The ADORNO Project

Aircraft Design and nOise RatiNg for regiOnal.

The ADORNO project focuses on the development of aircraft models for a regional aircraft engine platform. The main objective is to provide aircraft requirements (e.g. thrusts, offtakes, etc.) as well as trade factors for specific fuel consumption, engine drag and engine weight on fuel burn for both a year 2014 reference aircraft and a CS2 target aircraft. In addition, an aircraft noise method will be developed and integrated in an aircraft design chain.

The overall work plan is divided in three (4) work packages (WPs), following listed:

  1. WP1 - Management, Dissemination and Exploitation
  2. WP2 - Aircraft design and emissions assessment
  3. WP3 - Noise and Emissions Software
  4. WP4 - Advanced Trade Factor Methodology

ADORNO has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 8210437

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Topic Leader



Lead Tech


Main Results

Success of the ADORNO project is measured with respect to a reference A/C system, set for a reference aircraft configuration, which will be established in the first phase of the project. The following quantitative objectives ‘measures’ are set:

  • 60% reduction in necessary preliminary design time to converge for A/C and engine design loop by means of the integration of dedicated tools and interfaces.
  • Ability to include noise and emissions prediction tools inside the design process with a minimum required user input.
  • 40% reduction in time necessary to analyse data and to perform trade-off studies through the implementation of Enhanced Trade Space Exploration methods and Machine Learning technique.
  • 50% reduction in time necessary to perform an optimization study due to software architecture (object-oriented software with several dedicated apps).
  • 20% accuracy improvements on aerodynamic and stability prediction, which reflect on weight, performance, fuel consumption and noise and emission augmented fidelity.

Milestone 1

By the end of February 2019, in agreement with the project schedule shown in the Gantt diagram of the Project section, the first Milestone has been reached.
The Airbus A220-300 has been selected as reference 2014 aircraft model in terms of TLAR to be used for Work Package 2 activities.
The A220-300 is a narrow-body, single-aisle, twin engine, medium-haul jet airliner, previously known as Bombardier CS300.
It has been designed from ground-up and has been initially produced by Bombardier Aerospace, but is currently marketed by Airbus and built by CSeries Aircraft Limited Partnership joint venture (CSALP). It belongs to the Airbus newly branded A220 family.

The following tables provide information and data regarding the principal aircraft characteristics in terms of:

  • Aircraft geometry.
  • Interior arrangements.
  • Data concerning maximum weights and capacities.
  • Engines specifications.
  • Top-Level Aircraft Requirements.

All gathered data comes from several sources, mostly comprising technical documents provided by the manufacturer, official brochures, and EASA type-certificate data sheets.

Definition of UM and RM reference aircraft models

After the definition of the set of TLAR, the design activities related to the Work Package 2 have been focuesd on the definition of both Underwing-Mounted engines (UM) and Rear-Mounted engines (RM) configurations related to the reference 2014 aircraft model. At the end of April 2020, this task has been completed.
Both aircraft configuration has been designed by means of a dedicated MDAO process carried out using the UNINA JPAD software.
As can be seen from the following flowchart, starting from a statistically-defined baseline aircraft model, a population of aircraft has been generated for each configuration by varying lifting surfaces planform parameters and positions, as well as engines longitudinal position in the case of a RM configuration.
Each aircraft model has been analyzed considering a complete multi-disciplinary cycle including weights, balance, ground stability, ground operability, aerodynamics, static stability, performance, emissions, environmental noise and costs.

The result of this process has been a set of response surfaces related to main aircraft characteristics in terms of noise (EPNL) and performance (block fuel) as shown below.

Using both the design mission block fuel and the EPNL as driving parameters, a multi-objective optimization process has been carried out using a combination of metaheuristic algorithms.
As a result Pareto fronts for each configuration have been generated allowing the selection of the final optimum aircraft model. Those are shown in the following figure, while a summary of the main results coming from their complete multi-disciplinary analysis cycle is reported in the following tables.

Definition of target 2025+ UM aircraft model

Once the design activities for both reference 2014 A/C models were completed, time was spent to identify the set of advanced airframe technologies and solutions to be equipped on target 2025+ A/C models.
The set of advanced airframe technologies to be tested and equipped on the target UM A/C was elaborated based on expected Technology Readiness Level (TRL) by 2025. The selection was supported by the Clean Sky 2 Development Plan and by the International Air Transport Association (IATA) Aircraft Technology Roadmap.
The application of advanced materials (both advanced alloys and composites) was restricted to a limited number of components. In addition, concerning the On-Board Systems (OBS) architecture, a bleed-less configuration was selected. Finally, although the initial set of technologies included Natural Laminar Flow (NLF), it was concluded that its adoption in place of a Hybrid Laminar Flow Control (HLFC) system was unfeasible, since the selected value for the cruise Mach number of the target A/C models was well beyond upper limitations suggested by the literature.

