James Baeder

United States of America

 

From: Leadership Profile, Vertiflite May/June 2025

Prof. James Baeder, Professor, Aerospace Engineering, University of Maryland

As the Igor Sikorsky Distinguished Professor at the University of Maryland (UMD) Alfred Gessow Rotorcraft Center in College Park, Maryland, James Baeder advises graduate researchers who utilize computer models to understand vertical flight. He explained, “Some work is done on the actual development of the tools, such as computational fluid dynamics [CFD] and aeroacoustics. In fact, we have a suite of CFD solvers that we’ve developed over the years as well as an aeroacoustic solver. Then, some work is the application of those tools to understand the physics details and resulting engineering quantities.” The powerful tools shed light on innovative rotorcraft configurations. “Currently, we’re doing some work looking at the aerodynamics of the Da Vinci rotor — the Aerial Screw. I’m also looking at the aerodynamics and acoustics of a quad-biplane tailsitter that has two wings and two rotors on each wing, along with a center body. It takes off like a quadcopter and goes through an arc to fly like a regular biplane.”

Prof. Baeder teaches the graduate-level introductory CFD course at UMD each fall and most years conducts a follow-on class in CFD modeling. He oversees research in computational aerodynamics and aeroacoustic algorithms with a special focus on coupling CFD to comprehensive rotor analysis. “When I came here in 1993, I don’t think anyone believed the CFD. It was crude at that time. Our computers weren’t great. Our software wasn’t great. But now, the companies are using them, and they have avoided problems or understood problems using CFD and fixed them, and that saved a lot of money.”

Baeder acknowledged, “The tools have gotten a lot better over the 30 years, but still, they’re not easy to use. They still require a fair amount of computational resources and time. You can run a case and get results, but like any simulation, it takes a fair amount of user knowledge to make sure you’re getting good results.”

The UMD research advisor noted, “Most recently, about half my funding is on machine-learning applications, using our computational tools to generate a bunch of data and then using that data to train a machine-learning model to be a surrogate model. I can then run this machine-learning model and get answers close to what I’d get from CFD, but they’ll run in milliseconds vs. hours or sometimes days with CFD. If you want to look at a thousand different configurations, you can’t have something that’s going to take one day per configuration. You really want to look at those thousand configurations overnight.”

Rotary-wing configurations pose inherent modeling challenges. “With fixed-wing [aircraft] at cruise, everything is steady. For rotorcraft in cruise, you have the rotor blades with all kinds of unsteady loads. You have the fuselage with the downwash changing. It’s all much more interactional and more unsteady.” Baeder added, “The acoustics are even more important because with rotorcraft, we want to operate closer to people, so you can’t be as noisy.” Innovative rotorcraft and other vertical takeoff and landing (VTOL) configurations add to complications. “They’re more complicated when you have multiple rotors, wings and a fuselage. From an aerodynamic sense and structures, they’re all interacting with each other.”

Mechanical to Modeling
Jim Baeder attended grade school in Westfield, New Jersey, but moved with his father’s career, starting high school in southern California near Los Angeles and graduating in Houston, Texas. Donald Baeder was a chemical engineer and headed a research lab in the oil and gas industry. “That made me think about engineering,” acknowledged the UMD scientist and educator. “On my mom’s side, my grandfather was a chemistry professor at the University of Texas. That had me thinking about graduate school.”

The aerospace professor recalled, “I was fascinated by astronomy when I was eight or ten years old. I knew all the constellations and stars, but then it didn’t seem like there were many opportunities in that area. So, I started to get interested in the space program when I was a teenager but then got into aviation. By the time I was at Rice University, they didn’t have a separate aerospace department, but I took all the aerospace classes I could get, pretty much on the aviation side.”

Baeder majored in mechanical engineering at Rice in Houston. “It was a smaller school and a very good school. It also wasn’t that expensive at the time. Rice is a pretty technical engineering school, but they also have a school of music and other things — they’re a full university. That was appealing to me.”

Graduate studies at Stanford University in California earned Baeder his master’s in aeronautics and astronautics. A job in the US Army Aeroflightdynamics Directorate (AFDD) at NASA Ames Research Center at Moffett Field, California, provided an introduction to helicopters. “I applied first to NASA. They weren’t hiring, but then the Army had a position. Jim McCroskey at Moffett Field was looking for someone to do computational fluid dynamics on helicopters. I answered, ‘I don’t know anything about helicopters, but they sound exciting compared to fixed-wing.’”

