(For those wondering why my comments disappeared for a while this week, all I can say is that I was recovering from horrifying flash-backs brought on by Leigh’s kidney stone post. LOL)
Two weeks ago, I posted here asking what readers thought of mixing romance and mystery genres.
I wondered: When do the two genres make a good fit, why does this happen (or not), and how can a writer mix the two genres to best effect? I received many excellent comments, which I’ll talk about in my post on June 27th.
I’ve also thought a lot about those comments, as well as other ideas associated with genre mixing, and have formulated an idea I’d like to submit here. That, too, will have to wait until my next post, however, if you don’t want to read something seven pages long.
So, in the interest of brevity (he said, a bit deceptively), I will first tell you a humorous story that is very important to the idea I plan to submit for your comments on the 27th. It’s about how explosions create sine waves, and ways in which the amplitude of these sine waves may be manipulated—which probably sounds as entertaining as doing the laundry. But, please: bear with me. I think you’ll like this.
A Quick but Important Explanation
Harmony and resonance are two terms most people probably identify with music. Being more comfortable with explosives than music, however—as my grade school band leader could undoubtedly attest!—I’m probably more inclined to think of harmony and resonance in relation to shockwaves created by the carefully synchronized detonations of properly located charges.
They don’t just travel through the demolition target however. These explosion-created sine waves travel through the surrounding earth and air (or, in some cases, water), and can sometimes be felt miles away from the blast site, usually manifesting themselves as a rumbling roar and causing plates or windows to rattle, walls to crack, or glass to shatter.
How I Learned to Play With Sine Waves
Using sine waves to proper effect is an important part of explosives theory, of course, which I learned in the demolitions portion of the Special Forces Qualification Course.
Years after I graduated the Q Course, however, and was on an A-Team, we had a fellow from a civilian blasting company come out to share information about how he used explosives to break up rock at a nearby quarry. Around twenty of us (SF Demo Sgts.) went down to one of the demolition ranges at Ft. Bragg, where we met a nice young man. His boss had sent him down there, saying the young guy might learn something, too, if he kept his eyes and ears open while working with a bunch of SF guys. He proudly showed us the sausage charges and “nonel” ignition system he used, as well as his computer.
Then, we monkeyed around with them in a manner that really freaked this guy out, and got us in trouble.
What We Played With
“Nonel” is considered an instantaneous non-electric firing system because that thin, orange plastic-tubed “fuse” carries a powder train designed to ignite at the rate of around 2000 meters per second. Thus, the person doing the blasting (called “the blaster”) connects a firing machine to one end of the nonel, then pulls a trigger, or pushes a button, which creates a spark that ignites the powder train. The flame shoots down the length of the fuse at around 2000 meters/second, finally shooting a brief spit of flame into the blasting cap at the far end and—BOOM!
Nonel is not really instantaneous, of course. It takes a little while—maybe half-a-second, or a second or two—from the time the blaster hits the button, to the instant of explosion, depending on distance from blaster to initial charge. But, nonel ignition is fast enough; it’s generally considered instantaneous.
|Nonel clipped together for firing.|
The photo above, right, shows a short segment of nonel with a blasting cap at one end and the clip at the other. The photo at left shows multiple nonel fuses linked together.
How It’s Supposed to Work
Our visiting quarry blaster normally used his computer to create a model, which told him where to place his charges and how many milliseconds to delay each detonation by, in order to reduce the impact on people or structures in the local area.
By placing his charges where the computer told him to and using the computer-suggested time delay between detonations, he was able to cause the explosive sine wave created by one detonation to be cancelled out, when it collided with the sine wave created by the next detonation, and vice-versa.
You may recall, from my earlier posts about explosives, that ‘low order’ explosives may be thought of similarly to ‘low gear’ in a truck—they push and heave heavy things, like dirt and rock. This means their sine waves are very powerful. So, using distance and time-delay to cancel-out the sine waves created by these explosions strongly muted what, otherwise, would have been a series of long, deep sine wave vibrations created by low order explosives, from shaking up people in the surrounding areas or potentially damaging buildings hit by the deep sine wave’s rumbling THUMP!
Roots of an Idea
The first time we took the explosives down-range and set them off, we did it the way the guy suggested. We wanted to see how well the technique worked. And, it worked pretty well. In fact, the result was rather boring.
Each man set up two charges, for a total of around forty charges. Since the blaster had only brought a limited amount of ‘standoff’ nonel fuse along, that day, we used time fuse to detonate the initial charge, daisy chaining the rest of our charges with those nonel sections that incorporated the 25-millisecond delays.
Forty charges went off, each about 25-milliseconds apart. Nothing to write home about. There wasn’t even a satisfactory big THUMP! in the ground beneath our feet, because the charges had canceled out each other’s sine waves.
While walking down to plant those charges, however, a few of us, who’d been talking it over, asked the visiting quarry blaster if he thought adjusting the calculations for charge location and timing, in ‘thus and so’ manner might result in something a bit more exciting.
“Oh, you wouldn't want to do that,” he said. “That might increase the amplitude of the sine wave instead of canceling it out.”
“Exactly!” we responded, smiling. At this point, we reached the location where we had to fan out and start planting our charges.
