Explosions - Personal experiences?

[ElectricBlue]

The opening barrages for the Battle of Passchendaele could be heard in London - ninety miles away.

The mines exploded under Vimy ridge could be heard two hundred miles away.

The last eruption of Krakatoa was heard a thousand miles away, if I remember some historical recounts correctly, and the effects of the ensuing tidal wave were detected on tide gauges in Great Britain (as an anomaly in daily readings) a week or so later.

The loudest thing I've ever heard was a firepower demonstration at Puckapunyal, where the Oz military get to use up some of their ammo before it reaches its use-by date. Four Chieftain tanks firing shells into the other side of a valley is loud, a two-thousand bomb dropped from an F111 is louder. Literally a whoomp of air immediately followed by the sound. A Pig thundering into the sky on its afterburners is pretty impressive too. Whoa!

 

[wheres_the_beef]

Now if one is very close to an explosion, on top of it almost, say in a protected vehicle or ground position, would it be possible to see a flash, perhaps feel it but not hear anything at all? I was told years ago by a man whose armoured vehicle was blown up that all he remembered later was a flash and then recovering consciousness in hospital hours later. Was that memory an accurate summary of the event or faulty recollection of the experience?

I have been in and around tanks firing on many occasions along with many other things that go boom. Ahh, gloriously well spent youth.

The sound from the contained explosion that is firing the main gun mostly comes out of the end of the gun tube. It is relatively directional because of the nature of how the energy is released out the end of the barrel. Inside the tank is not that loud in my experience, even with the hatch above me open. The noises that stood out more were the sounds of the gun recoiling and extracting. There was a pressure wave that I more felt on my body than heard. The gun recoiling is a big chunk of metal moving back rapidly and reducing the already limited space inside the turret. I always assumed that was creating a pressure wave for the air in the turret that I felt. Interestingly, you would not hear that on the recording that was taken from the intercom for qualification ranges. The pressure I felt did not trigger the crew microphones as a sound. The playback just had a metallic tink when the gun fired.

I could still hear the sounds of other tanks firing next to me when down inside the turret. It was louder if I stuck my head up out of the turret. Driving behind firing tanks in a HMMWV as a range safety fell somewhere in between. I mostly had the bulk of the tank between me and the muzzle on most shots in that case. I could hear the difference on the engagement where the range road curved to the side and the tank was firing over its flank with me able to see the muzzle.

Terrain could also make a difference in how the sound propagated. Out of direct line of sight of heavy weapons fire you could see some strange effects. At one tank range moving further away from the firing tank could make it louder. There was a small valley with one end facing out towards the firing tank and the other end quite a bit back in the range area. As you moved back towards the mouth of the valley the sound got louder. The sound also came from the "wrong direction." The sound was apparently in line with the angle of the valley mouth it was funneled through.That did not line up with the direction where I knew the firing tank was.

There are also some other factors involved. On a tank, we wear helmets that covers both ears. It both makes sure the crew voices are not drowned out by all the noise of the tank and also provides hearing protection. Everything nearby is muted. It is also pretty common to get so focused on the task at hand that the tank gun firing was mostly ignored. I was really only interested in knowing that the gun went off when under stress. I had more important things to focus on like where to shoot next and keeping my extremities from getting smashed by the turret monster. With training I got pretty good at not noticing much else. Finally there is adrenaline. Get a big dump of adrenaline in your system and your perceptions change. Time distorts, peripheral vision narrows, and sounds get excluded. Call it misperception but it is your brain reacting to deliberately focus perceptions. Think of it as the hard coded and chemically triggered form of learning to ignore certain stimuli and focus that comes with training.

Mix all of it together and there is no one way that someone will remember the experience of an explosion. A number of factors can come into play making the perception significantly different between people. Even two people sharing the same fighting position when an artillery round lands nearby may have very different perceptions of the event. Those differences can make for interesting story writing. It is just not as easy as having one way to describe the experience.

 

[Salacious_Scribe]

Mythbusters did an episode where they blew up a cement truck in an abandoned quarry. They filmed it with a high-speed camera. The mushroom cloud was well-formed before there was visual evidence of the shockwave. In real-time, the difference was a fraction of a second, but on the high-speed camera, there was a noticeable lag.

There are several variables to be able to answer your question. Some of these are...

Distance from the explosion
Air Pressure/Altitude
Terrain (woods/canyon/urban)
Explosive force (grenade vs nuke)

I'm sure there's more I can't think of now.

 

[jaF0]

Just don't ask those morons to test fire a cannon.

