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Old 11-04-2015, 12:19 PM   #11
Nereidalbel
 
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Default Re: Dust Explosion - Grain, flour, wheat

Out of curiosity, are any anachronistic metals known to alchemists/metallurgists? And by that, I mean things that weren't discovered in the real world until long after TL4 was done with.
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Old 11-04-2015, 03:30 PM   #12
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Default Re: Dust Explosion - Grain, flour, wheat

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Bear in mind that all realistic options amount to "and the 30-50 guys get killed while causing modest damage to the enemy". The normal use for a force that small is to do popup attacks that distract the enemy and get them off going on sniper hunts instead of something more useful. If you want a result other than that, you're going off on cinematic tangents and realism may be moot.
If each of the 30-50 guys were flying a F-35 Lightning II, I'm not all that sure this would be true. If the 30-50 guys are combat engineers setting off several days' worth of mines and explosive traps where the enemy is trying to get through, I'm sure it isn't. Powerful devices of war which require only a few humans to operate are not only realistic, they are real. In this case, the setting is a fantasy one, with most positions of political and military power occupied by what amounts to superheroes.

The 30-50 guys in this case are mages who will be flying. That's not realistic, I admit, but it doesn't have to be cinematic. Most of the 30-50 guys are not really superheroes, but are instead fairly realistic humans, other than having Magery 1-2 and a few spells. That, in turn, makes them able to use magical objects that allow them flight at up to Move 40 for less than twenty minutes a day, while carrying up to Heavy encumbrance (which, however, slows them). They also carry at least one magical weapon each, with most of them having something like a Wand of Fireballs (6d burn ex/2, Range 75/150; 5-15 charges left).

I realise that this is a far cry from a modern fighter jet. But if we treat their supernatural abililities in a realistic fashion in the setting, they still might be able to have an impact on the battlefield that is only marginally related to their small number. It doesn't require cinematic rules, only the fact that they have a capability that the other side can't match.

The enemy can arrange for flying opposition, but did not expect to have to do so and do not have much tactical expertise at directing summoned flying creatures to secure the air above the battlefield. So far, anything flying that the enemy has brought has succumbed to PC-related injuries. I realise that this might change, but the PCs are planning for air supremacy*, at least for a brief window of 15-20 minutes.

If the flying mages fly low enough to cast spells at the enemy, they will be in arrow, sling and spell range from the other side and will quickly die. At 500+ yards, survival becomes theoretically possible. At 1,000+ yards and not lingering long enough for an organised response of summoned creatures to emerge, the risks might even be tolerable. At least enough so that the PCs have decided to risk a flying sortie shortly before or during the enemy evening assault on the city.

The flying mages can carry up to 2 tons of weight while still being able to fly at a reasonable rate and maintain control fairly well. Bulk considerations might lead to a much lower load, of course. I know that 2 tons of Alchemist's Fire would be very effective as an air-to-ground weapon, but there isn't that much available of it. And in any case, it already comes in artillery shell form, which means that what the PCs have of it will be deployed on the enemy anyway.

The PC in command suggested trying to use some of the massive amount of grain there to cause a dust explosion among the enemy army. It seemed the best source of finely ground powder and a TL3 port city didn't seem to offer anything more destructive per weight to drop from a height of 1,000 yards on an army. Now, the flour obviously won't be destructive at all unless he can create perfect conditions for a dust explosion in a given area. So I'm looking for guidelines on how much flour you'd need to have a chance of a dust explosion inside, say, a 10'-30' high cloud of flour that is at least 50 yards in radius.

The character in question has TL4 versions of Alchemy; Engineering (Combat); Explosives (Demolitons); Explosives (Fireworks); Expert Skill (Natural Philosophy); Intelligence Analysis; Mathematics (Applied); Mathematics (Surveying); Naturalist; Tactics (Air-to-Ground); Weather Sense at skill levels 13+. His Scrounging skill is 17. He has spells such as Measurement, Tell Position and Predict Weather.

A djinn ally can be a great help in spreading the flour around, with the ability to turn into a magical tornado and generally a fairly precise control over the atmosphere around him. He can't do all the work himself, but if 2 tons of flour were haphazardly thrown to the ground from 1,000 yards in the air, he could probably undertake to move things along a lot closer to ideal distribution of flour to air. Under combat conditions, of course, it won't be anywhere near ideal, but that just means that less of the flour actually burns/explodes.

Under imaginary perfect conditions, how many pounds of flour do we need to distribute in a low-hanging cloud that is at least 50 yards in radius for it to be explosive? I have to admit that I have no idea. Are we talking 100 lbs. or 100 tons? More?

*Because if they don't manage to secure it, the odds are pretty good that the army with the far larger number of people and the much higher Troop Strength will win.
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Old 11-04-2015, 03:34 PM   #13
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Default Re: Dust Explosion - Grain, flour, wheat

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Originally Posted by Nereidalbel View Post
Out of curiosity, are any anachronistic metals known to alchemists/metallurgists? And by that, I mean things that weren't discovered in the real world until long after TL4 was done with.
Sure.

Orichalum, mithril, adamantine and a host of others.

It is not likely that very many pounds of any of them, except orichalum, is present in the city at all, however. And that orichalum would be armour and weapons from defeated champions. I don't know how much of it would be available to the PC and his men during the ca 12 hours of preparations that they have to do Administration and Scrounging tasks to gather up something more effective as air-to-ground weapons than spare crossbow bolts.
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Old 11-04-2015, 03:48 PM   #14
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Default Re: Dust Explosion - Grain, flour, wheat

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Sure.

Orichalum, mithril, adamantine and a host of others.