AFDD enabled its new CFD researcher to pursue doctoral studies at Stanford part-time. “I probably pioneered some of the applications of the CFD towards acoustics. That ended up being my thesis project, looking at what was called 2D BVI — blade vortex interaction — looking at high speeds where you might have shocks on the airfoil as a vortex goes by and how the sound would generate and propagate in this transonic flow.

“The next work I did at the Army lab, I looked at high-speed impulsive noise where, if you have the rotor going fast enough, you can get shocks at the tips of the blades that actually propagate all the way to the far-field. With the old Huey helicopters during Vietnam, they didn’t understand the transonic effects very well, so the tips would actually generate a mini-sonic boom that would go out from the advancing side of the rotor blade. The enemy could detect this helicopter from 20 or 30 miles [30 to 50 km] away. I was actually able to predict the noise.”

Baeder remained at AFDD from 1984 to 1993 when he applied to the University of Maryland. “In the back of my mind because my grandfather was a professor, and I enjoyed being in front of people and explaining things — it was like acting — I thought maybe academia would be something to try. I also thought of moving away from the Army lab partially because of economics. Once I had my second child, I needed some place that was not so expensive. Even though DC is not a cheap area, it’s much less expensive than the San Francisco Bay area.”

Compute and Experiment
Baeder today teaches and advises researchers in CFD and acoustics at UMD. “Our biggest product is our graduate students,” he said. One of Baeder’s students became the lead application developer for the Army’s Combat Capabilities Development Command (DEVCOM) Aviation & Missile Center (AvMC) Design, Simulation & Experimentation group in California. Another heads the big computational program at the University of Michigan. US and international graduate students come from a mix of disciplines. “Most are from aerospace engineering, some mechanical. Some might come with a strong math background — I have had a couple come through our Applied Math and Scientific Computing (AMSC) department.”

The student researchers leverage powerful resources. Baeder noted, “The College Park campus actually has a high-performance computing system — Zaratan. Two years ago, when we moved into the UMD Idea Factory, Lockheed Martin gave us some funds for equipment. I got three high-end computational nodes just for my research. I can run a hovering rotor or forward flight rotor or the quad-biplane system on one of these nodes and not wait in a long cue.”

Research topics come via the Army-funded Vertical Lift Center of Excellence (VLRCOE), other government sponsors and industry. “As far as the VLRCOE, I’ll come up with the ideas and run them by the government people and industry to see if these seem like some areas they’d be interested in. I also do some work with companies like Advanced Rotorcraft Technology where they have SBIRs and STTRs [Small Business Innovation Research and Small Business Technology Transfer programs].”

Industry also offers interesting opportunities. Baeder’s researchers worked with Sikorsky on the X2 coaxial rotor technology, and other topics like turbomachinery. “I have a post-doc who’s been looking at jet engines. By the end of years of operation, the front blades of the jet engine have had particles or rain or ice hit them such that the leading edges get eroded. We have a company that has some funding from Delta Airlines and the FAA [Federal Aviation Administration] to look at coatings on these blades so that they won’t erode as much.”

Ongoing machine learning investigations aim to enhance rotorcraft efficiency. Baeder said, “Most of my applications so far have been, ‘For this one condition, I want an airfoil that can do this.’ I could just run this surrogate model in seconds and say, ‘This would be a better airfoil.’ My hope is to do an actual rotor or a full wing, but we’re a little away from that. Again, to train it, I’m going to need to run thousands to tens of thousands of cases.”

Baeder works with experimenters in Dr. Inderjit Chopra’s and Dr. Anubhav Datta’s research groups at UMD. “I would say I’ve always seen the best payoff on things when they’re a combination of experimental, computational and flight test. You learn something different from each of those.”

Jim Baeder joined the Vertical Flight Society (then the American Helicopter Society) as a PhD candidate in 1985 and has since served on the Aerodynamics and Acoustics Technical Committees. He presented his first paper at Forum 42 in 1986. “Obviously, one benefit of VFS is a place to present technical work and the resulting questions and answers at the conferences; the general interactions you have at the Forum and at the Specialist Meetings — they’re a little bit smaller. You get to know the people in government, industry and in academia at the other universities. Sometimes research projects just happen out of informal conversations in the hall because someone saw your paper and you started talking to each other.”