TassieTiger wrote:As I said, It maybe a stupid question lol.
This is an analogy broken down to slow ass - so my head can comprehend - speeds.
If you have a can of petrol and lay out a line of fuel 5m long, you then use a lighter to light that line, it will burn consistently along the line (eg powder).
But if you ignite that same line of fuel with a petrol bomb or a flash bang, that line will Effectively be shortened to maybe 4m because the initial “ignition” (magnum primer) will overtake what would be the nominal burn rate of the fuel...?
I just read that back to myself and I might have to check myself into a mental institution...
Ok...so lets take your fuel burning analogy a step further & give it a third dimension, so that its true to gunpowder...
The fuel doesnt burn, the vapour does yes...
So the vapour has been ignited along one metre of the line of fuel, as opposed to just at the very end...
So that 4m mark of your fuel line--that fuel will have burned anyway, its just that the first metre has all started to burn at the same time, therefor everything will have burned quicker due to more being ingnited intially, but the vapour doesnt burn any faster, because its not vapour yet...it will still vapourise & burn at the same rate.
Powder is granules, so each of those granules are ignited by the one next to it...
Lets imagine you have a case full of granules...each granule is surrounded by & touching 8 other granules but only burns 4 of them at once, & each one takes one second to burn & ignite the ones next to it ...
So if you start with igniting only one granule, at the end of 2 seconds, 5 granules have burned...get me so far...?...yes...?
Then after 3 seconds, 20 granules have been burned...(the 5 granules have each burned 4 of the granules they are touching--5x4=20)...
But...
If you start by igniting 2 granules at the same time, after those same 2 seconds, 10 granules have been burned. & after 3 seconds 40 granules...
(& this analogy is not exactly correct, but im trying to simplify my thoughts)
This acceleration rate of burning will only happen for a short time obviously, because you reach the point where (in cross section) each granule on a given level across the entire cross section is ignited & only ingnites the ones forward of it...so at this point youve reached the maximum burn rate for that case,
In other words...imagine a case FULL of powder--100% load density...
Try & picture how powder burns if you start by igniting 3 of those granules, as opposed to 8 of those granules...
Or...if you pour an even depth puddle of powder, say, the size & shape of a dinner plate on the ground & drop a match in the middle of it, it burns outwards...
But If you drop a ring of say 10 matches in the centre in say a 2 inch diameter ring centrally to the pile of powder, it still burns the same rate, but the over-all burn time is quicker---you've generated the same amount of expansion gasses in a slightly shorter time...which in an enclosed environment will create a greater pressure...
Or...over the entire time the powder is burning, it burns at a more even rat because you reach the maximun burn rate in shorter time, due to igniting more granules to begin with...
Thats how i imagine it anyway...

But stuff it...im going...i just cant explain myself in the proper'est way...
The man who knows everything, doesnt really know everything...he's just stopped learning...