Airframe technologies and their effect on disciplines and quantities such as aerodynamics, engine power off-takes (and then fuel consumption), A/C components weight, and direct costs were accounted by UNINA A/C design framework by means of calibration factors and offsets. These calibrations were based on suggestions retrieved from the available literature on the effect of these technologies. Once implemented in the A/C design chain, they were individually tested and checked against expected fuel burn benefits, as provided by IATA.

In addition to airframe technologies, an advanced engine model has been designed by MTU based on both engine requirements and a preliminary linear trade factors generated by UNINA. In particular, trade factors were focused on the effect of both SFC and engine dry mass on the overall block fuel for a design mission of 3100nmi.

The design of the target 2025+ UM aircraft model has been carried out by UNINA using its preliminary design framework, named JPAD.
A description of the workflow adopted for this task is shown below. Four sets of constraints have been considered for the optimization phase. These were related to the combination (ON/OFF) of the following characteristics:

  • A limitation on the maximum allowed wingspan to 36m (ICAO Aerodrome Reference Code Category C).
  • An additional fuselage centre tank to increase the maximum fuel capacity.

Results of the optimization process concerning the case of a constrained wingspan (36 m) and the presence of the additional fuselage central tank are shown below. This set of constraints has been selected as the most reasonable one for this type of aircraft. The final solution considered for the design of the ADORNO target 2025+ UM aircraft model has been related to the one with the minimum design mission block fuel.
The following figures highlights the main results obtained for the final aircraft configuration.

Finalization and validation of the environmental noise tool ATTILA++

The Work Package 3 of the ADORNO project deals with the development of Noise and Emissions software.
A tool for the calculation of A/C emissions was already included in the UNINA design framework at the beginning of the project.
A Noise tool was specifically designed and developed for ADORNO by UNINA, with the support from LeadTech, starting from a pre-existing tool, written in MATLAB, developed by the UNINA research group on Aeroelasticity and Acoustics. This tool has been used by UNINA within the context of the ADORNO project to carry out noise estimations at ICAO provided certification points. A three-month internship (from January to March 2020) at the MTU headquarter in Munich of one UNINA master’s degree student helped to strengthen the collaboration between the partners and MTU, to set the specifications of this tool, and to speed up the development.
ATTILA++ (AircrafT noise predicTion IncLuding performAnce), that is the name that was selected for the tool, has been programmed including the following requirements:

  • It was preferrable to adopt C++ as the programming language, following an Object Oriented Programming (OOP) approach, in order to ease its interfacing with the MTU framework.
  • The software had to offer to process both standard (i.e., for certification purposes) and user-defined flight paths, as well as standard and arbitrary microphone location.
  • Input data to the tool had to be provided through Comma Separated Values file (CSV, .csv file extension).
  • The software had to allow to include in the calculation noise contributions estimated with external tools.
  • The software had to exit clearly on errors, reporting events, exceptions and warnings in a log file.

The methodologies implemented derives from Engineering Science Data Unit (ESDU) estimating:

  • Airframe noise - contributions to aircraft overall noise emission of airframe components (wing, slats, flaps, tails, and landing gears, etc)
  • Atmospheric attenuation – effects of sound wave energy loss due to gaseous absorption.
  • Ground reflection – considers reflection of the sound wave by the ground.
  • Lateral attenuation – difference between the one-third octave band under-the-flight-path and sideline free-field sound pressure levels.

Engine noise contribution is also taken into account by ATTILA++ making use of external input files, which can be provided by the user or selected from an already available set.
The final version of the tool is now completed, validated and documented. It includes also new modules for the estimation of:

  • Shielding effect (according to ESDU 790115).
  • Additional noise metrics (such as Sound Exposure Level, SEL).

For the validation of the Noise tool, work was performed by UNINA and LeadTech.
LeadTech carried out the validation of the individual calculation modules of ATTILA++ by means of the test cases included in the documentation of the Engineering Sciences Data Unit (ESDU) methodologies implemented by the tool, while UNINA performed the validation of the overall noise (i.e., including the contributions of the airframe, of the engines, and of the propagation effects) based on real world data available in the literature.
An example of the work performed by UNINA to compare ATTIA++ results with public available literature data is shown below.

