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chocowrites
07-21-2009, 04:16 AM
A bomb/explosion big enough to demolish a buidling the size of a house. Does the sky turn a different color (like red)? Does ash rain down? Does the earth shake? Is it the loudest sound imaginable?

I'm trying to describe one, and I put all of the above in an description, but it occured to me that it might not be accurate.

Oh and how far away can you be without being injured, but still see it?

Perdoon
07-21-2009, 04:43 AM
I'm not sure about what it's like to be nearby. I assume experiences would change the further you are away, so if your character is far enough away to not be hurt, they might just hear a loud bang and see a lot of fire.

However, on how far away you can stand, I know that they speak in statistics. At X distance, the chance of being hit by shrapnel that's large enough and travelling fast enough to injure/kill you is Y.

Unfortunately, I don't know about what the numbers actually are. I used to have a general idea, but that was back in high school.

Basically, it depends on terrain and the size (and I assume type) of bomb. Is your character peeping over a solid brick wall or completely out in the open when they see the explosion? Is the explosion enough to immediately blast all the walls down (sending bricks and such flying) or do some survive it? How realistic do you want it to be?

I would assume that if he was in the open, on a flat road (not an incline) and the bomb didn't flatten the area instantly, so long as they ran for cover when they saw it, they could be as close as 30-50 metres away. That's just an educated guess though and someone might show up in a second and have more accurate, completely different figures.

jclarkdawe
07-21-2009, 05:28 AM
There's an incredible wide variation here. You can pretty much go with anything thing you've seen on TV and be arguably accurate. The main difference is most explosions aren't as big as they are on TV, but the mechanics are the same.


A bomb/explosion big enough to demolish a buidling the size of a house. Usually the bomb is off-centered in the house. Result is one wall blows to pieces while the other side might be fine. Remember that an explosion will follow the path of least resistance. Once when wall goes, a lot of the blast force will go out the wall. Collapse is actually a good thing in an explosion, as it absorbs the force of the blast. Look at pictures of Oklahoma City to see how the building absorbed the blast.

Does the sky turn a different color (like red)? Everybody I knows look at the blast. Ignoring the fact that blast forces exceeds the speed of sound, you look at the blast to decide whether you need to get down. Usually the blast produces a fire, which produces a lot of smoke, which fills the sky.

Does ash rain down? Depends upon the contents and construction of the building. Light fluffy stuff like books and magazines create a lot of ash. Wood tables do not.

Does the earth shake? Depends upon the blast force and location above the ground of the blast. Some blasts have been registered on earthquake devices. If you're close enough, yeah, it will shake.

Is it the loudest sound imaginable? First time it happens, it sure seems like it.

I'm trying to describe one, and I put all of the above in an description, but it occured to me that it might not be accurate.

Oh and how far away can you be without being injured, but still see it? Over a mile and depends on how big it is.

The reality is usually explosions are a lot less exciting than TV. To give you an example, there's one on the show NCIS where Gibbs shoots out a 25 gallon propane tank that blows up and destroys an entire trailer. Yeah, not in the real world.

There are a lot of videos on the Internet of explosions. Take a look at them. Some are pretty good.

It is an experience of what you see is what you get.

Best explosion was as the engine I was on was pulling up to a structure fire and the 500 gallon propane tank let go. Took off the side of the house. Gave a glow that lighted the sky in all directions. The probie with us decided he'd volunteered for a bit more than he thought he had.

Best of luck,

Jim Clark-Dawe

firedrake
07-21-2009, 05:30 AM
I heard an IRA bomb go off once, from about 3 miles away.
I didn't see any smoke or anything like that, but I'll never forget the flat, short almost non-descript bang.

Vanatru
07-21-2009, 10:53 AM
A bomb/explosion big enough to demolish a buidling the size of a house. Does the sky turn a different color (like red)? Does ash rain down? Does the earth shake? Is it the loudest sound imaginable?


From personal experience, I was caught in an explosion that....well....when the bomb goes off your senses are assaulted by sound and the force of explosion.....so that your mind and body are numb and you feel nothing.

