How we doing hard-chargers, I want to say thank you for tuning in and I hope you’re gearing up for a safe and wonderful independence day.
Today the topic of focus will be the blast wave. You know the concussion wave that occurs when you’re dealing with rocket/mortar fire, some have experienced this and some are fortunate to not deal with such things while in the combat zone.
So you take contact from enemy fighters, you’re engaging with M-4’s, 203, SAW’s, and as you get ready to call in for fire support, you hear that whistle in the air as a rocket propelled grenade is en-route to your position. 3-4 Marines, yell IDF!!!! (In direct fire) at this point you get down and brace for impact.
So what happens after that moment?????? Well many have different opinions and I’ll give you my own as I’ve dealt with a bit of rocket fire.
There is a bit of penetrating trauma from debris propelled by the explosion.
There is also the kinetic effects of the shock wave compressing soft tissue, particularly in the torso’s vital organs, which can tear that tissue and/or the embedded blood vessels. This effect may include a secondary possibility of brain or organ damage caused by compression induced spikes in fluid pressure in the circulatory system.
Then there is acceleration of the body (i.e. being propelled away from the explosion’s epicenter) causing impact damage to the brain as it bounces around inside of the skull, just like any other source of cranial acceleration trauma.
Depending on their distance, speed and angle, shells tunneling through the air make slightly different noises, so a heavy barrage weaves itself into a bewildering cacophony of sounds; but the rushing always ends the same way, with a thunderous detonation.Hollywood tries and I’ll give them an E for effort but they fail to convey the sharpness and loudness of battlefield explosions. The visual effects normally used to simulate shellfire with plastic bags of gasoline and aluminum silicate are equally misleading.
In reality the eye usually registers a shell burst as an instantaneous orange-yellow flash inside a dark, leaping fountain of mixed smoke and pulverized earth, sometimes studded and fringed with large pieces of slower-moving debris. The bigger, heavier chunks of earth and stones thrown up by the explosion fall near by first; the smaller debris, blown much higher, comes pattering and clinking down for a considerable time afterwards and over a wider area.
The instantaneous pressure wave from the explosion moves outward at supersonic speed this is the expanding ring effect seen fleetingly in, for example, aerial footage showing the explosions of bombs.
It is followed after a slight, but appreciable interval by a blast wind the bulk of hot gases, fragments and ground debris away from the explosion. People in the target area experience the pressure wave as a sharp squeezing sensation in the chest, and its shock is also felt through the ground underfoot.
This shuddering of the earth is powerful enough to make those sheltering in trenches fear that they are about to be buried alive, and those who are lying flat feel themselves being shrugged violently into the air. These sensations are accompanied by stupefying noise and under heavy and persistent fire all the physical senses are overwhelmed.
Completely impotent to affect their chances of survival, Marines/Soldiers find sustained shelling and mortaring the worst ordeal of battle; those experiencing it often become temporarily unhinged, losing all muscular control (including of the bladder and sphincter) and the capacity for any rational thought.
These effects are particularly marked among those exposed to shellfire for the first time.
In the minority of cases when men suffer a virtually direct hit from artillery, the result is complete destruction of the body. The shell literally destroys the body, leaving, perhaps, a booted foot, a section of the human cranium, a bunch of fingers, a bit of clothing.
When a body is blown up, the spinal column surprisingly resilient often survives; after a shell has fallen among a group of men, counting the remaining spines is often the only way to determine the number of dead.
Most injuries, however, occur further out from the site of the explosion. Blast injuries to the human body are categorized as primary, secondary and tertiary. The first is the direct effect of the pressure wave; the second is the effects of fragments and debris carried by the blast wave; the third, would be the result of the body being thrown through the air and striking the ground or other obstacles.
The most obvious sign of primary injury is rupture of the eardrums, which may occur when air pressure rises to anything between 5 and 15 pounds per square inch; men who are killed by blast often appear peacefully asleep apart from the tell-tale bleeding from the ears.
The lethal internal damage caused by pressures of 50psi and upwards do not present dramatic outward signs. It is the gas-containing organs which sustain immediate and often fatal damage from the pressure wave; the lungs and occasionally the colon suffer catastrophic injury from the instantaneous compression effect of the blast. Large, blood-filled cavities are formed in the spongy alveoli of the lung, and fatal air embolisms are released into the arterial system; less often, the bowels may rupture, as may the spleen and liver.
Secondary injures will be more obviously dramatic. When a shell bursts the steel case breaks up into fragments of all shapes and sizes, from tiny beads to twisted chunks weighing several pounds. These, together with stones, pieces of weapons and equipment, and even large bone fragments from casualties nearer the blast whirl outwards from the center at different speeds.
The effects of being struck by shell fragments vary as widely as the size and speed of the shards. Sometimes a man is unaware that he has been pierced by a small splinter until somebody points out the bloodstained hole in his clothing. Larger fragments, cart wheeling unevenly through the air edged with jagged blades and hooks, can dismember and disembowel.
In many cases the evidence confronting an eyewitness is all too vivid. In others the immediate reaction is one of simple puzzlement: blast and steel can play such extreme games with the human form that the observer does not understand what he is looking at. When some random physical reference point suddenly jerks the whole image into a comprehensible pattern, the shock of recognition may be appalling.
God-speed to those who have endured such scenarios while being engaged by enemy fighters. My hat goes off to you and I want to say thank you for your service and the ultimate sacrifice to this country. I hope I was able to give you a better understanding of what takes place within seconds on the receiving end of rocket/mortar fire.
Isaac J. Hall II