In addition, UNINA has also performed sensitivity analyses. This provided both a verification of ATTILA++ sensitivity to changes to aircraft components and other significant input parameters, and a meaningful overview on which input parameters affect noise analyses carried out with ATTILA++ the most.
Sensitivity to changes is undoubtedly fundamental for a preliminary design tool such as ATTILA++, aiming at allowing fast downselection of aircraft geometries and configurations when carrying out MDAO studies involving noise analyses.
Tool sensitivity was checked for the following case studies:

  • Tool sensitivity to changes to the main geometry of the aircraft (lifting surfaces span and surface; flaps span and surface, number of slots and deflection angle; landing gears strut length, number of units, number of wheels per unit, wheels diameter).
  • Sensitivity to changes to parameters influencing the calculation of propagation effects (influence of ground type, air turbulence and receiver’s height from the ground on the calculation of ground reflection; impact of engines positioning, with respect to the airframe, and receiver’s sideline distance, with respect to the noise source, on the calculation performed by the module accounting for lateral attenuation effect.
  • Sensitivity to changes to the source trajectory (aircraft flight speed and climb angle).

An example of sensitivity study is shown below.

Design and description of the reference aircraft set for advanced trade factor studies

The main objective of initial activities related to Work Package 4 of the ADORNO project was to provide information on the set of aircraft models designed by UNINA around the characteristics of three different advanced engines, whose dataset in terms of performance, mass and main dimensions was elaborated and provided by MTU.
The first part of this work has been related to the collection of information regarding the set of advanced engines designed by MTU. As for Work Package 2 activities concerning the design of the target 2025+ UM aircraft model, UNINA has provided MTU with dedicated trade factors necessary to carry out parametric analyses on engine Bypass Ratio (BPR).
Three engines were elaborated by MTU, characterized by distinct BPR values. For each engine, characteristics in terms of SFC, powerplant mass, maximum nacelle diameter, and nacelle cowl length were provided to allow UNINA to correctly model them in its aircraft preliminary design framework. Of the three engines of the set, the one with the highest value of BPR was the one which had been already used by UNINA for the analyses of the target 2025+ UM aircraft model in Work Package 2. Thus, one of the aircraft models of the final aircraft set to be produced had been already designed.

In terms of airframe technologies, the same set used for the target 2025+ UM aircraft model in Work Package 2 has been adopted. This included the full set of technologies and is related to the maximum block fuel reduction on a 3100nmi design mission.
Starting from the target 2025+ UM aircraft model, this has been equipped with the two engines characterized by a lower BPR value and, once adjusted in terms of characteristics of the landing gear group by lowering the main landing gear group uncompressed leg length to ensure the same minimum clearance of the baseline aircraft model with respect to the ground, it was used to carry out a parametric study in terms of wing planform parameters. For each of the two engines, 56 different aircraft were analysed, thus leading to a 56-point response surface. This process is also shown in the next flowchart.

These response surfaces were then provided to a sub-module of the UNINA preliminary aircraft design chain dedicated to the optimization task. Here a single-objective optimization on fuel burn has been performed for each response surface including the set of constraint also applied for the target 2025+ UM aircraft model of the Work Package 2. This optimization process is described in the following flowchart.

A summary of the main outcomes of the analyses of the three A/C models designed with the set of engines provided by MTU are reported below.
The geometry of the three optimized A/C models is practically the same. All three target A/C have a MTOW noticeably lower than the reference one, which is linked to the lower fuel mass and the lower OEW. It is important to notice that, due to the increasing weight of the powerplant, the aircraft models equipped with the higher BPR engines have higher OEW and higher MTOW, despite a lower design fuel mass, which for sure has a negative impact on the aircraft performance.
The aircraft model equipped with engines with higher BPR is still the one enabling the greatest reduction in terms of fuel used for the 3100nmi design mission. Nevertheless, the difference with respect to the remaining two models is quite small. This happens despite the data on the SFC advantage of higher BPR engines with respect to the others would suggest much differently. But a higher BPR value implies higher PPS mass, higher fan diameter thus higher maximum nacelle diameter, and longer nacelle cowl length, which, at some point, also due to the snowball effect on the aircraft, end up exceeding the sole SFC advantage.