The explosion literally went off above me, as I fell to the ground, and I could feel the vibrations of the explosion rippling across my body as I was knocked back to the ground.....before it, all I could think of was the insurgent who threw the bomb at us, the expression of surprise on his face as I shot him, and the ensuing blast wave as it threw it me back onto the ground. It was like someone had slammed into me....someone who was f'ing pissed the f' off and made sure every fiber of my body felt it. It was so fast and so hard I almost didn't realize what had happened until it was over. Like a sucker punch. BAM and then it's gone.



I'm trying to describe one, and I put all of the above in an description, but it occured to me that it might not be accurate.

Oh and how far away can you be without being injured, but still see it?

I was literally under the explosion.....my foot caught in rubble saved me from damage...as my ankle twisted and dragged me down the explosion went off above me as the artillery shell went off......in my mind I could see the ripples of the shell going off and booming out away from me. Sorry....it's hard to explain....my mind was so numb from shooting the insurgent, seeing the surprise on his face and then being whip-slammed into the ground and then seeing an RTO above me looking down into my face with concern...as close as I can tell ya, it's like being at a rock concert, close to the big ass speakers when they crank up the bass and the vibrations slam into you and you feel numb. No thought. Just fuzziness.

Aquilegia
07-21-2009, 01:44 PM
What size and type of bomb? Demolition? Incendiary? Cluster? Also, I don’t know if this makes a difference, but was the bomb planted inside the building or dropped from the air?

Anyway, minimal experience here, but the ones I saw from around a mile and half away (yeah, pretty far) lit the sky with a white-yellow light, but it was a very quick flash for each bomb. There was minimal smoke. The ground was jolted, but hard, not shaky-trembly-like. As for sound, I know was some sound, but I honestly can’t remember that part. I remember there being a sound, but I can't remember the "details" of it.

These were aerial bombs meant to destroy large buildings (in an aggressive manner, not a controlled, peaceful manner). I’m guessing they were one- or two-ton demolition bombs, but I’m not a military person, so I’m not absolutely sure.

Michael Davis
07-21-2009, 03:23 PM
When I worked for ther Navy I was at one of their prep ranges where pilots prepared for deployment. When they would drop a MK84 2000 pound bomb, I was a good distance away and I felt the pressure wave in every part of my body. I don't just mean the sound in my ears, I mean the sensation of a quick jolt of instant pressure against my face and arms.

Richard White
07-21-2009, 06:25 PM
Another good spot to go to see explosions is Mythbusters.

Those guys LOVE to blow stuff up.

DavidZahir
07-21-2009, 08:06 PM
I was half a mile away when a ten-story building in Manhattan collapsed. It sounded like someone had fired a cannon.

errantruth
07-21-2009, 10:34 PM
Vanatru, that description really shook me. (!!!)

*stumbles out of thread in a daze*

Oh wait, --see how disoriented I am?-- the OP mentions bomb/exposion as if they're the same. Surely they're not? Is yours (OP) a bomb or an incendiary device of another type, and is it hidden in a building or is it dropped or is it part of enemy fire (ie dropped by planes)?

Just curiosity and to help the thread, maybe. I, for better or worse, slept through a bombing. In my defense I was under a lot of Nyquil, and thought there was a lot of thunder and lightning. So I can't provide anything useful to you on this one.

RJK
07-21-2009, 11:49 PM
different explosive materials explode at different velocities. TNT is high explosive, and has a velocity of over 6900 meters/second. Gasoline has a velocity of about 1500 meters/second. the blast would be quite different assuming you were far enough away to survive the explosion. If you are hit by debri, all bets are off. If you are hit by the air shockwave, it will depend on the distance from the explosion. Close enough, and you could be lifted off the ground and thrown a considerable distance. If you were that close, you could say goodbye to your eardrums, and you could possibly rupture internal organs.
I investigated one explosion where the victim was split open, right down the front of his body. I've heard of others where the victim is literally torn limb from limb.

