Driving Reliability In Aerospace

“Well, I'd say I probably always had an obsession with planes. An obsession, right? I don't know if I can stress that enough.”

James Johnson had dreams of being a pilot growing up, but his knack for mathematics and love for creating things led him down the path of building the aircraft he had once hoped to fly.

Johnson is currently in his second year of his PhD in the Department of Aerospace Engineering and Mechanics at the University of Minnesota and has been working on research in conjunction with Collins Aerospace. The research is focused on improving pitot-static probes manufactured by Collins, making it much easier and faster to tell if the probes will perform correctly without lengthy testing procedures.

These pitot-static probes are used in aircraft systems to measure airspeed and altitude, making them an essential piece of equipment that manufacturers must put through rigorous testing to ensure their performance is up to par. Some of these probes end up not meeting the specifications for reasons unknown and need to be tuned to attempt to fix them, which isn’t always successful.

At the end of the day, manufacturers don't want to spend valuable time and resources testing probes only to find out that they don’t work. This is where Johnson’s research hopes to make a difference.

“These are really sensitive devices and they need to be super accurate to measure pressure within a very small range,” says James. “The question is can we simply scan these and predict whether or not they're going to perform aerodynamically without all the testing?”

Creating a system that can quickly scan the pitot-static probes could help spot defects that a person may miss during the standard testing process.

Johnson spent his summer at Collins testing models he created in a wind tunnel and has continued building more with the goal of figuring out what parameters are most important. Another key method that he’s been using in this research has been Computational Fluid Dynamics, or CFD, to see if he can follow a similar path in simulation and reproduce experimental results.

“Simulation can be a very useful tool, especially when it gets expensive to make a ton of different models,” Johnson explained. 

Over the next few years, Johnson hopes to gather as much data as he can while continuing the research. Preliminary findings have shown just how finicky these small probes can be.

“It's been surprising how sensitive the models are to different manufacturing defects,” said Johnson. “We're looking at such small pressure differences, which has led to the observation that these really, really tiny defects can matter a lot.”

Although the research process has been strenuous and challenging at times, Johnson is thankful for the opportunity it has provided to sharpen his skills and learn new ones in the process. A highlight of his work has been getting more comfortable designing experiments, which hasn’t been easy due to the sensitive nature of wind tunnels.

In addition, the work has helped improve his focus, a skill that he has honed through "many hours of staring at a computer trying to get simulations to work correctly." Looking back to when he began the research, Johnson has seen how far he’s come.

“You don't know what's happening, but at some point you look back and you realize somehow you’re an expert, and that you've just ended up learning and doing a lot.”

Johnson’s continued efforts to understand and predict probe performance have the potential to significantly reduce testing time and improve manufacturing reliability. As he moves forward in his PhD, Johnson is not only pushing the boundaries of aerospace engineering research but also steadily realizing the passion for aviation that first inspired him.