A story of massive falling damage, and a question on crater size.

[Cheddarwurst]

So a while ago, the DM foolishly made a density potion for a specific dungeon puzzle that increases your density by a thousand, and rather foolishly left something like 50 doses in the dungeon, which we took all of.

Anyway, tonight we were fighting this Malebranche that had disguised itself as a candy king from a demi-plane that was basically candy land. We were a thousand feet in the air and this great beast was pummeling our knight who was in front of me on a broom of flight. Two others in the party had ridden a gryphon up and as the knight was knocked off the broom, the ninja turned invisible, jumped onto the demons head from the back of the gryphon and forced the potion into its mouth. The ninja then leaped from the beast onto the broom that I was somehow still astride and the demon plummeted, its weight magically increased to something like an oil tanker. It died, and so did everyone in the small town that it landed on.

Anyway, I'm wondering what the hole this thing left would have been like.

Edit: I'm going to write this up in a story for r/gamertales on Reddit and call it The Candy Crush Saga. It's just too perfect not to.

[goto124]

Demon Falls, Everyone Dies?

[Ephemeral_Being]

Here's a calculator for determining crater size. (http://www.lpl.arizona.edu/tekton/crater_c.html)

Problem is coming up with what variables to feed it. MM2 doesn't list any physical characteristics, so we have to estimate here.


A Malebranch is probably about three meters wide
A Malebranch is probably about the same density as the average human (1062 kg/m3)] (http://en.wikipedia.org/wiki/Orders_of_magnitude_%28density%29). You said the potion increased this "by a thousand?" I'm assuming a factor of 1000, so 1,062,000 kg/m3
A Malebranch has a much larger cross-sectional area than a person would, due to its wings. But its mass also increased by a factor of 1,000. Here's a calculator for his terminal velocity. (http://www.calctool.org/CALC/eng/aerospace/terminal) I went with a mass of 1,360,000 kg, assuming he was around 1360 kg (or 3000 lbs) (dungeons.wikia.com/wiki/SRD:Table_of_Creature_Size_and_Scale) before the potion was fed to him. The average human has a Cross-sectional area of 0.7 m2 (http://onlinelibrary.wiley.com/doi/10.1256/wea.29.02/pdf). So a Malebranch, being 4x as large would have a CSA of 2.8m2. The other information you need is in the sidebar, on the calculator page. I got a Terminal Velocity of 1739.04 m/s, or 1.73904 km/s.
For the sake of simplicity, say he hit the ground at a 90 degree angle.
The earth's average density at the surface is 2.7 g/cm3 (http://jersey.uoregon.edu/~mstrick/AskGeoMan/geoQuerry57.html). That works out to 2700 kg/m3 Unless anyone has information to the contrary, I'm assuming the world you're on is the same.
And then gravity, we're also assuming is the same (9.8).
Last thing is to pick the terrain type. I'm going with "Competent Rock or Saturated Soil."


That gets us to a final answer of a crater that is 504 meters (1650 feet) across.

That's pretty decent.

EDIT: That CSA is likely very wrong, though. I'm realizing now it probably should have been increased by a factor of 16, not 4. Or possibly even more, because of the wings. Which would reduce his terminal velocity by a great deal. Making the CSA 12.2 (16*0.7) gives you a terminal velocity of 833.124 m/s. And an impact crater of 365 m (1200 feet). So, I guess it depends what configuration he was in when he fell. If he's on his side, that first figure might be about right. Wings furled and on his back/stomach, the second calculation is decent. With the wings open trying to slow himself as much as possible, we have to bump the CSA higher. And the concavity of the wings adds in another element to the puzzle, if I'm reading this correctly.

Take the first or second estimate, and insist his wings were closed. That's my vote.

[Cheddarwurst]

I did my own math, thanks for the tool, and came up with

Projectile Descriptors

Projectile Diameter 1.829 meters
Projectile Density 539670 kg/m3

Impact Conditions

Impact Velocity 278.25 km/sec
Impact Angle 90 degrees

Target Descriptors

Target Density 2700 kg/m3
Acceleration of Gravity 9.8 m/sec2
Target Type competent rock or saturated soil

Results
The three scaling laws yield the following transient crater diameters (note that diameters are measured at the pre-impact surface. Rim-to-rim diameters are about 1.25 times larger!)

Yield Scaling 1.22 x 103 meters
Pi Scaling (Preferred method!) 1.64 x 103 meters
Gault Scaling 0.18 x 104 meters
Crater Formation Time 2.97 seconds

Using the Pi-scaled transient crater, the final crater is a crater in the transition between Simple and Complex with a rim-to-rim diameter of 2.55 x 103 meters.

This impactor would strike the target with an energy of 6.69 x 1016 Joules (0.16 x 102 MegaTons).

I can't stop laughing. The three people on the ground should be dead and we effectively nuked a small town.