Forgive me if this has been asked before, but the Search function doesn’t seem to be working at the moment. I watched Die Hard today for about the 100th time and once again there was something about the scene where two of the terrorists are shooting at the LAPD armored personnel carrier with a rocket launcher and John, frustrated, pulls out a brick of C4, jams three detonators into it, sandwiches it between a chair and a monitor, and tosses it down the elevator shaft, that bothers me. Aside from the other goofs in this scene (the size of the explosion, the massive fireball), would the detonators even set off the explosive without being connected to some sort of charge initiator? Or are the detonators themselves impact-sensitive?
As primary explosives, detonators are sensitive to mechanical shock, but the manner in which they are used in the film would not be very reliable.
But then, John McClane wouldn’t have survived jumping off of a roof woth a firehose wrapped around his waist or grabbing a duct opening with his fingertips after falling several floors, either. Die Hard, while remarkably consistent in plotting, operates in the realm of movie physics not far separated from Warner Bros. cartoons.
Stranger
Don’t the detonators he uses have chemical timers? I don’t recall attachment points for wires.
They ise nonel (non-electric) detonators for the charges. The coil you see Heinrich walking around with is some kind of det cord, and you can see this later when Hans goes up to the top floor to examine the explosives, finding the det cord unattached. This is standard use for building demolitions because it can’t be inadvertantly set off by ESD or a high power radio or microwave signal; the only electrical impulse is at the main initiator, which is shorted or inerted by a SAFE/ARM device that only functions when receiving a specified signal.
Stranger
But when John jams the three detonators into the brick, you can see yellow and black wires coming out of the tops of them. I knew the yellow cord you see them wiring the roof with is det cord, which raises another question - wouldn’t det cord, being a high explosive itself (IIRC it has a detonation velocity of somewhere around 22,500 fps), set off C4 without the use of detonators? If that is indeed the case, why such a fuss made about them?
Detonating cord has a core typically made with PETN or RDX and a polymer plasticizer. It is fairly insensitive to mechanical shock and will burn without detonating in normal conditions, but can be set off by a direct pyrotechnic shock or slapper shock. Detonaters, on the other hand, have primary explosives that are sensitive to high mechanical or eletrostatic shock, as well as a deflagration-to-detonation transition above thr autoignition temperature. The small quantity and low aspect ot det cord makes it essentially impossible to initate and maintain auto-detonation from normal conditions; a detonation wavefront has to be initated by something else in order to get a sustained detonation.
Stranger
Why would he not have survived the fire hose jump? I assumed that the hose’s reel provided enough resistance that he fell fairly slowly and the jerk stop at the end wouldn’t have been that hard.
Falling more than six feet being restrained by nothing but a hose around your waist would pretty much guarantee spinal injury. Also, note that the hose reel came loose during the fall and jammed up against the half-wall on the roof, so McClane had at least that much drop. He also would have been seriously injured busting through the plate glass window, perforated by bullets or no.
Die Hard gets credit for making the hero seem more human than most 'Eighties action heroes but allowing to be injured and bleed, but realistically, McClane would have been down by the end of the second reel.
Stranger
Worth mentioning that old CRT monitors had high-level capacitors in them that retained a lot of juice, even when not plugged in. Tinkering with one could give a potentially lethal shock. Is that enough of a jolt to trigger a detonator?
Only if in direct contact across the terminals of an electric detonator. Otherwise, it is highly unlikely. Despite all of the safety training and cautionary stories, inadvertant initiation of a detonator not wired into a circuit or in an explosive train is vanishingly rare. I once worked with a powder monkey who kept detonators loose in a sawdust filled box in the bed of the same truck he would transport hundreds of pounds of dynamite, Seismopak, and reels of debt cord (totally against DOT regulations, but this was a decade before the Oklahoma City bombing when enforcement was infrequent and inconsequential) and never had any accidents except for nearly demolishing his truck with an errant tree stump.
Stranger
Apologies for the unrequested copyediting; the board’s spellchecker was (and still is) hemorrhaging prior to my corrections.
The real point is…
Does that mean there really was something to the portrayal of wrapping the C4 brick up with the CRT? The electrical shock from the CRT exploding would have been enough of a “detonation wavefront?”
—G?
I can forgive the C4 blowing up since it made for a nice explosion. What bugs me, and I’ve never figured it out from that scene is why wasn’t Huey Lewis and Fu-Man-Chu both killed in the blast? Plus how the hell did they both get back up the stairs to be killed later on.
Out of the whole movie that’s always bugged me, everything else I can over look.
The chair-bomb exploded when it hit the elevator on the floor where the rocket launcher was, which appears to be two or three floors above the ground floor. Presumably Huey and Mr. Endo were sufficiently shieded from the blast and able to make their way back up. The freight/express elevator was still working even at the end of the film.
Stranger
Not Fu-Manchu…Genghis Kahn
I’m still unclear how the thieves were going to escape. Eleven of them cram into an ambulance that (somehow) none of the cops will notice is coming from inside the building’s parking garage?
That’s a possibility. It’s hard to see where the C4 hit exactly. One of the local theaters usually plays Die Hard on Christmas Eve, I might have to go see it, just to look for that scene of course.
The elevator is just for transporting Hans and the bearer bonds. Everybody else dresses as a rescue worker and walks out in the ensuing chaos. Remember, this film came out in 1988 when security around major terrorist events was still relatively loose. The more damning question is why they needed the FBI to cut the vault’s power supply. Even if the circuits could not be cut off by manual operation, they should be able to physically cut through the power lead. They also seemed unprepared for the case that a party guest or someone else in the building might escape and make a signal (e.g. no guard in the stairwell to block off that route, not disabling the fire alarm, et cetera). In retrospect, the ‘terrorists’ don’t seem to have quite as slick of a plan as they think. But if they did, even John McClane wouldn’t have had a chance and there would be no story. Within the plot of the film (accepting the premise of the “German bearer bonds” and the ridiculous physics, the plotting is clockwork, which can hardly be said of recent action films.
McClane watches the elevator go down and stop at that floor. He earlier got a glimpse of the rocket launcher (or at least the crates containing it and the munitions) earlier in the film while escaping upward (though why they had it on such a high floor initially defies explanation since they clearly intend to use it from a lower floor).
And I watch this film every Christmas Eve. This, Trading places, and Kiss Kiss Bang Bang. “This isn’t ‘Good Cop, Bad Cop’, this is fag and new Yorker. You’re in a lot of trouble.”
Stranger
Here’s what always bugged me about that scene (and I’m sure I’ll be educated if my consternation is unfounded):
Let’s just take for granted that an impact will trip the detonators; now, John shoves in one then two then says, “fuck it,” and shoves in another. My question is … what difference would that make? Wouldn’t one detonator be sufficient to cause detonstion? If John had stuck 27 detonators in the thing would he have blown up LA completely?
It just gives more likelihood of complete detonation. In demolition work, where getting reliable and complete detonation is mandatory, redundant detonators (usually in opposite sides of the charge) are frequently used. The effective energetic output of the main charge will be essentially unchanged.
Stranger
You know, this can all be resolved with a simple test. Where’s the nearest high-rise bank building?