 

[Bramblethorn]

And most explosions of military grade don't have a giant fireball. There is a visual of what ever is exploding, then the boom and shock wave.

Go watch a Mythbusters explosion. They do it in slow motion so you can see what is happening. You see the explosion, then you see the shock wave traveling through the air and you hear the boom.

Only explosion of chemical plants an anything dealing with natural gas or petroleum products produce a fireball. Oh and Hollywood special effects.

Also, just about anything flammable, when powdered finely and suspended in air near a spark. Coal dust, grain dust, aluminium dust, even plant spores will all make a fiery fuel-air explosion.

Military explosives usually contain their oxidiser and are typically contained in something - thus, although the explosive "burns" very quickly, that's contained to a small area and hidden inside the packaging, so there's not much fire to be seen. But some recent weapons do use fuel-air principles:

https://www.youtube.com/watch?v=GmRASCHJe2Q

The method is much the same as a BLEVE: use a small explosive to mix fuel with air, then spark it.
https://www.youtube.com/watch?v=UM0jtD_OWLU

 

[jaF0]

Also, just about anything flammable, when powdered finely and suspended in air near a spark. ... grain dust

Grain Elevators make some really nasty kabooms.

 

[TarnishedPenny]

I listened to a conversation a day or so ago about individuals experience of an explosion, eventually all parties to the discussion agreed that they did not really know.

We knew that in the movies the sight of an explosion is at the same time or immediately after the bang, however, if one observes a real explosion at say 3000 yards one sees it well before one hears it. I am less certain of this but is it also true that one also feels the ground vibration and pressure wave before hearing the bang?

Now if one is very close to an explosion, on top of it almost, say in a protected vehicle or ground position, would it be possible to see a flash, perhaps feel it but not hear anything at all? I was told years ago by a man whose armoured vehicle was blown up that all he remembered later was a flash and then recovering consciousness in hospital hours later. Was that memory an accurate summary of the event or faulty recollection of the experience?

The bang and the pressure wave are one and the same. Once you get beyond the immediate vicinity of the explosion, it moves at the speed of sound, which is as already noted, is why we see it first. I was running some very large bangs years ago - one tonne each, more or less. From our vantage point on a hill a mile and a bit away, we'd see the fireball, then watch the pressure wave streak through the long grass towards us. Scary, exhilarating and (I blush to admit it) fun! Ground vibration? No so much in my experience.

But (absent Boris and Natasha's Hush-a-Bomb), every explosion comes with sound. That a survivor wakes up in hospital not remembering it is like somebody with a concussion not remembering falling off the bicycle; it's a brain thing.

 

[Bramblethorn]

Grain Elevators make some really nasty kabooms.

Back in my early D&D days, I had a Dungeon Master who'd been training in workplace health and safety. Our party was poking around an old granary...

"It's dark near the flour. Do you want to bring your torch closer to get a better look?"

"Not on your fucking life. I know where you're going with this."

Oh, the look of disappointment on her face.

 

[Voboy]

I suspect your ability to recall the explosion, which is based on many factors others have listed above, is also partly dependent on whether you're expecting it.

I was only "surprised by" three or four explosions in my time, and now that I think about it I recall the sight far better than I recall the sound.

Most military demo charges (door breaching charges and shaped charges for cratering) have an explosion I would describe as "flat." They're directional, meaning the blast wave goes somewhere predictable, and unless you're standing downrange the sound is like a massive crack. Sort of like a really loud gunshot from close by.

The funnest demo I ever saw was a flame fougasse, which is like a big-ass fixed flamethrower that shoots homemade napalm out of a 55-gallon drum. It was impressive, though not loud (it was only a blasting cap).

Fun thread.

 

[TarnishedPenny]

Come to think of it, most real explosives don't produce a big Hollywood fireball. Directors pay the SFX team to do some special chemistry, 'cause that's what the paying audience expects and demands. In real life, military explosives going off often seem pretty 'dull' to onlookers expecting the big fiery thingy. As for commercial explosives, most of them are used in v confined spaces, like at the end of a hole drilled well into solid rock in a quarry or mine - v little fireball to be seen.

Mileage will vary in accordance with the particular explosive and how it's been set, of course.

 

[Zeb_Carter]

If you watch that Mythbusters link I posted you won't see a fireball, well not a hollywood fireball, only a very small bit of one in the very beginning that was so quick only the slow motion camera caught it. They used about 100 100lb bags of ammonium nitrate(a commercial grade high explosive) in that cement truck. It basically disappeared in the blink of an eye.

