Fires and Magazine Explosions

[SteveAlt (OP)]

Fires
Fire is a major threat on board warships, both in reality and in Aurora v4.0. Damage control is a key factor in preventing such fires from gutting a ship. Up until now, damage control in Aurora has been mainly used for repairing systems after combat and therefore high damage control ratings were not essential. With the introduction of fires in v4.0, damage control ratings will become a significant factor in warship design. Fast reactions (i.e. high damage control ratings) to fires will be essential to avoid them spreading out of control.

When any system is destroyed, there is a 10% chance a fire will result. The strength of the fire will be equal to the HTK of the system that was destroyed. If multiple systems trigger fires, the fires will be treated as one large fire with the combined HTK of the affected systems. During each damage control phase, which takes place after movement and before combat, damage control teams will attempt to extinguish the fire. The percentage chance of success is equal to Damage Control Rating x (Length of Increment / Strength of Fire)

For example, if there is a strength 5 fire on board a ship with a damage control rating of 3 and the clock is advanced by 30 seconds, the chance of extinguishing the fire is equal to 3 x (30/5) = 18%. If there is a strength 10 fire on board a ship with a damage control rating of 14 and the clock is advanced by 5 seconds, the chance of extinguishing the fire is equal to 14 x (5/10) = 7%

If the fire is not extinguished during the damage control phase, there is a small chance it will either increase in strength or cause further damage. If it increases in strength, it will be by a random amount up to half the existing strength. If damage occurs, it will be a random amount between 1 and the strength of the fire. This chance is equal to (Strength of Fire x Length of Increment) / 20

For example, if the clock is advanced by 30 seconds, a strength 5 fire has a (5 x 30) / 20 = 9% chance of causing damage or increasing in strength. If the clock is advanced by 5 seconds, a strength 10 fire has a (10 x 5) / 20 = 2.5% chance of causing damage or increasing in strength.

I might still play around with these numbers a little, based on playtesting, but the general process will remain the same.

In space, there is an alternative way to put out fires and that is to evacuate the atmosphere from the affected sections of the ship. This is a drastic measure that could have serious implications for the crew and for equipment that is not designed to operate in temperatures close to absolute zero. I considered having this as a separate option with associated appropriate penalties but I decided that would be too much micromanagement. Instead, it is assumed to be part of the normal damage control process. Quick reactions to fires will probably involve this method. However, perhaps due to battle damage, system failures, the location of the fire or the presence of sensitive equipment, it will not always be possible. These types of situations could explain the circumstances for story purposes when fires get out of control

While fires are burning, the maximum increment allowed will be 1 minute. Otherwise, incrementing by an hour or so would guarantee to put out the fire without further damage.

Magazine Explosions
Secondary Magazine explosions have been fixed for v4.0. There is a 10% chance that any magazine hit may cause a secondary explosion. For the purposes of simplicity, it assumed that empty magazines will be hit first. When a magazine containing missiles is hit, the 10% chance is checked. If an explosion occurs, all warheads in the magazine will detonate simultaneously, probably with catastrophic results.

Steve

[jfelten]

10% means that large ships taking damage are extremely likely to have large fires.  Not sure if that is your intention.  

This is also going to favor smaller ships since there will be less to loose.  If I build a single 20,000 ton ship there is a chance that one unlucky hit is going to start a fire that could grow to destroy the entire ship.  If I build four 5,000 tons ships the risk is "firewalled".  Not sure if you want that result either.  I guess you could add some sort of bulkhead system to divide a larger ship in to fireproof sections.  All it would take is a thin layer of vacuum between sections of a ship which would limit any fire spreading threat to power etc. connections which could be fire hardened near the bulkhead.  Actually, if fire was such a great threat to space warships, I would think that would be an intrinsic part of the design of all ship compartments.  Engineering adapts to risks.   Materials science progresses along with the rest and is essential to much other progress.  

Instead of opening sections to vacuum I suggest that automated systems would reduce air pressure and/or oxygen content enough to greatly slow the fire but not so low as to be fatal to people.  At battle stations I would expect the crew to be in pressure suits anyway or at least have them readily available.  

Nuclear warheads, especially future tech versions, are not going to nuclear detonate accidentally or from external explosion/fire.  Things have to happen in a precisely controlled sequence that some external explosion cannot cause.  Fuel/Detonators might be explosive, although it seems unlikely that the fuel of missiles able to reach such speeds in a non-newtonian manner is going to be powered by a chemical reaction so is unlikely to be flammable.  Of course since that part is completely made up you can call it however you wish, it just seems extremely unlikely so is a bit hard to achieve suspension of disbelief about.  It could make quite a mess of things but isn't going to go up in a massive nuclear explosion.