Applicability of conventional and improved linear trade factors

Aero engine manufacturers typically adopt simplified approaches to perform fast and realistic predictions on the impact at A/C level of a new engine design in terms of fuel burn. One of these approaches consists in using linear trade factors for A/C fuel burn with respect to main powerplant parameters, such as TSFC, engine mass, nacelle maximum diameter, and nacelle cowl length. These linear trade factors can help to determine, even at an early design stage of a new powerplant, the overall impact at A/C level of a higher BPR, which on one side leads to higher propulsive efficiencies and lower TSFC values, but that on the other can determine an increase in the overall size and mass of the PPS.
For ADORNO, three sets of linear trade factors were determined, using JPAD as the tool for the analyses:

  • Two involving conventional trade factors, implying frozen characteristics in terms of main geometry for the A/C used as a baseline for their calculation. To produce the second set, the effects of advanced airframe technologies were accounted.
  • One set of what were defined as improved trade factors, which were calculated by assuming that the geometry of the underlying baseline A/C for the analyses could be optimized to minimize fuel burn for each change applied to the PPS, while ensuring the fulfilment of operational and feasibility constraints. In this case too, the effects related to the installation of advanced airframe technologies were accounted.

Applicability of these trade factors was tested against the results in terms of block fuel of the A/C models designed for D4.1, and the results of this test are provided in the table below.
This table highlights how the improved trade factor approach grants fuel burn forecasts the closest possible to the actual values coming from the optimization and the detailed mission analysis of the A/C. However, the conventional approach still provides results satisfactorily close to the expected ones, depending on the fact that the differences in terms of main geometric parameters between the A/C models of D4.1 were almost negligible. It is also fundamental to consider that the improved trade factors approach is the one requiring the highest effort in terms of necessary analyses, since each trade factor is the result of several A/C optimizations (at least two, to get a linear trade factor). If differences between powerplants are not too dramatic, so that it is reasonable to assume that the optimization on wing planform parameters for block fuel will not lead to noticeable differences in terms of A/C geometry, adopting a conventional trade factor approach would still probably be a reasonable choice.

Development of design methods and guidelines for A/C elements majorly impacted by the design of the PPS

Work was performed in D4.2 to define trade factors and design guidelines for major A/C geometric parameters mostly affected by changes applied to the PPS. Design methods were developed for the effect on wing planform geometry (wing surface and AR) of changes applied to the TSFC, dry mass, maximum diameter, and nacelle cowl length of the engines. Moreover, for the study related to the impact of the nacelle diameter, investigations were carried out and design methods were developed also for the effects on the landing gear system geometry for a UM configuration.

With regards to the study on engine dry mass, the investigation was carried out assuming to vary the engine dry mass in the range from -15% to +15% with respect to a baseline value. In terms of wing main geometrical parameters, effects on the optimum values for minimum block fuel of both wing area and wing AR were analyzed, with and without the effects of geometrical constraints (i.e., the cap on 36 m maximum wing span set by ICAO for category C A/C). For each considered engine dry mass value, at fixed AR, the optimum value of the wing area related to the minimum block fuel was comprised in a narrow interval around 120 m2. This aspect is highlighted in the figure below, which applies for a wing AR of 14. However, due to the constraint provided by the cap on the maximum wing span, minimum block fuel values cannot be actually achieved.

With regards to the investigation on the effects of nacelle maximum diameter, results similar to the ones presented above were collected for the study concerning the combined effect on block fuel of changes applied to both the nacelle diameter and wing planform characteristics. Concerning instead the investigation on the impact on landing gear system, a first chart was derived for a reference UM A/C configuration, identified as the BPR 12 A/C of D4.1. This chart, reported below, allows to estimate the effect that a new larger engine may have on the minimum nacelle ground clearance. This chart can be used as exemplified by the figure. If, for example, an increase in BPR determines a 10% increase of the nacelle maximum diameter, the minimum nacelle ground clearance would be reduced below the selected lower boundary, set as 0.5 m. The steps provided in the figure highlight how much the main landing gear leg length should be increased to solve the issue.

However, in case of retractable landing gears, an increase of the necessary main landing gear leg length typically leads to several considerations on the design of the landing gear system. These considerations are linked to the retracting mechanism and to the accommodation of an overall larger system in the available space in the lower body of the A/C. Moreover, changes in terms of landing gear strut length and wheeltrack imply several considerations and checks on the ground stability and on the certification of the A/C. These implications, along with examples of corrective actions, were all provided and discussed in details in D4.2.

