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ELWIPS Report Summary

Project ID: 307869
Funded under: FP7-JTI
Country: France

Final Report Summary - ELWIPS (Electro-thermal Laminar Wing Ice Protection System Demonstrator)

Executive Summary:
The principal objective of ELWIPS was to design a functional prototype of a full scale laminar wing for a High Speed Business Jet equipped with Electro-thermal ice protection system (ETIPS) which was to be tested at an icing wind tunnel (IWT). ELWIPS was executed by consortium consisting of Meggitt Artus (ELWIPS Coordinator), Meggitt Polymers and Composites (Programme Lead and System Integrator), AeroTex UK LLP (Icing Specialists), and the University of Sheffield (Advanced Manufacturing Research Centre).

The first part of the project was the definition of the ice protection performance and operational requirements as specified by the Topic Manager. These requirements were used by AeroTex UK LLP (ATX) to define both anti-ice (AI) and de-ice icing (DI) solutions.

The ETIPS aspects were innovative through a focus on minimising power consumption, using sensors to allow power demand management and thereby achieve a Smart ETIPS. Different types of heater technologies were tested by Meggitt Polymers and Composites (MPC) in a range of configurations, in order to optimise ice protection coverage and power consumption. This resulted in development of an advanced heater technology.

The Advanced Manufacturing Research Centre (AMRC) undertook studies to support the definition of an optimal structural solution.
A technology demonstrator prototype representative of a laminar wing with incorporated technology was designed and manufactured, to support the validation of the icing solutions. The AMRC provided the Leading Edge and wing after body. MPC provided the advanced heater technology which was incorporated in the Leading Edge and after body.

The ATX icing solution was tested by the performance of full scale tests in the NASA IRT icing wind tunnel (IWT) with the support of the Topic Manager. Artus provided 270VDC power switches while MPC developed the ice protection control environment. Investigations where performed on both AI and DI solutions. .

Accomplishment of the NASA icing tests and with the approval of the Topic Manager resulted in the confirmation that the developed advanced heating technologies satisfied the requirements of TRL 6, while the tested icing solution satisfied the requirements for TRL 5.

A further objective of ELWIPS was to provide system definitions of the impacts of installing an ETIPS system on a target aircraft. System analysis undertaken by MPC and Artus with the support of both ATX and the AMRC resulted in the definition of a system architecture that is fully capable of meeting both specific aircraft level and regulatory requirements. At the system implementation level, the Topic Manager has approved that analysis supports the requirements for TRL 3.

The aims of ELWIPS are consistent with the environmental goals (ACARE) in respect to reduced emissions (efficient ice protection reduces fuel consumption) and the CSJU objectives within the Smart Fixed Wing Aircraft ITD related to drag reduction by using laminar flow wings.

Project Context and Objectives:
The ELWIPS project must be considered in the context of developing icing solution for a laminar wing and that in-flight icing is a potential hazard to aircraft. Ice contamination distorts the flow of air over the wing, diminishing the wing’s maximum lift, reducing the angle of attack for maximum lift, adversely affecting aeroplane handling qualities, and significantly increasing drag.

ELWIPS was conceived to develop and test an icing solution for the laminar wing of a High Speed Business Jet. The following provides an overview of the technical results achieved in the six technical work packages.
• WP2 Trade Study Planning
• WP3 Structural Definition and Heater Technology
• WP4 ETIPS System Study
• WP5 System Selection and Justification
• WP6 Prototype Manufacture
• WP7 Icing Wind Tunnel Test
Note that WP 1 provided for project and programme management.

WP 2 Trade Study Planning
Work Package 2 provided for the Trade Study planning phase and was undertaken to support the definition of research and technology development in support of the trade-off elements identified with the CfP. WP2 resulted in definition of a comprehensive analysis against the High Level Technical Requirements (HLTR) provided by the Topic Manager.

