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Re: (TFT) 1 point of 'damage' vs. 1 point of Fatigue

----- Original Message ----- From: "Mark Tapley"
Subject: Re: (TFT) 1 point of 'damage' vs. 1 point of Fatigue

At 19:09 -0400 5/4/11, PvK wrote:
* horsepower is a power measure, closer to force.

Here's my breakdown on things:

To Break: To Move:
--------- ---------
Unit: Energy Momentum
Rate: Power Force

Or in words, *breaking* a certain amount of stuff (armor,
bones, skin, etc.) takes a certain amount of energy. *Moving* a
certain amount of stuff (boxes, "pushing back" an opponent, etc.)
takes a certain amount of momentum.

How quick you can put energy into something (sword, punching
bag, etc.) depends on how much Power you can generate.

How quick you can change the momentum of something
(wheelbarrow, door, etc.) depends on how much Force you can generate.

Confusingly, the two columns are related by *distance*
through which the force acts. This is what throws most people. A
200-Newton force, applied to a nearly stationary object (like an
ocean liner) will transfer momentum at the same rate as if it were
applied to a highly mobile object (like an arrow). At the end of one
second, both the ocean liner and the arrow will have 200 N-s of
force. If you crunch on the unit N-s, it comes out to:

(kg m/s^2) * s = kg m/s

which is mass times velocity, or momentum.
The arrow, although it has the same *Momentum*, will have
vastly more *Energy* than the ocean liner, because the 200-N force
acted on it through a very long distance (because it started moving
at the beginning of the second and kept accelerating all second long).

So, to generate a lot of Energy quickly, you need *both* to
put a lot of force on an object, *and* to keep applying the same
force while the object moves a long way. There is an interesting
trade-off having to do with the mass of the object - too light, and
your arm (or whatever you are using to apply the force) can't move
along with it. Too heavy, and the maximum force you can apply won't
accelerate it much, so you can't put much energy into it in a given
length of time.

Conversely, a lever allows you to multiply the *force* you
are applying to something, but *not* the Power you are putting into
it! The higher force is counteracted by a slower motion of the short
end of the lever, so the force * distance/time = Power is the same.

I don't think it's possible to simplify the above much
farther and stay consistent with real-world physics.

Hope this helps.

Fantastically put Sir!

uhhhhhh here's todays babble... I include your text so the "holes" are readily apparent if you pardon the pun... I think what your speaking of has to do with the info on hand shock and penatration forces but I'll give it all a re-look in light of your wonderful assistance.

5 pounds of pressure

"Typical force-displacement curves from the stab-penetration tests of synthetic chamois are shown in Figs 7a and b. The maximum penetration force and the corresponding displacement for all test conditions are given in Table 4. Synthetic chamois shows some sti?ening while approaching the point of maximum force (15 N) just prior to initial penetration. After initial penetration, the force drops dramatically to a third of the peak value and, while it ?uctuates as the blade ?anks widen the cut, no additional force is required for continued penetration."

1 Newton is ~0.2248 foot pounds.
~3.28 Newton's is 1 newton meter.

The 'Warner-Bratzler shear force test' for meat measures the kilograms of force needed to shear a 1 cubic centimeter muscle sample. The tender cuts have a shear force of ~2.6 (~5.7 pounds) and the toughest topped out around 5.3 (~11.5 pounds)

Figures for the tensile strength (not strongly related to the puncture force) of chamois and pig skin in the paper referenced are given in units of MPa, a measure of pressure.

20 psi

Bone / compressive strength (in Mega Pascal's, 1MPa = 1 Newton per square meter)

femur (upper leg) 167
humerus (upper arm) 132
radius (forearm) 114
tibia (shin) 159
cervical vertebrae (neck) 10
lumbar vertebrae (lower back) 5

1 MPa = 145.0376 psi

A conversion of pressure to torque depends on the efficiency of the system doing the work.


In practical knife fighting the targets are body locations that have a high probability of damaging an internal organ, severing a major muscle group, or cutting an artery, etc.

As proportioned in classical art the six foot tall human body can be divided into a silhouette using the following 9" by 6" (0.375 sq ft) areas I call Head Units (HU).

The head / 1 HU by 1 HU
The chin to the nipples / 1 HU by 2 HU
The nipples to the navel / 1 HU by 2 HU
The navel to the groin / 1 HU by 2 HU
The groin to the middle of the thigh / 1 HU each
The middle of the thigh to the knee / 1 HU each
The knee to the middle of the shin / 1 HU each
The middle of the shin to the feet / 1 HU each

Each arm is 1.5 HU from shoulder to elbow and 1.5 HU from elbow to wrist

In gauging the severity of a burn both the depth of the damage and the area need to be determined. When accessing the size of a burn medical personal use the Rule of Nines to estimate area. This assigns numbers to 6 major regions of the body representing the surface area of the region to the body's total surface area.

The silhouette is accessed from the front and back so a figure of 4.5 for a region only indicates one side with the whole region front and back totaling 9 or ~9% of the body's total area.

Head 4.5
Each arm 4.5
Chest 9
Abdomen 9
Each leg 9

(notice that the total for the front or back is only 49.5, the groin gets the extra 1% in this system)

I'll not give adjustments for children as describing this stuff is pretty morbid to begin with without going there right now. Halflings and giants can wait.

In accessing internal injury to the organs the abdomen and chest are divided into quadrants.
Each quadrant is ~0.5 HU.
The organs within each quadrant can be identified by an aid responder through percussing and palpating.