Design of the RM target A/C

D2.3 provided a complete description of the activities that were carried out within WP2 of ADORNO to design and analyze a target (entry into service 2025+) regional turbofan aircraft with engines installed on the rear portion of the fuselage. The same assumptions made for the UM target A/C of D2.2 in terms of new advanced technologies were also made in this case: hybrid laminar flow control devices, riblets, variable camber wing with new trailing edge devices, advanced composites and alloys, more-electric aircraft architecture, new high-BPR geared turbofan engines. Moreover, a U-Tail configuration was selected, to allow the RM target A/C to record a remarkable reduction in terms of environmental noise with respect to today’s regional A/C.

A description was provided for the surrogate models that were implemented in the UNINA design framework for the preliminary estimation of the aerodynamics and structural weight of an unconventional U-Tail configuration. A detailed description of the design workflow adopted for the target RM aircraft was given, here summarized in the workflow illustrated by the figure below. The set of design input variables driving a preliminary full-factorial parametric study was justified and reported, as well as the set of constraints used for a subsequent multi-objective optimization, in which the block fuel and the cumulative EPNL at certification points were used as objectives. Constraints on the optimization were set in terms of limitations related to the geometric feasibility of the airplane, the fulfillment of a given set of top-level A/C requirements, and the matching of certification constraints.

This optimization process led to the selection of the final RM target aircraft, given in the three-view drawings and in the 3D representation below. This solution represented the best compromise possible between fuel efficiency and environmental noise, as highlighted by the Pareto front reported in the figure below. The balanced solution highlighted in this figure represents in fact the final RM target configuration selected for ADORNO. This model was then analyzed in detail and its performances in terms of gaseous emissions and noise for the selected ADORNO reference mission of 3100 nmi were reported.

A comparative analysis between all the aircraft models conceptually designed for ADORNO was included in the final section of D2.3. Target models, both UM and RM, were compared to their respective reference models in terms of geometry, design weights, aerodynamics, performance, emissions, environmental noise, and direct operating costs. In addition, target models were also directly compared to possibly determine the most promising configuration. From this analysis it was concluded that both the target models allow to match Clean Sky 2 environmental objectives in terms of CO2 and NOx emissions with respect to 2014 reference models. In fact, both allow emissions reductions greater than 20% against their respective reference models. The model with underwing-mounted engines has a slight advantage in terms of fuel burn and emissions with respect to the one with rear-mounted engines (in the range of 1%), but this could be offset by a greater environmental noise reduction. It is important to notice that RM target noise values were calculated by using the same engine noise deck used for the environmental noise assessment of the reference A/C (UM and RM).
The tables below provide an overview on the differences in terms of pollutant emissions and environmental noise between the RM models of ADORNO (reference and target) and the target (UM and RM) concepts developed and analyzed for the project.

Dissemination activities

Year Number Title Authors Type Journal/Conference DOI
2022 4 Bypass Ratio Parametric Analyses on a Narrow-Body Aircraft Using a New Tool for Turbofan Rubberization

Di Stasio, M., Trifari, V., Nicolosi, F., De Marco, A., Schaber, R.

Conference paper

AIAA AVIATION 2022 FORUM, June 27-July 1, 2022, Chicago (IL)


2021 3 Multidisciplinary Optimization of a Regional Jet Including Advanced Airframe and Engine Technologies

Di Stasio, M., Trifari, V., Nicolosi, F., De Marco, A., Fuhrmann, S., Schaber, R.

Conference paper



2020 2 Noise, Emissions and Costs trade factors for regional jet platforms using a new software for aircraft preliminary design

Nicolosi, F., Della Vecchia, P., Trifari, V., Di Stasio, M., Marulo, F., De Marco, A., Marciello, V., Cusati, V.

Conference paper



2019 1 Implementation of a Noise Prediction Software for Civil Aircraft Applications

Casale, C., Polito, T., Trifari, V., Di Stasio, M., Della Vecchia, P., Nicolosi, F., Marulo, F.

Conference paper

AIDAA XXV International Congress, 9-12 September 2019, Rome, Italy


Exploitation activities

Year Number Title Author Type University Date
2022 2 Efficient Gas Turbine Modeling for Low Emission Aircraft Preliminary Design Workflows

Di Stasio, M.

Ph.D. Thesis

University of Naples Federico II, Department of Industrial Engineering

April 2022

2020 1 Design methodologies for aircraft noise estimation with parametric analysis

Marciello, V.

Master's degree Thesis

University of Naples Federico II, Department of Industrial Engineering

July 2020

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