Date: Fri, 06 Jun 1997 05:32:42 PDT From: "Henrik Larsen" Subject: Heat Rules 3 - Even Hotter Line Eater Chow! Now With Extra Fat! OK, lets try this again. I've done some adjustments and changed the "damage" system, on encouragement from A Jackson, and attempted some better wording, thanks to Dataweaver. I would still like constructive critisism, but also oppinions from people who consider it usable, as, if it works, I intend to have it go in the Archive, not to mention use it in a campaign setting for the Net. The Source of Heat. Heat is a by-product of any power-using component. It varies greatly with quality, but for a standard, use (75 - (TL X 5)) percent of power output or requirement, depending on component. As such, a TL 10 fusion reactor producing 4000kW would produce (4000 X (75 - (10 X 5))%) 1000 kWs of heat per second, while your TL 14 laser, using 800kW per shot would produce (800 X (75 - (14 X 5))%) 80 kWs per shot. Whether TL15+ components produce heat is up to the GM. Heat and Damage. Just because they build a little heat does not mean that components explode, or even break down. All components have a Heat Capacity (HC) and a Heat Dissipation (HD). The HC is how much heat, the component can contain without taking damage, and the HD is how many kWs of heat lost per second. For standards, consider HC to be TL X mass, and HD to be TL X surface area / 100 (round up). This assumes a minor layer of heat ventillation on the surface of the component, which avoids heat simply being transfered into other components, and thin veins running through the component. This is calculated into the standard weight and volume, and removing it has no significant benefit (but serious problems). If a component soaks up more heat than its HC, it risks shut-down. When the component begins to produce excess heat (i.e. after HC is used up and cooling systems cannot remove the heat fast enough), roll HT. On a success, it continues to function, but if it in skill-based use, such as the drivetrain (Driving, Piloting and similar skills used), these will be at -1. For every 10% above component HC in heat produced and not cooled immediately, another roll is made, at cumulative -1 per 10% above component HC, and the penalty to skills increase by -1, also per 10% above HC. On a failure, the component shuts down, unable to function until cooled. Once it cools off 10% of HC in kWs (even if this still sets it above HC), another HT roll can be made, with any applicable penalty. A success means the component kicks into action again. Rolls continue as usual hereafter. On a critical failure, the component shuts down _violently_, inner parts coliding, plasma leaking, etc. This causes 10% of HC damage, plus 5% extra per full 10% of heat above HC. HT rolls to restart is as above. Note: HT for a Component is calculated as Structural HT: (200 X HP / mass +5) Example: Using the fusion plant above as an example, we get a mass of 2800 lbs and surface area of 100. Thus, HC is 2800, HD is only 1, and HT is (200 X 100 / 2800 + 5) 12. This means it builds up 999 kWs of heat per second, letting it last 3 seconds before starting to roll HT. After 3 seconds, it has 197 kWs more than HC, so the roll is unmodified. As there are no real rolls needed for power plant use, the penalty is insignificant (had it been a jet engine, Pilot would be at -1). Next second, excess heat is a whooping 1196 kWs, requiring a HT roll at -4 (and a jet would give Pilot -5). Heat and Cooling. There are some basic options for getting rid of heat: Evaporation and Passive Cooling. Both these systems works by simply giving the component some extra material to soak up heat, thus increasing HC. The standard passive system can be assumed to weigh .2/TL lbs. and cost $2/TL per HC added, while evaporation systems are .05/TL lbs. and $.5 per HC. Passive systems usually have very low HDs, to avoid heat going back into the system, and are often replaced after being fully used (usually to be cooled actively). Evaporation systems let the spent material evaporate. Active Cooling. These work by leading the heat to extra cooling vents or the vehicles surface, depending on effectiveness. They basically add HD. Assume stats to be 2/TL lbs., 1/TL kW requirement, and cost $(100/TL) per HD. A system for the fusion plant would be .2 lbs., .1 kW and $10 per extra HD. To allow permanent operation, it would have to have HD 999, which would be 199.8 lbs. and cost $9990, while requiring 99.9 kW (which would itself require power plant, which would require cooling). The cooling system does not require cooling itself, though the extra power requirement might. If someone wants to use an Active cooling system to cool down a Passive one, this can be done simply by cooling the component down, and then keep the Active system in operation, draining the Passive one at equal rate. Thus, if the fusion plant had only a 499 HD Active system, but a 5000 Passive one as well, it could run for 10 seconds without heating the component itself. After 5 seconds more, the fusion plant is almost reaching its HC limit, and is switched to stand-by (minimum output without stopping the entire chain reaction in the core). The Active system and component HD remove the component heat in (2800/500) 5.6 seconds. After that, the Active system frees 499 points of HC from the Passive system per second, leaving it almost as good as new after 10 seconds. That gives 15.6 seconds of cooling after 15 seconds of use, if HT rolls are to be avoided. If HT rolls of up to HT - 3 are acceptable, this adds 1120 kWs of time, which is only 2 seconds more. Such cooling systems are a part of the component, enlarging it. The final mass equals the mass of the component plus that of all cooling systems in it. Its surface area will also need to be recalculated, but this does _not_ improve its HD, HC or HT, since the extra space consists of the cooling system itself. It does, however, increase the amount of armor and the like needed, and it also increases hit points (I may work out a way to differentiate between damage to the component and the cooling system later). Heat and Enviroment In non-terran atmospheres, HD is multiplied by atmospheric pressure, but cannot go below 20% (even in vacuum, some heat is lost). Also, the following enviromental factors alter HD by the multiplicator given. To find the final HD, multiply all the multiplicators. Moist (e.g. jungle): X .75 Very Moist (e.g. deep tropics): X .5 Cold Winds: X 5 (unless using air for coolant, as in fans) Drizzle: X 1.5 Heavy Rain: X 2 Submersed in Water: X 3 Hot (90+): X .75 Veru Hot (130+): X .5 Extremely Hot (190+, not on Earth): X .25 Cold (40-): X 1.25 Very Cold (10-): X 1.5 Extremely Cold (-20-): X 2 Titan Moon Cold (with Methane ice!): X 4 In Methane Ice(!): X 8 Note, that the three last factors, and Extremely Hot, would usually demand special vehicles, to avoid break-downs. The two last most certainly do! By Henrik Steen Larsen, helped by Anthony Jackson and Dataweaver.