From Leadership Profile: Vertiflite March/April 2022
Prof. Giuseppe Quaranta, Politecnico di Milano
Within the department of aerospace science and technology at Italy’s Politecnico di Milano, Professor Giuseppe Quaranta leads researchers in the Fixed and Rotary Wing Aircraft Multidisciplinary Engineering (FRAME) Laboratory. He explained, “Our objective is the analysis of aircraft as complex dynamic flying systems, investigating all the dynamic phenomena that involve more than one basic discipline of aerospace engineering such as structural dynamics, aerodynamics, aeroelasticity, servosystems and control and biodynamics.” The laboratory has fixed- and motion-based simulators readily reconfigured for different cockpits, and it uses the university wind tunnel to measure rotor and wake interactions. According to Quaranta, “FRAME-Lab works on one side on the numerical and experimental analyses to understand interaction phenomena, and on the other side on methodologies and tools to simplify these complex interaction analyses.”
Recent wind tunnel tests in the Galleria del Vento, for example, flew a 1/12-scale Airbus BO105 helicopter to landings on a model ship deck. Quaranta said, “The idea is to provide data about complex aerodynamic interactions at a fraction of the cost of a flight test. This same approach could be followed also to investigate the operation of advanced air mobility [AAM] vehicles in the urban environment. The interaction between multiple rotors, obstacles and flow fields generated in the urban canyons, and even the interaction between multiple vehicles, could be tackled with this approach.” The lab is also building a new hover test facility for AAM full-scale rotor models. “We want to use this facility for aerodynamic, noise and aeroelastic test in hover and at low speed.”
Half of FRAME-Lab funding comes from European Union (EU) projects, 35% from industrial partners such as Leonardo and 15% from Italian government research projects. In addition to his research role, Prof. Quaranta teaches graduate courses in structural dynamics and aeroelasticity and in the aeroservoelasticity of fixed- and rotary-wing aircraft. He recalled, “When I was young, I was very passionate about aviation. The most influential person for me was my uncle Augusto who was a hydraulic engineer. I was fascinated by his way of solving every issue he had, technical and non-technical. I learned that what is known as engineering judgment or engineering intuition was making the difference not only at work but in life. Augusto also taught me that engineering, contrary to current perception by many people, is a very creative word. In fact, I always like to remind my students of a quote from Theodore von Kármán: ‘Scientists discover the world that exists; engineers create the world that never was.’”
Giuseppe Quaranta grew up in the port city of Bari, on the Adriatic Sea in southern Italy. “In my hometown there was an engineering university, but given my passion, I wanted to go to a school where aerospace engineering was taught. I discovered my interest while in Milano. The course in rotorcraft design taught by Prof. Lanz opened an almost unknown world for me at that time. The intrinsic higher complexity and multidisciplinarity of all problems associated with rotorcraft was extremely fascinating to me.”
With an aerospace engineering degree, Quaranta gained business insight on Wall Street. “My brother-in-law at that time had a trading company in New York City. I learned a lot about how the stock market works, and I learned even more about the economic relevance that the aerospace sector has on the American economy.”
The young aerospace engineer returned to Politecnico di Milano to earn his Master’s degree in aerospace engineering with a thesis on multibody simulation applied to the aeroelastic stability analysis of tiltrotors. “Tiltrotors are wonderful machines,” observed Quaranta. “From the point of view of a researcher the number of engineering problems that are to be solved, the complexity, is always positive because it makes our work more challenging and more interesting. However, the complexity of the aircraft is reflected in more complex operations. Right now, there are clear niches where the capabilities of tiltrotors can make the difference. I expect with increasing operational experience in the civil field, it will be possible to identify more scenarios where the tiltrotor can outperform current designs.”
Quaranta remained in Milan as a junior research fellow working with his mentor Prof. Paolo Mantegazza on aeroservoelastic analysis software for Aermacchi (now part of Leonardo's Aircraft and Aerostructures Division) for its M-346 fixed-wing jet trainer. In 2001, he won a scholarship sponsored by AgustaWestland (now Leonardo Helicopter) to pursue doctoral studies dedicated to the aeroelastic analysis of tiltrotors based on fluid structure interactions. Quaranta noted, “Tiltrotor complexity is driven by the fact that the rotors are heavy and are attached at the end of flexible wings creating a large variety of complex aeroelastic phenomena. The most known phenomenon is the whirl flutter, an aeroelastic instability where the dynamics of the flexible gimballed rotors are destabilized by the interaction with the flexible wing.”
