A ballistics question

[John Dolva]

I wonder if anyone has come across a test that approximates something like this?

An oval shape rougly the size of an adult head. Perhaps a plastic bucket with edges pinched in to make oval shape.

Mounted off center on a preferably flexible tube, perhaps a plastic agricultural pipe, tied down with flexible ... and weighted perhaps with a plastic shopping bag of mud in the top 'chamber'.

Fired at with sub and supersonics from various directions (incl elevations)

and filmed?

I'm particularly interested to see what an 11 oclock at 18 degree elevation, off center

3 oclock off center at 30 degrees

6 and 8 and 9 oclock at 10 degrees

does on a 18 fps camera

# hard to do in australia with the tight gun controls in place here.

The inportant thing is the oval shape mounted off center. I want to see what happens in the first few frames after strike.

[John Dolva]

also: the 'bucket' should be tilted (or angles adjusted to accommodate a tilt.)

and

a shot from locations with same oclock and elevation but strike at, above, and below, the pivot point.

so the inportant things are off center mounted oval shape, flexible mount, and shots above, and below, and at, pivot point

[John Dolva]

wrap an inner tube tightly over the short knuckle of a drive shaft. Mount a plywood oval off centre on this. The long diameter of the oval the same as the (plastic) bucket at half full level. Tie a 5 foot bit of wire onto the long knucle and make aloop about halfway up the drive shaft. This is for strapping down the bucket over the platform. Chuck the lot with assistants into a ute and head for the shallowest dam(unless you like getting very wet) with the most space and contour surrounding it.

Bury the drive shaft firrnly (not forgetting to put the long knuckle perpendicular at the bottom of the hole to stop the shaft from turning) at the edge of the water. put wet sawdust in a bucket slip it qiuick over upside down over platform make snug with the sawdust compressed, strapping the edge down tight (if the edge of the bucket is too weak, tie a rope around here to catch the lip of the bucket and have the straps hooked to this) to meet the profile of the platform. This will then represent the various tendons and tissues holding a head up.

Estimate the location of the pivot and paint marks on 4 opposite sides of the bucket to aid locating the pivot point in the film (don't forget the camera (pref 2 for other than z position.) meanwhile perhaps one of you would create the perimeter with warning signs and locate a good vantage point for help and lookout for stray kids.or animals. Perhaps a third assistant is advisable to patrol the perimeter exclusively.

Mount camera on tripod lock and load. bang away recording distances, super/sub bullet, angles, etc for each shot.

for each shot shoot above at and below pivot point

[Al Carrier]

wrap an inner tube tightly over the short knuckle of a drive shaft. Mount a plywood oval off centre on this. The long diameter of the oval the same as the (plastic) bucket at half full level. Tie a 5 foot bit of wire onto the long knucle and make aloop about halfway up the drive shaft. This is for strapping down the bucket over the platform. Chuck the lot with assistants into a ute and head for the shallowest dam(unless you like getting very wet) with the most space and contour surrounding it.

Bury the drive shaft firrnly (not forgetting to put the long knuckle perpendicular at the bottom of the hole to stop the shaft from turning) at the edge of the water. put wet sawdust in a bucket slip it qiuick over upside down over platform make snug with the sawdust compressed, strapping the edge down tight (if the edge of the bucket is too weak, tie a rope around here to catch the lip of the bucket and have the straps hooked to this) to meet the profile of the platform. This will then represent the various tendons and tissues holding a head up.

Estimate the location of the pivot and paint marks on 4 opposite sides of the bucket to aid locating the pivot point in the film (don't forget the camera (pref 2 for other than z position.) meanwhile perhaps one of you would create the perimeter with warning signs and locate a good vantage point for help and lookout for stray kids.or animals. Perhaps a third assistant is advisable to patrol the perimeter exclusively.

Mount camera on tripod lock and load. bang away recording distances, super/sub bullet, angles, etc for each shot.

for each shot shoot above at and below pivot point

On previous posts here and on Lancer I described the easiest way to recreate the skull for shot impact and exit wounds. Fill a standard latex balloon with 5-7% ballistic gelatin and then coat the outside with plaster coated strips of paper and layer them five deep. The hardened paper will be fairly consistent with the layered skull plating, the latex balloon will simulate the dura and the thinned ballistic gelatin will simulate the brain cavity. It will give you through and through realistic resistance and pressure that one would look for to repeat a wound cavity and disruption in a human skull.

Al

[John Hunt]

FWIW: A latex baloon is highly elestic. The dura is highly inelastc.

John Hunt

[John Dolva]

Yep, John that's true. Like the bag of skin containing the head, tough and inelastic, but flexible.

However, that's good to know a recipie for a standardhead in studying wound ballistics. Al, is that gel from boiled hide? Like the stuff in kids Jelly (which BTW at 50% makes an excellent wood glue)

_______

anyway.. the setup I'm trying to picture here is one where the immediate movement of the head is studied, not blood etc dispersal. So a setup where there is minimal dispersal of stuff, but an absorption of energy and the resultant movement.

The rubber winding and the straps provides some of the characterisitics of the muscles and tendons. The sawdust (wetted) provides weight and inflexibility like the brain itself is inelastic, but transmits force.

Everything tight to stop the whole thing flying apart too quickly, but not sealed so that the cavitation is bled off to some extent.

Cheap, and simple to repeat the same setup, a supermarket plastic bucket at less than a dollar each, and all the rest are standard items: so cheap, rough ready and easily doable.

Naturally should anyone undertake something like this, modifications are made to suit.

Whatever the setup chosen, can an answer be made, or has someone already done so:

to the question of 'how does a head move at the instant of being streuck by a bullet?'

for example : "would a tangential shot from the front on the temple area cause an initial twist movement? "

if so 'in what direction?" etc.

Maybe a setup entirely or partly different from what I picture here is needed. Whatever it is, cheap, easy and reproducible is important.

It's the very initial movement, captured in a mere instant by film but not the eye, that's of interest in this particular.

[John Dolva]

Yep, John that's true. Like the bag of skin containing the head, tough and inelastic, but flexible.

However, that's good to know a recipie for a standardhead in studying wound ballistics. Al, is that gel from boiled hide? Like the stuff in kids Jelly (which BTW at 50% makes an excellent wood glue)

_______

anyway.. the setup I'm trying to picture here is one where the immediate movement of the head is studied, not blood etc dispersal. So a setup where there is minimal dispersal of stuff, but an absorption of energy and the resultant movement.

The rubber winding and the straps provides some of the characterisitics of the muscles and tendons. The sawdust (wetted) provides weight and inflexibility like the brain itself is inelastic, but transmits force.

Everything tight to stop the whole thing flying apart too quickly, but not sealed so that the cavitation is bled off to some extent.

Cheap, and simple to repeat the same setup, a supermarket plastic bucket at less than a dollar each, and all the rest are standard items: so cheap, rough ready and easily doable.

Naturally should anyone undertake something like this, modifications are made to suit.

Whatever the setup chosen, can an answer be made, or has someone already done so:

to the question of 'how does a head move at the instant of being streuck by a bullet?'

for example : "would a tangential shot from the front on the temple area cause an initial twist movement? "

if so 'in what direction?" etc.

Maybe a setup entirely or partly different from what I picture here is needed. Whatever it is, cheap, easy and reproducible is important.

It's the very initial movement, captured in a mere instant by film but not the eye, that's of interest in this particular.

topical bump

Edited September 9, 2006 by John Dolva