At one time, the storage capacity of compact discs (CDs) seemed unimaginably large. Who could possibly need hundreds of megabytes of storage on a single removable disc? And aside from the capacity, the rainbow created by light diffraction on the surface of a CD let you know that you were looking at the future. But as these things always go, that future is now the past. A whole generation has grown up since that time with smaller, faster, and better removable storage media like SD cards. The CD has now been relegated to the bargain bin in second-hand stores.
YouTuber Aaed Musa recently got his hands on a large quantity of Mini CDs. Having been born in the 2000s, Musa initially looked at them with confusion before realizing that they are obviously ammunition for an archaic wrist-mounted device intended to slice fruit and water balloons. Unfortunately, the civilization that created this device must have existed long ago, and no launchers seem to have survived those many years. So Musa set out to recreate what it must have looked like.
Being a relic of a time so long past, it was not all that difficult to reproduce it with today’s technology. The launcher itself is simply a flat plate with a flywheel spinning just above it. Powered by a drone motor, the flywheel can easily spin at up to 40,000 RPMs. But Musa quickly realized that above a certain speed, the CD will slip underneath the wheel, causing it to be ejected with less force.
After mapping out ejection speeds, Musa found the optimal range. Not quite content with the result, a second flywheel was added to increase the speed without slippage. This had the effect of increasing the launch speed from about 17 miles per hour to over 27 miles per hour. The flywheels were also angled such that the CDs would spin after being launched, which gave them the gyroscopic stability they needed to stay on target.
For rapid fire fun, Musa also 3D-printed a magazine for the launcher. A spring-loaded hopper holds 25 CDs, and an RC servo motor pushes out one at a time, right underneath the first flywheel, which whisks it away. An impressive firing rate of five CDs per second was achieved using this method.
Initially, a 3D-printed wrist mount was created. That is a good option, to be sure, but plastic just does not look as cool as metal. So Musa had a metal version produced with a CNC machine. That gives the launcher the look of a weapon that belongs in Terminator 2 , but in reality, this far-less-than-lethal launcher is much better suited to playing a round of Fruit Ninja in real life.
Musa digs into the math and physics of the build in the project video, but if that is not your thing, don’t worry — you can fast-forward to the destruction of fruit and water balloons, and some heroic feats of CD marksmanship.
So that’s what CDs are for… (📷: Aaed Musa)
Take that, banana! (📷: Aaed Musa)
Launching CDs may result in data loss (📷: Aaed Musa)
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