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The Dresden Files => DFRPG => Topic started by: kgy121 on September 10, 2014, 11:28:48 PM

Title: Extrapolating Car Crashes from the Falling rule
Post by: kgy121 on September 10, 2014, 11:28:48 PM
Ten feet of falling, once all other possible outcomes have been removed, does five stress boxes, removable by supernatural armor and spells.
That's 9 meters per second, or 32 feet per second. About three fourths of a second into the fall, the person reaches that ten feet.
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This puts the speed for five stress boxes at about 25 feet per second.
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And, of course, this puts the speed for five stress boxes at 17 miles per hour.

Doing the calculations for the next distance does indeed double the miles per hour for an additional 5 stress boxes, which gives the damage a nice linear relationship with speed. Every ~3.4 miles per hour is one stress box worth of damage before consequences have to be taken, reduced by armor factors.

With a relatively mild car crash on a freeway, that leads to a 17 box hit, should the 60 MPH vehicle be brought to a stop by some solid object. It's a good thing modern cars have safety features out the wazoo, providing mundane armor for that specific type of crash.
Title: Re: Extrapolating Car Crashes from the Falling rule
Post by: citadel97501 on September 10, 2014, 11:37:02 PM
I did this math for the World of Darkness from White Wolf as well.  I terrify people whenever I mention Forces Magic and cars now. 
Title: Re: Extrapolating Car Crashes from the Falling rule
Post by: Sanctaphrax on September 11, 2014, 12:15:17 AM
Don't use the falling rules, they're awful.
Title: Re: Extrapolating Car Crashes from the Falling rule
Post by: solbergb on September 11, 2014, 04:08:29 AM
A big explosion and a typical surface-street vehicle accident are both about 5 shifts.

Harry often compares his force effects to being hit by a car, so it's worse than being hit by a gun, but from a story standpoint and DFRPG mechanics in the 5-7 shifts range likely, with 7ish being a high speed collision into a wall and maybe 9 for being hit from both sides by two cars each going 60mph and dropping all of their energy into you, or having something the size of a semi pin you to a tree while going at highway speeds

and yeah, the falling rules are just dumb.   Just estimate lethality similar to how other shifts go based on how high up the dude falling is and what he's falling onto.  Remember that we're doing adventure novel physics here, and that stress shifts represent dramatic chances of being removed from the story, not kilometers per second squared type momentum.
Title: Re: Extrapolating Car Crashes from the Falling rule
Post by: kgy121 on September 11, 2014, 09:24:51 AM
So one of the things I can do now that I have this data is, since this is extrapolation, is determine how fast I can crash cars into the giant monster before its maximum of 10 stress boxes gets filled in, or consequences.  For playing a pure mortal, it's important to know that hitting a max endurance mythic toughness zombie dinosaur at 50 (50/3=17 stress boxes by the math) miles per hour can probably inflict a mild consequence or two. Sure there's still 9 more to go, but at least now you've made a hella dramatic entrance and gotten it to focus its rage on the party rather than the make a wish kitten hospice.

This is not about falling at all. It's about cool things you can do with force estimations.

(Sanctaphrax's test thing in his sig)
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Title: Re: Extrapolating Car Crashes from the Falling rule
Post by: Haru on September 11, 2014, 09:51:46 AM
Quote from: kgy121 on September 11, 2014, 09:24:51 AM
For playing a pure mortal, it's important to know that hitting a max endurance mythic toughness zombie dinosaur at 50 (50/3=17 stress boxes by the math) miles per hour can probably inflict a mild consequence or two.

That's not really how this works. Well, you can make it work like that, sure, but I think there's an easier and far more flexible way to handle this. You simply attack using the drive skill.

You can determine a weapon rating for attacking with a car, let's say it's a weapon:4 for now. And before you attack, you can create a number of aspects that represent backing up to have more distance to gather speed, actually gathering speed, etc, and you tag all of those when you do the actual attack. That's not only more interesting, but it also involves the player in doing something towards his goal. Just saying "well, I'm driving fast" and taking the speed as the attack value is really anticlimactic.

And I don't think Sue would have been too impressed if someone hit her with a car. She crashed into houses while turning a corner, and she had by and large the same speed, and she was fine.
Title: Re: Extrapolating Car Crashes from the Falling rule
Post by: kgy121 on September 11, 2014, 10:22:00 AM
A T-Rex's top speed is usually judged to be between 10 and 25 mph, or 3-8 shift; with Armor 3 from Mythic Toughness and 'oh god' stress boxes, yeah running into a building is absolutely no problem for a necromantically charged behemoth of a specter/zombie. Cars be fast though.

Weapon rating for cars is a good point. Just calling it a number of weapon makes no differentiation between accidentally backing over your foot, a wizard smashing a car on someone, or actually using the car in a way that (in)sane mortals would to maximize damage. If someone throws the car at someone, it's probably going about 12 miles per hour, which would be, yes, four shifts. Swinging a baseball-bat of a car, probably the same. HOWEVER, a thinking person using drive, using an aspect every turn for a +2 (6mph) would assuredly do more damage than the aforementioned large club.

So yes, I agree with you completely. I quite like having rules that fit the story, reality, and fun.
Title: Re: Extrapolating Car Crashes from the Falling rule
Post by: Tedronai on September 11, 2014, 12:28:46 PM
Stress and Weapon Ratings are not linear.

Weapon 3 is a big sword.
Weapon 4+ is the territory of 'battlefield weaponry'.  Grenades (these things leave people in pieces), anti-material rifles (these things put holes in armoured vehicles), and things even nastier.

Assign a weapon rating, tag/invoke some aspects, and make your roll.
Title: Re: Extrapolating Car Crashes from the Falling rule
Post by: Quantus on September 11, 2014, 02:52:55 PM
Quote from: kgy121 on September 11, 2014, 10:22:00 AM
A T-Rex's top speed is usually judged to be between 10 and 25 mph, or 3-8 shift;
  Just to throw some extra math into the mix, there is a somewhat wide range of their top speed.  And per Jurassic Park T-rex/frog clone hybrids can top out at 32 mph.  From a purely dramatic standpoint I'd have them top out at just a bit faster than your party, in whatever cehicle they happen to be in at the time.  With extreme speed loss in turning.   

Quote
Scientists have produced a wide range of maximum speed estimates, mostly around 11 metres per second (40 km/h; 25 mph), but a few as low as 5–11 metres per second (18–40 km/h; 11–25 mph), and a few as high as 20 metres per second (72 km/h; 45 mph). Researchers have to rely on various estimating techniques because, while there are many tracks of very large theropods walking, so far none have been found of very large theropods running—and this absence may indicate that they did not run.[97] Scientists who think that Tyrannosaurus was able to run point out that hollow bones and other features that would have lightened its body may have kept adult weight to a mere 4.5 metric tons (5.0 short tons) or so, or that other animals like ostriches and horses with long, flexible legs are able to achieve high speeds through slower but longer strides. Additionally, some have argued that Tyrannosaurus had relatively larger leg muscles than any animal alive today, which could have enabled fast running 40–70 kilometres per hour (25–43 mph).[98]