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EastKingdom Schlager Punch Test - Forwarded
More fencing stuff!!
Terafan
>>> Dylan <dylan@netaxs.com> 01/21/96 10:26am >>>
Ed. note: Don Thomas and I that this report will help to clear the waters
surrounding armor requirements for schlager. Tom and I plan to continue
testing in the next week or so, making use of the information obtained
here.
This report will be available via WWW at
http://www.netaxs.com/~dylan/fencing.html
Last of all, if there is enough interest, I will set up a distribution list for
schlager issues in the next couple of days (ie, as soon as my contact
reads my email :)
dylan
------------------------>8 snip snip snip 8<------------------------
Punch Tests
There have been several reports lately on results of punch test
experiments with schlagers. While each has provided useful
information, each one has had its weaknesses. It is our hope to provide
some punch test data that is both comprehensive and scientific in
nature. This will give us solid data to help us determine armour
standards and future punch test requirements.
Objective: To create a test situation that would measure the penetration
abilities of various blades. This test was designed with certain
secondary requirements. 1. To control as many variables as possible.
(For example, while the ground in Texas may still be nice and soft, the
ground near Philadelphia in January is rock solid.) 2. That the test and
the results be easily reproducible. 3. That the data returned is
quantitative rather than qualitative.
Test Procedure: To measure the resistance of the fabric samples, we
dropped a weighted blade onto the sample. The sample was stretched
over the top of an open coffee can, so that the fabric had nothing
behind it. The weight was increased until the blade punctured
completely through the sample, and the weight required was recorded.
Test Apparatus: The Samples: The coffee can was a standard 23 oz.
coffee can, 13 cm in diameter. The sample (about 8 inches square)
was duct-taped onto the top of the can. The sample was pulled taut,
but was not overly stretched. The sample would not push into the can
more than 2.5 cm in any test.
The Blades: There were four test blades: a broken foil, broken 22.5 cm
from the tip, a broken epee, broken 17.5 cm from the tip, an untipped
schlager with a factory tip (slightly pointed shovel-shape), and an
untipped schlager, with a flattened tip. Note that during these tests, the
flex of the blades did not significantly affect the outcome. Therefore the
only significance of the distance of the breaks (for the broken weapons)
is to indicate the approximate surface area of the striking surface. The
blades were all weighted by sticking the tang through a coffee can (12
oz) being taped to stabilize it, and filled with nuts (the nuts-and-bolts
kind, not the edible kind). Weights were measured with a kitchen scale,
with a scale of 4.5 kg (1 kg=2.2 lbs). While not a scientific instrument,
this is more accurate over our ranges than my bathroom scale.
The Drop: The tip of the blade was held 30 cm above the sample, and
dropped straight down through a 35 cm length of copper tube to prevent
deflection (and creaming Dylan on the noggin).
This test controls several of the variables that have not been addressed
in other tests. The surface behind the sample has usually been "carpet"
or "ground". By testing the sample without any backing, we have
eliminated any variations in the backing. By using the force of gravity (a
constant most places on the planet) rather than person power, we have
created a test that can be repeated with the exact same amount of
force applied to the sample.
Testing Theory:
What follows is the physics details of the test. Feel free to ignore it if so
inclined.
When a sample is struck, the blade imparts energy to the fabric. If the
energy is more than the fabric can absorb, it tears. The equation for
kinetic energy is
K= 0.5(mv^2)
where K is the kinetic energy (in Joules), m is the mass of the
drop-weight (in kilograms) and v is the velocity of the object (in
meters/second). Since we know the mass of the weight, we need to
know the velocity. To find this, we must resort two equations:
d=vt
Distance equals velocity multiplied by time. We solve this for velocity
v=(d/t)
Since we also know the distance, we need to know the time required to
fall. The second equation enters here
d=0.5(at^2)
where a is the acceleration. We solve this for time, since we know the
acceleration is due to gravity and is a constant of 9.8 meters/second2.
t=(2d/a)^1/2
So we now can combine the two to get
v = d
----------
(2d/a)^1/2
Now we know velocity and can determine the energy.
K = (1/2)m *( d )^2
( ----------)
( (2d/a)^1/2)
We can simplify this to the following (knowing a 9.8m/sec2)
K=4.9md
Which is really very simple. It is a nice, linear equation. If the distance is
off by 1%, the energy will be off by 1%. This should keep things within
a reasonable tolerance of error.
