Smart Fixed Wing Aircraft (SFWA)

Overview

Co-led by Airbus and Saab, the SFWA ITD addresses the integration of passive flow, active flow, and load control technologies into new Smart Wing concepts, as well as the integration of other novel components such as Innovative Power-Plant, Empennage and Rear-Fuselage concepts for large aircraft and business jets.

The purpose of the SFWA ITD is to take innovative technologies, concepts and capabilities that had reached TRL 3 – and which demonstrate the potential to contribute to providing a step-change in fuel consumption levels and noise reduction – and develop and validate them up to TRL5 or, in some cases, TRL6. These include:

  • Smart Wing concepts which feature substantially reduced aerodynamic drag through a significantly changed laminar wing design. This design will be based on including passive and active flow control and a completely rethought multidisciplinary new structure and system concept, using advanced materials and manufacturing methods, sensors and actuators. The objective is to prove that a smart wing can be produced at “industrial scale” and used with guaranteed performance, and at low maintenance and operational costs throughout its lifetime;

 

  • Innovative Power-Plant, Empennage and Rear-Fuselage concepts which have the potential for substantial reduction in fuel burn and noise reduction. The aim is to develop integration concepts at aircraft design level for the innovative power-plant and empennage arrangements.

 

This project builds upon the knowledge and experience gained in other European framework programs such as AWIATOR and NACRE, and will culminate in demonstration and validation of the technologies and concepts using a number of on-ground or in-flight demonstration vehicles, to reach the following objectives:

  • Reduce aircraft drag by 10% by reducing the wing drag by 25% using laminarity, and by reducing the aircraft weight and drag through innovative control surfaces and load control;
  • Reduce fuel burn of aircraft by 20%, by integrating advanced engines, in close cooperation with the Clean Sky SAGE ITD
  • Reduce aircraft noise by up to 10 dB by engine noise shielding configurations, in particular for business jets.

 

Organisation/Structure

The work break-down structure of the Clean Sky SFWA ITD is aligned with a process of developing, integrating, and validating the technologies along increasing Technology Readiness Levels (TRL):

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  • WP1 – Smart Wing Technologies

In this WP, all key elements of technologies required to develop, design and build an all new smart laminar “low drag” wing, are picked up at “laboratory levels” - typically TRL 2 or TRL 3 - to be advanced to a TRL 4. This relates to a development at subcomponent or system level, with features and performance validated at realistic condition in test rigs. This does not only apply to hardware, but includes aerodynamic and structural design and calculation methods, fabrication or repair tools.

 

  • WP2 – New Configuration

In this WP, the integration of the smart wing and the innovative power plants as major components takes place, including the preparatory R&T to integrate the major parts into the overall aircraft concept.

  • For the smart wing a number of dedicated “feature” ground and rig demonstrators are planned to mature and validate the new wing with respect to bird and lightning strikes, icing, and also with manufacturing and repair methods of related innovative structures and systems;
  • All activities related to the integration of laminar wing technologies and integration of innovative power plants including the design of a modified, innovative empennage are addressed;
  • The detailed assessment of the value and potential of the individual SFWA technologies at component and aircraft level are also part of WP2. Acting as interface to the Clean Sky Technology Evaluator, this WP provides the reference aircraft, the conceptual aircraft, and the related models for the parametric assessment of the SFWA results.

 

  • WP3 - Flight Demonstration

This WP accommodates the flight demonstration activities to validate and demonstrate the SFWA target technologies under real operational conditions in an aircraft environment at large or even full size. These demonstrators provide the key information to advance the SFWA technologies from TRL5 to TRL6.

In order to improve the technical coherence and alignment in SFWA towards the ultimate goal, which is to mature the SFWA key technologies toward high TRL levels, an additional layer of “SFWA ITD Technology Streams” has been established.

The 8 Technology Streams define the technology roadmaps for the respective technologies which serve as pacemakers for the work packages. In other words, the technology streams are the “internal customer” of SFWA, providing all relevant milestones, reviews, and gates as part of the master plan to support the work packages.

 

Major Demonstrators

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In the following chart, the most significant and representative demonstrators of SFWA ITD are presented with the highlights of their content.

