Swedish Rocket Knives

There are trends in YouTube videos among various video producers. A few weeks ago, it was all about fidget spinners until some niche tech blog ran that meme into the ground. Before that, the theme was red-hot knives cutting through stuff. The setup was simple; just heat a knife up with a blowtorch, cut through a tomato or golf ball, hit stop on the high-speed camera, and collect that sweet, sweet YouTube money.

[David] from RCExplorer.se isn’t like most YouTube stars. He actually knows what he’s doing. When the latest trend of rocket-propelled knives hit the tubes, he knew he could blow this out of the water. He succeeded with a fantastic rocket-propelled machete able to slice through watermelons and fling itself into the woods behind [David]’s house.

Unlike most of the other YouTube stars trying their hand at rocket-powered slicers, [David] is doing this one right. He’s using hobby rocket motors, yes, but they’re reloadable. [David] crafted an engine casing complete with a proper nozzle machined out of stainless for this build. The rocket sled itself is an aluminum bracket bolted to a piece of carbon fiber plate that travels down a rail with the help of four skateboard wheels. A machete is then bolted to the plate, which is propelled down the track a bit faster than 200 km/h.

When it comes to rocket-propelled knives, the word ‘professional’ really doesn’t come into play. This, however, is an amazing piece of craftsmanship that you can check out in the videos below.

19 thoughts on “Swedish Rocket Knives

  1. David is such an awesome maker. Got his Tricopter kit a while back. He was such an inspirational and charming dude on FliteTest way back when. All the best, dude, if you’re reading this!

  2. I think I rather The Backyard Scientist’s one. Simple, effective and a good hommage to the Mythbusters episode that inspired all of these. :)
    I wonder if he was the first to do it or if there was others. Jan 2017.

  3. Youtubers are the worst. They just blindly follow every trend and then hammer it into the ground. It is just about the dumbest form of entertainment. Some of these people are pretty smart. It is too bad they are selling their soul for a couple bucks when they could be putting their talents to good use.

    1. That’s a pretty wide net you’re casting.

      A lot of these smart people would love to ‘put their talents to good use’ but it’s hard to get past the gatekeepers for these industries. Running a successful Youtube channel or blog is a decent resume builder and definitely a good way to showcase your talents. More than a few of these successful youtubers have put or are putting their talents to good use (Jeri Ellsworth, Applied Science, EEVBlog, Mark Rober, 60 Symbols, Mathologer, Periodic Videos, AvE, Paul Sellers). Then you have others who like to do something a bit different from their day job

      Sure you have people who just follow the path of least resistance but you can just not watch their content.

  4. To be honest I have found some of the youtube hits to be genuinely interesting, but this is downright boring. Literally taking a knife and cutting a piece of fruit.

    The rocket engine build was interesting, it looks like they at least spent some time on the machining even if they didn’t really know what they were doing (as evidenced by their terrible performance, if they had started with a similarly sized hobby rocket motor they could have easily accelerated their blade to supersonic speeds). A shame to waste it on such a lame goal

    1. “Literally taking a knife and cutting a piece of fruit”? Wow. Would you describe the Apollo missions as “a couple of guys going somewhere real far away”?

      If you have to ask what the point of strapping a giant knife to a rocket going 125mph is, you won’t get it. (Also the rocket is deliberately underpowered so it doesn’t fly off into the woods like the early tests did)

  5. Is title a pun on Swedish Pocket Knives? I am not sure when I’ve seen a reference on them last time, but I’d wager maybe it was in Mark Twain’s “Tom Sawyer” or “Huckleberry Finn”.

  6. I don’t “get” it.
    The apparatus isn’t streamlined, the drag and weight of the blade don’t seem to be compensated on the other side of the rocket. I see why it needs a “rail” to ride on. Maybe a ring of flashing LEDs around the rocket body will make it easier to find in woods…

    1. Better yet have the LEDs multiplexed off an Arduino networked to a RaspberryPi and hve the whole thing triggered by cutting a fidgit spinner in half with a red hot knife hooked to a hydraulic press!!!

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