It is not likely that very many pounds of any of them, except orichalum, is present in the city at all, however. And that orichalum would be armour and weapons from defeated champions. I don't know how much of it would be available to the PC and his men during the ca 12 hours of preparations that they have to do Administration and Scrounging tasks to gather up something more effective as air-to-ground weapons than spare crossbow bolts.
I was thinking more along the lines of "has anybody figured out what filings of aluminum and rust do yet?"

Also of note, in perfect conditions (somebody should do a ritual spell to make it so), 1 pound of flour dust has the equivalent of 4 pounds of TNT. But yeah, found a lot of calculators for this!

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Old 11-04-2015, 03:49 PM   #15
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Default Re: Dust Explosion - Grain, flour, wheat

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Two tons of flower? What else can your mages and/or army grind into dust? If you can grind things fine enough, almost anything is explosive, even aluminum and wood. Do note that sawdust should be readily available, and probably a bit cheaper than flour.
The cost of a couple of tons of flour or grain dust is irrelevant at this point. They've captured so many thousands of ton of grain that they can't usefully account for it all before they have to fight off the army trying to take their recently acquired city.

With good enough Administration rolls, the PC could manage to get maybe several dozen sailors acting as foremen for an unknown number of recent POWs and/or local slaves to work for them during the 12 hours they have. But grinding sawdust to save the cost of a couple of tons of grain dust is insanely low on the priority scale. Far better to have all available workers move artillery from the coastal forts to the land walls, collapse houses near likely breach points, erect obstacles around the gates, etc.

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Awesome! So, judging by these stats, under perfect conditions, distributed evenly, around one and a half tons of grain dust in a cloud 20' high and 50 yards in radius is just about enough concentration to explode.

That means that two tons under combat conditions is not going to be enough for such a big cloud. On the other hand, a unit of thousand men might only occupy 20 yards by 50 yards when massing for an assault through a breach and an explosion of half the volume above would tear the heart out of one (and probably everyone nearby)

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Pretty cool.
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Old 11-04-2015, 03:51 PM   #16
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Default Re: Dust Explosion - Grain, flour, wheat

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Awesome! So, judging by these stats, under perfect conditions, distributed evenly, around one and a half tons of grain dust in a cloud 20' high and 50 yards in radius is just about enough concentration to explode.
While the initial fireball doesn't meet the goal, the shockwave will throw powder from the ground into the air, which ignites, throws more powder into the air, ignites again...basically, you have a cluster bomb.
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Old 11-04-2015, 03:56 PM   #17
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Default Re: Dust Explosion - Grain, flour, wheat

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I was thinking more along the lines of "has anybody figured out what filings of aluminum and rust do yet?"
No chance of the PC being able to get that much aluminum or even rusted iron in time.

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Also of note, in perfect conditions (somebody should do a ritual spell to make it so), 1 pound of flour dust has the equivalent of 4 pounds of TNT. But yeah, found a lot of calculators for this!
Ah! That's what I'm talking about.

Of course there is no chance of anything like perfect conditons for most of the grain dust or flour. But drop two tons in the area and have a djinn tornado around for a while mixing it with the air and the hope is that there will be pockets of explosive conditions when the Alchemist's Fire starts raining down.

It seems like a reasonable thing to try, at least, considering that the alternative is scrounging up a lot of arrows and crossbow bolts and dumping them all more-or-less randomly outside the walls from a great height.
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Old 11-04-2015, 04:01 PM   #18
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Default Re: Dust Explosion - Grain, flour, wheat

Assuming the PCs survive the initial attack, thermite is a wonderful thing to drop on the enemy navy as part of a counter attack.

With a djinn helping out, you may end up spreading the flour from explosive death into the range of a large flash of flame, causing severe burns on all exposed flesh, and igniting all flammable materials. And unless the enemy has Sealed armor, dust particles will be quite happy to helo ignite the padding under their armor.
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Old 11-04-2015, 04:02 PM   #19
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Default Re: Dust Explosion - Grain, flour, wheat

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Why not use catapults for delivery by the way?
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Flying mages can follow up with fireball wands to ignite things right after they hit the ground.
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Right but the can fire at catapult targets as well and wont be as tired trying to haul sacks of grain around. Or as much of a target.
The larger catapults are located near the sea walls. They can shoot outside the land walls, but only around 100-200 yards away from them. Smaller ballistae can reach 300-350 yards from the walls.

The PCs would be more comfortable if the explosion took place maybe 500 yards away from the walls, unless there is just no good concentration of enemy troops that far out.*

Also, I think falling from a 1,000 yards** in a bag spreads flour or grain dust around better than being shot from a ballista a mere 300 yards.

*In which case the PCs may throw caution to the winds and elect to aim for a point closer to the walls anyway, in typical PC fashion. Hoping that they calculate the blast radius close enough to correctly so that they don't scour the walls clean of their own men.
**Or higher, if desired, given that the higher they go, the safer the mages are.
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Old 11-04-2015, 04:08 PM   #20
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Default Re: Dust Explosion - Grain, flour, wheat

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The larger catapults are located near the sea walls. They can shoot outside the land walls, but only around 100-200 yards away from them. Smaller ballistae can reach 300-350 yards from the walls.

The PCs would be more comfortable if the explosion took place maybe 500 yards away from the walls, unless there is just no good concentration of enemy troops that far out.*

Also, I think falling from a 1,000 yards** in a bag spreads flour or grain dust around better than being shot from a ballista a mere 300 yards.
Why not both? You've got plenty of flour, after all, and the more you can send over, the better your chances of getting a boom.
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