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Potential applications

In terms of technologies and future target product applications:

 

TS - Natural Laminar Flow (NLF) Smart Wing with associated Advanced Flight Test instrumentation

  • Based on extensive numerical simulations, ground and wind tunnel tests, and thanks to the development of innovative flight test instrumentation, the BLADE flight tests will pave the way for manufacturing and assembly technology improvements of such laminar lifting surfaces for future commercial aircraft.

  • Additionally, intensive research is being conducted in National Programmes and Clean Sky 2 in order to reduce the lead time for manufacturing and cost, to improve the surface quality, the optimization of high lift and anti-icing systems.

 

TS - Hybrid Laminar Flow (HLF) Smart Wing

  • Potential application for Large A/C or Business jets on Vertical Tail planes for short/medium term application and continuation in the EU AFLoNext project for the development of a simplified HLF control on A320 DLR ATRA

 

TS - Fluidic Control:

  • Maturation of active flow control technologies in AFloNext and Clean Sky 2 towards TRL 6

 

TS - Loads Control function and Architectures 

  • Potential application for next Business jets (vibration control laws and alleviation systems)

 

TS - Buffet Control

  • A standalone experimental database has been created as well as promising solutions to get some buffet shift. Further exploitations could then be done to see potential applications.

 

TS - CROR engine Integration

  • After the maturation of the CROR concept and related technologies, it is necessary to improve its economic viability via weight reduction and improved power plant integration. This axis of research is pursued in Clean Sky 2 for a TRL 6 expected around 2023

 

TS8 - Innovative Turbofan Engine Integration

  • The main expected benefit is a significant improvement in noise footprint reduction for the next generation of Business jets through noise shielding, using innovative tail concepts and rear-end turbofan integration.

Last but not least, the PANEM (Parametric Noise and Emission Model) tool will be exploited in Clean Sky 2 for the operational noise and emission evaluation of a set of integrated technologies at A/C and fleet level by the Clean Sky 2 Technology Evaluator.

 

Members

The SFWA consortium consists of 39 beneficiaries affiliated to Clean Sky ITD members (see below 8 ITD leaders and 9 Associate members).
 

 

Leaders

Associates

Airbus

Saab AB

Dassault Aviation

EADS-CASA

Fraunhofer

Rolls-Royce

Safran

Thales

DLR

ONERA

INCAS-Cluster

Netherlands Aerospace Cluster

QinetiQ

RUAG

Aernnova

Airbus Group SAS

Airbus Defence & Space GmbH

 

Partners

By the end of 2014, 105 additional partners had been elected through the Clean Sky Calls for Proposals process to join the project.

TS - Natural Laminar Flow Smart Wing

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1 – Meeting of team in front of the NLF-wing sections of GKN and Saab at the Final Assembly Line at Aernnova in Spain; 2 – A340 in the SFWA-Hangar in Tarbes; 3 – Flight Test Instrumentation on A340; 4 – Wing upper cover section prepared for entering the Autoclave for curing.

 

Objectives

  • Application of Natural Laminar Flow (NLF) on Short Range Aircraft and Business Jets with low sweep lifting surfaces;
  • Application of advanced technologies for achieving a high technology readiness level including high wing surface quality. 
  • Application of innovative aerodynamic design tools, large scale wind tunnel tests, Ground Based Demonstrators and comprehensive flight tests

 

1.1 Challenges and approach taken

The primary challenge of this Technology Stream is the realisation of laminar flow at full scale, high Reynolds number industrial wing; the data is needed to validate the applied design criteria for future industrial laminar wing designs. Advanced wind tunnel facilities such as the European Transonic Wind Tunnel (ETW), as well as innovative instrumentation (e.g. for wing deformation measurement) were used to prepare the A340 Natural Laminar Flow test flights.

