distance straight up

Discussion in 'Handguns: General Discussion' started by deadeye dick, Jul 4, 2016.

Thread Status:
Not open for further replies.
  1. Longhorn 76

    Longhorn 76 Member

    Joined:
    Feb 17, 2012
    Messages:
    237
    Location:
    South Carolina
    VACUUM! Damn it! At least spell it correctly.
     
  2. JTQ

    JTQ Member

    Joined:
    Apr 6, 2009
    Messages:
    8,482
    Location:
    NW Florida
    Spelled it wrong, man, that sucks.
     
  3. Acera

    Acera Member

    Joined:
    May 26, 2007
    Messages:
    3,169
    Location:
    Free State of Texas
    It is, at least you recognize your own issues...................
     
  4. JohnKSa

    JohnKSa Moderator Staff Member

    Joined:
    Jan 1, 2003
    Messages:
    16,741
    Location:
    DFW Area
    Hatcher's testing conclusively demonstrated that some bullets DO remain stable and fall back base first. Those are considerably more aerodynamic than the ones that tumble.
    In a vacuum, the final downward velocity would be identical to the muzzle velocity. In the atmosphere, considerable energy is lost to friction. As a result, the final energy will be based on terminal velocity which is completely independent of the initial muzzle velocity.

    When the bullet fired STRAIGHT up stops at the top of travel, it then accelerates downward under the force of gravity until the air resistance matches the force exerted by gravity. That is terminal velocity.

    For a tumbling bullet, that's about 150-200fps based on testing Mythbusters did. That's really quite unlikely to be lethal.

    For a bullet that remains spin-stabilized and falls base first, the velocity could be much higher--perhaps 300-400fps or maybe higher based on Hatcher's testing. That could easily be lethal under the proper circumstances.

    If the bullet is fired at a steep angle, but not directly upwards then that's another story. Then the bullet will retain some horizontal velocity, will likely remain spin-stabilized, and will also acquire downward velocity from gravity. The total velocity will be the vector sum of the horizontal and vertical velocity which would definitely have lethal potential.
     
  5. Steve Cover

    Steve Cover Member

    Joined:
    Feb 25, 2010
    Messages:
    226
    Location:
    Colville (NE) Washington State
    I'd have to dispute that.

    Any properly stabilized bullet will hit the ground before losing all of it's angular momentum.

    Hatcher did experiments in the 1930s where bullets were shot straight up.
    Normal bullets came back to earth aligned vertically tail first.
    By ballistic calculation they would have only lost about 30% of their original spin.

    Some experimental longer bullets were also fired, but the rifling in the machine gun was not fast enough to stabilize them and they tumbled in flight and landed on their sides.

    It was not because they ran out of spin, but were just not spun fast enough to stabilize.
    When a bullet key holes a target do you believe that it is because the spin induced by the rifling has stopped?

    You will have to offer some documentation to make me believe that properly stabilized bullets will tumble out of the sky.
    (Please don't reference the Mythbusters episode as proof. That has already been proved to be a flawed test)

    Steve
     
    Last edited: Jul 6, 2016
  6. JohnKSa

    JohnKSa Moderator Staff Member

    Joined:
    Jan 1, 2003
    Messages:
    16,741
    Location:
    DFW Area
    In Hatcher's testing, some rifle bullets remained stabilized, others did not. His testing with the .30-06 caliber showed that 150gr bullets remained stabilized and hit base first while 175gr bullets tested started tumbling at some point on the way back down.

    Mythbusters did some testing with pistols and found that the pistol bullet they were able to recover (only one bullet and one caliber tested) had begun tumbling at some point before impact. They were unable to recover any rifle bullets, but assumed that they would tumble as well.
     
  7. Steve Cover

    Steve Cover Member

    Joined:
    Feb 25, 2010
    Messages:
    226
    Location:
    Colville (NE) Washington State
    Quite true about the Hatcher tests.

    I didn't want to get into chapter and verse about the test.
    Hatcher found that the longer bullets needed faster rifling to stabilize.

    For example: When the U.S. Army dropped the 55 grain bullet in the 5.56 cartridge and went to several different heavier bullets, the had to re barrel all the M-16s with faster twist rifling barrels.
    Longer bullets need to spin faster to stay stabilized.

