Design and manufacture of a flight worthy intake system (scoop/NACA divergent intake) SCOOP AND NACA DIVERGENT INTAKE TRIAL (SANDIT)

Project Information

SANDIT

Grant agreement ID: 308183

Closed project

Start date 1 January 2013

End date 31 March 2016

Funded under

• Specific Programme "Cooperation": Joint Technology Initiatives

Total cost € 874 641,83

EU contribution € 466 354,63

Coordinated by

GKN AEROSPACE SERVICES LIMITED
United Kingdom

Final Report Summary - SANDIT (Design and manufacture of a flight worthy intake system (scoop/NACA divergent intake) SCOOP AND NACA DIVERGENT INTAKE TRIAL (SANDIT))

Executive Summary:
This programme supported the supply of an innovative, composite “scoop” intake for an aircraft Environmental Control System (ECS), qualified to a sufficient level to support flight trial activities. The intake was required to have integrated ice protection heaters and acoustic attenuation technology.

In SANDIT (Scoop And NACA Divergent Intake Trial), the objective was to design, manufacture and qualify a flight trial demonstration intake assembly for flight trial use. This activity will enable flight validation of the overall electric ECS and the intake technology that supports it, with an overall aim of enabling more efficient aircraft systems.

In the initial design and research phase, GKN used preliminary data to carry out trade studies of suitable materials and processes for the manufacture of the scoop intake. Work also took place to evaluate the mould tooling technology that would be used to produce the relatively small and highly complex intake geometry (tooling provided by EPM Technology).

AeroTex used its suite of aircraft icing design software tools, together with results from previous icing wind tunnel testing to identify the number, location and intensity of ice protection heating zones necessary to provide efficient anti-ice protection of the scoop intake. Thermal modelling was also carried out to determine the maximum structural temperatures.

GKN used its powder-bed Additive Manufacturing (AM) process to produce a net-shape acoustic liner sub-component. A design was proposed for integration of the acoustic liner with the ice protection heating, so that acoustic panels could be applied to areas of the design which were also subject to icing. The innovative, additively manufactured and heated acoustic liner concept was further developed during this phase and was fully integrated with the scoop design and manufacturing process.

GKN also evaluated ‘sprayed on’ erosion protection, previously demonstrated on the previous wind tunnel test article. However, the selection made for the scoop erosion protection was an electroformed nickel pre-formed component.

One of the most significant challenges of the programme was the integration of the SANDIT scoop with the aircraft belly fairing panel on which it was mounted. During the detailed design and analysis phase the first round of structural analysis was performed by Altair. This highlighted a potential failure of the modified belly fairing panel under the critical load case. In order to mitigate this issue a further design loop was completed between GKN, Altair and EPM Technology, in collaboration with the topic manager.

Two complete intake assemblies were manufactured in a sharing of work mainly between GKN and EPM Technology. One unit had fully functional ice protection heaters and heated acoustic liners. The second unit was a hard-walled, structural part only (no heaters or acoustic liners). The tests were passed and both units were successfully delivered to the topic manager in time for the flight test activities.

The project results will benefit the environmental impact of future aircraft design through enablement of electric systems architectures, reduction in aircraft noise levels and reductions in manufacturing waste.

The project developed technology equivalent to a Technology Readiness Level 5 status (TRL5).

Project Context and Objectives:
4.2.1. State of the art – Background

Ice can form rapidly on aircraft surfaces in flight; especially at low altitudes. Ice growth can disturb the local airflow and radically alter handling or performance. Traditionally, larger civil aircraft use hot gases diverted from the engines to remove ice from flight-critical surfaces.

This technology is incompatible with future generations of aircraft, where composite materials will be used extensively due to the high strength-weight ratios that can be achieved. However composite materials also provide opportunities for increased functionality of aircraft structures using electric systems – e.g. for ice protection.

Also of key importance is the desire for greater fuel efficiency, in order to reduce the cost and environmental impact of civil aviation. The current reliance of aircraft design architectures on engine bleed air for systems such as Ice Protection Systems (IPS) and Environmental Control Systems (ECS) is a barrier to this goal, because it impacts the engine efficiency.

As passenger numbers increase around the world, efforts to reduce the environmental impact must move forward. This also extends to the impact of additional noise in and around airports and flight paths.