[Cassaralla]

Perhaps a tech line of fire proofing and fire fighting could be introduced to reduce this chance to represent systems evolving to better combat the risk?

[jfelten]

Perhaps a tech line of fire proofing and fire fighting could be introduced to reduce this chance to represent systems evolving to better combat the risk?

It is logical that such would automatically be incorporated in military (and civilian) research.  Real world warships continually improve in fire resistance and fire fighting technologies.

[SteveAlt (OP)]

Perhaps a tech line of fire proofing and fire fighting could be introduced to reduce this chance to represent systems evolving to better combat the risk?

There is already a line of damage control systems

Steve

[SteveAlt (OP)]

10% means that large ships taking damage are extremely likely to have large fires.  Not sure if that is your intention.  

This is also going to favor smaller ships since there will be less to loose.  If I build a single 20,000 ton ship there is a chance that one unlucky hit is going to start a fire that could grow to destroy the entire ship.  If I build four 5,000 tons ships the risk is "firewalled".  Not sure if you want that result either.  

I think the reverse is actually going to be true. Your enemy is going to cause the same amount of damage regardless of the size of your ships. Therefore, whether large or small, assuming similar armour, a ship is going to take the same amount of amount of damage and 10% of that will result in fires. Larger ships will usually have more engineering sections and will have the option of fitting additional damage control system so their damage control rating will be much higher and they will extinguish fires far faster than smaller ships.

I guess you could add some sort of bulkhead system to divide a larger ship in to fireproof sections.  All it would take is a thin layer of vacuum between sections of a ship which would limit any fire spreading threat to power etc. connections which could be fire hardened near the bulkhead.  Actually, if fire was such a great threat to space warships, I would think that would be an intrinsic part of the design of all ship compartments.  Engineering adapts to risks.   Materials science progresses along with the rest and is essential to much other progress.  

Fire is a great threat to modern surface warships. They still catch fire despite all engineering efforts to prevent it. The Sheffield was lost not because of the exocet damage but because of the resulting fire. More than one Japanese carrier in WW2 was lost to fire damage because of inadequate damage control whereas the US ships had very good damage control and saved many ships that might have been lost.

Instead of opening sections to vacuum I suggest that automated systems would reduce air pressure and/or oxygen content enough to greatly slow the fire but not so low as to be fatal to people.  At battle stations I would expect the crew to be in pressure suits anyway or at least have them readily available.  

Those sound reasonable and we can assume they are part of the damage control process.

Nuclear warheads, especially future tech versions, are not going to nuclear detonate accidentally or from external explosion/fire.  Things have to happen in a precisely controlled sequence that some external explosion cannot cause.  Fuel/Detonators might be explosive, although it seems unlikely that the fuel of missiles able to reach such speeds in a non-newtonian manner is going to be powered by a chemical reaction so is unlikely to be flammable.  Of course since that part is completely made up you can call it however you wish, it just seems extremely unlikely so is a bit hard to achieve suspension of disbelief about.  It could make quite a mess of things but isn't going to go up in a massive nuclear explosion.

The main reason is that ships blowing up due to magazine explosions is fun (well in a game at least) and fun gameplay is the most important factor. In terms of technobabble, you could argue that the warheads are actually anti-matter and they probably would explode.

Steve

[jfelten]

Fire is a great threat to modern surface warships. They still catch fire despite all engineering efforts to prevent it. The Sheffield was lost not because of the exocet damage but because of the resulting fire. More than one Japanese carrier in WW2 was lost to fire damage because of inadequate damage control whereas the US ships had very good damage control and saved many ships that might have been lost.

That is true but aside from a handful of nuclear powered ships, all naval warships are powered by petroleum which is very flammable and carried in large quantities.  And the lubricants for much of the machinery is also petroleum based = flammable.  They also carry ordnance that is flammable / explosive.  It is unlikely a space going warship in the future would have a fraction of such flammables on board.  Most things will burn if you get the hot enough but the greatest danger of a fire getting out of control is from petrochemicals and explosive ammunition.  Also keep in mind that for fire you have to have an oxidizer (oxygen).  It is a reasonable assumption that there is only so much oxygen inside a ship and a very limited rate at which it can be replenished.  Depending on the fuel, the mass of air required to burn can be much greater than the mass of fuel (in modern cars I think it is round 15:1 air:fuel).  So no matter how much fuel you have to burn, the amount of air/oxygen available is probably what is going to limit the fire.  I just don't think there is enough air inside a ship to sustain a big fire and allow it to grow out of control even if you have plenty of fuel.  On a wet navy ship there is a limitless supply of air.  