The Data:
Test blade: broken foil
Drop height: 30 cm
Sample Weight required to puncture
1 layer trigger 0.5 kg
2 layers trigger 1.4 kg
3 layers trigger 1.6 kg
4 layers trigger 2.2 kg
1 layer denim 1.4 kg
2 layers denim 2.3 kg
Test blade: broken epee
Drop Height: 30 cm
Sample Weight required to puncture
4 layers trigger 2.4 kg
Test blade: factory schlager
Drop Height: 30 cm
Sample Weight required to puncture
4 layers trigger 2.0 kg
Test blade: flattened schlager
Drop Height: 30 cm
Sample Weight required to puncture
4 layers trigger 2.9 kg (that's a lotta nuts)
We also collected data on more subjective level. With the help of Cadet
Esteban (because we would never be dumb enough to do this to
ourselves) we got an idea of what it was like for a person to be hit with
this amount of force.
Test blade: flattened schlager
Drop Height: 30 cm
Sample Weight Reaction
4 layers trigger over 2.9 kg OUCH!!! That's more than I ever want
Cadet Esteban's thigh to be hit with in a bout.
Even though Esteban complained, the blade did not punch through any
layers of the trigger. This was a really really painful thing, but not
damaging to the sample or Esteban. (It did leave a bruise.)
Test blade: factory schlager
Drop Height: 25 cm (note - different height)
Sample Weight Reaction
4 layers trigger over 0.75 kg OUCH!!! That hurts a lot, but just
Cadet Esteban's thigh barely less than the last one.
The weight was the weight of the complete weapon. This drop also
produced no damage to the sample or Esteban. (A little bruise.)
Conclusions: There were several surprising conclusions from these
tests.
1. The epee did not penetrate significantly more than the foil.
2. The accepted premise that 2 layers of trigger is about equivalent to
one
layer of denim seems valid.
3. The factory schlager required about 10-18% less drop weight to
penetrate
the four layer sample than the foil or epee. This supports the concept
that the untipped factory schlager is more likely to penetrate than a
broken foil or epee. 4. Esteban is a wimp.
5. The weight required to penetrate the sample by flattened schlager
was
almost 50% more than the factory schlager. This indicates that the
untipped weapon can be made much safer by flattening the tip. 6.
The weight required to penetrate the sample by the flattened schlager
was
20% more than the epee and 33% more than the foil. If we accept that
four layers of trigger is acceptable protection while using foils and
epees the data suggests that, it is also acceptable protection from
untipped flattened schlagers.
7. While we did not directly test a broken schlager, we believe that the
broken schlager would require more weight to penetrate, since the
broken
weapon has a greater surface area.
8. Where a given weight would penetrate an unbacked sample, that
same weight
would not penetrate any of the sample layers when backed by
Esteban's
thigh. This suggests that these weights are valid measurements of
the
relative force required to penetrate, but do not correspond directly to
the actual amount of force necessary to penetrate a combatant's
armour on
the field. 9. The data collected opens the possibility of further testing
being done to
define a new standardized punch test for all SCA armour, that would
be
less subjective in its application. 10. A Free Sample Prodigy diskette
placed at the bottom of the sample can
prevents repeated punctures of the bottom of the can, and possibly
your
carpet. While one can postulate that puncture-proof armour can be
made
from such disks, further testing is needed.
The Junior Scientists: These tests were conducted by Don Dylan ap
Maelgwn (m.k.a. John D. Murray, 239A Roesch Ave, Oreland, PA
19075 (215)-887-0348 dylan@netaxs.com) and Don Thomas de
Castellan (Thomas F. Zadlo, 314 W. Fifth St, Lansdale, PA 19446,
(215)-362-1808 thomasdc@msn.com).
Editor's Note: In accordance with the Society for the Prevention of
Cruelty to Cadets, the editors wish it known that no actual cadets were
harmed in the collection of this data. Esteban is in fact a fiction created
by the authors to cover the fact that they were stupid enough to drop
untipped blades on their own legs in the name of science.
dylan Winner of the 1995 Award "I want a car as powerful
John D. Murray for Outstanding Achievement as a gorilla, yet soft
Philadelphia, PA in the Field of Excellence and yielding like a
dylan@netaxs.com OAFE '95 nerfball" - H. Simpson