Final Report Summary - NLFFD (NLF Starboard Leading Edge & Top cover design & manufacturing Trials)
Executive Summary:
The NLFFD program is an ongoing area of research aimed at developing the capability and understanding of Natural Laminar Flow (NLF) for the next generation of civil aircraft. It is undertaken in support of the Smart Fixed Wing Aircraft (SFWA) program to mature a NLF technology stream for a future short range transport aircraft and is intended to support the TRL process by the design, manufacture, test and demonstration of an integrated NLF wing leading edge assembly, as a flight test demonstrator
The NLF aerofoil coupled with improved aero-smoothness, offers higher efficiencies in aerodynamic performance and a reduction in drag, contributing to an overall increase in an aircraft’s efficiency. This in turn allows for potential reductions in aircraft emissions by reducing fuel burn. Achieving these reductions would be a significant step towards reaching the ACARE goals for 2020, including a 50% reduction in CO2 emissions and an 80% reduction in NO emissions.
The requirements of a NLF wing differ significantly from a conventional turbulent wing, requiring changes to the architecture of the wing, the aerofoil definition, the detailed design concepts and manufacturing processes. The aerodynamic performance of a natural laminar flow wing is highly dependent on meeting very high aero-smoothness tolerances including steps and gaps, surface roughness and surface waviness tolerances, in the regions where laminar flow is to be maintained.
Project Context and Objectives:
The Natural Laminar Flow (NLF) aerofoil is considered to be one of the key technologies to reduce drag and improve the performance of an aircraft, therefore reducing emissions. The NLF wing is recognized as a potential key technology for the next generation of aircraft.
The requirements of a NLF wing differ significantly from a conventional turbulent wing, requiring changes to both the architecture of the wing, the aerofoil definition and the detailed design and manufacturing concepts. The performance of a NLF wing requires very tight surface roughness and waviness tolerances and contamination free surfaces in the areas where laminar flow is to be maintained. This work package aims to meet these target tolerances, providing validation data on their manufacturing achievability. NLF wings also require alternative Leading Edge (LE) moveable concepts, novel LE/Wingbox joints, and slender LE sections. This proposal is for the design and manufacture of the starboard LE and Top Cover for a NLF wing flight demonstrator, including A-scheme maturity work. The baseline is a metallic LE and composite Top Cover. The LE and Top Cover will be joined to a wingbox (outside of scope) and attached to the flight test demonstrator. This will be an A340 with the outer third of the starboard wing (from Rib 28 to wingtip) replaced as shown below. The design will be capable of accommodating a Krueger flap (out of scope) support structure in the deployed position. The demonstrator aims to validate that a jointed wing concept (leading edge + Top Cover) can be designed and subsequently manufactured (via a separate call) in realistic and repeatable conditions appropriate to a civil short range aircraft to the required level of aerodynamic surface quality to achieve laminar flow.
In Phase 1 of the Clean Sky Ground Based Structural Sytems Demonstrator programme
(GBSSD), the problem of how to achieve an aerodynamic surface of sufficient quality to support natural laminar flow has been addressed by GKN. In particular a number of mechanical joint concepts have been evaluated against a set of high tolerance criteria including steps and gaps, surface finish, aerofoil profile, waviness and fastening techniques.
In Phase 2 of the GBSSD (GKN bid accepted by Clean Sky) work on the LE will be focused into five specific development activities:
• Innovative LE ribs and Integrated LE/Cover design schemes
• Integration of Krueger flap kinematic solution into the D-Nose
• Continued Investigations on potential Wing Ice Protection (WIPS) solutions
• Lightning Strike protection for the LE zone.
• Innovative concepts addressing Bird strike requirements in the presence of a Krueger
Flap System.
This work will provide GKN with further experience of Leading Edge architecture and lead to better understanding of the risk involved, particularly with regard to the challenges specific to narrower LE profiles and accommodation of a Krueger actuation mechanism.
For this call, the Flight demonstrator, GKN will employ existing LE and Cover design and manufacture capability employed with Airbus, along with composite materials and advanced manufacturing techniques to provide the step change in technology required to meet the challenging aerodynamic performance, weight and cost criteria for the next generation of large civil aircraft fitted with advanced NLF wings. Figures 4 and 5 below give an overview of the baseline assumptions on which the costing of this description of work is based.
Baseline Work Package consists of the following components (Starboard Wing Only)
• Top Cover similar in size to A340 Panel No 4 Top – Composite
• Co cured Stringers to enable required stiffness of Top Cover – Composite
• Co cured Rib Feet and Spar Cap to attach Top Cover Assembly to wingbox –
Composite
• Leading Edge Ribs – Metallic
• D Nose (Leading Edge Skins) – Metallic
• Joint and Attachment brackets for above – metallic
• Corner and crown tension fittings for attachment to Transition Structure
Project Results:
Five substantial engineering reports have been issued with the results of NLFFD:
1. WP1 Development Lessons Learnt
2. Manufacturing Spring Assessment
3. A-Scheme Drawing Set
4. B-Scheme Drawing Set
5. Stress Development
Potential Impact:
The manufacture, flight test, and certification of a Composite Natural Laminar Flow Wing marks two important milestones. Firstly it would indicate that the advantages posed by composite materials are being fully exploited and allow for the next generation of wing design to fly. Secondly it would significantly contribute to the reduction in fuel consumption and CO2 emissions.
