Stories
Slash Boxes
Comments

SoylentNews is people

posted by Fnord666 on Monday July 20 2020, @12:18PM   Printer-friendly

Scientists 3D print gunpowder substitute, achieve 420m/s bullet velocity - 3D Printing Industry:

Researchers from the Xi'an Modern Chemistry Research Institute in China have 3D printed a functional gun propellant using SLA technology. The gunpowder-esque substance is a carefully constructed blend of photopolymer resin, RDX (a high explosive), and other reactive additives. Initial gun testing of the 3D printed propellant has garnered some promising results, as the scientists managed to achieve a more-than-lethal muzzle velocity of 420m/s. This, of course, depends on your definition of 'promising'.

[...] Currently, the main ways to improve the ballistic efficiency and damage potential of propellants are to increase the burning surface or the burning rate. This is commonly done by foaming the propellants, coating them, or packing them in their casings in selective layers. According to the researchers, simply filling the cylindrical casing with a granular propellant works but is quite limited in its energy release efficiency. So, the team looked to 3D printing to see if it could pack a greater punch.

[...] Once the UV safety of the newly formulated explosive was confirmed, the team 3D printed a set of thin disks, each about 40mm in diameter. These disks could be stacked on top of each other to form a longer cylinder, resembling the body of a bullet casing. Each layer featured a honeycomb-like structure with holes and was about 5mm thick.

Then came time for the grand finale – the gun test. The cylindrical stack was loaded into a 30mm barrel with a 200g mass acting as the bullet, although at 200g it's probably closer to a mini cannonball. The team set up a high speed camera and an internal pressure gauge in the barrel before pulling the trigger. Once the smoke cleared, the researchers calculated a rather high pressure exponent value of 1.46 and a muzzle velocity of 420m/s, with plans to increase the chamber pressure in future tests.

Journal Reference:
Weitao Yang, Rui Hu, Lin Zheng, Guanghu Yan, Wenrong Yan. Fabrication and investigation of 3D-printed gun propellants [open], Materials & Design (DOI: 10.1016/j.matdes.2020.108761)


Original Submission

 
This discussion has been archived. No new comments can be posted.
Display Options Threshold/Breakthrough Mark All as Read Mark All as Unread
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
  • (Score: 5, Informative) by Booga1 on Monday July 20 2020, @01:06PM (11 children)

    by Booga1 (6333) on Monday July 20 2020, @01:06PM (#1024073)

    The cylindrical stack was loaded into a 30mm barrel with a 200g mass acting as the bullet, although at 200g it's probably closer to a mini cannonball.

    Yeah, that's not a bullet. Here's what some common caliber bullets are like(quick sourced off Wikipedia):

    • .22 long rifle: 2.6 g @ 370 m/s
    • .380 ACP: 6 g @ 312 m/s
    • 9mm: 7.45 g @ 360 m/s
    • .44 magnum: 16 g @ 450 m/s
    • .223: 3.5 g @ 990 m/s
    • 7.62×39mm: 10 g @ 641 m/s
    • .308: 11 g @ 810 m/s
    • .50 BMG: 42 g @ 923 m/s

    So, their bullet is about five times the size of the largest of what I would consider "normal" calibers in common usage. Still, the velocity holds up to subsonic handgun ammo.

    Starting Score:    1  point
    Moderation   +3  
       Interesting=1, Informative=2, Total=3
    Extra 'Informative' Modifier   0  
    Karma-Bonus Modifier   +1  

    Total Score:   5  
  • (Score: 2) by Booga1 on Monday July 20 2020, @01:14PM (2 children)

    by Booga1 (6333) on Monday July 20 2020, @01:14PM (#1024075)

    Apologies for the short post, but I apparently mus-remembered the speed of sound which about 343 m/s, depending on altitude and temperature of course. So, strike the word subsonic off the comment...

    • (Score: 4, Interesting) by JoeMerchant on Monday July 20 2020, @01:19PM (1 child)

      by JoeMerchant (3937) on Monday July 20 2020, @01:19PM (#1024078)

      What I find lacking in TFS is a comparison of how standard gunpowder would perform in a similar application (equivalent volume of gunpowder propelling the same mass out of the same barrel...)

