Quantcast
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

The THOR Armor Penetration Algorithm

Discussion in 'Rifle Country' started by 481, Apr 8, 2013.

Thread Status:
Not open for further replies.
  1. 481

    481 Member

    Joined:
    Feb 22, 2009
    Messages:
    1,971
    Lately, I have been testing out the ability of 7.62x39 ammo to get through mild steel plate and have seen it make it through 1/2" plate (12.7 mm), and on some occasions, when using steel core ammo, through 3/4" (19 mm) mild steel plate at close range.

    Being the nerdy, "math-geek" type of shooter that I am, when I stumbled upon the THOR armor penetration algorithm-

    V[sub]r[/sub] = V[sub]i[/sub] – 10[sup]α[/sup] x hA[sup]β[/sup] x M[sup]γ[/sup] x V[sub]i[/sub][sup]δ[/sup] x (sec Ф)[sup]x[/sup]

    -I just had to see how it did when compared to my results.

    Using a penetration curve generated by the THOR algorithm, the table predicts the performance of 7.62x39 FMJs against mild steel plate from the muzzle (2330 fps) to 100 yards (2050 fps) and 200 yards (1750 fps) and agrees with a lot of what I have seen so far.

    THORArmorPenetrationAlgorithm21APRIL1961_17655_image001_zps6ea738f1.gif

    So far nothing has gotten through the 3/4" thick mild steel plate beyond 25 yards (~2275 fps) as predicted by the THOR algorithm and at (much) closer ranges, I have seen the round (most of it steel core, not surprisingly) make it through 3/4" mild steel plate.

    For the sake of comparison, here is how .50BMG M2AP (even if it is a bit of a stretch with an L/D of ~4.5) fares against both mild steel and rolled homogenous armor (RHA) according to the THOR algorithm-

    THORArmorPenetrationAlgorithm50BMGRHAvLowCarbSteel_image001_zpsa6969c7d.gif




    *A note of caution and my disclaimer: For those contemplating shooting at any steel plate with any firearm- it is extremely dangerous and should not be done at close range without adequate protection. Rifle bullets (and in many cases, pistol bullets) can rebound from the steel plate face with enough velocity to cause serious injury or death. Just because I am silly enough to do so (behind some serious cover- I ain't that crazy!) does not mean that I recommend such behavior. Neither I, nor THR, is responsible for the injury or death of anyone who elects to engage in this dangerous activity. Please don't do it. ;)
     
    Last edited: Apr 8, 2013
  2. joeschmoe

    joeschmoe Member

    Joined:
    Dec 27, 2012
    Messages:
    1,291
    In what application is mild steel plate used as armor? None that I can think of.
     
  3. zhyla

    zhyla Member

    Joined:
    Jul 12, 2009
    Messages:
    894
    cimg3370-armor-suit-with-bullet-hole.jpg
     
  4. wally

    wally Member

    Joined:
    Jan 2, 2004
    Messages:
    12,750
    Location:
    Houston, Tx
    Yup, and it wasn't generally effective against the firearms of its era!
     
  5. PlaneJain

    PlaneJain Member

    Joined:
    Feb 26, 2013
    Messages:
    121
    Location:
    A liddo Northwest of you
    What is going to keep the bullet fragments from ripping out your throat?
     
  6. 481

    481 Member

    Joined:
    Feb 22, 2009
    Messages:
    1,971
    The THOR algorithm has available several target material coefficients for the following metals and alloys -magnesium alloy, 2024 T4/T3 aluminum, Ti6Al4V titanium, cast iron, mild steel, RHA, FHA, pure copper, lead, and uranium- some of which are not used for armor. The model is used to evaluate penetration against these alloys, but such evaluation does not imply that they must be used as armor.

    The model can also be successfully used to evaluate the terminal performance of projectiles with L/D ≤ 3 against those alloys. The 7.62x39 projectiles that I am using have an L/D of 2.87 (L=0.893"/D=0.311").
     
    Last edited: Apr 8, 2013
Thread Status:
Not open for further replies.

Share This Page