Left Upper Quadrant - left lobe of liver, spleen, stomach, left kidney, body and tail of pancreas, splenic flexure of colon

Left Lower Quadrant - sigmoid colon, left uterine tube, left ovary, left ureter

Right Upper Quadrant - right lobe of liver, gallbladder, pylorus, duodenum, head of pancreas, upper part of right kidney, hepatic flexure of colon

Right Lower Quadrant - lower portion of right kidney, cecum, appendix, ascending colon, right uterine tube, right ovary, right ureter

Midline - uterus, bladder


"The adult human body has 206 bones. An infant may have from 300-350 bones at birth. Some of these fuse together as the infant grows. When some bones fuse and become one bone (most obvious examples are in the skull, sacrum and hip bones) the number of overall bones drops to the 206 bones that most adults have.

Of the 206 bones in the adult human body, more than half (106) are in the hands and feet. The adult skeleton consists of the following bones:
28 skull bones (8 cranial, 14 facial, and 6 ear bones)
The horseshoe-shaped hyoid bone of the neck which is the only bone that does not articulate (connect via a joint) to another bone 26 vertebrae (7 cervical or neck; 12 thoracic; 5 lumbar or loins; the sacrum, which is five fused vertebrae; and the coccyx, which is four fused vertebrae) 24 ribs plus the sternum or breastbone; the shoulder girdle (2 clavicles, the most frequently fractured bones in the body, and 2 scapulae)
the pelvic bones (3 fused bones called the coxal bone, or Os Coxae)
30 bones in each of the arms and legs (a total of 120)
a few partial bones, ranging from 8-18 in number, which are related to joints

There are individual variations: for example, some people are born with an extra rib or lumbar vertebra and not everyone has Inca (sutural) bones."

When using square-hexes each square is ~13 inches a side.
For more detailed description I blow up a square-hex to a scale-hex 4 times the origional size on the graph making each square ~3.25 inches a side, an area roughly the size of the palm of a hand. One of the things I use a scale-hex for is describing the silhouette for weapons. The idea here is that a hand weapon puts the force on a point, along a line, or across an area. If I know the force and scale-hex squares involved I can describe injury in some detail.

Let's look at cutting an arm off with a sword.
Bear in mind that the dice describe a bell curve...
Also worth noteing, most swords or even stuff like kali sticks are around 3 feet long because of issues of contact with the ground and, worse, legs and feet.

So here's some stuff on sword swings

Let's call a strong male adults arm ~300 mm in circumference or ~4" in diameter.
TFT AM says under Aimed Shots (an optional rule) that 8 points of damage severs an arm.

I call 1 point of ST 5.5 pounds moved 1 foot in 1 second.
How much does a sword weigh?
"The average weight of swords from the 10th to the 15th centuries was 1.3 kg, while in the 16th century it was 0.9 kg."
1.3kg is ~2.86lbs.

So 1 point of ST swings an average medieval sword ~2fps or around 1.36 mph.
Joe Average gets a velocity of around 13.63 mph.
At ST20 the velocity is around 27.27 mph.
60 fps is about 41 mph.
Let's see if this is in the ball park at all.

Can't seem to find specific data for swords... let's see...

Bat Swing Speed Batted Ball Velocity
20.5mph (9.2m/s)  62.0mph (27.7m/s)
27.3mph (12.1m/s)  68.8mph (30.7m/s)
34.3mph (15.3m/s)  76.2mph (34.0m/s)
41.0mph (18.3m/s)  83.8mph (37.4m/s)
47.9mph (21.4m/s)  91.4mph (40.8m/s)

Not too horrible.

F = =m * v^2
To get joules I'm in metric.
Half of 1.3 kg is 0.65 kg.
So ST30 should get a 1.3kg mass moving at ~18.3m/s for 217 joules or about 160 foot pounds.
160 / 5.5 = 29.
ST20 comes in at ~95 joules or roughly 70 foot pounds.
70 foot pounds isn't 13ST.
The information on sword impact force mentions a KE of 140 joules in the section on edge impact dynamics. ST25 moves the 1.3kg sword ~15.24 m/s by my count which works out to 151ish joules.

As can be seen it's FAR from perfect but it certainly doesn't seem like I'm barking up the wrong tree completely with all this, and the vast bulk of the calc's would be buried in the weapons lists from a play pov.

So 1 inch is ~2.5cm and the toughest cuts of meat take about 2ST per cm to cut. 4 inches would be roughly 20ST to cut through minimum and I haven't put a bone in yet. 132 newton meters (humerus compression strength) is ~97.35 foot pounds or about 17.7ST.
The humerus diameter is about 20mm or around three quarters of an inch.
This would suggest about 15ST of muscle and 18ST of bone in a large upper arm or ~33ST of force to get through an arm minimum. So if 1pt ST generates 1pt of damage (@ 100% efficiency) then it takes over 4 times the amount of damage to sever an arm as that given by the optional Aimed Shots rule.

Just for jollys
~3000 joules per gram of TNT
1 average sized d6 ~5 grams
~5d6 across 3.25"
~125 d6 in one scale-hex cube
~375,000 joules in one scale-hex cube or about 275,000 foot pounds or ~50,000ST
~1,000,000 grams per ton
Hiroshima was hit with an explosion roughly equal to 20,000 tons of TNT (highly questionable as I'm getting conflicting info from a casual web search but this is just a back of the envelope thing)

That's very roughly 45,000,000,000,000 foot pounds or ~8,000,000,000,000ST at the source (air burst I think) or ~400,000,000,000ST per kiloton.
1900 foot air burst
Earths curvature @ 100 miles is ~1650 feet
I wonder how far in hexes to feel about 5 pounds of pressure from such a pop?
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