Powder combustion vs altitude

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts
  • grayfox
    Chieftain
    • Jan 2017
    • 4295

    Powder combustion vs altitude

    At what altitude does a powder's completeness of combustion become a concern? Specifically, at 8000-9500 elevations, with the air thinner, naturally there would be less oxygen, so do some calibers have an issue with incomplete powder burn? What about faster vs slower burn-rate powders... Maybe for most cal's it's no problem, but anyone have some ideas? Thanks.
    "Down the floor, out the door, Go Brandon Go!!!!!"
  • IceAxe
    Warrior
    • Jan 2014
    • 168

    #2
    I don't believe it can have any effect on propellant burn as the oxidizer is present in its chemical composition.

    Comment

    • NugginFutz
      Chieftain
      • Aug 2013
      • 2622

      #3
      Fpni

      A cartridge will fire in an absolute vacuum.
      If it's true that we are here to help others, then what exactly are the others here for?

      Comment

      • sk8inrj1
        Unwashed
        • Apr 2017
        • 15

        #4
        and under water

        Comment

        • grayfox
          Chieftain
          • Jan 2017
          • 4295

          #5
          Interesting!! I didn't know it carries its own oxidizer... thought it needed some oxygen for the burn...
          "Down the floor, out the door, Go Brandon Go!!!!!"

          Comment

          • LRRPF52
            Super Moderator
            • Sep 2014
            • 8569

            #6
            It's a sealed cartridge. It doesn't know what altitude it's at.

            The 4 components constitute a sealed container with a combustible propellant inside, capped with a primer on one end, and a projectile machine-pressed into the neck.

            They are generally waterproof as well. A loaded cartridge has a very long shelf life. I've seen the 100yr figure before.
            NRA Basic, Pistol, Rifle, Shotgun, RSO

            CCW, CQM, DM, Long Range Rifle Instructor

            6.5 Grendel Reloading Handbooks & chamber brushes can be found here:

            www.AR15buildbox.com

            Comment

            • Cockednlocked
              Bloodstained
              • Jun 2016
              • 50

              #7
              Originally posted by grayfox View Post
              Interesting!! I didn't know it carries its own oxidizer... thought it needed some oxygen for the burn...
              It does need oxygen, just not atmospheric oxygen. When heat is applied in the form of flame or spark to ignite the powder, the decomposition releases the oxygen in the compound to support and accelerate the reaction. Nitrocellulose and nitroglycerin are the two major compounds in "smokeless" gunpowder, and are composed of carbon, hydrogen, oxygen and nitrogen. Nitrocellulose is used in single-base powders, nitroglycerin is added to that for double-base powders. There is also a 'triple base' powder that adds nitroguanidine, but those powders are generally used for large munitions such as artillery. The shape of the powder (disc, flake, ball, stick, or cylinder) and other chemicals added to the base mix for the specific purpose, determine the burn rate.

              Comment

              • sneaky one
                Chieftain
                • Mar 2011
                • 3077

                #8
                For all you aspiring astronauts- bring ammo and a rifle along, you can be safe on any planet.

                I would not go hotter than earth tho, Maybe a pressure spike? If hotter, find a way to keep ammo cool on trips outside...

                Comment

                • rickOshay
                  Warrior
                  • Apr 2012
                  • 784

                  #9
                  Just imagine how flat your trajectories will be on the moon.

                  Comment

                  • Drillboss
                    Warrior
                    • Jan 2015
                    • 894

                    #10
                    Originally posted by grayfox View Post
                    Interesting!! I didn't know it carries its own oxidizer... thought it needed some oxygen for the burn...
                    You actually knew the answer, you just hadn't thought about it. It's all a sealed combustion chamber until the bullet leaves the barrel.

                    Comment

                    • grayfox
                      Chieftain
                      • Jan 2017
                      • 4295

                      #11
                      Originally posted by Drillboss View Post
                      You actually knew the answer, you just hadn't thought about it. It's all a sealed combustion chamber until the bullet leaves the barrel.
                      Yeah basically... I know the cartridge is a loaded system and knew some basics about its chemical composition, but did not regard it as perfectly air-tight/ sealed... "somewhat sealed" is about where I put it. (Speaking about handloads and bulk commercial ammo, not the wax/sealant style ammo from some military mfrs.) So as one traveled from say sea level to 8000+ feet there seemed to be the possibility that over time the interior oxygen (air) in the case, which had been initially loaded with denser air, might equalize (via a slow diffusion across the bullet/case neck and/or primer/case boundary) with the high-altitude air and thus present a more rarified oxygen level when fired. I wasn't sure how much time it might take to "equalize." I also had heard about rounds being fired under water but only felt that that might speak to a sea-level quantity of O2 was sufficient... the water would increase back pressure of the combustion but wouldn't dilute the O2. So the gist of it seems to be that the powder itself carries its own O2; any contribution of the case interior is just "extra".
                      I hope it wasn't too dumb a question, I don't mind learning something new every day.
                      Thanks guys.
                      "Down the floor, out the door, Go Brandon Go!!!!!"

                      Comment

                      • grayfox
                        Chieftain
                        • Jan 2017
                        • 4295

                        #12
                        And, the more I think about it (as per DB), the more it does make sense... What I meant earlier in saying "oxidizer" - that was the wrong term, oxygen supply is what I really was thinking... as CockednLocked says. It also explains why powder burns so rapidly... and why underwater explosives work...
                        Ok, done beating a dead horse!!
                        "Down the floor, out the door, Go Brandon Go!!!!!"

                        Comment

                        • IceAxe
                          Warrior
                          • Jan 2014
                          • 168

                          #13
                          And not all explosives require oxygen. Consider one of the most sensitive contact explosives "Nitrogen Triiodide" when it is dried out of solution, you can set it off by placing a feather over it. It is basically NI3, a molecule composed of a Nitrogen atom bonded to three Iodine atoms via three single bonds. When detonated it becomes a fixed triple bonded Nitrogen molecule N2 and Iodine I2. Oh and a lot of heat.

                          Comment

                          • Cockednlocked
                            Bloodstained
                            • Jun 2016
                            • 50

                            #14
                            Chemical compounds release energy in different ways: decomposition (such as the Nitrogen Triiodide), deflagration, and detonation. Deflagration and detonation differ mainly in the speed at which they occur. Deflagration is a subsonic propagation reaction, and gunpowder falls within this range, and heat must be applied to start the reaction (ignition by the primer); it can be referred to as a "low explosive". Detonation is a supersonic propagation reaction (high explosive) and can be initiated by heat or high impact shock (TNT and plastic explosive being examples using both, and Tannerite as one requiring high impact shock.
                            Stability of the compound is part of what determines its usefulness. Nitrogen Triiodide has no real use, since it is too unstable to store or transport, and must be handled only in a liquid state while the compound is developing. The energy release is due solely from the chemical separation (on a molecular level) of the two elements forming the compound. Once exploded, you have Nitrogen in its gaseous state, and Iodine. With common explosives and gunpowders, the compounds that exist post combustion/explosion are different from what you started with.

                            Comment

                            Working...
                            X