Here’s How an Explosion in Water Looks at 5 Million FPS

Let’s have some fun this week. You may remember when The Slow Mo Guys did a fun experiment by recording a bullet smashing eggs at an incredible 1 million fps. Now, they are taking things up a few notches by recording an underwater explosion at an insane 5 million fps.

To put that 5 million fps figure into perspective, if you took 1 second of real-time footage and played it back at 24 fps it would run for over two days. To capture this they needed some help and a custom camera rig called the Shimadzu from the Colorado School of Mines. Let’s check it out.

The subject of this video are shaped charges. It is actually something they have done before, but only up to 200,000 fps. This is doable with a more conventional camera like Phantom.

To get over a million they needed to borrow the Shimadzu HPV-X. There are a couple compromises to get that high. One is that it will only capture that speed in black-and-white, which makes sense since they used the same trick to get to 1 million in the other video. The other is that it will only capture about 250 frames at a time.

That’s fine here as that plays back in around 10 seconds.

Back to the charges. Shaped charges are interesting because of how they direct their energy in a very specific way. The military often uses them for breaching doors. The guys got a solid door with a locking mechanism that they plan to break the lock on.

This first explosive is recorded with a Phantom at just under 120,000 fps at 1280 pixels wide and in full color. What else can I say about it, it’s a fun shot of an explosion in slow motion and you really just need to go watch it.

Image Credit: Phantom

After the door they moved into blowing a hole through a series of three steel plates. This they brought out a trio of cameras. A Phantom 4K is going to record at 1,000 fps. The T3610 is shooting at 36,000 fps. And, the Shimadzu is going to hit a cool 1 million fps. This will be interesting to see how the different frame rates compare.

With this explosive it made it through all three plates but made a smaller hole as it traveled farther. The 1 million fps take shows off a lot more interesting details – that’s what makes it so valuable for scientific applications.

In black-and-white, you can see the explosion create the penetrative shape and then how it reacts as it makes an impact. The explosion actually got brighter as it made contact with the second plate, something you just can’t see any other way.

Having a little more fun, they moved on to just regular old dinner plates. A lot of them.

This is cool because while they couldn’t really tell what happened at 1,000 fps, when they moved up to 93,000 fps they could see exactly how many plates the actual charge penetrated. The way the charges work is that they get much weaker over distance and that is a far distance even though plates are relatively weak.

Again at 1 million fps you can actually see how the explosion reacts as it hit and then how the plates catch and reflect some of the explosion back.

Where it gets exceptional is how they captured the shaped charge on its own at 5 million fps. You can actually see the explosive create the cone that it uses to create a strong, penetrative force.

Last is the promoted underwater explosion. They direct the charge at a tube of water and captured it at 1,000; 94,000; and 1 million fps. It’s cool, and at the fastest frame rate you can see how the explosive gets caught by the water and expands out with all the brightness stopping just as it hits.

It is always so cool to see this hyper-specialized equipment in use since most of us won’t get a chance to check it out in person. 

Have any of your own slow mo ideas you want to try out? What would you do if you could get your hands on one of these extreme options?

[source: The Slow Mo Guys]

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