Our R&D Journey

The last blog I wrote, “Why the Neutron™ may be used for MIMO Modal Testing,” explored my own private journey with Modal Testing and took a rather personal turn—perhaps even more than I had anticipated. This month, I thought it would be interesting to explore the journey our company, Acoustic Research Systems (ARS), has taken with Research, Development, and the subsequent Publications that have helped drive our technology forward. Since I’ve found joy in the participation, perhaps you will enjoy reading about it too.

The Story About Research…

All research tells a story. The trouble is that, sometimes, it may not be one worth reading. Surely, there are “investigators” out there who write the fiction first and then craft the “research” around the story (thinking of you, Dutch Boy), but those who take the time to put work into the science often find the hopeful conclusion they entered the project with rapidly vaporizes when data speaks the painful truth: Your theory is wrong.

I understand this danger when entering every research project, and rather than repel me, it drives me toward the unknown. It’s almost impossible not to arrive at each project with preconceived notions about what will work best, how to do the most work in the shortest time, or how the experiments will align with your designs. However, steering clear of those distractions is typically wise. That’s not to say those inclinations aren’t useful.

In the planning phase, it’s nice to harness all that energy to formulate a path forward. Arriving with a plan helps to gear up for the research, anticipate pitfalls, and provides a sort of framework for all that uncertainty. In some research projects, we entered with over a hundred possible test cases, only to perform about ten before completely changing course. Not following the plan turned out to be advantageous because the emerging data revealed that our plan was flawed to begin with! For some, this may be disappointing, but I found it rather exciting to be steered away from my initial thoughts on the subject and toward a more effective and adaptive solution.

An example of this was my very first foray into research for Direct Field Acoustic Noise (DFAN) testing. Up until that point, it was widely accepted that concert-type sound systems (line arrays) were the most effective way to produce launch vehicle acoustics, albeit with some clever processing and (unfortunately) patented control technologies. Undeterred, I was hoping to find my own way to control such a system and, as such, arrived with an ambitious test plan to reach never-before-seen test levels with a screamingly awesome speaker technology. That speaker technology? Screamingly awesome, but mostly for audiences of people listening to their favorite band. The test levels? Underwhelming. The technology? Patented for a reason: It was the only way to drive concert sound systems to the levels required by rockets.

This project led me to the question I should have been asking all along: Why are we limited by these concert systems? And what can we do to break those limitations?

Development and Diversion

It was around this time that an old friend called me and asked a strangely relevant question: “If you had to design a system for DFAN testing, how would you do it?” I wasn’t the only one consulted, of course, but I instantly felt the gravity of the question. I spouted off a few observations driven by my recently futile research, namely, the following:

• Don’t use bandpass boxes; it botches the timing and, subsequently, the phase across frequencies.
• Make it easy to set up—so easy I could do it. (An inside joke that persists to this day.)
• It should be more powerful than necessary. (More on that later.)

After the question was asked, I didn’t think much of it for a while. I fell into the rhythm of time, career, and family, and thought little of it. That is, until the coronavirus changed the nature of large gatherings, especially music venues, and another call arrived. At this point, two major events converged. The first was that the frequency of requests for an alternative to DFAN testing sharply rose. The second was that the same old friend called again, this time with a proposition: “If I can bring you a device that fulfills all of your requests, I’d like you to test it.”

The development of this device, what would ultimately become the Neutron™, happened without my direct involvement, but it felt like the ultimate homage to my experience in the research I had conducted up until that point. Upon seeing and ultimately testing this device, it became clear that a diversion from the known was necessary to create progress. That’s not to say that what had been done before was useless, but rather that it created a worthy steppingstone to something more.

Functional Findings

On the first testing day, I arrived at a large hangar, previously occupied by a mobile Medivac facility, in a capable airport located in West Virginia. Even entering the facility was a minor chore, as security mandated a nearly hidden gate entry with a four-digit code that I forgot and had to look up in an email. In my vehicle, I carried a cluster of microphones provided by the gracious folks at PCB Electronics and a loaner data acquisition system from the company that currently employed me, m+p International.

Though intangible, I also carried with me a sense of hopeful skepticism: This may not work, but I’ll rely on the results to tell the story. Following that uncertainty, we arranged everything in the worst possible way on purpose. The microphone array was placed in the least optimal locations, the test article was less reflective than any ever made, and the test specifications were among the hardest ever to reach.

A particular moment from that testing stands out in my mind. After arranging the system in a way that had never been done before, breaking all conventions thus far, we achieved a test level not seen with such little power in history. After all was over, everyone looked at me with uncertainty and possibly even fear.

There was so much to say about how this was the most powerful system I had ever laid eyes (ears?) on: It had achieved levels above any other system without any of the patented technologies required before it, it had better uniformity than any system before it, and drew so little power to get there that we were concerned we had made a mistake in the measurements. With all that on the tip of my tongue, none of it could be said.  All I could muster was to shout, “WHOOOOO!” They got the point.

Publication and Public Reaction

We published the results of that test proudly, but we were immediately interrupted by the myriad questions arising from any disruption in technology. “How can you do this without using the existing patents?” “Isn’t this only for small stuff because you are so small?” “How can we trust you?”

We didn’t need existing patents because we weren’t using the same approach. We were small, but the system was designed for big things. We could be trusted because we made it as hard on ourselves as our (newly found) competitors made it on us.

Our drive to publish every result in its raw form brought a level of criticism that, although unanticipated, helped shape our product in the years to follow. We invited industry leaders to poke and prod the Neutron™ system and provide feedback, with the ability to make nearly instant changes to the production for the benefit of end-users.

For me, this was unanticipated. I didn’t expect the publication to drive the development; instead, I expected the research to do the trick. Again, I was happy to be surprised by the reversal of my plan and the subsequent results it would bring.

Conclusion

Research, Development, and Publication have always been a part of the ARS ethos, and I hope to be an integral part of this in the years to come. At the 43^rd IMAC, we co-published our findings about Acoustic Modal Excitation with ATA Engineering in an experimental fashion with a notional test article. Though interesting, this is not completely original, and we are even more excited to present our findings co-published with NASA Johnson Space Center on a similar approach with a real test article.

Unique to this test is the fact that force data were collected during the acoustic excitation, helping to predict what is possible with subsequent tests, both commercial and private. This data told a story, and we are excited to follow it to the conclusion, even if we don’t like how it reads. Fortunately for us—and you—so far, we do.