Born: Italy
Primarily active in: Italy

From Leadership Profile in Vertiflite, July/August 2023

Antonio Visingardi, Senior Researcher, Italian Aerospace Research Center

Antonio Visingardi heads the rotorcraft aerodynamics laboratory of Centro Italiano Ricerche Aerospaziali (CIRA) in Capua, north of Naples. His is one of five labs in the fluid mechanics unit reporting to the CIRA director of research. Visingardi explained, “From the purely technical point of view, my activity consists of developing computational methodologies and performing numerical simulations. Most of my work is carried out in collaboration with other colleagues having different specialties — rotorcraft are extremely multidisciplinary.”

Visingardi collaborates mainly with researchers in aeroacoustics, structural dynamics, guidance navigation and control (GNC), and propulsion. “I deliver numerical results and databases, and technical documentation describing how testing is carried out.” The career computer modeler added, “I also put at their disposal my know-how in rotary-wing interactional aerodynamics for developing configurations based on distributed electric propulsion” used for electric vertical take-off and landing (eVTOL) aircraft configurations. “In recent years, I am definitely more involved in eVTOL-related activities because of the strong commitment of research establishments, industries, universities, subject matter experts and start-ups.”

Visingardi continued, “The architecture of eVTOL aircraft relies on the distribution of the propulsion system to improve aircraft efficiency and reduce energy consumption. This implies that numerous propellers/rotors, fixed or tilting, are employed to generate lift, propulsion and control. In addition, these aircraft can have wings and other aerodynamic surfaces, which may be fixed or tilting. As such, the interactional aerodynamics of these configurations is much more complex than conventional helicopters or tiltrotors to model. Visingardi added, “Given the importance of noise in rotorcraft comfort and public acceptance, especially if we talk about eVTOLs, most of my recent activities are carried out in collaboration with the aeroacousticians.”

CIRA collaborative researchers share wind tunnels and other cutting-edge facilities. Visingardi noted, “Recently, my colleagues and I have been involved in research activities on the wake characterization and acoustic signature of hovering propellers for eVTOL applications in a laboratory environment using both the CIRA test instrumentation for particle image velocimetry [PIV] and time-resolved PIV measurements in our semi-anechoic chamber.” He explained, “My numerical simulations are currently run on a cluster multinode-multiprocessor architecture with 45 nodes and 70 TFLOPS aggregate peak performance. A significant upgrade of this architecture is being finalized.”

While Visingardi’s rotorcraft aerodynamics laboratory builds computer models of innovative rotorcraft, the CIRA adaptive structures laboratory builds physical demonstrators and prototypes, recently including a shape memory alloy twist actuator tested by DLR – The Germany Aerospace Center on a whirl tower. The actuator integrated on a Bo 105 helicopter main rotor blade is meant to increase efficiency and possibly reduce noise in hover and forward flight. Visingardi said, “My involvement in this project was in collaboration with my aeroacoustics colleagues to evaluate the best installation layout and optimum amount of actuation.”

Distributed electric propulsion drives a range of potential rotorcraft investigations.The CIRA researcher offered, “Electrification of flight can help reduce emissions and noise pollution. Pursuing better handling qualities is certainly important because it has a direct impact on the comfort of passengers and pilot workload, enhancing the safety of flight. Nevertheless, aeroacoustics is where I would put more emphasis in future rotorcraft research. It is well known that rotorcraft are noisy. The annoying aspects of noise become even more important when considering new eVTOL configurations for urban air mobility [UAM].”

Modeling Flows
Antonio Visingardi grew up in Naples where his parents Ugo and Rita were both employees in a public building agency. The rotorcraft researcher recalled, “My father was a brilliant and competent guy able to solve theoretically and practically many technical problems of mechanical, electric, hydraulic and structural nature. The majority of my relatives were high school teachers and engineers, but none of them were in aviation.”

At 13, the high school student found mathematics and physics more appealing than classical studies in Italian, Latin and Greek. “When the time came to decide about a university, I made the practical choice of engineering, a major to my eyes able to open more job opportunities than math or physics.” Visingardi confided, “Moreover, at that time, I was fascinated by Formula One race cars, not by their powerful engines but by their streamlined shapes with those wings and other aerodynamic appendages. That was sufficient to encourage me to choose aeronautical engineering, and my parents supported it.”

Visingardi’s hometown University of Naples was recognized for its aeronautical engineering curriculum. The CIRA aerodynamic researcher recalled, “I enjoyed those studies very much, and I had the lucky opportunity to take Aerodynamics and Aircraft Design [courses] with professors Luigi Gerardo Napolitano and Luigi Pascale. Both were acknowledged worldwide, and both were pupils of the aviator-explorer General Umberto Nobile. My first approaches to applied aerodynamics and my first simulation codes were thanks to Professor Valentino Losito. He was highly appreciated by his students for his profound aeronautical culture, teaching capability and sense of humanity. He became my thesis advisor.”