Mike Martyn
07-22-2009, 01:12 AM
I've never been near an exploding house but I worked on a drilling and blasting crew when I was 17 years old ( and therefore immortal). We were doing a road cut about 200 feet deep about 500 feet wide and about 4 miles long for a new highway through solid granite. We drilled for about two weeks, loaded explosives (Amex plus 4" by 32" sticks of dynmite to set off the Amex which is an ammonium nitrate plus diesel fuel) In all we loaded 25,000 pounds of high explosive. I being the puppy of the group got the honour of setting it off.
So, there was I with my hard hat on and my finger on the green button of the blasting machine sweating out the wait until the three whistle blasts of the all clear. I pressed the green button and listened to the high pitched ascending whine as the capacitors in the blasting machine charged until the red light came on. I reached forward and pressed the red button and my hard hat fell off. The noise was sort of a deep rolling crump like the voice of God in an especially apocholyptic mood. I pressed myself into the dirt and a chunk of fly rock flew by taking off the top of the tree behind which I had sheltered.

After that, I got a desk job!

benbradley
07-22-2009, 02:11 AM
Youtube has many "interesting" videos. There's several versions of this very dramatic house explosion (as in even the guy holding the camera was obviously way too close for what happened):

http://www.youtube.com/watch?v=KjAKjdA5Lzw

There's surely a whole story and report of exactly what they did and what happened, but my guess is they thoroughly soaked the inside of the house with gasoline, then waited a while to make sure (well, perhaps not intentionally...) a bunch of it evaporated, becoming an explosive mixture with the air inside and underneath the house. Only then did they start the camera and ignite it...

Chase
07-22-2009, 02:27 AM
When I was a teen, I helped the neighbor farmer blast oak trees out of his pasture. We tunneled beneath roots and buried three to five sticks of 40% dynamite directly under the bole, packing the hole and roots iwell with semi-dry mud.

Our electrical leads got shorter and shorter, and soon we lay closer than comfortable while trying to put oaks in orbit.

I held my palms over my ears and opened my mouth to equalize pressure. I swear the shaped blast wump! from less than fifty feet away lifted me an inch off the ground, but that may have been a kid's perception. I could feel concussion on every inch of skin, even though we were behind another tree or dug in behind boulders.

Dust caked our clothing, and each night both of us experienced monster headaches, something I still get whenever I smell nitroglycerin.

Summonere
07-22-2009, 04:30 AM
Big Boom, though not so near.

April 19, 1995, at about 9:00 am, I was driving south on the Hefner Parkway, five or six miles from the Alfred P. Murrah Federal Building, when Timothy McVeigh blew the place up. I drove into the pressure wave generated by the blast. At that distance, the blast front hit my car like an unusually strong gust of wind. WHOOM! and gone. Strange thing to run through on a bright, sunny morning, and being almost imperviously incurious while on my way to teach a bunch of English undergrads, I kept going.

Then I saw a column of white smoke rising above the city south and slightly east of my direction of travel. I thought, hey, grass fire. Then the dark smoke started. I thought, hmm, something else is burning. The smoke column simply grew and grew and went from white to very dark gray and black. I thought of all kinds of things. Train derailment fire. Toxic chemicals spilled from train on fire. Plane crash. Something serious, in any event. So I flicked on the radio. All local stations were intermittently running regular programming and a few news briefs about the explosion. As the scope of the explosion became increasingly apparent, all local programming simply turned to wild speculation about what had blown up, the most often-cited cause being “gas line.” Since nothing definitive was coming out of the radio, I turned it off and kept driving.

I was teaching at a local college then, and by the time I arrived (about another six miles south of the blast site), there was much chatter about the federal building having blown up, but no one knew why, yet. So off to class I went, and what a bizarre-o-world that turned into, what with one student plugged into her radio, a bunch of others fruitlessly trying to make phone calls, still no one knowing what had happened, but news leaking out from our plugged-in student indicated that almost half of the Alfred P. Murrah Federal building was gone and the blast site was a mess of wreckage, smoke, confusion, and rescuers.

