  Wind tunnels are a key source of data collection, but their cost and size can
be a significant obstacle to their acquisition and usage, especially for
applications such as instrument calibration, instruction, or in-class
demonstrations. Here we propose a design for a cost-effective, desktop wind
tunnel. This design takes advantage of readily available, inexpensive
materials. Special consideration was taken to allow the wind tunnel to be
serviceable, as well as giving the operator the ability to change key features
without a complete redesign. There are three main sections, the first being a
fan enclosure, which holds seven ducted fans in a hexagonal array. The second
section holds honeycomb flow straighteners, and provides an enclosed volume
suitable for larger, lower-speed experiments. The third section is a
contraction, terminating in a 2in x 2in, higher-speed square section. The wind
tunnel has a footprint of approximately 13.5in x 5.5in, making it small enough
to be portable and to fit on a desk. An off-the-shelf masked stereolithography
apparatus (MSLA) 3D printer was used to prepare the parts. This allows the wind
tunnel to be built for under \$500; even including the cost of a 3D printer,
the overall cost remains under \$1,000. This design is able to produce flow at
up to 44.1 m/s, enabling a variety of aerodynamic demonstrations.
