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posted by martyb on Thursday December 02, @12:50AM   Printer-friendly [Skip to comment(s)]
from the whip-it-good! dept.

Supersonic Projectile Exceeds Engineers Dreams: The Supersonic Trebuchet:

The trebuchet is a type of catapult that was popular for use as a siege engine before gunpowder became a thing. Trebuchets use a long arm to throw projectiles farther than traditional catapults. The focus has typically been on increasing throwing distance for the size of the projectile, or vice versa. But of course you're here to read about the other thing that trebuchets can be used for: speed.

How fast is fast? How about a whip-cracking, sonic-booming speed in excess of 450 meters [~1480 feet] per second! How'd he do it? Mostly wood and rubber [bands] with some metal bits thrown in for safety's sake. [David]'s video explains in full all of the engineering that went into his trebuchet, and it's a lot less than you'd think. There's a very satisfying montage of full power trebuchet launches that make it audibly clear that the projectile being thrown is going well past the speed of sound, with a report quite similar to that of a small rifle.

Link to 15m45s YouTube video with demo near the end.


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  • (Score: 4, Interesting) by Anonymous Coward on Thursday December 02, @01:55AM (1 child)

    by Anonymous Coward on Thursday December 02, @01:55AM (#1201335)

    The article should really be how awesome it is doing a presentation using LaTeX.

    • (Score: 2) by richtopia on Thursday December 02, @04:15PM

      by richtopia (3160) Subscriber Badge on Thursday December 02, @04:15PM (#1201539) Homepage Journal

      Cool video. I'm unsure if those LaTeX slides were screenshots pasted into Impress or native; but how he was writing on them I suspect it was cut and paste. Still looked good.

      I used LaTeX for my Master's Thesis presentation with Beamer: https://latex-beamer.com/quick-start/ [latex-beamer.com]

      Ultimately, it does make some great looking graphics and I really like how it can dynamically generate progress bars on the slides. However, in industry I've found it is so much faster to use a WYSIWYG editor for presentations given their very graphical nature.

  • (Score: 3, Funny) by khallow on Thursday December 02, @03:43AM

    by khallow (3766) Subscriber Badge on Thursday December 02, @03:43AM (#1201351) Journal

    There’s a very satisfying montage of full power trebuchet launches that make it audibly clear that the projectile being thrown is going well past the speed of sound, with a report quite similar to that of a small rifle.

    Now do that with a cow.

  • (Score: 1, Interesting) by Anonymous Coward on Thursday December 02, @11:18AM (5 children)

    by Anonymous Coward on Thursday December 02, @11:18AM (#1201432)

    Anyone on here want to run the numbers on how high a hobby rocket could go when coupled with a Trebuchet that ignites the engine at the top of the arc?

    • (Score: 2) by PiMuNu on Thursday December 02, @11:52AM

      by PiMuNu (3823) Subscriber Badge on Thursday December 02, @11:52AM (#1201438)

      How would the trebuchet ignite the engine?

    • (Score: 3, Insightful) by canopic jug on Thursday December 02, @01:13PM (2 children)

      by canopic jug (3949) Subscriber Badge on Thursday December 02, @01:13PM (#1201463) Journal

      At those G-forces, the model rocket would shear into pieces on a trebuchet. A ballista would provide a more appropriate thrust. As for the ignition, a very short fuse could do the job if they are still for sale anywhere. The timing would be very difficult. It's fine if the engine ignites at or before apogee. However, after that, thrust will make the thing very dangerous by sending it sideways and down. Even if it hits nothing, going sideways with lots of thrust will make it very hard to fetch and recover.

      --
      Money is not free speech. Elections should not be auctions.
      • (Score: 1, Touché) by Anonymous Coward on Thursday December 02, @07:12PM

        by Anonymous Coward on Thursday December 02, @07:12PM (#1201597)

        Nah... sideways is how we get to orbit.

      • (Score: 2, Informative) by Anonymous Coward on Friday December 03, @08:26AM

        by Anonymous Coward on Friday December 03, @08:26AM (#1201780)

        An Estes Gnome is listed as 0.29oz. An A10/3T engine is 0.29oz and produces a maximum of 13N thrust. 0.79oz=0.0224kg. This gives us ~60g peak acceleration. At 60g it takes 0.77s to reach 450m/s.

        This requires a 172m power stroke, assuming constant acceleration. That is a *very* large ballista.

    • (Score: 0) by Anonymous Coward on Thursday December 02, @01:49PM

      by Anonymous Coward on Thursday December 02, @01:49PM (#1201471)

      You should ask Bezos. He seems to be into making hobby rockets.

  • (Score: 1, Funny) by Anonymous Coward on Thursday December 02, @08:55PM (1 child)

    by Anonymous Coward on Thursday December 02, @08:55PM (#1201629)

    It's small enough to mount on a shark!

    • (Score: 0) by Anonymous Coward on Friday December 03, @07:03AM

      by Anonymous Coward on Friday December 03, @07:03AM (#1201760)

      how is this score 0? sometimes I wonder about this site...

  • (Score: 1, Insightful) by Anonymous Coward on Friday December 03, @04:57AM (1 child)

    by Anonymous Coward on Friday December 03, @04:57AM (#1201739)

    before gunpowder became a thing.

    before the invention of gunpowder.
    FTFY, (mumble mumble)...millennial reporters...(mumble mumble).

    • (Score: 0) by Anonymous Coward on Friday December 03, @07:10AM

      by Anonymous Coward on Friday December 03, @07:10AM (#1201765)

      I think you'll find it was discovered a long time before it really became a thing

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