Come to find out later, this blast was so powerful that folks in my neighborhood, eleven miles north of Oklahoma City, had all come out of their homes when the blast front swept over them, rattling walls and windows and dishes. To a man and woman and child, all thought that something heavy had hit their rooftops hard enough knock holes. Even the dogs didn't like it, all of them spooked and barking. Rooftops, however, remained intact.

Did the sky turn black? No. Did ash rain down? No, again, but a bunch of Ryder truck parts landed on rooftops and streets all around the blast site. Did the earth shake? Yeah. Twice. Once from the bomb. A second time from the building falling apart. Each of these seismic waves, ten seconds apart, were measured by two separate seismographs, one located about four miles away, another about sixteen miles away.

Is it the loudest sound imaginable?

Six miles away, in a car with the windows rolled up, I didn't hear anything more than a really loud gust of wind. Near enough to the site itself, I imagine it likely sounded like a pretty big boom, but the closest I've been to exploding things has been downrange during an artillery demonstration, and closer still to much smaller destructive devices. Much like firedrake's report, those sounds have been pretty unremarkable. The artillery shots on a vehicle group, using airburst shells of some sort, just made a loud BANG! with a small, unimpressive poof of smoke. The vehicles were riddled with holes, though.

Histry Nerd
07-22-2009, 07:40 PM
A bomb/explosion big enough to demolish a buidling the size of a house. Does the sky turn a different color (like red)? Does ash rain down? Does the earth shake? Is it the loudest sound imaginable?

I'm trying to describe one, and I put all of the above in an description, but it occured to me that it might not be accurate.

Oh and how far away can you be without being injured, but still see it?

My experience is with military explosives, primarily grenades and artillery shells, so I can only speak to that. And I haven't been anywhere near as up close and personal with them as Vanatru has.

If you're close enough to feel the blast wave (anywhere from 100 yards to 600 or even more, depending on the size of the charge) it makes a very loud boom. Louder than you would think something of that size could make. If you're in an enclosed area, like between buildings or in a tight valley, it may be a twin boom as the blast wave and sound echoes off the nearby obstacles.

If you're outside the blast wave (farther than 600 yards or so from a 105mm shell, and maybe 75-100 yards for a grenade) the sound is more of a crunch.

Visually, it's not very impressive: an instantaneous fireball followed by a puff of dark smoke, plus dust thrown into the air if the explosion occurred on or near the ground. Obviously, it's a good deal more impressive from the receiving end.

The impressive part is how the shockwave feels as it travels through air and stone and your body. Like a huge hand pushing against every blast-facing surface of your body until it travels through you and out the other side. It happens so fast you might wonder what happened the first time, but every time after that you don't have to wonder.

As to how close you can be to a bomb big enough to bring down a house: It depends, obviously, on the size of the bomb and the house. If it's not a controlled demolition, an explosion big enough to level a house will probably partially destroy the houses on all sides of it, assuming a typical suburban neighborhood. Houses farther away will probably receive structural damage, with cosmetic damage to structures farther out as flying debris hits them. Forget being in the front yard when it goes off, like in the cop shows, unless you want to convince your character he is immortal or under divine protection.

Now, if all you want to do is bring the house down rather than completely destroying it, the damage will be much more localized. Probably the houses on either side will have damage to brick or walls or foundations from the shockwave, but they'll be livable with some repair. Depending on the composition of the house and the bomb (i.e., how much shrapnel they produce), you might be able to survive it from across the street behind a sturdy mailbox or a car.

Note of caution, though, if you want to use the car: they are not nearly as tough as the movies make them out to be. Unless the vehicle is hardened against high-velocity projectiles, shrapnel will rip right through it like it wasn't there. An iron engine block will offer some protection, an aluminum one not so much.

For what it's worth.
HN

Mike Martyn
07-22-2009, 09:30 PM
When I was a teen, I helped the neighbor farmer blast oak trees out of his pasture. We tunneled beneath roots and buried three to five sticks of 40% dynamite directly under the bole, packing the hole and roots iwell with semi-dry mud.