    The Mythbusters test not only did not have a statistically significant quantity of results to be taken seriously, but also was sloppy in getting the bore aligned vertically.

    A properly stabilized bullet will keep it's nose oriented in the direction of travel as the trajectory bends.
    (Think about the nose orientation of a football during a long pass as an example. The rotating football axis stays oriented to its line of travel as it arches over.)
    A bullet not perfectly vertical to gravity will try to do the same thing as it starts to come over the top of its arch.
    In this case the arch being so extreme, the bullet only achieved around 90 degrees by the time it hit the ground.
    However, it for sure wasn't tumbling.

    For anyone interested, I can provide the address of a discussion that goes pretty deep into this, discussing all the forces involved and the math behind them.

    But really, just accept the fact that a properly stabilized bullet will remain stabilized for longer than its flight time when shot in any direction and will not suddenly start tumbling out of the sky.

    Steve
     
    Last edited: Jul 7, 2016
  8. Twiki357

    Twiki357 Member

    Joined:
    Jan 26, 2011
    Messages:
    2,035
    Location:
    Prescott Valley, AZ
    All these technical explanations are interesting, and quite frankly, don’t seem to come to any consensus. I do know that during the 1980s and 1990s when I lived in Los Angeles, I picked at least 15+ bullets out of my asphalt shingle roof. Mostly 9mm, but a couple of 30 calibers also hit. They all hit nose first. They would penetrate the asphalt shingle and expose a tad bit of wood. I have no idea what angle (Or straight up) they were fired at, but it indicates to me that they had a lot less energy coming down than they had going up.
     
  9. Vern Humphrey

    Vern Humphrey Member

    Joined:
    Dec 30, 2002
    Messages:
    20,202
    Location:
    Deep in the Ozarks
    During Tet of 1967, I was TOC officer on night duty and a .45 bullet came through the roof of the TOC and left a dent on the desk in front of me.
     
  10. redbone

    redbone Member

    Joined:
    Dec 24, 2002
    Messages:
    408
    Location:
    High ground
    VH: curious what the roofing material was?

    Tnx.

    RBH
     
  11. Vern Humphrey

    Vern Humphrey Member

    Joined:
    Dec 30, 2002
    Messages:
    20,202
    Location:
    Deep in the Ozarks
    Thatch -- palm leaves and stuff.
     
  12. redbone

    redbone Member

    Joined:
    Dec 24, 2002
    Messages:
    408
    Location:
    High ground
    Roger that. Tnx.
     
  13. 45_auto

    45_auto Member

    Joined:
    Jan 3, 2011
    Messages:
    2,168
    Location:
    Southern Louisiana
    Well, did it hit nose first or was it tumbling? Don't leave us wondering!
     
  14. 200Apples
    • Contributing Member

    200Apples Member

    Joined:
    Jul 6, 2013
    Messages:
    1,456
    Location:
    Los Angeles
    .
    Was it the F-14 or the F-15 that was the first aircraft able to accelerate in a directly-vertical climb?

    What... oh. Nevermind. Because firearms.
     
    Last edited: Jul 8, 2016
  15. Vern Humphrey

    Vern Humphrey Member

    Joined:
    Dec 30, 2002
    Messages:
    20,202
    Location:
    Deep in the Ozarks
    How would I know? It hit WHACK! without any warning, and scared the **** out of me. But the dent looked like it hit nose first.
     
  16. Steve Cover

    Steve Cover Member

    Joined:
    Feb 25, 2010
    Messages:
    226
    Location:
    Colville (NE) Washington State
    I was flying gunships out of Bear Cat.
    I'm sure that all the minigun fire landed nose first.

    Steve
     
  17. Vern Humphrey

    Vern Humphrey Member

    Joined:
    Dec 30, 2002
    Messages:
    20,202
    Location:
    Deep in the Ozarks
    I was at Xuan Loc -- and yes, the minigun rounds impacted point first, and went ricocheting off. With tracer it was a spectacular show. Spooky, though was even more spectacular.
     
Thread Status:
Not open for further replies.
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice