Michael's UV Resin slugs have weird aerodynamics
Added 2020-10-01 18:01:12 +0000 UTCThis is definitely a testimonial to the strength of the 3D printing resin Michael used. I could not fit more powder into the 3" hull and still chamber them in Gregg's shotgun. We pushed these as hard as I could using rather fast burning powders (e3 and Titewad) and almost reached Mach 2. Around 2100 fps. We mostly used a full-rifled barrel to get these spinning but they had a side-effect of cork-screwing STRANGELY through the air.
Be sure to watch the long-range tests near the end.
Comments
This may not be due to the shape alone. Reference Holdover vlog: He's shown that overpowering many kinds of pellets makes them spiral. I'd be curious to see if the light weight of the resin is responsible and if a lead or brass round would fly straight with the correct weight and powder load.
Desistx
2020-10-06 13:06:36 +0000 UTCGives a new meaning to "accuracy nodes": if your target happens to be at a distance where this thing has a zero-crossing with your point of aim, it is MONEY.
Ryan Simpson
2020-10-02 22:15:41 +0000 UTClol
TAOFLEDERMAUS
2020-10-02 22:07:22 +0000 UTClol
TAOFLEDERMAUS
2020-10-02 22:07:08 +0000 UTCwe tried a rifled choke giving is very little spin and it hit backwards. A bullet shape projectile will always need spin for stability.
TAOFLEDERMAUS
2020-10-02 22:06:56 +0000 UTClol
TAOFLEDERMAUS
2020-10-02 22:06:05 +0000 UTCexcellent points!
TAOFLEDERMAUS
2020-10-02 22:05:59 +0000 UTCCool....a projectile that knows how to do evasive manoeuvres, try stopping that one with another bullet or a sword! Those are completely normal ways to stop a bullet/projectile right? RIGHT? :|
Buzzin
2020-10-02 15:15:15 +0000 UTCDid you try a smooth bore and I missed it?
Scott Cress
2020-10-02 14:27:14 +0000 UTCI wonder if the barrel and projectile even twisted in the same direction
Tim Matthews
2020-10-01 22:55:47 +0000 UTCBad at 20 and 40? Try odd number distance,,,,,,,,,,,,like 3 yards.
2020-10-01 22:51:40 +0000 UTCSo light it zigged and zagged like an empty canoe in rapids. Amazing
2020-10-01 21:32:34 +0000 UTCAbout a year or two ago, I read an external ballistics paper that documented similar instability in, of all things, 5.56mm Nato ammunition. I think it was related to a test of rifling twist in general, but the bullets were "overstabilized" and followed a similar, but damped, corkscrew flight pattern - centered on a barrel axis extension line - until some few yards out of the muzzle before settling down to a normal flight. At the end of the bullet's trajectory, it destabilized once again - as it passed through to subsonic velocity - and resumed a corkscrew flight pattern, that increased with distance. It suggests that - for these lightweight, long, large bore bullet-shaped projectiles - there is some combination of rifling twist and muzzle velocity (i.e., spin rate) that would produce a stable flight pattern (assuming that the bullets themselves are reasonably well-balanced). It would be interesting to figure out what that twist rate is for these projectiles; I'd guess a very slow twist. I also think that the spiral grooves on the nose were meant for firing from a smoothbore; out of a rifled barrel, I'd think an uninterrupted, smooth ogive would introduce fewer complications. Interesting video, as always.
George Steele
2020-10-01 20:39:47 +0000 UTCI can't believe that Gregg didn't say "failure & mediocrity" which was also the name of an 80's grunge band I was in. Great vid!
Aaron Neumeyer
2020-10-01 18:53:48 +0000 UTC