The future of aircraft design centres on the application of composite materials to reduce weight, performance and efficiency, while also improving cabin environmental conditions for passengers and reducing noise. Aircraft designers are increasingly considering larger electric systems instead of the traditional bleed air methods. In the process this is fundamentally changing the design architecture of modern aircraft.

4.2.2. Objectives

This programme supported the supply of an innovative, composite “scoop” ECS intake, qualified to a sufficient level to support flight trial activities. The intake was required to have integrated ice protection heaters, and acoustic attenuation technology.

SANDIT (Scoop and NACA Divergent Intake Trial) was a Clean Sky European-funded research and development programme which is part of the Systems for Green Operation (SGO) section of Clean Sky 1. The theme identification is JTI-CS-2011-3-SGO-04-004.

This programme is a direct follow-on from SIPAL (CS-GA-2009-255656-SLD_SCOOP), in which a small scoop air intake for an aircraft Environmental Control System (ECS) was designed and manufactured including electro-thermal ice protection and acoustic attenuation technology. The full-scale intake was manufactured and tested in the GKN Icing Wind Tunnel at its Luton facility, and was also subject to acoustic testing.

In SANDIT, the objective was to design, manufacture and qualify a flight trial demonstration intake assembly for flight trial use. This activity will enable flight validation of the overall electric ECS and the intake technology that supports it, with an overall aim of enabling more efficient aircraft systems.

GKN Aerospace Luton was the lead co-ordinating partner. The other partners in the programme were AeroTex UK LLP, EPM Technology Limited and Altair UK.

GKN and its partners possess a successful pedigree in intake design, coupled with a wealth of experience in complex structures. Coupled with the ECS intake design experience from the last programme, the consortium was very well positioned to optimise design solutions and provide the most appropriate design for icing and acoustic performance. Additionally the manufacturing techniques employed in the previous programme were to be optimised.

Key to programme success was evaluating material selection early to meet the harsh environmental requirements encountered by the scoop. Material selection directly affects ice protection efficiency, structural capability, weight and validation of system performance.

Component manufacture was to incorporate the novel technology approaches applied in the previous program including lessons learned. Within this partnership a wealth of experience exists in composite manufacture of complex structures to develop exploitable manufacturing technologies applicable to flight-standard parts.

As a supplier of electro thermal ice protection systems for a multitude of applications such as wing ice protection and engine intake systems, coupled with a significant pedigree of successful acoustically optimised nacelle application technology, GKN has a foundation in providing design solutions for key technologies that support bleed-less architectures. The scoop ECS divergent intake system is seen as a key step in providing all-electric aircraft ice protection systems to support a change in systems architecture for future generations of aircraft.

Project Results:
In the initial design and research phase, GKN used preliminary data to carry out trade studies of suitable materials and processes for the manufacture of the scoop intake. A combination of mechanical coupon testing (for tensile and compressive structural properties) and functional testing (thermal cycling to simulate IPS heating) was used to compare different composite materials. As part of this, the known baseline material was compared to more innovative proposals such as Out-Of-Autoclave (OoA) and Resin Transfer Moulding (RTM). These innovative solutions have the potential to reduce recurring costs in a rate manufacturing environment.

Additional materials used in the overall construction were selected from standard lists of already qualified materials in order to keep development costs down and focus resources in the key technology areas.

The topic manager supplied the aerodynamic geometry and detailed design requirements for the intake. In response, GKN produced a Statement of Work document; and a design review took place to detail all of the parameters that will determine the final design.

In this phase, work also took place to evaluate the mould tooling technology that would be used to produce the relatively small and highly complex intake geometry, and that would incorporate lessons learned from the previous programme. EPM Technology manufactured tooling for evaluation that included:
- Different tool materials (e.g. carbon fibre, aluminium)
- A novel “cast and melt-out” alloy tooling which allows closed geometries to be moulded
- Multi-piece tool assemblies to accommodate the complex part geometry

Using a set of agreed flight test design points covering all flight phases, and scoop CFD solutions provided by the topic manager, AeroTex used its suite of aircraft icing design software tools, together with results from previous icing wind tunnel testing to identify the number, location and intensity of ice protection heating zones necessary to provide efficient anti-ice protection of the scoop intake. A thermal analysis was then conducted to predict the temperatures that would occur within the composite structure of the scoop during operation of the Scoop IPS (SIPS).

Alongside the initial material and tooling selections, GKN evaluated a number of innovative technologies which could be used in the final design.

