Mechanical Arts

[Samloyal23]

Excuse my ignorance but why does a dwarves natural resistance make it hard for THEM to cast spells? I ask because I am wondering if I am missing any rules (since i dont give a dwarf a penalty for casting spells).

In the setting I'm working on one subrace of dwarves lives in an area rich in an anti-magical mineral, it gets in their food, water, mother's milk, and ends up embedded in their bones. Because of this they have trouble casting spells but are resistant to the powers of others. I'm just trying to make my idea playable...

 

[Loonook]

But how do you measure BTUs in game terms? How many BTUs does it take to cause 1 hp of damage?

I did the math for the valuation of the substance... Now, we can look into the basics of BTUs of open flames and immolation.

Now, let us take the options of various heats. A British Thermal Unit is the amount of energy required to make 1 g of pure water raise temperature by 1 degree Centigrade. Full-body immolation occurs ~ 740 C, and the flashpoint of human skin is around 162 F (72 C). The average starting temperature of the human body would be ~ 37 C. Human flesh, being made mostly of water, would 'boil' its reserves at 212 F (100 C), leaving behind crisp flesh.

Now we need to deliver heat to the body at a rate to do serious damage. Let us say that we want to deal enough damage to destroy the epidermis (I'm literally pulling this out of my backside at this point ). If we assume that an AHB in D&D terms, represented by a single-HD humanoid with a 10 Con, would be 14.5 pts from full-health to death. That is going to be best approximated by taking a fireball to the face with no save from a 5th level caster (average damage: 17.5).

Let us stick with BTUs and assume that dealing third-degree burns on our nude humanoid across 100% of the body = death (which has been the case almost universally until the creation of Burn Wards, and is only mildly improved today).

Let us say our average humanoid is a male of average height, body fat, and skin weight. 7 lbs (3.17 kg) is as good a measure as any for the weight of the epidermis in our Everyman, and 2-4% body fat on a US average 190 lb (86.63 kg) human comes to a 3% average of 2.59 kg. Altogether we have 5.76 KG of mass to convert into a sticky goo.

I am not going to convert Fat and Skin to their specific Caloric amounts. A kilo of fat (which will have a higher caloric burn than the skin) come to 7700 calories. 44352 calories or 175 and change BTUs worth of energy in the flesh itself if we were to burn it .

Now we need to figure out the Specific Heat of this mixture. While not perfect, we know the Specific Heat of Lard in KJ/KG/C to be 2.26. 1 KJ is .947 BTU, so I'm going to keep the number as is as we are doing WAGing here .

Our average temp is 35C off our desired base crispy-critter temp to leave a pile of skinless beings who are fried to muscle. So 2.26 * 5.98 * 35 to get our baseline for fried humans.

473 BTU for a flash burn to burn a pile of unattended flesh. To be safe (considering air, radiant insulation from the rest of the body, etc) I would bump this up by around 100* at minimum.

47300 BTU to flash-fry a human.

Honestly, I think it would be way higher than this simply because of surface area, but I don't feel like doing complex math... I like winging it .

----

Of course there are so many effects. But that seems like a working system... The cost of casting a fireball with this system would be somewhere around 420 GP/'round'. This is slightly more expensive than a Scroll of Fireball, but would not require that pesky Mage to be attached to the spell.

420 / 17.5 - 24 GP/HP of average damage/area effect. 1.6667 energy units expended. Means each use of your 'death ray' (I would figure it at a 10d6 to 20d6 power, or 35-70 damage) costs 840-1680 GP to fire. This puts it at worse than a scroll of cone of cold on the low end, to cheaper than a Chain Lightning on the other end.

For your 'dragon gates' to be a more permanent effect let's multiply that by 10x. 8400-16800. By this reckoning it is cheaper (and more effective) than a permanent Wall of Fire with Permanency even at its highest level of effective casting for your low-end ability, and much more effective (if more expensive by 6k) than a permanent WoF on the high end.

tl;dr: Overall I feel that, for magic effects, 1 2/3 EU/HP damage in a 20' span would be fair and fit the unit well.

Slainte,

-Loonook

EDIT: This takes Fireball as the spin-off, and assumes a radius/cone of effect that extends at least the range of the fireball. For spells such as Burning Hands (as an example) which require lower output for smaller area of effect? Look to reduce the overall cost to bring it more in line with the figures... But really, why are you expending this ability for anything but mass carnage? .

 

[dragonfriend7738]

--snip--
But really, why are you expending this ability for anything but mass carnage? .