Quaranta received his PhD in 2004 and started work as post-doctoral researcher on several EU-funded research projects, including ADYN (advanced European tiltrotor dynamics and noise) and NICETRIP (novel innovative competitive effective tilt‐rotor integrated project) studies. Both provided insight into whirl flutter.
In 2006, Dr. Quaranta joined the GARTEUR (Group for Aeronautical Research and Technology in Europe) project researching helicopter rotor/pilot coupling, dangerous high-frequency interactions between the pilot neuromuscular system and cockpit control inceptors. “During the GARTEUR project, thanks to the collaboration with the University of Liverpool, it was possible to set up a series of experiments to characterize the pilot’s biodynamic response called pilot feedthrough. Using these pilot data, it was possible to set up flight experiments in the Liverpool flight simulator designed to experiment with controllable and reproducible pilot-assisted oscillation (PAO).” Research into PAO continued in the EU-funded ARISTOTEL project, led by Prof. Marilena Pavel at the Technical University of Delft in the Netherlands (see “Leadership Profile,” Vertiflite, July/Aug 2020).
In 2016, Prof. Quaranta coordinated Project NITROS (Network for Innovative Training on ROtorcraft Safety), working with TU Delft, the University of Liverpool, University of Glasgow and industrial partners looking at vehicle dynamics, pilot behavior and the environment to enhance safety. “We have to consider that if we are going to have the explosion of VTOL traffic that is promised by the AAM revolution, we are going to have a larger pool of less trained pilots, so the aircraft will have to be necessarily more resilient to different levels of pilot skills.”
Growing computational power now allows designers to exploit more complex, physics-based, multidisciplinary models in flight simulators. Quaranta observed, “Up to now, the development of rotorcraft has been mostly an art. We need to transform it more into a science that can be taught, and in this sense the digital revolution may help a lot.” Current FRAME-Lab research investigates use of simulators in rotorcraft certification testing — the Clean Sky 2 Rotorcraft Certification by Simulation (RoCS) project. Quaranta explained, “Flight testing is costly, time consuming and may carry with it significant risk. It is anticipated that certification compliance demonstration through flight simulation, under the right conditions, may yield a benefit in all of these respects. However, to use simulation, it is necessary to show in a robust way that the models are credible.”
Quaranta said, “One of the ideas we are trying to exploit is to perform a sort of hardware-in-the-loop simulation where the data measured in the wind tunnel can be transmitted directly in real-time into a flight simulator to enhance the quality of the flight simulation. We are also exploring the possibility of using sensor fusion and artificial intelligence to transform the quantities, which can be measured directly on models into quantities that are of interest for full-scale flight test. The FRAME-Lab researcher added, “RoCS is a project coordinated by me, but many other institutions are working on it. We have NLR [Royal Netherlands Aerospace Centre], DLR [German Aerospace Center], University of Liverpool and Cranfield University, in partnership together with Leonardo Helicopter and the European Union Aviation Safety Agency [EASA].”
Quaranta offered, “I think that new types of propulsion more compatible with the environment like electric or hydrogen are crucial if we want to reduce the impact of aviation and if we want to increase VTOL operations. The opportunity to develop advanced air mobility can be realized only if we are able to solve issues like very high reliability and reduced impact on the population — perceived safety and noise. So, the regulatory framework is also crucial to make this work successful. In this sense, simulation, with the possibility to develop digital twins, will be crucial to bring many new AAM concepts to actual systems proven in the operational environment and affordable in terms of economic investment required.”
Giuseppe Quaranta became a full Professor at Politecnico di Milano in 2019. “I joined AHS in 2010. I am still the secretary of the VFS Italy Chapter. The Chapter is dedicated to Enrico Forlanini, an Italian engineer who studied at Politecnico di Milano in 1877; he developed an early helicopter powered by a steam engine. Participation in the VFS Annual Forum is a great occasion every year to learn where the research and the industry are going in the field of rotorcraft.”