      --
      🌻🌻 [google.com]
      • (Score: 2, Funny) by Anonymous Coward on Monday July 20 2020, @02:01PM

        by Anonymous Coward on Monday July 20 2020, @02:01PM (#1024110)

        I think the whole thing is a ploy by the Chinese to get Americans to try this and blow themselves up.

  • (Score: 3, Informative) by Muad'Dave on Monday July 20 2020, @01:17PM

    by Muad'Dave (1413) on Monday July 20 2020, @01:17PM (#1024076)

    Looking at the energy of that projectile, we get E = 0.5 m * v^2. For 0.2kg and 420 m/s that's 17.64 kJ. That's very close to the same as your .50 BMG bullet at the speed you specified.

  • (Score: 3, Informative) by c0lo on Monday July 20 2020, @01:25PM (2 children)

    by c0lo (156) Subscriber Badge on Monday July 20 2020, @01:25PM (#1024081) Journal

    .50 BMG: 42 g @ 923 m/s

    That's 179kJ

    By comparison, this one has an energy of 17.6kJ

    --
    https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
    • (Score: 3, Informative) by c0lo on Monday July 20 2020, @01:30PM (1 child)

      by c0lo (156) Subscriber Badge on Monday July 20 2020, @01:30PM (#1024086) Journal

      I'm off by one order of magnitude for BMG: 0.042*923*923/2 = 17890 J [google.com]

      --
      https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
      • (Score: 3, Funny) by Booga1 on Monday July 20 2020, @01:33PM

        by Booga1 (6333) on Monday July 20 2020, @01:33PM (#1024090)

        Just missing a . is all. Such a little, trifling thing. I'm sure nobody will notice around here. ;)

  • (Score: 1, Informative) by Anonymous Coward on Monday July 20 2020, @01:26PM (3 children)

    by Anonymous Coward on Monday July 20 2020, @01:26PM (#1024082)

    And it was a 30mm barrel. The largest caliber in your list was the 50 BMG, which is 1/2 inch. or about 12.5 mm. What they used was much bigger than any gun you'd find in use today - outside of heavy military ordinance, or mini-cannons.

    They also didn't mention barrel LENGTH. Barrel length is vital for bullet velocities. The longer the barrel, the longer the force is applied to the bullet, and the faster it goes. Once a bullet leaves the barrel it starts to slow down. Yes, assuming pressure can be maintained in the barrel behind the projectile, etc., etc.

    • (Score: 1, Informative) by Anonymous Coward on Monday July 20 2020, @03:44PM (1 child)

      by Anonymous Coward on Monday July 20 2020, @03:44PM (#1024141)

      A little historical context, 30mm is the size of heavy WW2-era aircraft cannon designed to bring down heavy bombers or occasionally for ground attack. It is also the caliber of the GAU Gatling gun used on the A-10. More ordinary aircraft mounted cannon are 20mm. So, this is a military weapon only at current size.

      • (Score: 2) by Booga1 on Monday July 20 2020, @11:11PM

        by Booga1 (6333) on Monday July 20 2020, @11:11PM (#1024307)

        Now ya done gone and made me look it up. The A-10's GAU-8 Avenger uses 30×173mm according to Wikipedia. [wikipedia.org] I found this ammunition brochure [gd-ots.com] for the caliber, but I'm not 100% sure it's the exact stuff the A-10 uses. Still, it's at least a ballpark for the caliber.

        Here's a couple of examples from the brochure:

        • 140 g @ 1600 m/s
        • 388 g @ 1090 m/s

        So, faster and with weights above and below their 200 g projectile. Though, nobody would want to be on the receiving side of any of that!

    • (Score: 0) by Anonymous Coward on Tuesday July 21 2020, @07:01AM

      by Anonymous Coward on Tuesday July 21 2020, @07:01AM (#1024488)

      The longer the barrel, the longer the force is applied to the bullet, and the faster it goes.

      Until bore friction causes the bullet to fuse to the barrel, creating a blockage, and a bomb instead of a gun. Or, as with Germans, you barrel is so long it droops. They call it, "The angle of the ballistics".

      But, everyone is ignoring the nitro in the room! It's 3D printed! Put that in your 3D printed gun you downloaded off the internets, along with some 3D printed bullets, and 3D printed casing and primer, and smoke it! Oooogh, 3D printed concealed carry rig? 3D printed butt-plugs! And 3D printed, . . . never mind.