Because they're dwarves, and their primary concern is using it as a forge rather than a death beam? And as such, they'd need a much higher and more constant output of energy to heat, melt, and treat the various metals and alloys that they are putting into the machine.

Besides, I thought we were trying to figure out the in-game mechanics of something like this rather than the math behind a real-life application.

 

[Loonook]

Because they're dwarves, and their primary concern is using it as a forge rather than a death beam? And as such, they'd need a much higher and more constant output of energy to heat, melt, and treat the various metals and alloys that they are putting into the machine.

Besides, I thought we were trying to figure out the in-game mechanics of something like this rather than the math behind a real-life application.

Which, if you read the thread, I outline to a base energy unit that can be interpreted to use in a variety of platforms including baking, lighting the way, ovens... Really all you need to do is take the example of constant output of 1 EU - 864 hrs of output @ ~1400 BTU. If one were to surmise the heat of a clean-burning efficient forge @ 30-40k BTU you can place the cost of powering said forge as 308 GP, 3080 for 'rechargable' forge, with EUs that will need to be replaced/recharged every 108 days. As stated previously, the recharges pay for themselves after the 13/14th charge, and turn this cost to (61gp 6sp)/period.

Yeah, all the math is there for use. Of course if you look up most heat-based applications you will find charts or examples to help you...

But I believe you didn't read either of my posts fully.

Slainte,

-Loonook.

 

[Samloyal23]

I hate math... Okay, how many gp for a basic solar oven and a simple solar forge? If you tilt a solar oven or forge to reflect heat at a target, how much damage does it do and what's the range?

 

[Loonook]

I hate math... Okay, how many gp for a basic solar oven and a simple solar forge? If you till a solar oven or forge to reflect heat at a target, how much damage does it do and what's the range?

Listed above. 3080 for a single-person small Forge with a rechargeable set of energy retainers that doesn't burn out after it expends its EUs. The forge can deal 12.8 damage on average, which is ~ 26 max. If we want to stick with the facts, sitting smack dab between 4d6 or 5d6. Of course when you discharge all of that energy you're going to be dealing damage to the actual forge itself, and isn't optimal. To keep it in line with the cost of a Fireball of 5d6 (420 GP)... I'd make it 4d6.

I put the cost of other sources in the listing below for a 10d6 and 20d6 'blast' at 840-1680. These forges would have 35-70 EU output. Remember than an EU of 14.4 GP gives a BTU average output of 1375 or 1 damage/20' radius. A space heater @ 5 EU that warms a chilly cottage explodes? Probably killing your average human commoner unless they are stabilized within 42 seconds (2 hp, 5 damage, -3 to -10, 7 rounds to death). The local bakery explodes? Think big, like the explosion we had discussed before in your natural gas thread. 181 damage at the epicenter will kill anyone inside short of a fire immune creature or a dragon, and probably start a major fire across the area. For these larger explosions I would probably use a halving principle from the focus of the 20d6 maximum.

181 damage at epicenter (20' radius)... 90 damage at a 40' radius, 45 damage at 60' radius (and halving stops). Now that bakery costs 26040 GP to create just the oven's energy source. For a 52d6 (rounding up) effect... You've made an atom bomb. Well, not as powerful against humans (16d8*10 to humans in D20 Modern), but definitely fearsome. Again I would also change the weight of larger capacity energy stones so that a 118 EU stone is not going to weigh a little over 2 lbs to prevent abuse. For these large applications I would assume that the 'raw stone' weight stays at 118. But the material required to actually cause the reaction to be focused and usable as something more than a giant lantern battery weighs 3 lbs/EU (same size as a Bullseye Lantern we used for the original Burner analogue).

So the oven's full power supply weighs 356.7 lbs (~162 KG). The space heater's power supply weighs 15.06 lbs (~7 KG).

Slainte,

-Loonook.

 

[Samloyal23]

Okay, sort have my head wrapped around this idea. I am thinking the alchemists of Burghausen are making small solar crystals to carry light into their mines and to heat air and water on a vary limited scale, not the type of thing you could turn into an A-Bomb, but may something that could be used like a grenade. I want to keep a lid on this to avoid abuse.

Now, a conventional solar oven made from a set of mirrors, just big enough to heat a pot of stew, like [ame="http://www.amazon.com/Sylvan-Solar-Oven-Sun-Cooker/dp/B005JOSXTC/ref=sr_1_15?ie=UTF8&qid=1334612717&sr=8-15"]this one[/ame] is around $200 in American money, but it would make a great trade item for the Burghausen merchants in Skytop Village. I can't seem to find the weight, but it doesn't look too heavy. How much is a buck worth in game terms?