The main reason is that ships blowing up due to magazine explosions is fun (well in a game at least) and fun gameplay is the most important factor. In terms of technobabble, you could argue that the warheads are actually anti-matter and they probably would explode.  Steve

There are a couple things I don't like about it.  The game currently tries to be realistic in areas that it can be such as orbital mechanics.  At least to the extent that it can be immersive.  But if something goes totally over the top such as nuclear warheads going off like popcorn, it ruins the experience since nobody will believe it is possible, like a bad movie or such.  Antimatter would be much more believable but I thought you specified somewhere that missile warheads were nuclear based?  

Another concern I have is the golden BB effect.  Now that could be believable since there is plenty of historical precedent for it.  Although I would argue that is almost always something like a magazine explosion which gets less and less likely as technology progresses.  But even if believable or realistic, it is a game killer.  As you mention, sometimes gameplay has to come first.  Nobody past puberty wants to play a game where the battle can be totally thrown to a single wildly lucky chance event.  Eventually someone is going to loose the game because a tiny ship gets a lucky "die roll" on the intact enemy super dreadnought.  It might make a good movie when the evil guys death star gets blown up by the heroes,  but it doesn't work in games against evenly matched players.  I've seen many a home brew campaign game die an early death because some sort of golden BB rule resulted in something ridiculous happening.  That is not "fun".  Even the winner looses in the end when the others stops playing the game.  

I'm not saying these ideas can't work and add color.  But I want to urge caution because I've seen similar things effectively ruin game systems in the past.  It even crosses game genres.  You can get away with a lucky hit causing extra damage (aka a "critical hit") but if you allow golden BB's to outright destroy intact ships and such, in my opinion it will poison the game.

[Hawkeye]

Instead of opening sections to vacuum I suggest that automated systems would reduce air pressure and/or oxygen content enough to greatly slow the fire but not so low as to be fatal to people.  At battle stations I would expect the crew to be in pressure suits anyway or at least have them readily available.  

I would even go so far as to assume, that a warship approaching combat will blow off its atmosphere in order to prevent preasure waves from enemy weapon hits.
I would assume a nuke going off 50m to starbord (or a megawat laser explosively evaporating part of your hull/railgun slug hitting with some 10.000 km/s) will crate quite a shockwave from hitting the hull. No need to give that shockwave a medium to travel through the ship.

[IanD]

I tend to agree with jfelten on the subject of fires. Lets face it its not rocket science to design an auto venting system into a compartment that activates once it gets hot enough. I think the current chance of exploding damaged systems causing a follow-on explosion is pretty good, all you would need to add would be a number of the crew being caught in the compartment and injured/killed by either the initial explosion or venting of air from the compartment if not at battle stations (and presumably suited-up). Would that mean casualties from maintenance failures would be higher that that from combat, since the crew would not be suited-up?

What would be the effect of crew casualties? Are there any at present?

As for propellant exploding, just how inert is sorium?

Regards
Ian

[IanD]

Steve wrote

Fire is a great threat to modern surface warships.

One thing I really like about Aurora so far is that its not just the wet navy in space.

Regards
Ian

[schroeam]

One thing everyone is forgetting is that the VAST majority of fires are not caused by fuel, propellants, or explosives, but by electricity.  Various safeguards are put into place regarding the prevention of fires from the obvious explosives (Halon, AFFF, CO2, PKP, flashpoint temperature, etc.).  Electrical fires are the catalyst and the resulting big fire is the flammable material (paper, linens, plastics, insulation) that catches fire and spreads.  As long as there is oxygen present a fire will burn, well below the limit for humans to stay conscious, or live, therefore lowering the oxygen available in the space is not an option, totally eliminating oxygen to the fire is the only option, or cooling it.  As the temperature from the fire rises, the space affected with eventually reach a point where everything will catch fire.  Some chemical fires create their own oxygen (counter-measures, phosphorous, magnesium) and pose a much high risk due to their higher temperatures and inability to remove the oxygen.  Nukes are not a danger as an explosive until they are armed, but I agree with the 10% rule Steve has imposed, and would think that it might actually be a little higher during battle.  If anyone has questions on the effect of a fire on a ship caused by an electrical fire look up the USS BONEFISH fire.  Sure, WWII ships suffered from fuel fires, but that is unlikely in this reality until we learn what point Sorium burns, or explodes, when in fuel form.  Steve is also right in that the number one way to prevent fires from limiting your ability to fight your ship is your Damage Control ability.