List of Websites:
www.gkn.com
The NLFFD program is an ongoing area of research aimed at developing the capability and understanding of Natural Laminar Flow (NLF) for the next generation of civil aircraft. It is undertaken in support of the Smart Fixed Wing Aircraft (SFWA) program to mature a NLF technology stream for a future short range transport aircraft and is intended to support the TRL process by the design, manufacture, test and demonstration of an integrated NLF wing leading edge assembly, as a flight test demonstrator
The NLF aerofoil coupled with improved aero-smoothness, offers higher efficiencies in aerodynamic performance and a reduction in drag, contributing to an overall increase in an aircraft’s efficiency. This in turn allows for potential reductions in aircraft emissions by reducing fuel burn. Achieving these reductions would be a significant step towards reaching the ACARE goals for 2020, including a 50% reduction in CO2 emissions and an 80% reduction in NO emissions.
The requirements of a NLF wing differ significantly from a conventional turbulent wing, requiring changes to the architecture of the wing, the aerofoil definition, the detailed design concepts and manufacturing processes. The aerodynamic performance of a natural laminar flow wing is highly dependent on meeting very high aero-smoothness tolerances including steps and gaps, surface roughness and surface waviness tolerances, in the regions where laminar flow is to be maintained.
Project Context and Objectives:
The Natural Laminar Flow (NLF) aerofoil is considered to be one of the key technologies to reduce drag and improve the performance of an aircraft, therefore reducing emissions. The NLF wing is recognized as a potential key technology for the next generation of aircraft.
The requirements of a NLF wing differ significantly from a conventional turbulent wing, requiring changes to both the architecture of the wing, the aerofoil definition and the detailed design and manufacturing concepts. The performance of a NLF wing requires very tight surface roughness and waviness tolerances and contamination free surfaces in the areas where laminar flow is to be maintained. This work package aims to meet these target tolerances, providing validation data on their manufacturing achievability. NLF wings also require alternative Leading Edge (LE) moveable concepts, novel LE/Wingbox joints, and slender LE sections. This proposal is for the design and manufacture of the starboard LE and Top Cover for a NLF wing flight demonstrator, including A-scheme maturity work. The baseline is a metallic LE and composite Top Cover. The LE and Top Cover will be joined to a wingbox (outside of scope) and attached to the flight test demonstrator. This will be an A340 with the outer third of the starboard wing (from Rib 28 to wingtip) replaced as shown below. The design will be capable of accommodating a Krueger flap (out of scope) support structure in the deployed position. The demonstrator aims to validate that a jointed wing concept (leading edge + Top Cover) can be designed and subsequently manufactured (via a separate call) in realistic and repeatable conditions appropriate to a civil short range aircraft to the required level of aerodynamic surface quality to achieve laminar flow.
In Phase 1 of the Clean Sky Ground Based Structural Sytems Demonstrator programme
(GBSSD), the problem of how to achieve an aerodynamic surface of sufficient quality to support natural laminar flow has been addressed by GKN. In particular a number of mechanical joint concepts have been evaluated against a set of high tolerance criteria including steps and gaps, surface finish, aerofoil profile, waviness and fastening techniques.
In Phase 2 of the GBSSD (GKN bid accepted by Clean Sky) work on the LE will be focused into five specific development activities:
• Innovative LE ribs and Integrated LE/Cover design schemes
• Integration of Krueger flap kinematic solution into the D-Nose
• Continued Investigations on potential Wing Ice Protection (WIPS) solutions
• Lightning Strike protection for the LE zone.
• Innovative concepts addressing Bird strike requirements in the presence of a Krueger
Flap System.
This work will provide GKN with further experience of Leading Edge architecture and lead to better understanding of the risk involved, particularly with regard to the challenges specific to narrower LE profiles and accommodation of a Krueger actuation mechanism.
For this call, the Flight demonstrator, GKN will employ existing LE and Cover design and manufacture capability employed with Airbus, along with composite materials and advanced manufacturing techniques to provide the step change in technology required to meet the challenging aerodynamic performance, weight and cost criteria for the next generation of large civil aircraft fitted with advanced NLF wings. Figures 4 and 5 below give an overview of the baseline assumptions on which the costing of this description of work is based.
Baseline Work Package consists of the following components (Starboard Wing Only)
• Top Cover similar in size to A340 Panel No 4 Top – Composite
• Co cured Stringers to enable required stiffness of Top Cover – Composite
• Co cured Rib Feet and Spar Cap to attach Top Cover Assembly to wingbox –
Composite
• Leading Edge Ribs – Metallic
• D Nose (Leading Edge Skins) – Metallic
• Joint and Attachment brackets for above – metallic
• Corner and crown tension fittings for attachment to Transition Structure
Project Results:
Five substantial engineering reports have been issued with the results of NLFFD:
1. WP1 Development Lessons Learnt
2. Manufacturing Spring Assessment
3. A-Scheme Drawing Set
4. B-Scheme Drawing Set
5. Stress Development
Potential Impact:
The manufacture, flight test, and certification of a Composite Natural Laminar Flow Wing marks two important milestones. Firstly it would indicate that the advantages posed by composite materials are being fully exploited and allow for the next generation of wing design to fly. Secondly it would significantly contribute to the reduction in fuel consumption and CO2 emissions.
List of Websites:
www.gkn.com