Other major challenges had to be tackled during the manufacturing and assembly process for the large composite surface panels for the A340 outer wing test sections

  • Completely new technologies and production processes were required to enable design and production of those very large and complex innovative all-composite structures with extremely high requirements on tolerances, shape and surface quality
  • Specific tooling and jigs for wing disassembly and join-up were necessary (Figure 2)

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Figure 2 Assembly of the BLADE NLF Wing in the Jig (developed by ARITEX)

 

  • Knowing the exact bending of the wing during the test flights is crucial for the interpretation of the flight test results. Reflectometry, an optical tool for measuring the state of the surface, was employed for this purpose (Figure 3)

 

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Figure 3 Wing Reflectometry by 5 microns GmbH (qualifying tests on A320, Nov 2014)

Major achievements and benefits

Successful experiments have been conducted to better understand and control the laminar-turbulent transition phase, e.g. the impact of isolated holes, steps and gaps (Figure 4). These tests prepared the groundwork for the full-scale wing design and flight test; specifically for large transport aircraft, it is the first time such realistic test data has been available for future aircraft design.

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Figure 4 High Reynolds Business jet testing of laminar wing at ETW

As part of the push towards Technology Readiness Level 6 and to be representative of a real design and production environment for the NLF Structural Concept, a typical full scale element of a Short Range Aircraft leading edge was designed and manufactured including all relevant systems (Figure 5)

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Figure 5 Ground Based Demonstrator (4,5m long by 1m wide, on equipping fixture)

 

The flight test demonstrator has been conducted in the BLADE (Breakthrough Laminar Aircraft Demonstrator in Europe) project of the SFWA ITD.

Major steps of the ambitious and challenging demonstrator are:

  • The detailed design of the laminar wing elements which started in 2011 under the constraint that modifications of the Airbus A340-300 test aircraft, apart from replacing the outboard wings, should be kept to a minimum.
     
  • Manufacturing of special components for the flight test:
    • a large Aero-Fairing to separate the outboard laminar wing section from the remaining, turbulent inboard wing.
    • a wing-tip pod to assure a defined flow pattern at the outboard end of the laminar wing section and to provide containment for flight test instrumentation, with optical access close to the laminar wing, a diffusion zone passing the wing loads and torque form the laminar wing to the datum wing structure.
    • A digital Mock-up (DMU) of the laminar wing outside of the outer port engine of the Airbus A340-300 datum wing as shown in Figure 6.

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Figure 6 Digital Mock up (DMU) of the laminar wing attached to the Airbus A340-300 datum wing

 

  • The port wing has been designed and built as a large panel fully integrated leading edge – upper cover in CFRP under leadership of SFWA ITD member SAAB; the starboard wing is designed and built with a metallic leading edge connected to a CFRP large panel upper cover. The assembly of the wing is ongoing at SFWA consortium member Aernnova in Vitoria, Spain (Figure 7)          

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Figure 7 Left and right wing sections at the final assembly lines of Aernnova

 

The main working party of BLADE started in January 2016 and will last until the end of February 2017, mostly in a fully dedicated hangar at the Tarbes Airport in southern France. (Figure 8)

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Figure 8 Wing join-up assembly rig for A340 modifications in BLADE

 

The flight test campaign directly associated with SFWA in the fourth quarter of 2017 comprises 45 flight test hours; it is primarily intended to validate the area of laminarity that can be achieved for a large variety of cruise flight conditions with respect to altitude, flight Ma-Number and wing loading.

For a typical short-medium range aircraft, the calculated drag benefit is up to 8% at typical Ma 0,75 cruise flight at aircraft level, which translates to ~4,5% fuel burn reduction for a typical mission.

Outlook

  • Continuation in German and UK national frames and Clean Sky 2 for the reduction of lead time for manufacturing and cost, surface quality and optimization of high lift systems, electrical de-icing, etc.
     
  • Further improvements, potentially in the Clean Sky 2 framework of the innovative Flight test instrumentation that has been developed for the BLADE project such as reflectometry and Infra-red measurements.
     
  • Potential application on new Short Medium Range aircraft wings for the next generation of business jets.
TS - Integration of Innovative Turbofan Engines to Business Jets (Bizjets)

Objectives

The main objective of the IITE Technology Stream was to investigate innovative integration of conventional turbofans on medium-size long range aircraft such as business jets. The final goal is to bring this turbofan-fitted innovative after body to TRL “5+”.

