Impact case study database

The UK is a world leader in aerospace technology, but global competition is intensifying. The combined rotorcraft world market for the next decade is significant and hence key to the national economy, with a projected production of more than 17,600 rotorcraft worth an estimated USD202,000,000,000 in 2018 (Forecast International). The national helicopter industry is deeply embedded in the UK’s industrial base, directly employing more than 7,300 people, generating national revenues of more than GBP2,300,000,000 and exports worth GBP1.3B yearly, and supporting the work of more than 2,300 companies in the supply chain. Although increasing demand for new civil rotorcraft is expected to more than offset the anticipated decline or plateau in military demand, in order to maintain or improve, the UK needs to generate unique innovations. Research conducted at UoL is making important contributions to this objective.

Enabling Long Term World-Leading Rotorcraft Innovation in the UK

The NRTF rotor rig is a physical mechanical/software mechanism, unique in the UK, that enables performance optimisation studies of rotor blades and their impact on rotor-vehicle aerodynamics, facilitating more efficient blade and body designs, reduced noise, improved airworthiness and better handling qualities.

The rotor blade control is governed by the unique algorithms developed by UoL, which have changed rotor blade design processes and increased capabilities for manufacturers to test the safety of the design. These algorithms were based on “ advanced novel H-infinity methods which were able to accurately control the rig pitch when implemented on the rig satisfying the required accuracy demands” [E4]. They are “ one of the key enabling technologies” for the NRTF according to the Aerospace Technology Institute [E2].

The test rig can also be used for other rotor-related studies, including new actuator technologies and flight algorithms, and enabling fundamental research of rotorcraft phenomena not yet well understood, such as whirl flutter, which can have catastrophic consequences for the operation of new vehicles operating at higher speeds. The rig is unique in the UK and is key to boosting the UK's vertical lift capabilities in an increasingly competitive market. “ The participation of the University of Leicester has been vital in the construction of the National Rotor Rig Test Facility” (Aircraft Research Association) [E1].

UoL research has significantly improved industrial understanding and awareness of advanced control design methodologies; notable examples of this include the Aircraft Research Association (ARA) for the NRTF rig and Muretex for the entire control system. ARA is an independent research and development organisation providing a range of specialist services to the global aerospace industry including aerodynamic design and consultancy, computational fluid dynamics, high precision wind tunnel model design and transonic wind tunnel testing. As a result of collaboration with UoL, ARA were able to “ greatly increase our awareness and understanding of their novel control algorithms some of which have been fully implemented into the NRTF and experimentally tested” and they also comment favourably on the algorithm’s “excellent performance, meeting demands of less than 0.1-degree accuracy for the rotor shaft tilting motion” [E3]. The result of this collaboration is that operators now understand the use and benefits of the UoL algorithms with ARA stating that “ These algorithms alleviate the operator’s workload significantly, hence improving the safety under standard operation” [E3].

Systems engineering company Muretex specialise in augmenting human performance through automation and control systems development and are a partner in the NRTF development. In addition to algorithm development, UoL provided Muretex with “advanced know-how to the control systems team, which allowed the implementation of algorithms crucial to the rigs’ functionality” and unique contributions that “ not only enabled rig functionality to be achieved, but also enhanced the appreciation of advanced control techniques by Muretex personnel”. As a result, the Muretex control system development toolbox is now “ more complete thanks to the collaboration with Leicester” [E4].

Changing Aircraft Design Processes, Policies and Opening New Markets

Excessive vibration in rotorcraft causes a multitude of significant issues including making pilot control more difficult causing reduced flight quality, rotorcraft reliability and flight safety, increasing fuel consumption through reduced efficiency and negatively affecting passenger comfort and experience. New algorithms developed at UoL [E1, E2, R5] provide 50-75% reduction in vibration compared to standard industrial methods whilst also guaranteeing increased reliability. This is accomplished through a combination of more accurate robust stability tests and having low-order and a single set of control algorithms operating over the flight envelope. This facilitates the system’s certification for production and provides an economical computational infrastructure.

Leonardo is one of the biggest suppliers of defence and security equipment to the UK Ministry of Defence. It makes a significant contribution to the UK economy with revenues of over GBP2,000,000,000, around 50% of which are in exports. According to Leonardo: “[Morales’] expertise in advanced control system design for vibration reduction highlighted the importance of actuator limitations and how comprehensive algorithms that take this information into account can be exploited to further improve both airworthiness and performance with respect to existing methods” [E1].

Leonardo confirmed that the results of the collaboration are now “ applied to vibration mitigation systems currently operating on our products, such as the Active Control of Structural Response (ACSR) system” [E2] which are included as key selling points on the AW101, AW169 and AW139 helicopters [E5]. As of October 2020, Leonardo had sold 71 AW101 machines as well as at least 450 AW169 and 1100 AW139 units generating revenues of up to USD23,900,000,000 [E6].

The Aerospace Technology Institute (ATI) promotes transformative technology in air transport through substantial research and development funding and responsibility for defining the technology strategy for the UK aerospace sector. UoL research and involvement has achieved significant impact on ATI through providing “ new understanding and awareness into [their] design methods’ leading to ‘impact on policies and design procedures for both the UK Aerospace Strategy and for the rotorcraft industry in the UK” [E1, E2].