Whats the pratical diference between BP grain sizes

[Pirotecnia]

Hello,

 

I never understood the real diference between grain sizes of BP.

Which of them burns faster: small grains or larger ones?

Which is the best for lifting?

I'm using 5 mm grains mixed with smaller others with about 1 to 2 mm and i can reach the best results with circa 10% weight of the shell.

 

Thanks!

[Seymour]

Finer grain burns faster, though in bulk, fire travels faster through coarse grain, so the ideal size grain for fastest burn depends on the situation.

 

In mining and other situations where you're using as much BP as all the APC members use in one year in one blast, the grain is very coarse (think 1-2cm grains) because the speed at which the fire can spread is the limiting factor.

 

Back in our world we are using very small quantities, usually less than a kilo, so the distance that the fire has to travel is not such an issue, and so a much finer grain is going to be fastest. Not as fine as possible though, if the grain is too small, like corning dust, the gaps between the grains are small enough to restrict the spread of fire.

 

Your 5mm grain is probably very good for 10" shell lift, but for 2", 3", 4" and maybe even 6"I would use your 1-2mm. for the 2", 3" and smaller stuff I might go finer still.

[Pirotecnia]

Finer grain burns faster, though in bulk, fire travels faster through coarse grain, so the ideal size grain for fastest burn depends on the situation.

 

In mining and other situations where you're using as much BP as all the APC members use in one year in one blast, the grain is very coarse (think 1-2cm grains) because the speed at which the fire can spread is the limiting factor.

 

Back in our world we are using very small quantities, usually less than a kilo, so the distance that the fire has to travel is not such an issue, and so a much finer grain is going to be fastest. Not as fine as possible though, if the grain is too small, like corning dust, the gaps between the grains are small enough to restrict the spread of fire.

 

Your 5mm grain is probably very good for 10" shell lift, but for 2", 3", 4" and maybe even 6"I would use your 1-2mm. for the 2", 3" and smaller stuff I might go finer still.

 

Yes. you have all the reason.

Today, i tried to launch a 2" shell with 5 to 10mm grains of BP and it only reached a very low altitude, and the mortar doesn't make the "traditional" sound.

 

Thanks!

[Potassiumchlorate]

For a 2" you better use 0.5-1.0mm.