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Congrats to MAKE Contributing Editor Bill Gurstelle for his “Gonzo Engineering” profile in the June issue of Popular Mechanics.

“We’ll be doing some flinging before long,” says the man in the jumpsuit, William Gurstelle, the catapult’s builder. On one side of the machine’s central fulcrum hangs a counterweight filled with 400 pounds of rocks and lead shot. On the other side of the pivot is an elegantly tapered 5-foot-long throwing arm pointing skyward. Gurstelle grabs the tip of the arm and pulls it down nearly 180 degrees until it’s almost perpendicular to the asphalt, then latches it to the catapult’s base. The 400-pound weight rises in opposition, poised like a boot ready to kick. Gurstelle gathers the ammunition: baseballs impaled by eyebolts, a box of gym socks and a bottle of lighter fluid. He drops a ball into a sock, hooks it to a sling at the throwing arm’s tip, soaks the stuffed sock in accelerant and sets it all on fire.

Gurstelle steps back as the flames flicker and tightens his grip on a 6-foot rope tied to the latch pinning the throwing arm. He counts to three and yanks the line. The latch springs, the weight drops, the catapult creaks, and the throwing arm rises like a basketball player making a hook shot. The ball slings upward so fast that the flames seem to disengage. But the stocking stays ablaze, a low-level comet in a sizzling line drive. It hits the grassy hill with a thunk, ricocheting embers of sock elastic, and rolls down to the parking lot. “Is that a tray-boo-chit?” a bystander asks. “Correct,” Gurstelle says, “except that it’s treb-yoo-SHAY.”

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Photos by Chris Buck for Popular Mechanics

Bill Gurstelle Teaches Science With Trebuchets

Gareth Branwyn

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of a dozen books on technology, DIY, and geek culture, including the first book about the web (Mosaic Quick Tour) and the Absolute Beginner’s Guide to Building Robots. He is currently working on a best-of collection of his writing, called Borg Like Me.


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Comments

  1. MgkBull says:

    I have always loved old mechanical feats such as this one. Wouldn’t mind slinging a giant rubber band ball in one.

    By the way, anyone else notice the photoshop fail in the last picture? The bottom of the cart is repeated. Not sure why.

  2. Gareth Branwyn says:

    Yeah, isn’t that weird? I have NO IDEA what’s going on in that image. Did it really end up in the magazine that way, I wonder? Anybody have the June issue?

    1. MgkBull says:

      If it was my guess, the photographer wanted a larger composition, so repeated the bottom but forgot to wand out the cart. Just guessing.

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