 

[gunhilltrain]

You get a great flame from a battleship's large guns:

https://youtu.be/40YNZ2kbT50

https://youtu.be/KB4kdeDjz38 (3.44 onwards)

Heavy cruisers had impressive flames too. What were those, eight to ten inch guns?

I may be anti-war, but those old battleships were great. Of course, they have long been completely obsolete. I toured the USS New Jersey once (it's at Camden, NJ) and that is an amazing ship. I realized that the guns on there, had they been operational, would be capable of firing shells twenty miles and dropping them into Trenton.

 

[oggbashan]

Heavy cruisers had impressive flames too. What were those, eight to ten inch guns?

I may be anti-war, but those old battleships were great. Of course, they have long been completely obsolete. I toured the USS New Jersey once (it's at Camden, NJ) and that is an amazing ship. I realized that the guns on there, had they been operational, would be capable of firing shells twenty miles and dropping them into Trenton.

Most WW2 battleships had a range of twenty-five to thirty miles, and with radar control could drop a shell inside a fifty-foot wide target.

As supporting gunfire on D-Day they could take out an individual German tank. A 2,000 lb shell didn't leave many tank remains.

 

[ElectricBlue]

Most WW2 battleships had a range of twenty-five to thirty miles, and with radar control could drop a shell inside a fifty-foot wide target.

As supporting gunfire on D-Day they could take out an individual German tank. A 2,000 lb shell didn't leave many tank remains.

I read up on the WW 1 Battle of Jutland, one of the few fully fledged big gun battleship encounters that ever took place. Absolutely amazing stuff, Two Royal Navy fleets up against the German High Fleet, with long lines of battleships hurtling twelve gun broadsides at each other, "crossing the T," executing high speed turns with twenty ships all at the same time.

One of the great understatements of any military commander: "There seems to be something wrong with our ships today," as the third or fourth battleship sunk.

 

[oggbashan]

I read up on the WW 1 Battle of Jutland, one of the few fully fledged big gun battleship encounters that ever took place. Absolutely amazing stuff, Two Royal Navy fleets up against the German High Fleet, with long lines of battleships hurtling twelve gun broadsides at each other, "crossing the T," executing high speed turns with twenty ships all at the same time.

One of the great understatements of any military commander: "There seems to be something wrong with our ships today," as the third or fourth battleship sunk.

Not battleship - battlecruiser.

The battlecruiser idea was flawed from the start. The idea was to have a ship with the firepower of a battleship but with reduced armour so that it was lighter and faster. The idea was that it could outrun any ship that had bigger (or as big) guns and outgun anything smaller.

But true battleships became faster and no battlecruiser could outfight a battleship.

The main factor was the way the Royal Navy handled ammunition. They used bags of cordite. The German encased their cordite in metal. Even that wouldn't have been enough to make a difference but the British decided that rate of fire was more important than anything so the safety doors, designed to prevent a flash-through, were left open, and the next cordite bags were stored in the turrets.

A hit on a turret would flash through to the ammunition store below and blow that battlecruiser apart. The Germans were much more careful with their safety doors and all spare ammunition was NOT in the turret until it was loaded into the guns so a hit on a German ship's turret would only affect the turret, not the ammunition store.


HMS Hood, destroyed by the Bismarck in WW2, was Britain's largest ship BUT it was a battle cruiser, not a battleship. Its armour was too thin against the Bismarck's guns.

 

[ishtat]

I am open to correction on this because I cannot find the reference, but if my memory is correct the German ships at Jutland had a self leveling device for their guns which greatly improved accuracy in heavy seas. The British had been offered this invention years before but the admirals turned it down.

British ships scored hits with only 3% of their attempts (their own calculation) while the Germans fired less but scored a significantly higher 'hit' percentage.

 

[oggbashan]

I am open to correction on this because I cannot find the reference, but if my memory is correct the German ships at Jutland had a self leveling device for their guns which greatly improved accuracy in heavy seas. The British had been offered this invention years before but the admirals turned it down.

British ships scored hits with only 3% of their attempts (their own calculation) while the Germans fired less but scored a significantly higher 'hit' percentage.

Another factor is that the German ships had superior optics on their rangefinders. Typically they were stereo with a 24 feet (or about) distance between lenses. The British had six feet.

At the battle of the Falkland Islands when the British were firing at German ships that they outranged and so had the chance of shooting without interference, their hit rate was appallingly low. The Royal Navy had introduced Director Control a few years previously and were still learning at Jutland.

The final factor was that the German so-called "High Seas Fleet" did not expect sailors to sleep on board. They would be in port every night. That meant, unlike the Royal Navy which expected sailors to live on board for months, that more of the German ships tonnage was available for protection and fighting capacity.