With his thesis investigating the non-linear aerodynamics of wing-fuselage configurations with and without flaps, Visingardi earned a Master of Science in aeronautical engineering in 1987 at the time of a CIRA recruiting campaign. “Prof. Losito encouraged me to apply for a position as a young researcher. I joined CIRA that same year. After a short period in which I was involved in the development of a flow visualizer code commissioned by the former Aeritalia — now Leonardo Aircraft — I was assigned to the new unsteady aerodynamics lab.”

CIRA was created by the Italian government in 1984 to perform space and aeronautic research and enable Italian industry to better compete in international markets. The late 1980s began an intense period of European-funded aeronautical research projects, and Prof. Luigi Morino of the University of Rome invited CIRA to join work in helicopter aerodynamics. Visingardi recalled, “It was a natural consequence that the unsteady aerodynamics lab represented CIRA in these projects. The first one I participated in was on helicopter rotor/fuselage interactional aerodynamics, coordinated by Agusta, now Leonardo Helicopters. This was the first of a long series of projects lasting for more than three decades.”

Visingardi noted, “The numerical simulations of rotary-wing components and configurations are much more demanding than those carried out on fixed-wing geometries. At the beginning, CIRA numerical simulations had been carried out by using a non-proprietary computer code, which had been written several years before and was limited to a single isolated rotor. The decision to develop RAMSYS — the Rotorcraft Aerodynamic Modelling SYStem — was made in 1994 in order to overcome these limitations and to provide CIRA with a fully in-house computer code able to investigate as many configurations as possible.”

Visingardi remains responsible for the RAMSYS numerical solver that is commonly used to study potential, unsteady and interactional aerodynamics. He explained, “What made RAMSYS and all the modern panel codes attractive in those years, was the capability to explicitly model the wake for as many rotor revolutions as required. Available solvers based on full potential equations were lacking this capability. Higher-fidelity 3D Euler solvers were still under development and, in addition, were suffering the same lack of wake-modelling capability. 3D Navier-Stokes for rotorcraft simulations were yet to come, but even when they were first applied, how to keep the wake for a long distance was a big issue.” Visingardi led RAMSYS evolution through successive versions and concluded, “Today, Navier-Stokes solvers are commonly applied to very complex configurations. However, the domain of RAMSYS has always been the preliminary investigation of a configuration.”

Looking Ahead
Visingardi served as the task package leader for aerodynamic numerical activities on the European TILTAERO and NICETRIP programs related to civil tiltrotors. The latter project concentrated on the ERICA configuration with two four-bladed proprotors tilting with their nacelles and a tilting outboard wing to alleviate downloads. The CIRA researcher noted, “Studies of a next generation civil tilt rotor [NGCTR] full-scale demonstrator, led by Leonardo Helicopters, are currently going on in the Clean Sky 2 joint undertaking, in parallel with the RACER compound helicopter technology demonstrator promoted by Airbus.”

In 2021, Visingardi became chairman of the GARTEUR group considering rotorcraft configurations. He observed, “Rotorcraft research is challenging because rotorcraft are extremely complex machines. The numerical investigation of these aircraft requires adequate computer facilities and suitable computational tools. Our numerical simulation of rotorcraft cannot be limited to the accurate analysis of an established configuration. It must also aid in the design process. We can even see the possibility of aircraft certification by simulation. To make this scenario viable, the most advanced computer technologies — artificial intelligence, cloud computing, big data management, high-performance computing, etc. — must be applied to guarantee that extremely intensive and complex computations can be cost-effective and performed with reduced computational time.”

Visingardi continued, “Another fundamental step ahead must be computer-aided engineering to promote authentic multiphysics, multidisciplinary simulations. The rotorcraft design phase now largely relies on efficient optimization procedures to select the optimal solution from a space of solutions. New modeling trends aim at workflow automation, starting from a computer-aided design model to the final analysis of the results. This new modality is seen as a key factor in increasing productivity while reducing the risk of human errors. All of this and much more are at the base of the new digital twin technology, which will likely revolutionize the concept of simulation in the forthcoming years.”

Antonio Visingardi became a member of the Vertical Flight Society (then the American Helicopter Society) in 1991, under CIRA’s small-business-class membership. He concluded, “AHS/VFS has always represented to me the main source of documentation for my rotorcraft research. The high-quality publications of The Journal and Vertiflite magazine, the papers from the Annual Forum and the rich website are all essential to keep me up-to-date about the worldwide research in this field.”