A Simple Simulator For Model Rocket Performance

August 4, 2025 by Zoe Skyforest 7 Comments

When building a model rocket, it can be fun to get into the maths of it all—calculating the expected performance of your build, and then seeing how it measures up in the real world. To aid in that task, [Rotislav Persion] has created a simple web-based simulator for charting the potential performance of your own rockets.

The calculator lets you key in the fundamentals of your hobby rocket. Punch in the diameter of your rocket, its mass, the standard rocket engine you’re using, and the diameter and delay time of your parachute, and it will chart the altitude profile expected during flight.

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Squishy Beyblades Made With 3D Printer Fail To Compete In The Arena

August 2, 2025 by Zoe Skyforest 7 Comments

When Beyblades first came out a couple of decades ago, they quickly became a fad across Japan and several Western countries. There was a whole ecosystem of parts that you could buy and use to build competitive fighting spinning tops. These days, though — 3D printers are ubiquitous. There’s very little stopping you from printing whatever Beyblade-compatible parts your heart desires, as [JettKuso] demonstrates.

For [JettKuso], the rubber attack tips were a personal favorite. They had high grip on the plastic arena floor and would allow a top to make rapid, aggressive moves that would knock other tops out of the arena. Not desiring to import specific Beyblade parts at great expense, he decided to print some rubber tips and associated parts instead. The result? Squishy Beyblades!

[JettKuso] built various tops with official and custom TPU parts, and put them in battles to see what worked and what didn’t. In many cases, the TPU replacement parts didn’t make a big difference or proved worse than the standard parts. However, when [JettKuso] got crazy, he found one thing that kind of worked. A mega-heavy TPU top blade, which weighed as much as the standard metal rings, was able to successfully win battles against less competitive standard builds.

Ultimately, the video serves as a testament to the developers of the original toys themselves. It’s not so simple to just print up some parts and have them be competitive with the tried-and-tested gear that comes off the store shelves. The experience ultimately gave [JettKuso] a greater appreciation for all the thought that went into the commercial toys. Video after the break.

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Farewell Shunsaku Tamiya: The Man Who Gave Us The Best Things To Build

July 31, 2025 by Jenny List 36 Comments

In the formative experiences of most Hackaday readers there will almost certainly be a number of common threads, for example the ownership of a particular game console, or being inspired into engineering curiosity by the same TV shows. A home computer of a TV show may mark you as coming from a particular generation, but there are some touchstones which cross the decades.

Of those, we are guessing that few readers will not at some point have either built, owned, or lusted after a Tamiya model kit at some point over the last many decades, so it’s with some sadness that we note the passing of Mr. Tamiya himself, Shunsaku Tamiya, who has died at the age of 90.

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Building A Color Teaching Toy For Tots

July 25, 2025 by Zoe Skyforest No comments

Last year, [Deep Tronix] wished to teach colors to his nephew. Thus, he built a toy to help educate a child about colors by pairing them with sounds, and Color Player was born.

The build is based around the TCS34725, an off-the-shelf color sensor. It’s paired with an ESP32, which senses colors and then plays sounds in turn. [Deep Tronix] made this part harder by insisting on creating their own WAV playback system, using the microcontroller, an SD card, and its on-board digital-to-analog hardware.

The toy operates in three primary modes. Color-to-tone, color-to-sound, color-to-voice. Basically, a color is scanned, and then the Color Player creates a tone, plays back a pre-recorded audio sample, or spells out the name of the color that was just scanned.

[Deep Tronix] also included jolly mode, which just color cycles a few RGB LEDs. However, there’s a game inside jolly mode as well, created for an older nephew to play with. Enter the right button combination, and you unlock it. Then, the device suggests a color and you have to run around, find it, and scan it to score.

We love a good color game; somehow this build seems even more compelling than Milton Bradley’s classic Simon toy.

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PVCSub: A Submarine From The Plumbing Aisle

July 18, 2025 by John Elliot V 11 Comments

Today in the submersibles department our hacker [Rupin Chheda] wrote in to tell us about their submarine project.

This sub is made from a few lengths of PVC piping of various diameters. There is an inflation system comprised of a solenoid and a pump, and a deflation system, also comprised of a solenoid and a pump. The inflation and deflation systems are used to flood or evacuate the ballast which controls depth. There are three pumps for propulsion and steering, one central pump for propulsion and two side pumps for directional control, allowing for steering through differential thrust. Power and control is external and provided via CAT6 cable.

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2025 One Hertz Challenge: Building A Better Jumping Bean

July 17, 2025 by Seth Mabbott 4 Comments

Do you feel nostalgia for a childhood novelty toy that had potential but ultimately fell short of its promise? Do you now have the skills to go make a better version of that toy to satisfy your long-held craving? [ExpensivePlasticCrap] does and has set off on a mission to make a better jumping bean.

Jumping beans, the phenomenon on which the novelty of [ExpensivePlasticCrap]’s childhood is based, are technically not beans, and their movement is arguably not a jump — a small hop at best. The trick is that the each not-a-bean has become the home to moth larvae that twitches and rolls on the ground as the larvae thrash about, trying to move their protective shells out of the hot sun.

The novelty bean was a small plastic pill-like capsule with a ball bearing inside what would cause the “bean” to move in unexpected ways as it rolled around. [ExpensivePlasticCrap]’s goal is to make a jumping bean that lives up to its name.

Various solenoids and motors were considered for the motion component of this new and improved bean. Ultimately, it was a small sealed vibrating motor that would be selected to move the bean without getting tangled in what was to become a compact bundle of components.

An ATtiny microcontroller won out over discrete components for the job of switching the motor on and off (once per second), for ease of implementation. Add this along with a MOSFET, battery and charging board for power into a plastic capsule, and the 1 Hz jumping bean was complete.

[ExpensivePlasticCrap] offers some thoughts on how to get more jump out of the design by reducing the weight of the build and giving it a more powerful source of motion.

If insect-inspired motion gets you jumping, check out this jumping robot roach and these tiny RoboBees.

Smart Mjolnir Makes Questionable Judgement Call On Your Worthiness

July 3, 2025 by Zoe Skyforest 3 Comments

Mjolnir, also known as Thor’s hammer, is a discerning thing, at least if you believe the modern Marvel canon. [alemanjir] decided to build a semi-functional replica that makes judgement calls of its own, though they’re perhaps a little less thought-out than the storied hammer of legend.

The build consists of a 3D-printed hammer prop, inside of which is a Raspberry Pi Pico microcontroller running the show. It’s hooked up to a MPR121 touch sensor that detects when someone grips the handle of the hammer. At this point, the Pico makes a pseudorandom “worthiness check” as to whether the holder is righteous enough to wield the hammer. If they are pure of heart, it unlocks a magnet which frees the hammer from whatever metallic surface it might be stuck to. [alemanjir] also included a little additional functionality, with the hammer playing various sounds when swung thanks to a speaker and a ADXL345 accelerometer secreted inside.

One wonders whether the electromagnet inside is strong enough to hold out against an unworthy person lifting it from the ground. While it’s perhaps not as powerful or as decisive as the mythical object, it’s nonetheless a fun learning project that likely taught [alemanja] some useful basics of embedded development.

We’ve featured some terrifying takes of the Mjolnir prop before, too, like this shockingly high voltage version.

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