Is this an explosive

[cheb]

Custard powder is an explosive, in fact any fine powder is... in the right (wrong) conditions.

Is my custard in a tin safe?

Is your custard so valuable it needs locking away?

[Mr. Dazzle]

burn fast enough it would be classed as an explosive.

'Deflagrate'?

It's one of those words; heard once, stuck in my head.

Deflagration means it burns by conduction, radiation and convection...I.e. one bit gets hot, heats up the bit next to it via one of those three and subsequently sets it on fire, which then heats up the bit next to it and so on.

Detonaton means heat spreads via a shock wave which travels suoersonically and compresses the material, heating it up. As you'd expect, that happens much quicker.

The difference between deflagration and detonation is basically the difference between explosives and high explosives. The difference between 'fire' and 'explosion' is a bit woolier.

However detonation ignition is also loads more efficient, if you can do it without blowing the engine up! There have been a few demos of (intentional) detonation engines but nothing on a large scale.

[Mr. Dazzle]

BTW....anyone who wants to see how explosive custard powder actually is could try the old school chemistry lesson demonstration.

Get a small pile of custard and stick a straw in it. Put a lit tea light on top of the pile and then an inverted paint can over that. Give the straw a hard blow. Try not to singe your eyebrows.

[Cousin Jack]

burn fast enough it would be classed as an explosive.

'Deflagrate'?

It's one of those words; heard once, stuck in my head.

Deflagration means it burns by conduction, radiation and convection...I.e. one bit gets hot, heats up the bit next to it via one of those three and subsequently sets it on fire, which then heats up the bit next to it and so on.

Detonaton means heat spreads via a shock wave which travels suoersonically and compresses the material, heating it up. As you'd expect, that happens much quicker.

The difference between deflagration and detonation is basically the difference between explosives and high explosives. The difference between 'fire' and 'explosion' is a bit woolier.

They are also quite difficult to keep apart. Many explosives burn (deflagrate) when ignited with a flame, but detonate when initiated with a detonator. However if the piece of explosive you are burning is big enough many will also burn to detonation, your nice fierce bonfire suddenly goes bang. Some also just detonate with almost any input of energy.

[Mr. Dazzle]

Quite.

Petrol will burn like a candle and/or it will blow up and take your entire street out. You've just gotta get the conditions right/wrong!

[Cousin Jack]

BTW....anyone who wants to see how explosive custard powder actually is could try the old school chemistry lesson demonstration.

Get a small pile of custard and stick a straw in it. Put a lit tea light on top of the pile and then an inverted paint can over that. Give the straw a hard blow. Try not to singe your eyebrows.

IIRC one of the biggest non-nuclear explosions of all time was a big flour mill.

[Yorick]

Custard powder is an explosive, in fact any fine powder is... in the right (wrong) conditions.

Is my custard in a tin safe?

Is your custard so valuable it needs locking away?

[demographic]

Quite.

Petrol will burn like a candle and/or it will blow up and take your entire street out. You've just gotta get the conditions right/wrong!

Petrol is another one that can be blown into the air by an initiator and used to demolish buildings.
Or so I read anyway.

[Horse]

burn fast enough it would be classed as an explosive.

'Deflagrate'?

It's one of those words; heard once, stuck in my head.

Deflagration means it burns by conduction, radiation and convection...I.e. one bit gets hot, heats up the bit next to it via one of those three and subsequently sets it on fire, which then heats up the bit next to it and so on.

The difference between deflagration and detonation is basically the difference between explosives and high explosives. The difference between 'fire' and 'explosion' is a bit woolier.

Only thing I know* about it is that it's how airbags work and the size of the pellets controls the rate at which the bag expands.**

* Recall
** Dredged from memory of what a colleague said, years ago.

[Mr. Dazzle]

Only thing I know* about it is that it's how airbags work .

They cost more lives than they save anyway!

[Horse]

Only thing I know* about it is that it's how airbags work .

They cost more lives than they save anyway!