Our electrical leads got shorter and shorter, and soon we lay closer than comfortable while trying to put oaks in orbit.

I held my palms over my ears and opened my mouth to equalize pressure. I swear the shaped blast wump! from less than fifty feet away lifted me an inch off the ground, but that may have been a kid's perception. I could feel concussion on every inch of skin, even though we were behind another tree or dug in behind boulders.

Dust caked our clothing, and each night both of us experienced monster headaches, something I still get whenever I smell nitroglycerin.


Chase, that headache is referred to amongst explosives people as a 'powderhead" and it results from absortion of nitroglycerin through your skin which can send your blod pressure through the roof. just handling sticks of 1" by 8" 40% dynamite shouldn't result in any headache since you're not actually touching the explosive. However, farmers have an unfortuante tendancy to hang onto stumping powder and store it some where hot for way too long and the nitroglycerin sweats out. My guess is you were using out sweaty explosives in which case, you were one lucky boy since nitroglycerine is very unstable.

Linda Adams
07-23-2009, 02:58 AM
This is my experience from being near an explosion.

It was in Saudi Arabia, and I was on guard duty at night. There was this large garbage dump just across the field (no idea on distance). Everyone in the battalion took their trash there, and then it would be burned on a regular basis. That day, someone had apparently tossed several containers of gasoline into the trash, so when the men came to burn the trash, it exploded.

Quite literally, I'm looking straight across at the dump, bored to death and Whump! One second the garbage dump looks fine, and then next thing, the whole thing is on fire. And I have this moment of shock, trying to process what just happened. Then I looked at my fellow guard and going, "What do we do?"

The sergeant who inadvertantly caused the explosion suffered burns on his hands but was otherwise all right. Oddly, everyone else slept through it.

Keyboard Hound
07-23-2009, 02:59 AM
since we're on the subject of blowing up stuff, I have a question.

If a gas tank buried in the ground was abandoned with some gas left in it (enough to make fumes readily smelled from the top of the ground when the cap is removed) and a match was held above it, what kind of explosion would be caused if it the fumes caught fire? The tank would be of the type used back in the beginning of automobiles. What would it do to the person holding the match?

Thanks to anyone who can give me any information on this.

Keyboard

benbradley
07-23-2009, 03:41 AM
since we're on the subject of blowing up stuff, I have a question.

If a gas tank buried in the ground was abandoned with some gas left in it (enough to make fumes readily smelled from the top of the ground when the cap is removed) and a match was held above it, what kind of explosion would be caused if it the fumes caught fire? The tank would be of the type used back in the beginning of automobiles. What would it do to the person holding the match?

Thanks to anyone who can give me any information on this.

Keyboard
It would depend strongly on the exact air/gas vapor mixture in the tank, but it could be quite a "bad" explosion. It would also depend on how deeply the tank us buried, but as it explodes it could throw up dirt into the air. I imagine worst-case the person could be killed by flying debris. See my earlier post about firefighters who did a "controlled burn" (no doubt firefighters everywhere learned from that incident). But too much or too little vapor and it would just go "woosh" with flames shooting out the fill pipe, probably burning the hand used to light it.

Many people don't know that dust (as in sawdust generated in woodworking or grain dust in a grain silo) can be an explosion danger (http://www.google.com/search?q=dust+explosion) (as well as being a problem for breathing).

I've tossed fine sawdust from a woodworking dust collector (I use with a band saw and drum sander) into a fire and it gave a pretty "interesting" woosh and flash of fire as if it were gasoline or other flammable liquid. It's surely something I should be more careful about doing...

Canotila
07-23-2009, 09:40 AM
Someone shot me in the face with a bird bomb once. That would be equivalent to an M80.

Not a giant explosion, but ricocheted off my forehead and exploded 2 feet away from my head.

