39 replies to this topic

[pjalchemist]

Okay i want to make my meal powder faster and have yet too have a press so been reading and looks like rice hulls are the way but can't find any UK shop for it.

So what can i use and get dead easy ie on the high street, supper market that would do the job?

[Night Owl]

Grass seed does it for me, works great:)

[pjalchemist]

Grass seed does it for me, works great:)

I just thinking that. How do you go about doing your out of intrest dude. Do you dampen you grass seed then add BP meal? Do you shake it all in a closed tub like some of the vids on youtube? Last qu, what do you use as your binder?

[Night Owl]

Ye I spread seed on news paper, spray it then put it in a tub of bp with dextrin, bout 4-5%, just the one coating works fine for me and its quite a good burst charge:)

Edited by shell shooter man, 06 November 2008 - 11:25 AM.

[wjames]

i heard someone talking about using cereal once.....Very specificaly shredded wheat.........


Anyone tried it/ heard of it yet ?

[pjalchemist]

Rice Crispies is what i was told i could use as well

[Mortartube]

Rice crispies and also dried sweetcorn have been used. Vermiculite from the garden centre is also good and very light. It holds moisture though so needs only the barest minimum dampening.

[Gary]

I am aware that rice hulls accelerate the rate of BP combustion, but what is the mechanism for this phenomenon? Could BP on rice hulls acheive a burn rate comparable to that of KP?

[Mortartube]

By increasing the available surface area of BP, the flame can travel more quickly, therefore releasing more gas in a given time. All of those little spaces in between the rice hulls help a great deal too.

[wjames]

using something coated in BP give a much greater surface area - hence a faster burn rate !

[wjames]

damn, you beat me to it !!!

[cooperman435]

It doesn't actually increase the burn rate guys. If you have slow BP it will still be relatively slow burst when coated on any carrier. The action of coating things essentially does a number benefiting things.

1. It gives large grains which allow fast propagation of flame through the whole burst charge as one

2. Due to the large grains it allows air gaps which act as a pneumatic buffer this may also be assisted by the crispies collapsing in on themselves under the pressure both extending the buffer (and cracking the BP into slightly airborne particles which again burn very fast) allowing more of the BP to ignite before the shell reaches bursting pressure

3. larger grains mean more surface area so more BP is exposed to the flame resulting in a faster burn rate

4. the crispies don't burn so effectively you have a hollow sphere of BP. This burns very fast but as a shell also bursts very fast with solid BP grains you are most likely to have unburned BP still combusting after the shell has cracked which would be wasted.

5. It saves you BP. A 6" shell is liely to take (just a guess) 1.2kg of BP granules whereas with crispies coated its more like 500g

[digger]

It doesn't actually increase the burn rate guys......

I agree with most of that, however maybe not with point three as smaller grains increase suface area to give a faster burn rate. However it does minimise powder thickness which allows the powder to burn through the thickness quickly.

[wjames]

cooperman...."It doesn't actually increase the burn rate guys"

then...." larger grains mean more surface area so more BP is exposed to the flame resulting in a faster burn rate "


nothing like self-contradiction !

[cooperman435]

You misunderstand my friend.

It doesn't increase the burn rate of a given powder but increases the burn rate of a MASS of that given powder. The actual speed of powder burn is not increased.

And Digger yes you are correct as ever. Through my poor explanation I mean that the thin walled spheres increased the surface area (I believe in maybe similar proportions to smaller grains?) as there is no BP contained within.

Is that better?