Two "after body concepts" studied in the framework of this technology stream were implemented on the two business jet platforms Low Sweep Business Jet and High Sweep Business Jet:

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Figure 9: HSBJ aircraft concept

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Figure 10: LSBJ aircraft concept

 

The U-tail concept shows very efficient noise shielding: The numerical evaluations show that this concept allows a reduction of 50% in noise, and 40% of fuel consumption.

A "V-tail concept" is proposed to improve high Mach number drag characteristics, reduce after body weight through structural simplifications (no “S” duct) and provide centre engine acoustic shielding.

 

Challenges and approach taken

The challenge of this Technology Stream was to implement two totally new concepts of aft bodies on the aircraft platforms. The aim of this project was to have a validated concept in terms of design, aerodynamic, acoustic and integration aspects.

Numerical simulations have been performed to predict the behaviour of those aft bodies. Those simulations have been validated by several wind tunnels and ground tests.

Major achievements and benefits

The implementation of the two aft body concepts has been studied on different aspects:

- Structural design has been performed on the U-tail and V-tail concept by RUAG and Dassault Aviation

  • Taking into account major layout constraints
  • Optimising area rule for high Mach cruise

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Figure 11: Aerodynamic and structural studies on the V-tail design selected

- Flutter test:

The aim of the WTT test is the characterisation of flutter behaviour and corner flow with ONERA, RUAG Dassault Aviation and AIRBUS Group. 

It will validate and improve comprehension of:

  • Unsteady aerodynamic fields
  • Flutter mechanisms
  • Flutter margins
  • Corner flow aerodynamics

 

The wind tunnel test is scheduled end October 2016.

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Figure 12: model in Vibration Test at ONERA Chatillon prior to test in ONERA S2 Modane

 

  • Aerodynamic and acoustic validation of the U tail concept in the DNW wind tunnel of the U tail concept with INCAS ONERA Dassault Aviation, ARA and FUTUR:

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Figure 13: Aerodynamic wind tunnel testing (DNW facilities, DNW picture).

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Figure 14: acoustic wind tunnel testing (DNW facilities, DNW picture)

This Wind Tunnel Test (WTT) validated Dassault Aviation numerical simulations for the prediction of the aerodynamic behaviour of the U tail and its shielding capacity. Evaluations of the aerodynamic of LSBJ wings and airframe noise have also been performed. The challenge of this WTT was to design, manufacture and qualify a large model including TPS (turbofan propulsion simulator), install modal detection inside of the TPS and electrical control inside of the model.

Performance validation of the U-tail configuration in high speed and high Reynolds number conditions: Wind tunnel test at ETW on a LSBJ model:

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Figure 15: © Dassault Aviation - S. Randé

All the objectives were achieved thanks to:

  • Robust design of the aero-shape
  • Smart design of the model
  • High quality manufacturing and finishing of the model
  • Efficient preparation and execution of the tests

A ground test with U tail After Body Demonstrator with INCAS, NLR and Dassault Aviation. This test is to validate different aspects on the U tail concept on a full size model: 

  • Noise shielding on real jet noise sources
  • Acoustic fatigue
  • Thermal measurements

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Figure 16: SHIELD ground testing

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Figure 17: SHIELD aft body and test rig

 

The preparation of this ground test was very challenging, due to the size of the model and the multiple configurations tested for the acoustic shielding.

The test will take place in Istres (Dassault Aviation test facility) during the second semester of 2016.

 

Outlook

After completion of the testing described above, the next step will be the final adjustment of the design methods and analysis of the optimised performances. Further progress on the inlet design and integration on the airframe are also possible.  Both are planned within Clean Sky 2.

TS - Fluidic Control Surfaces

Objectives

TS4: Fluidic Control Surfaces tackles the development and validation of separation delay techniques, applicable to business and transport aircraft.

The overall objectives are:

  • Improved low speed performance (take-off, landing) via separation delay
  • Simplification of movables
  • Support of laminar wing via simplified leading edges (e.g. droop nose or flow control instead of slat)
  • Extension of the low speed design space for aircraft designs with active flow control as an additional parameter
  • Exploration of opportunities for “Dual Use” of flow control for the purpose of load control

  

Challenges and approach taken

The technical challenges in this TS were to design and validate efficient flow control technologies, which enable delay of separation at minimum effort related, for example, to energy spent for actuation and related system and structural weight.