 

[Loonook]

Okay, sort have my head wrapped around this idea. I am thinking the alchemists of Burghausen are making small solar crystals to carry light into their mines and to heat air and water on a vary limited scale, not the type of thing you could turn into an A-Bomb, but may something that could be used like a grenade. I want to keep a lid on this to avoid abuse.

Now, a conventional solar oven made from a set of mirrors, just big enough to heat a pot of stew, like this one is around $200 in American money, but it would make a great trade item for the Burghausen merchants in Skytop Village. I can't seem to find the weight, but it doesn't look too heavy. How much is a buck worth in game terms?

The weight is listed on the site @ 20.7 lbs. Dollars don't necessarily translate well, as D&D has a wage of 1 SP/day of untrained labor. At current rates (silver has been around 30.00/oz for some time, or 480.00/lb) the average D&D worker would make $9.60 a day. That means they are making around 1.20/hr if you can assume an 8 hour day.

That means that your standard worker must work 144 days to afford a single EU of energy. If the person is practicing a trade they are making 6 GP/day if they practice a Profession. That's a little under ten times the amount of an untrained commoner by the 10/10/10 system of D&D... but with Gold's current rate of exchange to the dollar? You're looking at pure gold trading at 26430/lb, and those same coins being worth 500$ a piece! Even given 12 karat gold coins you're still looking at half-good pieces worth $250. That means that commoner would be making $78,000/year. Now, since apparently D&D just doesn't have enforced taxes... That is an issue.

Now, most who made a comfortable living (and many who didn't) in a medieval society would tithe and pay taxes. If we cut it down to 50% (generous) after costs of purchasing materials, tithing, etc. your average professional is making 18.75/hr.

Our economy doesn't do a one-to-one translation with the commodities costs.

Think of 1 SP as the cost of sheer survival/day/person. We're talking gruel, hardtack, and enough room to lay down on your back and pray for better. If we look into the DMG 3.5 (p. 130 has the insert) lists per-month upkeeps...

Self-sufficiency - 20 sp
Meagre - 50 sp
Poor - 120 sp
Common - 450 sp
Good - 1000 sp
Extravagant - 2000 sp

And so on. Self-sufficient means you're pretty much making everything, picking berries, stealing food, etc while sleeping in the streets (if you do not have a place to stay from other sources). Meagre assumes the occasional night in a flophouse. A Poor person could afford a cramped coffin apartment, just enough to make it for themselves... Then it gets better from there.

If you were a Commoner with no Profession you could work for 8 hrs and scrape by, gaining the occasional windfall, and in theory spend another 8 hrs hoofing it as a messenger at 2 cp/mile. If you had a Horse who you could graze you could make it being a Messenger, making 2 sp/day from riding at a full move constantly without tiring the horse, set them to bed outside the city, and make 9 GP/month untrained. A 1st level Commoner Professional makes 240 SP/month assuming 2 ranks, or 280 SP/month assuming a 10 on the roll and 4 ranks in their Profession. So any individual who actually has a Profession can support themselves and 1 more unit of individuals (another adult, 2 children...) in (semi-comfortable) poverty.

I'm still saying your best bet is trading in Lamps and Lampstones, and the Oven that we discussed above, and the weights I have supplied are well within the ranges you discuss. A small trade ship could carry around 1000 ovens or 7500 lamps without any issue.

Slainte,

-Loonook.

 

[Shaghayegh]

A dragon's gate sounds right up their alley, I like that idea.

The dwarves live on the mountainous side of a large island with a temperate climate and dense forests, they sit on top of the only known veins of an ore that makes casting spells difficult and throughout the area, but they have turned that into fine armour and weapons that resist magic. They have a small amount of coal, a few volcanic hot springs, and an extensive seaport. So spells cast in the area near their mines, say within 5 miles of their main city, have to overcome a 20% failure rate and take 1 round/spell level to cast. Divine spells are slightly easier, with a 15% failure rate and a casting time of 1 round/2 spell levels. Magic items that do not need to be activated, like most weapons and armour, are not affected. Any item that needs to be triggered has a 10% failure rate. They have no immediate enemies at their gates, but spies and assassins from another city on the island are a problem and there are bandits and pirates to be dealt with. I may tweak these numbers, I'm open to suggestions...

Just to simplify things make the failure rates for all types of magic the same, and determine if some areas have a weaker or stronger local effect...

 

[Samloyal23]

Just to simplify things make the failure rates for all types of magic the same, and determine if some areas have a weaker or stronger local effect...

Indeed. Hmm... Putting off doing maps...