All I remember was panicking, and pulling my hat down over my ears as I tried to duck over a log. When it exploded the only thing I could see was grey, and a bunch of burning debris got in my mouth. The sound of the explosion was muffled. For the next two days I was disoriented, and couldn't hear anything except ringing. I remember my body being shaky afterward, and couldn't stand up. I saw grey for a while, not sure how long. From the flash maybe?

90% deaf in my right ear now.

The concussion of an explosion can do some weirdo things to people's bodies, regardless of the actual noise.

Tsu Dho Nimh
07-24-2009, 07:14 AM
Let's start from what the plot NEEDS to have happen, then we can discuss how to make it happen realistically.

How big is this building you are blowing up?

I have personal experience with exploding oil tankers, grain elevators, a show store and a fireworks factory (by far the most spectacular).

Does the sky turn a different color (like red)? Not in my experience. You will see smoke and dust, looks like a fire, but even an exploding oil tanker didn't make the sky turn red.

Does ash rain down? No ... you can have bits of building - drywall, tennis shoes (one blast I was near was a shoe store with a gas leak), plaster - erupt in a cloud and come down in a fairly small radius, but unless there's a sustained fire and plenty of fuel, no rains of ash.

A fire at a recycling plant's paper storage yard - that produced a rain of ash for several miles downwind.

Does the earth shake? More like vibrate, like standing nest to the RR track when a train goes by, but you realize you aren't near the tracks.

The windows rattle, and may break, on the side of a building exposed to the explosion.

Is it the loudest sound imaginable? Nope. Loudest KABOOM I've ever heard was a lightning strike that hit about 20 feet from me. I was deaf and blind for a while.

Oh and how far away can you be without being injured, but still see it?

Depends on the building's construction, and exactly how big a kaboom you are thinking of. Something with lots of glass shards flying out of the windows is dangerous. If the top of the building is weak, most of the force can go up, not out, and you can be quite close.

chocowrites
07-24-2009, 09:57 AM
Wow, thanks for all the anecdotes and advice :) It's helping me a lot with the description.

dgiharris
07-24-2009, 10:12 AM
Of course, I've never been 'near' a big explosion for the sheer fact that being near one will kill you.

Unlike TV, the main problem in real life with being near a big explosion is the concussion wave that hits you. Eardrums rupturing is extremely common along with disorientation, being knocked unconscious, and being straffed with debris.

You'd also need to define 'near'. Explosion conform to the 1/r^2 rule.

Mel...

Vincent
07-24-2009, 10:23 AM
A few months ago a gang blew up an ATM in front of my local bank, a 2 minute stroll from my door. They went a bit overboard and blew the front of the bank into the street. Money was floating in the breeze and the ceiling was dangling by electrical wires.

I thought it was some hoon with a firecracker and didn't give it a second thought, till I walked past all the broken glass and cops the next day.

MacAllister
07-24-2009, 10:59 AM
I was quite unfortunately near an explosion a few years ago, where gas fumes had pooled in a burn-pit depression. The gasoline (it was supposed to be diesel, but the person fetching the fuel had misunderstood the instructions) had been poured over a bunch of big root bolls and trash wood bits, collected in a burn pit with the scooped-out dirt piled around the edges.

Gas fumes accumulated, and when I started the fire, there was about a split instant when all the air around me sucked out and I swear my ears popped with the sudden pressure change. I just had time to turn and jump down the outside of the pit -- and the explosion scorched the hell out of the jean jacket I was wearing, singed my hair and the side of my face (think bad sunburn) and I had second and third degree burns on the back of my left hand, which was trailing behind me when I jumped. But I was very close indeed to the actual explosion.

A friend (who had bought the friggin' gasoline instead of diesel and poured it all over the root bolls) who was about fifty or sixty yards away, said it sounded like a big whump, with a fireball flash that was there then gone almost like lightning.

I was just happy not to end up on that year's Darwin award list.

I think, though (and the firemen types here can probably tell you better) that that's a sort of peculiar phenomenon, related to the ignition of fumes -- as opposed to something like dynamite or C4, which would create a shock wave (if you were way too close) but wouldn't suck up all the local oxygen.