WP3 Structural Definition and Heater Technology

Work Package 3 was dedicated to
• Assessment of various potential structural solutions
• Assessment of differing heater technologies
• Thermal analysis to support definition of an icing solution, icing control algorithm and electrical powers

3.1 Assessment of various potential structural solutions
The AMRC was tasked with the structural design, specification and testing of a wing fixed leading edge structure applicable to an aircraft level solution and the application of the structure to a wind tunnel model for testing under icing conditions. This process was completed in a number of steps which will be discussed in more detail below:
• Initial Trade Study: An initial screening trade study was carried out into material, process and heater technology combinations. The objective of this study was to compare as wide as possible range of potential candidate solutions and to select the most promising options for further analysis.
• Material testing: Mechanical testing was conducted to derive material properties to assist the trade process to select the most appropriate material, to provide data to the computational modelling and to support the stress analysis conducted on the wind tunnel model. Thermal characterisation was conducted to acquire material thermal properties to support design and specification of the ice protection system.
• Ice-phobicity study: Ice phobic coatings were considered as a potential means of assisting the electrical ice protection system.
• Life cycle analysis: In additional to the financial cost analyses performed as part of the trade studies, an analysis of the environmental costs was also conducted to compare the different material and process options.
• Joint considerations. Attachment of the leading edge to the after body was considered as a crucial factor, particularly with regard to the stringent laminarity requirements. Several novel concepts were developed to create an upper wing surface free from visible fasteners.
• Manufacturing trials: Extensive manufacturing trials were carried out on sections of both wind tunnel model and low technical risk composite structures to demonstrate and refine the manufacturing process.
• The structural design process was supported by Finite Element Analysis; both linear static models and non-linear dynamic and Bird strike analysis
Candidate solutions were validated within WP5.

3.2 Assessment of differing heater technologies
MPC undertook investigations into various potential heater technologies which included Conductive Fabrics & Veils, Wire Heaters, Conductive Films, Metal Foil Heaters, Metal Spray, Conductive Films, and Nanomaterials. The advanced heater technology was down selected from many candidate technologies through a rigorous test and analysis programme. Candidate solutions where validated within WP5.

3.3 Thermal Analysis
Using their validated in-house codes, ATX performed Thermal Analysis to support the identification of potential icing solutions, control algorithms and electrical power requirements. Icing solutions against defined aerodynamic data provided by the Topic Manager where developed for both Anti-Ice and De-ice concepts. This included both aircraft level and specific analysis in support of NASA IRT IWT. Residual and inter-cycle ice limits where calculated and validated against the Topic Manager requirements. Chordwise power densities where established, assessed and implemented during IWT tests. Derived Control laws (heater on times) were also tested in the IWT. .

WP 4 ETIPS System Study
Work Package 4 was undertaken by MPC and Artus to support the definition systems architectures that can manage the electrical power distribution requirements and satisfy the certification requirements:
• To determine the optimum supply voltage for the ice protection system
• To identify the preferred control architecture configuration
• To make an assessment of HIRF, lightning and EMI protection methodologies
• To undertake a full system analysis and definition of the preferred Wing Ice Protection Control Unit (WIPCU)

4.1 Optimum Supply Voltage
Detailed analysis was undertaken on the merit of various aircraft generated power supplies. The final selection was superseded by the Topic Manager specification of 270VDC.

4.2 Control Architecture Assessment
In collaboration with the Topic Manager several control architectures where assessed against defined trade study criteria.

4.3 Full system analysis and preferred Wing Ice Protection Control Unit definition
A full system analysis was performed assessing the impacts of installing an ETIPS system on the target aircraft. The Controller definition was done down-to a detailed power part (components level) and a block schematic Control and Monitoring part. Dymola (Modelica) Functional and Behavioural models were developed. The development of HIRF and EMI protection methodologies was undertaken. Reliability analysis (MTBF calculation) and Safety analysis (FMEA) were done. Preliminary mechanical implementation (3D view and weight calculation) was done. A certification level Preliminary System Safety Assessment (PSSA) was performed for the complete system.

WP5 ETIPS Structural & System Selection
Based on the completed trade study process (WP3 & WP4) work package WP5 provided for the selection, justification and confirmation of the defined structural and system solution. An important selection criterion was assessment that the defined solution can be expected to satisfy the reliability and system safety objections for an ETIPS. The full ELWIPS Consortium was involved in the selection process. The technical choice for the prototype from amongst various possibilities was agreed with the Topic Manager.

