Supersonic Whip Launcher Puts a Repeatable Sound-Barrier Crack in Anyone’s Hands

Cattle herders have been punching small holes in the sound barrier for centuries. A bullwhip’s sharp crack is a miniature sonic boom, created when the last few inches of the lash accelerate past the speed of sound. Doing it by hand still demands practiced timing and a fluid arm motion most people never master. Craig Turner, the Australian maker behind Turnah81, wanted a device that delivered that same boom on demand, aimed where he pointed, with no prior skill required.

He begins by building the whip itself, which is a chain of thinner, lighter ropes stacked on top of one another with the goal of making it taper or narrower as the loop at the end uncurls, allowing the momentum to remain relatively constant while the mass declines. Later sections must travel faster since the whip behaves similarly to a rocket in flight. Turner connects polyester nylon and Dyneema segments together with stitches, taking care not to make a mistake; get a few of the stitches wrong and the energy is wasted, and the snap of the whip vanishes. The hefty part of the whip ends in a metal bit that is attached to a piece of elastic shock cord via a pullstring.

Just pulling the cord back and letting go produces a rather constant sound. Day to day, he simply packs the entire thing into a compact launcher. The elastic wraps around the back of a simple piece of wood and metal, with a piece of electrical conduit to keep the lash in place and a spring to shoot it out. There’s even an acrylic shield you can put in as a last resort safety measure. Once you pull the trigger, the whip always comes out at the same speed.

The whip now travels at speeds of well over 1,230 km/h and flies at approximately 1,300 km/h. That speed removes flower stems and leaves like a hot knife through butter, tears open tins, extinguishes candles, and knocks off bottle caps without spilling the contents. His wife is pretty skilled at it; on her first few attempts, she was landing shots with millimeter accuracy. When there’s even a small amount of dust or dirt on the tip, it just atomizes and becomes mushy as it makes the 180-degree turn; this is when the transonic squeeze occurs, before most people expect it to begin.

Turner designed the launcher such that even a total beginner can consistently produce a perfect sonic boom. He uses it to ditchweed the garden and, strangely, to make the neighborhood dogs bark. Because you can precisely aim the crack of the whip, the same equipment may enable high-speed photography of shockwave loads easier than capturing a freehand whip crack. There are still a lot of factors to work out, such as how far back you can push the boom before it happens, how adding stiff portions affects the shockwave, and how the elastic behaves if it ever gives up the ghost; nonetheless, for the time being, the machine works flawlessly.
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