Is burning rate vol/time or mass/time?

[cbuttre835]

I've seen the relative burning rate charts, but I've never seen what the burning rates mean.

Since VMDs vary quite a bit, is burning rate in units of volume or mass?

I don't think I'd substitute a powder away from published data based on the burning rate charts... just curioius. I've searched and searched and can't find out what they mean...

 

[Lost Sheep]

Neither. Burning rate is called "Quickness" and I don't understand it very well at all myself.

What I have found out so far is that there seems to be no absolute value that a lab could assign (energy per unit mass can be scientifically determined and can be verified by labs elsewhere on the planet). I have never seen powder quickness numerically tabulated and only seen lists of powders sorted by relative quickness (and not always do similar powders achieve the same ranking on the list).

So the question you ask is well-conceived. I look forward to any answers you get.

Lost Sheep

 

[rsrocket1]

Burn rate is mass/time, but is so incredibly subjective that it is only good to say that "in general, X has a faster burning rate than Y". For instance, a certain amount of Clays (fast powder) will reach a peak pressure sooner in the same chamber as the same amount of H110 (slower powder).

The speed at which they burn is also highly dependent on the pressure where they burn. Some rifle powders self extinguish when burned in a pile out in the open.

The total energy released by the powder is actually very closely equal if the powders were allowed to burn to completion. I've loaded 10 grains of Red Dot, Unique, Bullseye and Power Pistol under a 110g .308 bullet and they all came within a few 10's of fps out of a rifle where most of the total energy of the powder was released before the bullet exited the barrel. These powders perform very differently in a short barrel handgun.

 

[cbuttre835]

Some rifle powders self extinguish when burned in a pile out in the open.

Interesting that you mention that. I have noticed how slowly Varget burns at atmospheric pressure. I spilled a little, swept it up, and carried it out into the driveway... I had never burned any spilled powder before; so I was ducking and covering and lighting it with a long lighter and a welding glove on... and it did very... little...

Interesting how stuff is taken as gospel without quantitative data to back it up.

 

[gamestalker]

The most important usuful information regarding burn rate is in it's application. For instance, H110 can be compressed charged in a .357 mag case without pressures getting out of control. This is because it will reach peak pressure slower, although in mil-seconds. Where as a faster burning powder would use say 1/3 as much powder to reach simular pressures, but in a much shorter time span.

There are other factors that surround burn rates, and how they perform with lighter or heavier bullets. Trying to push a heavy bullet to maximum velocity with a fast burning powder would be pressure prohibiting in many situations. In general, slower burning pwoders are best suited for full tilt loads, where as fast burners are best suited for target loads.

GS

 

[243winxb]

The Closed Bomb Test

http://www.chuckhawks.com/powder_cartridge_testing.htm And the test unit > http://www.ditusa.com/closed_bomb.php Not sure if this is what your looking for? My guess = Pressure/Time?

 

[243winxb]

More charts on burn rate . http://www.ar15.com/forums/t_6_42/387343_.html&page=1&anc=bottom#bottom