WP6 Functional Prototype Realisation
WP6 provided for realisation of the selected prototype structure that was taken into the NASA IRT IWT. WP6 had the following distinct parts
• Manufacture of the IWT Test Article
• Verification that the IWT test model satisfied the requirements for a laminar wing
• Interpretation of the icing control solution into architecture
• Commissioning and IWT Test Environment

6.1 The AMRC with the support of MPC manufactured the IWT Leading Edge incorporating the advanced heater technology. Two specimens were manufactured; one for actual test and one as a provision against failure during test. The AMRC and MPC also collaborated in the manufacture of the wing after body. The wing after body included various features, such as additional heater mats to support efficient testing at NASA and a controllable flap for aerodynamic matching. This sub work package also provided for:
• Detailed design and manufacture of the leading edge and the after body including all associated sub-assemblies (AMRC with the support of MPC)
• Detailed design and manufacture of the advanced heater mat by MPC
• Definition of the required instrumentation to support icing validation (MPC with the support of ATX with the collaboration of Dassault Aviation)
• Integration of the advanced heater technology into the defined leading edge structure (AMRC with the support of MPC)
• Installation of the defined instrumentation by MPC
• Stress analysis to support the NASA IRT installation requirements by MPC
• Electrical harness design and manufacture for power, control and instrumentation by MPC
• Installation of the electrical harness to the test article by MPC
• Design, procurement and installation of flap actuator control by MPC
• Design of the aerodynamic pressure belt by ATX
• Design and development of the IWT control software environment by MPC
• Design, development and manufacture of the IWT control hardware environment by MPC with the support of Artus (270VDC power switching)
Design and manufacture of handling requirements to support transportation by 6.2 Verification tests were performed on the manufactured test article to demonstrate compliance with manufacturing tolerances for a laminar wing. This included First Article quality assessment

6.3 MPC interpreted the ATX icing solutions into both software and hardware configuration items (control environment).

6.4 The AMRC delivered the full IWT test article to MPC for commissioning and integration testing. Test scripts were developed. Test were undertaken by MPC with the support of ATX to ensure that the control environment fully implemented the IWT icing solutions. The test article and associate control environment was then shipped to the NASA IRT IWT.

WP7 Icing Wind Tunnel Tests
Work Package WP7 provided for the validation of the developed AI & DI icing solution at the NASA IRT IWT. WP7 provided for two principal activities:
• Trials Planning
• Test Execution and Reporting

7.1 Test Planning was undertaken resulting in the definition of a test matrix and test requirements/Tunnel interface documents. ATX produced a test matrix which described the:
• Objectives of the test
• Test points and test conditions
• Tunnel calibration against aircraft flight conditions
MPC produced the IWT interface document which included:
• Tunnel electrical and mechanical interface requirements
• Instrumentation interface and associated calibration requirements
• Definition of electrical safety provisions.

7.2 Validation test at the NASA IRT ITW was primarily undertaken by ATX and MPC with the support of AMRC and the Topic Manager. The IWT started with the test article installation within the NASA test section. System commissioning (power distribution, control, and instrumentation verification) and aerodynamic tests were conducted. Formal IWT tests were conducted eight days which included ice shapes on the unheated test article, and demonstration of both AI and DI control solutions. Test results were presented to the Topic Manager.

The Final act of ELWIPS was a TRL review held at the Topic Manager. The ELWIPS programme was represented by the full consortium and the Topic Manager. There were two aspects to the TRL review:
• Discussion of results of the NASA IRT IWT test programme
• Presentation of the aircraft level solution
It was at this review that the Topic Manager approved the TRL status for the Heater Technology (TRL6), the Icing Solution (TRL5) and the System Architecture Definition (TRL3)

Project Results:
The main results from ELWIPS are as follows:
1) Both AI and DI solution were developed for a laminar wing appropriate to a High Speed Business Jet. The solution limitations have been captured. Analysis and test results have been communicated to all relevant parties.
2) Advancements in heater technology have been made. Limitations in respect to performance have been identified and interoperability with relevant aircraft components and structures is understood. Critical manufacturing and reproducibility processes are recognised in respect to industrialisation.

Potential Impact:
The main impact of ELWIPS is demonstration of an advanced heater technology for the purposes of ice protection within the laminar wing leading edge of a Business Jet. The advances in heater technology are equally applicable to other fixed wing aircraft categories or to fixed surfaces of rotary wing aircraft. Versions of the advanced heater technology are being exploited within a Clean Sky 2 project.
Electro-thermal wing ice protection is considered an enabler for the More Electric Aircraft (MEA) and the bleedless engine. The progress made and lessons learned from ELWIPS furthers the understanding of the technical requirements needed to fulfil the enabler function.
The TRL achievements support the continued research and development into electro-thermal ice protection.
The industrial partners (MPC and Artus) of the consortium are in the position to further exploit the technical understanding developed during ELWIPS and to offer technical solutions to future projects.
ATX are in the position to further develop their codes based on the results of the IWT.
AMRC refined and improved their manufacturing processes and generated mechanical test data that will be of use in further research.

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