Game Mechanics. Thermobaric rounds.
 

Have any of you found or brewed your own game mechanics for depicting these weapons?

Construction and fuel mix will cause a lot of variation. Off hand I would say take the explosive weight, assume C4 and multiply the DPW by 3 to get the resultant blast plus a fireball of 1200C that covers the blast radius for 1-2 sec would be a good place to start if you needed something fast. I don't think the shockwave + vacuum effect really needs to be exploited. The larger DPW per unit mass is just simpler and gets the job done.

I may have to look more thoroughly into this later.

See that is part of it....... Everything takes burn damage, if only a flash burn...... but, it is the nasty out then in shearing forces of the vacuum effect.

I was thinking of one set of damage for the explosion..... then more damage, possibly half that of the original DPW, as the atmosphere rushes back in.

So are you proposing a table similar to the RE chart for round composition for the two effects, i.e. ethylene oxide causes X1 then Y1 dpw, ethylene oxide plus aluminum powder does X2 then Y2 dpw, etc.?

This then questions is there a difference in effect for the two blast effects? They happen very quickly one after the other which is why I suggested a single larger value with an implied greater RE for the explosive to simplify the use. If there is difference, how does that manifest in the application of the damage? Something like you are inside an armored vehicle with weapon ports open that spares you from the initial blast, but the sudden pressure changes rupture ear drums and may cause other whole body damage?

Found this article that gives some general figures for FAE used by Russian forces in 2000. Need to think more about how this could work in game.

http://fmso.leavenworth.army.mil/doc...ir/fuelair.htm

Plus Global Security gives some general formulas for calculating distance to 1 PSI over pressure in this article. Using these might get us on the right track.

http://www.globalsecurity.org/milita...itions/fae.htm

From wikipedia (Quoting the Defense Intelligence Agewncy)

"The [blast] kill mechanism against living targets is unique–and unpleasant.... What kills is the pressure wave, and more importantly, the subsequent rarefaction [vacuum], which ruptures the lungs.... If the fuel deflagrates but does not detonate, victims will be severely burned and will probably also inhale the burning fuel. Since the most common FAE fuels, ethylene oxide and propylene oxide, are highly toxic, undetonated FAE should prove as lethal to personnel caught within the cloud as most chemical agents."



I don't know if this helps, but the "Modern Firearms" website has this this description of the real-world 93mm thermobaric RPG-7 or RPO-A warhead

"The blast effect of the thermobaric / FAE RPO-A warhead,which contains about 2.2 kg of Fuel-Air Explosive is roughly equivalent to the blast effect of the 107mm / 4" HE artillery shell. Upon explosion, RPO-A warhead generates the cloud of high-temperature flame (blast) which is about 6-7 meters in diameter(blast radius 3 meters or more). The blast cloud lasts as long as 0.4 seconds, thus allowing for significant incendiary effect in addition to the massive pressure wave (typical HE explosion lasts much shorter)."

What rules do you need?

In my estimation..... Thermobaric rounds produce three effects in under a second...... burn, blast, and vacuum.

Burn... 1300 to 3000 degrees (exact amount?) So I think burn damage is appropriate.

Blast... the DPW does this. However, the shear (fracturing forces) is greater. There is a specific word for this in regards to explosive that is completely escaping me at the moment. So I was thinking that Thermobaric explosions should be more effective than normal explosives against hardened structures.

then Vacuum...... I don't know how to model this in game...... except to declare NPC dead on the spot.

The effects on personnel is extreme. People nearest the blast point that are not immediately vaporized experience an overpressure in excess of 14 PSI for over a second crushing them to death. A bit further out, burns and ruptured internal organs from the overpressure followed by the partial vacuum from the rarefaction do not kill quickly, but require extensive and expensive medical care to save. Still further they still get burns, but with moderate eye and ear protection and body armor can be spared extensive damage, through they still require medical attention. These effects are for the unenclosed detonation. Not something like the rounds with HEDP warhead in front of the FAE to punch a hole through armor so the FAE detonation can take place inside the tank or structure.

That's some serious firepower for the project to issue, but I guess since there is a flame thrower issued and those where banned under Protocol III (PROTOCOL ON PROHIBITIONS OR RESTRICTIONS ON THE USE OF INCENDIARY WEAPONS ) of the Geneva Convention.

What do you plan on using that with?

Soviets.....

There are several variations of thermobaric rounds as standard issue in the 90s.

This and I was thinking the FAE mine clearing round for some MARS unit.

Because..... there is a tradition in the modules of starting the PCs in some vehicle completely unsuited to the events and situations in the modules.


Plus, I want to beef up the Soviet threat in "Final Watch" and augment them ... maybe reinforcements that have arrived from Alaska or the Kamchatka peninsula.

the most accurate way to model thermobaric explosives would be to base your model off of a grain silo explosion. it is exactly the same mechanics at play. and the US have trained certain units to make them on the fly since the '70's with a block of C4 and crap you can get in any grocery store.

The way I learned to do this was a cardboard box with bags of sugar inside. Under the box was a block of C4, inside the box was thermite grenade with the sugar....... There is a non electric blasting cap fed by det cord.... the detcord goes to the C4..... the Thermite has a ignitor fed by x minutes of fuse. The thermite and the C4 are activated at the same time.. the thermite ignites 15 to 30 seconds before the C4 which is easy to do with timed fuse.

The thermite begins to burn in the sugar very well, then the C4 blast throws it all in the air into a cloud.... in one out of three tries this will just scatter everything and not make a fuel air explosion... the other 2/3 is pretty grand indeed.

Ahhh, the Improvised Explosives Manual returns!!!!

Another trick was to emplace a 55-gallon drum filled with a diesel/oil mixture on top of a C4 block and either have it command detonated, or a pull/release trigger, you get a nice coverage over your kill zone...

That one is in the Engineers field manual. Remember it is tipped at 45 degrees with the bottom half tamped with sandbags.

When I was still active, it was the Improvised Explosives Manual (toMAto, tomaTO), we would use a tank dozer to scoop out a position drop the drum in and rig and camouflage.

We would also park a tank next to a tree, climb into the branches and rig Claymores in the upper branches, interesting how dismounts never seem to look up?

And just to entertain the ones who went for cover in that nice, deep, safe ditch, claymore at each end firing the length, a roll or two of detcord...and seed liberally with toe poppers.

And those brave souls who charge the firing line...a line of claymore and a couple of 105mm cannons loaded with Beehive or canister rounds....it truly sucks when you go up against Armored Cavalry!!!

No, No, I mean the literal Engineers Field Manual.... It is a pocket sized book with improvised munitions, and charts and tables for building bridges or factoring the explosives to take down a bridge.

This little critter right here.

http://www.survivalschool.us/wp-cont...field-data.pdf

Got a copy of the manual, but when I was a (much) younger trooper, it was the IEM, which should date my happy a..err..can!

Still the important thing is the multitude of dirty tricks that one can pull on an unsuspecting target...

Ah well, Merry Christmas to ya!!

We should do an improvised explosives thread for those who were not "blessed" with a travel and adventure job with exceptional chances to engage foreign locals with deep philosophical debate! :)

I'm game....yet another reason for the NSA/FBI to monitor my emails!