We couldn't ask him more questions on the way up the range to the bunker, before firing that first shot, however, because he wasn't with us. Evidently, he’d used nonel all his life, and never dealt with time fuse before.
When we ignited the time fuse, to set off the initial charge, his eyes went wide and he said, “What are you doing?”
“Igniting the time fuse.”
“While we’re still here? Standing beside the charges!?!”
“Well, we’ve got four and a half feet of time fuse. That’s enough to let us get back to the bunker.”
“But … we aren’t leaving!”
“Right. We have to make sure the time fuse is burning, first. Then, we’ll remove the mechanical matches from the fuse, so we can reload them.”
“WHAT!?! The fuse is burning? NOW?”
“Yeah, see how it’s melting here? That’s good. In just a minute we’ll be able to remove—”
But that guy was gone, buddy! He looked like a character on Scooby Doo, legs churning wildly as he smoked-it back up the hill to the bunker.
The rest of us followed at a leisurely pace, a few of us discussing our idea of increasing the sine wave’s amplitude. We figured the idea made sense, but we had to decide how to calculate for it.
How We Pissed-off A Lot of People
By now, we’d formulated a few ideas about how to accomplish what we wanted. So, while standing in the bunker, waiting for the time fuse to burn down, we quizzed our visiting blaster about what he thought.
He professed not to know, saying there was no way to tell what the result would be. He even kept claiming he didn’t know what formulas his computer used to arrive at its conclusions. Naturally, a bunch of guys who walked around, on a daily basis, with umpteen charge formulas, relative effectiveness factors, and other arcane explosives details in their heads, found this claim a little suspect. Besides, he kept interspersing this claim with the statement: “You guys are scary. You’re really, REALLY scary!”
Unfortunately for this fellow, he’d chosen the wrong words.
His repeated “You’re scary” encouraged us to believe we were on the right path, so we continued with our discussion. And, other guys heard this repeated phrase and came over to find out what he was talking about. After all, they wanted to be scary too.
By the time our first set of charges had disappointingly gone off, everyone was discussing the idea. In the end, about fifteen of us decided to experiment with a rudimentary formula on the next shot, while the rest decided to just adhere to the original plan.
We ran our calcs, then took our charges (two per man, again) down-range and planted them. This time, our visiting blaster decided not to accompany us, staying at the bunker and trusting the sergeant in charge to connect his standoff line to the daisy-chained line segments.
With everyone back up in the bunker, the visiting blaster hooked up his blast machine and fired.
The charges of the first five guys—ten charges total—went off, cancelling each other’s sine waves.
Then, one by one, the next thirty charges went off …
… the sine waves building on each other as they went along.
Each time another charge went off, the blast got louder, deeper and more satisfying. Soon, though we wore earplugs, we had our hands over our ears, and the ground beneath our feet was dancing a nice jig. Finally, it all came to an end. The final shot was not visually exciting, but the roaring cacophony and deep thump in our feet were truly GLORIOUS!
Amid an extended round of whistles, yells and cat calls, I turned to look at the young quarry blaster. I can still see him in my mind’s eye: blonde hair sticking up on one side, where he’d yanked on it with his hand, face ashen, eyes wild. He looked as if he’d just survived a strafing run by an A-10.
I was still laughing when the field phone in the bunker went off. People were making a lot of excited noise, but the instant the sergeant in charge, who’d answered the phone, popped to rigid attention, all noise cut off abruptly. We knew what his behavior meant. It was Pavlovian, and we’d all responded in similar manner in the past. Every man in the bunker knew: somebody BIG was tearing into the sergeant on the phone.
In the sudden silence, we could hear the angry voice bellowing on the other end, but not what he was yelling. On his end, the sergeant just kept answering with things like: “Yes, Sir!” “Only twenty charges, sir!” “I’m sorry, sir. That wasn’t planned.” “No, sir. It wasn’t intentional.” “I understand, Sir!” “It won’t happen again, sir!” “Yes, sir! Yes, sir!” He concluded with the phrase: “Crystal, sir!”
After he hung up, the sergeant turned his back to us, asking: “So, I know most of it’s missing, because it just got royally chewed off, but . . . have I got ANY ass left?”
He explained that the caller had been the General commanding the 18th Airborne Corps and Fort Bragg. In other words, this was the guy who issued the commanding generals of the 82nd Airborne and 101st Airborne Divisions, and several other major units, their marching orders. He had none-too-gently informed the sergeant that his staff was receiving reports concerning our little science experiment from across Ft. Bragg and the gate town of Fayetteville, as well as personal phone calls from the commander of Pope Air Force Base next door, and the Fayetteville mayor who was upset that shop owners were complaining of damaged merchandise.
“Pray the tea set has no cracks,” said the sergeant. “The general said he’d call me back, if it was damaged.”
Thus, our little science experiment ended— at the direct orders of the 18th ABN Corps Commander.
Thankfully, the sergeant in charge never got a call about the tea set. But, I never forgot what I learned about amplitude modulation that day, and the way it can depend on location and timing.
And, that’s the take-away I want you to remember for my next post, on June 27th.
See ya’ then!