 

[gunhilltrain]

I read up on the WW 1 Battle of Jutland, one of the few fully fledged big gun battleship encounters that ever took place. Absolutely amazing stuff, Two Royal Navy fleets up against the German High Fleet, with long lines of battleships hurtling twelve gun broadsides at each other, "crossing the T," executing high speed turns with twenty ships all at the same time.

One of the great understatements of any military commander: "There seems to be something wrong with our ships today," as the third or fourth battleship sunk.

When I was younger, I considered joining the Navy. One thing I thought about was: no muddy trenches, no dusty marches, you take your bed and kitchen with you.

That's fine until there is naval combat, which has been rare since Word War II. But if there is combat, ships have a tendency to sink or blow up like big firecrackers. Submarines and aircraft can wreak havoc on surface ships.

The Royal Navy was shocked in The Falklands War by how much damage was inflicted by a few Argentine missiles.

 

[TarnishedPenny]

... if there is combat, ships have a tendency to sink or blow up like big firecrackers. Submarines and aircraft can wreak havoc on surface ships.

The Royal Navy was shocked in The Falklands War by how much damage was inflicted by a few Argentine missiles.

Word at the time attributed the loss to aluminum structural bits catching fire, which is just silly; aluminum melts, but won't burn unless it's very, very fine. A more lucid proposal was the loss of some critical damage control systems, which was odd as they were supposed to have been triply redundant. The claim at the time was that they had been redundant, but the lines were laid side-by-each, meaning that one Exocet would take them all out. Damfino; naval architecture was never my field.

 

[oggbashan]

Word at the time attributed the loss to aluminum structural bits catching fire, which is just silly; aluminum melts, but won't burn unless it's very, very fine. A more lucid proposal was the loss of some critical damage control systems, which was odd as they were supposed to have been triply redundant. The claim at the time was that they had been redundant, but the lines were laid side-by-each, meaning that one Exocet would take them all out. Damfino; naval architecture was never my field.

The aluminium superstructure was too light - to save weight above the waterline. It had virtually no resistance to an Exocet, which was basically a small missile. Any WW2 ship of that size would have ignored an Exocet, or even several Exocets. The General Belgrano, an ex-US WW2 cruiser, would have been unaffected by an Exocet.

And yes, the ships caught fire and the aluminium wasn't strong enough to contain the fire.

Later Royal Navy ships didn't use aluminium.

 

[Damoiselle]

Not an explosion, but I remember when someone shot at me and my boyfriend at the time when they drove by us in Tucson, there was a flash that I felt blinded by long before I registered sound.

I think it was a gang initiation thing. We were just lucky that they didn't shoot more than once or come back.

 

[stickygirl]

Don't know about Dreadnoughts and battleships except that a typical battleship could fire the equivalent of a Volkswagen Beetle over 20 miles, perhaps even a camper van.

 

[Voboy]

Not an explosion, but I remember when someone shot at me and my boyfriend at the time when they drove by us in Tucson, there was a flash that I felt blinded by long before I registered sound.

I think it was a gang initiation thing. We were just lucky that they didn't shoot more than once or come back.

Glad you came through.

I was surprised, when I finally heard a bullet snap past, how easily I could tell exactly how far away it was from me.

 

[ElectricBlue]

Don't know about Dreadnoughts and battleships except that a typical battleship could fire the equivalent of a Volkswagen Beetle over 20 miles, perhaps even a camper van.

Yes, a one ton shell. One description that stuck in my mind was that a broadside coming towards your vessel was like the end of a six-fingered hand coming out of the sky, the sailors could actually see the shells (hoping with the fear of God that the enemy range-finder hadn't got the distance right).

Different gunners had different techniques - one might place a shot with too much distance, the next shot too short, the third shot in between... Another might progressively increase the range, stepping their shots towards your vessel. The descriptions of the shelling battles are of maelstroms from hell, all in slow motion. Awful stuff, best imagined by not being there.

 

[TarnishedPenny]

Yes, a one ton shell. One description that stuck in my mind was that a broadside coming towards your vessel was like the end of a six-fingered hand coming out of the sky, the sailors could actually see the shells (hoping with the fear of God that the enemy range-finder hadn't got the distance right).

I remember reading about sieges in the US Civil War. Troops could indeed see incoming mortar bombs and got pretty good at predicting where they would land as they perceptibly drifted off to one side or the other, long or short of their own position. It was when that the ball in the air just seemed to hang in the air, not moving, just getting bigger and bigger...