EastKingdom Schlager Punch Test

[Dylan <dylan@netaxs.com>]

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