Aerodynamics have always been an important part of automotive design. A lower drag coefficient means that it takes less energy for a vehicle to overcome air resistance, or more simply put: better fuel economy. Normally, this type of measuring is done in a wind tunnel—a gigantic piece of machinery meant to simulate a vehicle moving at a given speed.
Typically, wind tunnels are too large and expensive for someone at home. If you need further proof, Honda just spend $124 million on a new tunnel earlier this year. Even scale tunnels can be costly, running hobbyists in the thousands of dollars for a simple setup. But now, using the magic of 3D printing, a Redditor has designed their own wind tunnel capable of housing scale models of cars, planes, and more.
According to the creator, the design is mostly 3D printed and utilizes a number of upcycled parts. For example, the rear-mounted fan is powered by an old drone propeller motor and pulls air into the enclosure from the front to minimize turbulence. When fresh air enters, it passes over an atomizer pulled from an old vaporizer to produce "smoke." The cloud of smoke is then dispersed through a series of holes and through a mesh grid to produce the visible air streams that flow through the observation chamber (which, by the way, is made from glass taken from broken photo frames).
It's worth pointing out that this particular wind tunnel only measures airflow via a removable anemometer mounted at the front of the observation chamber. There don't appear to be any other measuring devices—like transducers that can calculate downforce—built into the unit, so no advanced fluid dynamic calculations here. However, you can still see how the air flows around an object which helps to understand the object's basic flow characteristics. Plus, you have to admit that it still looks pretty darn cool.
The Redditor says that they have tested small airplane parts like wing sections and rudders. Sadly, Hot Wheels cars are a bit too small, but larger, scale models like the Dodge Viper shown in the video above make for perfect test subjects.
If you're looking to build your own in-home wind tunnel, the creator of this project says that they plan to release the 3D printable files at a later date. Just keep an eye on their Reddit thread for your chance to download them.