Reverse engineering an experimental drone – with a new speed record goal in sight

Posted: April 15, 2021
Image of Kali Boyd holding the UAV model while standing in a lab at ARC
Kali Boyd displays the one-fifth-size UAV model.

The Aerospace Research Center (ARC) has long been a hub of record-setting research. Among the current projects undertaken by faculty and students alike is one by graduate student Kali Boyd, involving reverse engineering a model of an aircraft to predict the flight characteristics of an unmanned aerial vehicle (UAV) that will be used as an experimental aircraft platform.

Headed by Cliff Whitfield, PhD, director of the Flight Vehicle Design and Testing Group, the project aims to push the boundaries of aircraft configuration research and development. As such, Whitfield needed a fast learner to take on the task of researching this UAV. Boyd, having graduated in 2019 with a bachelor’s degree in mechanical engineering from The Ohio State University, was the perfect fit.

Boyd’s project fits into a larger collaborative investigation undertaken by Whitfield and his colleague, Matt McCrink, PhD, research scientist in the Aerodynamic Flow Control and Advanced Diagnostics (AFCAD) research group at ARC. In 2017, AFCAD set a world record by flying a UAV at an average of 147 mph for 17 minutes, and this record hasn’t been broken since. Whitfield and McCrink hope to create a new UAV to be used in future research, including breaking that speed record.

Much work still needs to be done before the UAV is ready to be built, but Boyd’s research lays the groundwork for the rest of the stages along the road toward constructing it.

Boyd focuses her research on predicting the dimensions the UAV should have by examining a model. The model, which had already been built when Boyd took on the project, is one-fifth of the size of the proposed UAV, and it is intended primarily for testing the flight characteristics of the aircraft in the Battelle Subsonic Wind Tunnel at ARC before committing the resources to build the full-size one. Another model, a little bigger at one-third of the size, will be tested outdoors during later stages of the project.

Image of Kali Boyd at a work bench in ARC cutting out a mold with the UAV model beside her
The wind tunnel model awaits its new wings as Kali Boyd cuts them from the mold.

New wing design takes shape

To predict the best dimensions of the final UAV, Boyd broke down her project into a handful of steps.

“First, I reverse engineered the model to understand why it was built the way it was,” Boyd explains. Reverse engineering involves deconstructing the model, looking at each component and figuring out how it works.

“Then, I measured the dimensions to complete a performance analysis,” Boyd continues. “So, I ran through a bunch of computations to figure out the aircraft’s lift characteristics: how high it could fly, its speed, its takeoff distance, and so on.”

When she finished these computations, Boyd validated her findings by testing the model in the wind tunnel. Finally, she was ready to begin designing new wings.

The original model had Delta wings, which were shaped like a triangle, but Boyd wanted to test other high-speed wing shapes as well. She decided on an ogive shape, which is curved with a point.

To make the wings, Boyd says, “I created a negative mold of the ogive wing out of foam, using a Computer Numerical Control (CNC) machine. From there, I layered fiberglass and epoxy [in the mold] and set them in a vacuum-sealed bag overnight.”

Image of the UAV model suspended in a wind tunnel
The model undergoes testing in the wind tunnel.

Once the wings dried, Boyd cut the shapes out of the mold and sanded them down to make them smooth. Finally, the wings were able to be primed and painted, then connected to the body of the model.

Although Boyd’s project isn’t over yet, she’s already begun writing a thesis on her findings, which she will present to her committee. Until then, she’ll work on testing the ogive wings and comparing their performance with the Delta wings.

Reflecting on her time reverse engineering this model, Boyd says, “I’ve learned a lot from doing this project.” She’s confident that her experience will set her up for success in her career after graduation. “If I saw something on a different aircraft, I would be able to know why the aircraft was built that way.”

Boyd already has a job lined up after graduation: she’ll go on to work for the National Air and Space Intelligence Center in Fairborne, Ohio, putting her new knowledge to good use.

by Beck Schulz, professional writing intern

Categories: StudentsResearch