Every wanted a mini wind tunnel to check the aerodynamics of scale model cars, drones, or other small objects? Then check out [dannyesp]’s mostly-3D-printed DIY wind tunnel (video, embedded below). Don’t forget to also browse the additional photos in this Reddit thread.
There’s not much for plans available, since as [dannyesp] admits, this device was very much the product of trial-and-error and junk bin parts. The video and photos are more than enough for any enterprising hacker to work with.
The core of the device is a large fan made from a junked drone motor. This fan is located at the rear of the tunnel. A small anemometer is placed at the front, where some 3D-printed baffles also work to smooth out turbulent incoming air.
The foggy trails of vapor come from a hacked-up vape pen. Vapor gets piped through some tubing to the front of the tunnel. There, the vapor trails are drawn towards the low-pressure area at the rear, traveling over and around the object on the way. [dannyesp] also mentions that the platform holding the object is mounted on a rail, which incorporates some kind of pressure sensor in an attempt to quantify wind drag.
We want to take a moment to appreciate just how clean this “junk parts” project looks — even though it is made from things like broken photo frames. All of this comes down to thoughtful assembly. A hack doesn’t have to look like a hack job, after all. We also love the little control box that, instead of having a separate power indicator, lights up like a little nightlight when it has power.
Disposable vape pens, a sub-genre of electronic cigarettes, have been a fad for a few years now – they’re small self-contained devices with a rechargeable battery and some vape liquid inside. As the battery discharges and the liquid runs out, the entire vape pen is typically thrown out. [Dimitar] wants to change that, however, and teaches us how to reuse as much of the vape pen as possible — as yet another underappreciated source for parts we can use in our projects.
In an extensive worklog, he breaks down and documents a vape pen’s inner workings, coupled with a video we’ve placed below the break showing ways to disassemble them. In these, he shows how we can reuse the casing and the plastic parts, should any of us be interested in a project that happens to fit the e-cig form factor. Attention is paid to the sensor that triggers the evaporation — it may look like a microphone, but is actually a purpose-built pressure-sensor with a high-side switch! He tears into one of these in a separate video, showing how to reuse it as a capacitive touch controller. He also aiming to assemble a small database of related resources on GitHub, currently, hosting the files for the protection circuit he developed as part of his recommendations for safely reusing vape pen Li-ion batteries.
[Dimitar]’s journey is ongoing, and we can’t wait to see some fun uses for these components that he will certainly stumble upon on his way! For instance, here’s a hacker using an e-cig battery to power a pair of RGB LED-adorned sunglasses, replacing the AAAA battery they originally came with. We’ve seen hackers make guides on reusing each and every part of microwave ovens, printers and laptops, and we ourselves have talked about reusing ATX power supplies and computer mice.
Computer simulation is indispensable in validating design and used in every aspect of engineering from finite element analysis to traffic simulation to fluid dynamics. Simulations do an amazing job and at a fraction of the time and expense of building and testing a scale model. But those visceral ah-ha moments, and some real-world gremlins, can be easier to uncover by the real thing. Now you don’t need a university research or megacorp lab to run aerodynamic study IRL, you can just build a functional desktop wind tunnel for a pittance.
[Mark Waller] shows off this tidy little design that takes up only about two feet of desk space, and includes the core features that make a wind tunnel useful. Air is pulled through the tunnel using a fan mounted at the exhaust side of the tunnel. The intake is the horn-like scoop, and he’s stacked up a matrix of drinking straws there to help ensure laminar flow of the air as it enters the tunnel. (The straw trick is frequently used with laminar flow water fountains). It also passes through a matrix of tubes about the diameter of a finger at the exhaust to prevent the spin of the fan from introducing a vortex into the flow.
For analysis, five tubes pipe in smoke from an vape pen, driven into the chamber by an aquarium pump. There’s a strip of LEDs along the roof of the tunnel, with a baffle to prevent the light shining on the black rear wall of the chamber for the best possible contrast. The slow-motion video after the break shows the effectiveness of the setup.
The costume starts with the skull mask, which started with a model from Thingiverse. Conveniently, the model was already set up to be 3D printed in separate pieces. [Mike] further modified the design by cutting out the middle to make it wearable. The mask was printed in low resolution and then assembled. [Mike] didn’t worry too much about making things perfect early on, as the final finish involved plenty of sanding and putty to get the surface just right. To complete the spooky look, the skull got a lick of ivory paint and a distressed finish with some diluted black acrylic.
With the visual components complete, [Mike] turned his attention to the effects. Light is courtesy of a series of self-blinking LEDs, fitted inside the mask to give the eye sockets a menacing orange glow. However, the pièce de résistance is the smoke effect, courtesy of a powerful e-cigarette device and an aquarium pump. At 225W, and filled with vegetable glycerine, this combination produces thick clouds of smoke which emanate from the back of the wearer’s jacket and within the skull itself. Truly stunning.