Born: Brazil
Primarily active in: United States of America

From Leadership Profile: Vertiflite September/October 2023

Carlos E. S. Cesnik, Department Chair of Aerospace Engineering
University of Michigan

Professor Carlos Cesnik oversees a range of aerospace research at the University of Michigan (U-M) in Ann Arbor. “We work with things in electric vertical takeoff and landing [eVTOL], as well as fixed-wing aircraft,” he explained. “We work on problems in maneuver and gust-load alleviation, aeroservoelastic modeling and simulation of very flexible aircraft, sustainable aircraft and future aircraft configurations.” U-M investigations extend to the hypersonic realm. “Hypersonic aerothermoelastic modeling and simulation in terms of overall vehicle interactions is a multi-physics problem.” Cesnik summarized, “My field of interest is really about multi-physics modeling, analysis, simulation and experimentation — mixing structures, aerodynamics, flight controls [and] flight dynamics.”

Cesnik is the Richard A. Auhll Department Chair and Clarence L. (Kelly) Johnson Professor of Aerospace Engineering at U-M. His student researchers leverage a menu of experimental facilities. “I came to Michigan in 2001 and founded the Active Aeroelasticity and Structures Research Laboratory (A²SRL), housing some special types of equipment, including a 10-ft [3-m] rotor spin stand. We did tests on that with active blades using embedded piezoelectric actuators and active flaps in Mach scale. I have complete ground vibration testing equipment for the characterization of structures and a continuous fiber-optic measurement system that we use for monitoring deformations and strains.”

Researchers use U-M wind tunnels for their aeroservoelastic tests, and Cesnik noted, “We also do flight tests. We have a netted facility for VTOL-type vehicles. It doesn’t require any FAA authorization to fly or even permission from risk-management at the University. People operate safely from outside the nets and have this whole area to fly drones or whatever experimental vehicles they have.” Cesnik added, “There are several advanced computer facilities available to us for prototyping software and so forth. Along those lines, we have been developing computer software licensed by industry and government labs.”

The long-time rotorcraft researcher said vertical flight poses continuing research challenges on two different fronts. “Understanding the classic rotorcraft is so hard, we still have plenty to do there. We have HELIOS [HELIcopter Overset Simulations software] and other advanced codes that can do a lot, but we’re still struggling with the correlations to actual experiments.” Cesnik continued, “The other part that is super-exciting is all the things that we’re doing in the eVTOL space. That opened different kinds of problems — multi-rotors, electrically powered, a very rich set of configuration changes. We had rotor-rotor interactions before, and rotor-wing interactions with classical tiltrotors, but now we have multi-rotor interactions with the wing and its flexibility.”

Cesnik is U-M’s principal investigator collaborating with the Vertical Lift Research Center of Excellence (VLRCOE) at Georgia Tech. “Currently, I have projects on eVTOL multi-rotor-wing interactions for stability analysis. Part of our study asks, ‘What is the effect of that on whirl flutter?’ eVTOL companies don’t seem to have encountered this yet, maybe because they haven’t excited their systems far enough. The Army is very interested in that because they see Future Vertical Lift [FVL] configurations, and they know current design and predictive capabilities are not perfect. If you’re going to design aircraft like this, you’re going to need methodologies that adjust for this more complex aerodynamic and structural environment in a computationally efficient way.”

Fly then Drive
Carlos Cesnik was born in Piracicaba and grew up in Araras, both towns in the Brazilian state of São Paulo. His father, Roberto Cesnik, was a PhD agricultural engineer sent by a farmers’ cooperative to Columbus, Ohio, in the US for industry training. “I did my first-grade schooling in Columbus,” recalled the U-M department chair. Back in Brazil, neither Carlos Cesnik’s father nor his schoolteacher mother had ties to aviation. “I always loved planes. Nobody in the family flew. I took my dad on one flight and he said, ‘Nah, that’s okay for me.’ Later, in Ann Arbor, I took both of them up in a much nicer airplane — a Cirrus SR20 — and they didn’t last more than about 20 minutes.”

The future aerospace researcher earned his pilot’s license in 1981 on an old CAP-4 Paulistinha light aircraft. “In Brazil, you can drive only at 18 but you can fly at 17. I started my private pilot’s license as soon as I turned 17. My dad would have to drive me to the airport so I could fly a plane.” Cesnik acknowledged, “I didn’t discover helicopters until I was in college.” A visit to Brazil by Sergei Sikorsky, son of the helicopter pioneer, sparked Cesnik’s rotorcraft research career. “I knew about Sikorsky and heard a presentation he gave. That was very inspirational to me.”

Carlos Cesnik earned his undergraduate degree in aeronautical engineering at the Instituto Tecnológico de Aeronáutica (ITA) in São José dos Campos. Growing regional airliner manufacturer Embraer hired him into the company’s composite stress analysis group to help build a new research and development team. “I did my Master’s in Brazil at ITA, paid for by them. And then they could send me to pursue a doctoral degree anywhere in the world. I had to take classes and do a thesis, but I did work on parts of the Embraer 120, which was a 30-seater. I also have my signature on some drawings for the CBA 123.” However, the advanced 19-seat pusher turboprop failed to find a market.