These challenges were addressed in a multidisciplinary manner using numerical studies, design and laboratory testing of flow control hardware and wind tunnel validation with swept research type wings (most studies focussed on the DLR-F15 configuration).

 

These investigations were structured into 4 sub-streams:
 

C1: Shape design concepts, smart surfaces and materials

  • Passive high lift concepts with new kinematic technologies.

  • Smart material studies for leading edge application.

C2: Leading Edge (LE) flow control for slat-less wings

  • Active flow control through orifices at leading edges for wings without slats.

C3: Trailing edge (TE) flow control for high performance

  • Active flow control technologies applied at flaps and the spoiler region.

C4: Active flow control to support load control functions

  • Basic studies to exploit synergies of active flow control to reduce loads at off-design.

 

Major achievements and benefits

A high lift smart flap configuration with a significantly extended flap chord was studied. This novel smart flap concept comprises both a novel kinematic architecture for a flap drive system and the use of composite material for the flap structure.

Numerical studies and experimental validation revealed the anticipated increase in lift for the linear and the cl max region, which meets the demands for business jet applications.

 

Within concept 2, a laminar airfoil with leading edge tangentional blowing and suction was numerically investigated. The required lift increase was reached, but for this airfoil the actuation mass flow was so significant that further optimizations are needed before an industrial application is realistic.

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Novel flap concept for business type aircraft

 

In addition, fluidic vortex generators (circular type orifices are named fluidic VGs) were numerically designed and built for the DLR F15 configuration shown below.

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Leading edge flow control for slat replacement 

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Active flow control at the flap

 

Both concepts C2 (leading edge flow control) and C3 (active flap flow control) were experimentally tested in the DNW-NWB wind tunnel.

The overall summary conclusions are:

  • Pulsed jet actuation is efficient to delay turbulent flow separation.
  • Active flow control applied at the flap shoulder indicates larger lift gains than flow control at the leading edge. Hence, the leading edge concept requires further studies.

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DLR F-15 configuration in DNW-NWB

 

Based on evidence that active flow control is effective at enhancing the lift of high lift devices, a basic study was performed (using numerical predictions and wind tunnel investigation) to explore the use of flow control to adjust the loads at off design conditions.

With suitable settings of the flow control jets (mainly direction of the actuation jets) a sectional lift decrease was predicted. These “fluidic spoilers” were introduced into a large swept wind tunnel model. The overall conclusion is that active flow control applied at a 60% wing position can be used for load control.

With an appropriate setting of the flow control jets the root bending moment could be reduced significantly. This actuation is very fast, and could possibly also be applied to control gust phenomena. The reduction in root bending via flow control is greater than via a classical spoiler type deflection.

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Fluidic devices (upper: actuation region; lower: detail of jet actuation) at similar locations as classical spoilers to reduce local lift

 

Outlook

In European projects, studies are ongoing to further mature active flow control for specific areas. Application of flow control technology to the outer wing regions and to the pylon/wing junction for UHBR (Ultra High Bypass Ratio) looks very promising in terms of enhancing low speed performance. With such local applications, the way towards global application is systematically prepared. This is outlined in the following steps to industrial application:

Step 1: Basic studies of generic configurations (done before SFWA ITD). TRL1 scope.

Step 2: Proof-of-concept investigations, investigated during SFWA in TS4 via WP114, WP135, WP138, WP213. TRL2 and 3 scope for active flow control concepts.

Step 3: Adaptation of SFWA outcome for selected applications to achieve - with almost full size flow control hardware - a robust TRL4 for pylon/wing application. Ongoing in AFLoNext.

Step 4: Aerodynamic validation of active flow control for industrial wings  (CleanSky2).

Step 5: Flight tests of flow control, building upon large scale ground demonstrations (=TRL5). Transposition of outcome to future wing designs, and hand-over to customers (= TRL6).

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Bridging TRL3 (SFWA) to TRL6 via AFLoNext and CleanSky2

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