Funnily enough, that chap was doing work on the particulates released. Health concerns about breathing them in. Although headbutting a steering wheel might affect your health.

Edit: a major concern is how the various (and numerous) pyrotechnic devices are dealt with during vehicle end of life disassembly. Millions of them every year.

[DEADPOOL]

Don't bin it or weigh it in for sixpence though. I'll happily pay shipping if you want to send it to me to make something interesting from it. Drops and scraps are handy bits of stock to have kicking around in the machine workshop.

PM for details...

[Mr. Dazzle]

Edit: a major concern is how the various (and numerous) pyrotechnic devices are dealt with during vehicle end of life disassembly. Millions of them every year.

Obviously not that concerning to some people.

[Horse]

Edit: a major concern is how the various (and numerous) pyrotechnic devices are dealt with during vehicle end of life disassembly. Millions of them every year.

Obviously not that concerning to some people.

http://revtothelimit.co.uk/viewtopic.php?f=10&t=1501

[ZRX61]

Custard powder is an explosive, in fact any fine powder is... in the right (wrong) conditions.

:
I get an email every year from the ATF containing an alphabetical list of what they currently consider an explosive:
https://www.govinfo.gov/content/pkg/FR- ... -28404.pdf

A)
Acetylides of heavy metals.
Aluminum containing polymeric propellant.
Aluminum ophorite explosive.
Amatex.
Amatol.
Ammonal.
Ammonium nitrate explosive mixtures (cap sensitive).
*Ammonium nitrate explosive mixtures (non-cap sensitive).
Ammonium perchlorate having particle size less than 15 microns.
Ammonium perchlorate explosive mixtures (excluding ammonium perchlorate composite propellant (APCP)).
Ammonium picrate [picrate of ammonia, Explosive D].
Ammonium salt lattice with isomorphously substituted inorganic salts.
*ANFO [ammonium nitrate-fuel oil].
Aromatic nitro-compound explosive mixes
Azide explosives

It's most useful...


Mix with powdered aluminum in 2lb batches...


Add trash compactor bags with 3 gal of 100LL Avgas in them...


Run some Det cord & PHHOOOOFF!


Then create 200lb of mix with 600 gal of Avgas.. (my view)


Punters view:


Hence Rule #1 of Airshows.... "Don't annoy the pyro guys"

[KungFooBob]

I follow the A-10 display team on friend face, they use Pyro like that for the fake bombing runs at airshows.

[ZRX61]

I follow the A-10 display team on friend face, they use Pyro like that for the fake bombing runs at airshows.

Ya have to get the timing spot on. Guy I know almost got blown out of the sky in his F86 at an airshow a few years ago, quite a bit of damage to the Sabre. Apparently harsh words were spoken...
On the other hand, sometimes the pilot is an idiot. At the airshow I shared the Bearcat pilot is a known idiot. At the briefing they are told where to fly & minimum height etc. He decided 20ft right over the pyro was ok when he was clearly told to fly slight to the side of it at no less than 50ft. The only passes he made to the side were about eye level in the dip between where we were on a slight rise & the runway.
He's going to end it in a black smoking hole one day. I saw him almost crash at another airshow where he flat out lied to the FAA about what happened & several years ago he had a mid-air at Reno where the other pilot died. I know people with the FAA who watch him very closely just waiting for the opportunity to pull his ticket.

[1913]

When I was learning to fly I was told that I should not ever fly with one particular person.

Normally when I am told something like that I ignore it, usually the subject turns out to be the salt of the earth.

For some reason the presentation was such that I believed it.

About 12 months later he put an Invader in killing himself and the 4 other passengers.

[ZRX61]

When I was learning to fly I was told that I should not ever fly with one particular person.

Normally when I am told something like that I ignore it, usually the subject turns out to be the salt of the earth.

For some reason the presentation was such that I believed it.

About 12 months later he put an Invader in killing himself and the 4 other passengers.

Don Bullock, at Biggin...& there were 6 passengers.