Adam.

[jfelten]

One thing everyone is forgetting is that the VAST majority of fires are not caused by fuel, propellants, or explosives, but by electricity.  Various safeguards are put into place regarding the prevention of fires from the obvious explosives (Halon, AFFF, CO2, PKP, flashpoint temperature, etc.).  Electrical fires are the catalyst and the resulting big fire is the flammable material (paper, linens, plastics, insulation) that catches fire and spreads.  As long as there is oxygen present a fire will burn, well below the limit for humans to stay conscious, or live, therefore lowering the oxygen available in the space is not an option, totally eliminating oxygen to the fire is the only option, or cooling it.  As the temperature from the fire rises, the space affected with eventually reach a point where everything will catch fire.  Some chemical fires create their own oxygen (counter-measures, phosphorous, magnesium) and pose a much high risk due to their higher temperatures and inability to remove the oxygen.  Nukes are not a danger as an explosive until they are armed, but I agree with the 10% rule Steve has imposed, and would think that it might actually be a little higher during battle.  If anyone has questions on the effect of a fire on a ship caused by an electrical fire look up the USS BONEFISH fire.  Sure, WWII ships suffered from fuel fires, but that is unlikely in this reality until we learn what point Sorium burns, or explodes, when in fuel form.  Steve is also right in that the number one way to prevent fires from limiting your ability to fight your ship is your Damage Control ability.

Adam.

I believe you are thinking more in terms of peacetime fires vs battle damage fires?

[IanD]

While I cannot disagree about the danger of electrical fires the USS Bonefish fire was a result of being a wet navy boat.
From Wikipedia

While the sub was submerged, seawater began leaking onto cables and electrical buses in a battery supply cableway. Electrical arcing between cables caused an explosion which flashed into a fire within minutes

No doubt it would be possible to postulate a scenario where the water dispenser leaked leading to a fire, but all the causes of the fire would have to be internal maintenance faults or the result of battle damage and would have to have fuel. The fire suppression venting system should be automatic and it would not be the first or last time a hatch has been dogged with the knowledge that there were still live crew in the compartment.
It could well be doctrine that when going into combat the ship is depressurised just to try and eliminate such hazards as fire and decompression.

Regards

Ian

[schroeam]

No, actually the damage from concussions will affect the electrical distribution and potentially cause fires.  Not everything damaged is able to be seen right away.  A bolt/screw jarred loose that falls onto a terminal board shorting two wires together will cause some sort of electrical flash.  Whether that flash results in a fireball or just causes a fuse to blow is in the 10% Steve is using.  If we want to assume that every system on the ship is operating at 100%, that all the preventive maintenance was performed exactly right, on time, then we can assume that secondary explosions will occur in magazines and from fuel.  However, using a realistic approach that at least some of the vital equipment is actually closer to catastrophic failure would result in collateral fires due to concussion effects similar to that stated above.

Decompressing the ship prior to battle would have extremely negative effects on the ability of the crew to have the split second reactions necessary in battle.  Try walking around in an exposure suit for even half an hour, see how easy you are able to operate, and fast you get exhausted.

[jfelten]

Decompressing the ship prior to battle would have extremely negative effects on the ability of the crew to have the split second reactions necessary in battle.  Try walking around in an exposure suit for even half an hour, see how easy you are able to operate, and fast you get exhausted.

I'm not convinced of that.  It is far from uncommon for soldiers to have to fight in hostile environments loaded down with adverse weather gear plus weapons and equipment.  If a Roman soldier could lug 20+ Kg across continents by foot, I'm sure a sailor could wear a pressure suit for a few hours if it gave him and his ship a survival advantage in battle.  Our boys humping 30Kg on foot patrol in Iraq wouldn't have too much sympathy either.  Ever have to work in MOPP gear?  See someone decked out in firefighting equipment?  For the average crewman it doesn't have to be an Apollo moon mission space suite.  All it has to do is keep him alive for a few seconds until he can reach the next hatch or a pressure closet.  It is virtually guaranteed that suite technology will advance resulting in lighter and lighter suits.  

Besides, most of the split second stuff will be taken care of by computers.