Though ITA had no rotorcraft curriculum, the five-year engineering program provided Cesnik an opportunity for helicopter research. “I did a thesis calculating the aerodynamic inflow of rotors. That was my first formal rotorcraft exposure, besides a book club.” The degree candidate and his thesis advisor Prof. Donizete de Andrade formed a club to discuss Aerodynamics of the Helicopter by Alfred Gessow and Garry Myers. Drawn to vertical flight, Cesnik returned to the US for his doctorate. “I chose Georgia Tech because of the Rotorcraft Center of Excellence there. There was a conversation at the time that if we could start a new rotorcraft industry in Brazil, Embraer had all the ingredients to succeed, but rotorcraft never materialized.”

Work at Georgia Tech modeled composite rotor blades under the guidance of the late Prof. Dewey Hodges. Cesnik’s dissertation resulted in the widely used Variation Asymptotic Beam Section (VABS) analysis tool. “Today, its U-M version is being licensed by different companies, the Army and NASA. Even MSC NASTRAN has implemented our algorithms in their product.” The early 1990s nevertheless posed challenges for Embraer, and Cesnik was faced with a career choice. As a civil servant with a company controlled by the Brazilian Air Force, he had to return to Brazil, one year short of his doctorate. “I met my wife in Atlanta — she was a medical doctor at CDC [Centers for Disease Control and Prevention] — and she extended her activities there to let me finish my PhD. I could go back [to Embraer] without my PhD or my wife. I couldn’t leave either.”

With his doctorate in aerospace engineering, Cesnik looked for a job in the US. “I interviewed with Sikorsky. I interviewed with Bell. They all said, ‘Get your Green Card first.’ My only option was to return to academia. That’s when I went to MIT.” The Massachusetts Institute of Technology had little rotorcraft research then, but in 1999, Prof. Peretz Friedmann (see the Leadership Profile in the May/June 2015 issue of Vertiflite) became the FXB Professor of Aerospace Engineering at the University of Michigan. “His goal was to bring more rotorcraft research to Michigan, and he knew me from Georgia Tech and MIT.”

Lab Lessons
Carlos Cesnik became a U-M associate professor in 2001 and founded the A²SRL. He continues to teach. “At the undergraduate level, I have taught aircraft structures as a junior-year course and aircraft design as capstone design course. At the graduate level, I teach aeroelasticity and structural dynamics.” Cesnik’s student researchers sponsored by industry and government have gone on to positions in Airbus, Bell, Boeing, Joby and other industry leaders, as well as government labs and academia.

Cesnik leads fixed- and rotary-wing investigations at U-M. “My team is made primarily of PhD students and post-doctoral fellows. I have one assistant research scientist. I have other undergraduate and graduate students who come for specific projects. I now have a project with a visiting student for a composite shear-strength sensor based on a fiber optics.”

Airbus sponsored the Center for Aero-Servo-Elasticity of Very Flexible Aircraft at U-M from 2017 to 2022. Cesnik was the director. “The Airbus vice president for flight physics had a vision for Airbus in model-based systems engineering [MBSE] and advanced methodologies for future concepts. They called universities all over the world. Michigan was one of them. We showed them our proposal for aero-servo-elasticity in very flexible aircraft, and we got selected. We were exploring methodologies for multidisciplinary design optimization, analyses and simulation for more flexible wings, higher aspect-ratio airplanes and their controls.”

Advanced air mobility (AAM) is one of six thrusts in the U-M aerospace engineering strategic plan, and eVTOL aeromechanics investigations are part of it. Work continues on rotorcraft design tools. Cesnik explained, “We already know a lot and we have significant predictive capabilities today. One of the problems with this space of eVTOL and AAM is the configurations are so new that there is no historical data for us to validate our predictions. Whenever you take an edgewise rotor, or even a tiltrotor, you have some data points to work against. Right now, with eVTOL configurations, we don’t have that. We’re still going to require an experimental component to validate our simulations, our analyses.”

The U-M researcher continued. “We are currently developing modeling techniques that allow us to do a frequency domain-type analysis for stability using viscous vortex particle modeling [VPM] for the aerodynamics. Today, numerical calculations are very time-intensive, too intensive to use for design. We are developing a new methodology that will certainly cut the time and have the right accuracy for predicting whirl flutter in multi-rotor configurations.”

Carlos Cesnik joined VFS (then the American Helicopter Society) in 1989 and served as Forum 51 Technical Chair in 2005. He concluded, “VFS is like a family to me. It taught me a lot of what I know. It has always been supportive of my professional career. It helped me a lot in growing, in networking, in meeting people, learning new problems, solutions, new ideas.”