In an effort to reduce manufacturing cost for acoustic liners, GKN used its powder-bed Additive Manufacturing (AM) process to produce a net-shape acoustic liner sub-component which was already inclusive of the necessary honeycomb and perforate layers, removing the need for some of the autoclave processing, forming and machine drilling processes associated with standard acoustic panel technology.

A design was proposed for integration of the acoustic liner with the SIPS heating, so that acoustic panels could be applied to areas of the design which were also subject to icing. Currently on civil aircraft these functions have to be separated, but this technology allows designers to improve both the acoustic noise reduction and IPS performance by increasing the area available. GKN performed an initial thermal analysis and found that suitable operational temperatures could be reached using the hybrid system.

GKN also evaluated ‘sprayed on’ erosion protection, previously demonstrated on the previous wind tunnel test article. The potential advantages over conventional metal forming processes are:
- The ability to mould complex composite components which already have spray erosion protection, reducing the need for expensive tooling and leading to a vastly reduced costs.
- Removes the need for adhesive bonding of metal to composite, which can lead to shape distortion problems and is detrimental to thermal efficiency

The Preliminary Design Review (PDR) took place at the end of the initial design and research phase (September 2014), involving all partners and the topic manager. Following this, the consortium moved to address the key issues raised and mature all aspects of the design and manufacturing process for the scoop intake. This phase would be referred to as “Detailed Design and Analysis”.

Of primary importance was the clarification of design requirements, along with the envisaged means of validation and verification for the intake design and manufactured parts. The feedback from the SANDIT consortium during the PDR resulted in the topic manager releasing a revised design requirements document during this second phase of the programme. The Validation and Verification (V&V) matrix was updated accordingly.

Using the AeroTex Ice Protection design report from the initial design phase, GKN produced the detailed design of the electro-thermal SIPS heaters, including preliminary manufacturing drawings. Once other aspects of the design had been finalised (materials configuration and thickness changes), this information was provided to AeroTex in order to re-run its thermal models with the final design configuration. The positions of the temperature control sensors were then finalised, along with the temperature control limits needed as part of the overall tolerance stack.

GKN carried out the final down-selection of materials for the scoop intake. This included evaluation and selection of structural foam core materials, generating test data for adhesive, cohesive and dimensional stability under GKN process conditions. On the basis of this, a foam selection was made for the scoop intake, and machined foam core components were manufactured by EPM Technology.

Another key decision was the method to be used for erosion protection. Further development and testing of the GKN “sprayed” erosion shield technology included testing for adhesive strength and rain erosion. The results were encouraging for future applications, however further work was needed and there was not felt to be sufficient maturity for application to the scoop intake flight trial components.

The selection made for the scoop erosion protection was an electroformed nickel pre-formed component. This technology is well-suited to complex components where a high degree of shape accuracy is required, as was the case with the scoop intake geometry. GKN developed the bonding process for the nickel components to the composite scoop, informed by mechanical testing. High bond strengths were achieved, exceeding current baselines for Aluminium erosion shields on existing GKN products.

The innovative, additively manufactured and heated acoustic liner concept was further developed during this phase and was fully integrated with the scoop design and manufacturing process. This resulted in a process where the AM component can be assembled during the scoop composite lay-up; producing a part where the functioning acoustic liner is an integral part of the composite laminate without additional manufacturing steps. The flight test of the SANDIT intake will be the first flight of a GKN powder-bed AM component.

Further thermal modelling was used during this phase to assess the impact of different materials and configurations. A test specimen prototype was manufactured, and a lab test was carried out to verify the results of the thermal models (temperatures achieved by the heated acoustic liner).

A number of other trial demonstrator scoop heater mat components were produced in order to de-risk the overall manufacturing process. This work was underpinned by mould tooling manufactured by EPM Technology. A multi-piece mandrel tool was manufactured, which allowed the fully annular scoop to be extracted without additional component split lines.

One of the most significant challenges of the programme was the integration of the SANDIT scoop with the aircraft belly fairing panel on which it was mounted. The original panel is manufactured as a honeycomb sandwich panel with very thin aramid fibre skins, and had very little excess strength compared to its original design purpose. The initial design for the panel integration (produced by GKN), included a large cut-out in the panel sandwich section, through which the scoop intake was inserted. The scoop was attached to the inner face of the panel using a mechanically fastened interface. Additionally, the panel modifications were to include other interfaces required by the topic manager such as attachment points for the deflector flap and other Flight Test Instrumentation (FTI).

