Bigger is not always better, especially when it comes to airplane flight test instruments.

A team of Cal Poly students successfully conducted the first flight of a new, smaller and more efficient flight test instrument. A flight test data system is a temporary device installed to the outside of a plane to collect data measuring the conditions surrounding the plane. 

This project marks the first major revision of its design in decades and the first collaboration between Autonomous Flight Lab (AFL) and Boundary Layer Data System (BLDS), according to a statement released by the Mechanical Engineering department. 

Informally called “PressureWing” by its creator, mechanical engineering graduate student Charlie Refvem, it is the smallest and lightest instrument yet assembled by the BLDS team. 

Completed in August 2019, the smaller flight test instrument consumes less power, has a longer battery life and is easier to adhere to a plane than versions before it. 

“Our chief advantage of being quick and cheap and easy to install is we can do it even better with a smaller device,” College of Engineering professor and AFL project director Russ Westphal said. 

The student-led team was successful in reducing the device to a third of its size, weight and volume using all new components. 

“When the current design was frozen in 2009, the smartphone had barely come on the scene,” Westphal said. “The development of smaller, accurate, cheap sensing devices has happened in the last decade, and that’s all embodied in [the new flight test instrument].” 

A device’s battery is less likely to hold up at high altitudes and in really cold temperatures, but according to mechanical engineering senior Max Emerick, a more efficient device will record more accurate readings. Emerick was responsible for installing, operating and interpreting the device’s results. 

When Westphal began the project in the 1980s, his original idea was to create a device as small as a pack of cigarettes, which only recently became possible with PressureWing.

The new instrument used for testing was the first of several Flight Test Data System (FTDS) prototypes currently in development to fly, according to the College of Engineering.

The AFL’s Altavian NOVA aircraft was the test airplane used, which features a 10-foot wingspan, and can fly fully autonomously. 

Three test flights were conducted at the Cal Poly-owned Experimental Flight Range, progressing from less to more challenging configurations in order to obtain accurate measurements for all flight conditions.

Westphal said the biggest challenge for such devices is convincing clients such as Boeing, the U.S. Air Force and Northrop Grumman that newer and improved capabilities are worth the cost. Until then, he said he will continue to encourage students to get involved with flight test work. 

“The highlight of my summer work on the BLDS project was being able to work on developing a prototype that was a completely different idea than prior work on the BLDS,” mechanical engineering sophomore Isabel Jellen said. 

Westphal said he predicts that flight test instruments will eventually evolve to a size small enough to stay on a plane beyond flight tests, measuring the health of a plane permanently. 

“It was really cool to just be a part of that whole group and to work with some really bright people on these things,” Emerick said. “I was really blown away by how nuanced this [project] was and all the details that went into it.”

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