at a safe distance when firing.


    Your right, Clamp the gun put the rock in front of it so I'm having contact when the shaft is like 6 - 12 inches from Muzzle.


    I can get a "Cool Hand Luke" string to do trigger pull . Flying rock or metal fragments is a concern.


    I should break out the video camera too.

    Edited once, last by Linghunt: typo ().

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