During the detailed design and analysis phase the first round of structural analysis was performed by Altair. This highlighted a potential failure of the modified belly fairing panel under the critical load case. In order to mitigate this issue a further design loop was completed between GKN, Altair and EPM Technology, in collaboration with the topic manager, who revised the loading requirements as they were found to be highly conservative. The new load requirements were satisfied by the addition of three carbon fibre stringers on the inside of the panel, and a thin carbon fibre doubler to reinforce the outer surface.

The design for lightning strike protection was produced using standard techniques (e.g. braided bonding straps).

The Critical Design Review (CDR) was held during October/November 2015 with the involvement of all SANDIT partners and the topic manager. The top-level installation drawings and associated design documentation was released to the topic manager and approved.

The final manufacturing phase was a sharing of work between mainly GKN and EPM Technology. GKN manufactured the scoop heater mat intake components. EPM Technology manufactured the belly fairing modifications and scoop outer casings, as well as the bifurcation section which forms the aerodynamic interface of the intake to the ECS system.

Additional support was received from the topic manager, who supplied certain standard parts and machined metallic components used in the final assembly process.

GKN carried out the final assembly process and functional component-level acceptance testing.

Two complete intake assemblies were manufactured. One unit had fully functional SIPS heaters and heated acoustic liners. The second unit was a hard-walled, structural part only (no SIPS heaters or acoustic liners).

Prior to delivery to the topic manager, GKN carried out environmental qualification tests on the primary unit, including shock and vibration testing. The tests were passed and both units were successfully delivered to the topic manager in time for the flight test activities.

Potential Impact:
The delivery of the SANDIT intakes to the topic manager will have the following main impacts:
• Enablement of the flight test of the electric Environmental Control System (ECS). The scoop intake is required to induct air into the system and in order to achieve the wider objectives of the flight test. The flight test programme itself is significant in terms of financial value, future exploitation and job creation across multiple EU states, businesses and the supply chain.
• Enablement of the electric ECS system as a key step toward a more electric aircraft architecture, reducing the need for engine bleed air and increasing the fuel efficiency of future aircraft designs with the associated positive environmental impacts. The aerodynamic coupling between the scoop intake and the ECS will be studied and understood, including the impact of the deflector flap. This will validate the sizing and geometry of the ECS system.
• Enables the collection of critical aerodynamic data through the inclusion of various flight test instrumentation relating to a part of the aircraft fuselage where there has been relatively little aerodynamic study. Analysis of the aerodynamic concentration effects will allow computational predictions to be more accurate in a streamlined design process. This in turn will enable more optimal designs to be produced as the confidence in computational models increases.
• Flight demonstration of an intake component with a high level of functional integration in a small space envelope. The technology and know-how developed is applicable to the wider intakes market and supports the trend for increased functionality of aerospace composite structures.
• The intake will demonstrate survival and operability in the harsh environmental conditions of flight, and also reduce noise on-ground, with the aim of meeting current and future regulatory requirements.
• The SANDIT demonstration will minimise barriers to the wider adoption of electro-thermal ice protection on new and derivative aircraft platforms, as an efficient alternative to bleed-air ice protection.
• Visibility of the technology to the wider aerospace community
The following internal and external dissemination activities have already been implemented or are planned:
• Display of the SANDIT intake in the GKN Luton customer display area, allowing discussion of the technology with current and potential customers
• Display of the SANDIT intake at industry events and trade shows (e.g. Farnborough)
• GKN press releases via the GKN online presence and via suitable industry publications
• GKN internal reporting of key technology developments to aid future exploitation on other programmes
• GKN group communication of project results via internal media (newsletter, etc.)
• Presentation at the SGO annual review events
• Presentation alongside the topic manager on flight test preparation and results at flight test feedback event

List of Websites:
Coordinator contact details:
Mr. Ashley Brooks
Project Engineer
Percival Way, London Luton Airport, LU2 9PQ
[phone]
[e-mail]

Participating members

Richard Moser
Aircraft Icing Consultant
[phone]
[e-mail]

Trajan Seymour
Head of Engineering
[phone]
[e-mail]

Richard Boyd
Technical Specialist
[phone]
[e-mail]

Related documents

• final1-dev9101-sandit-final-report-publishable-summary-form.pdf
• final1-dev9101-sandit-final-report-publishable-summary-covering-document.pdf