Development of Validation Tools for Carrier Simulations for use in Fixed-Wing and Rotary-Wing Flight Simulation
Lead Research Organisation:
University of Liverpool
Department Name: School of Engineering
Abstract
Operating aircraft to/from ships is a demanding task for both the pilot and aircraft, particularly in the launch and recovery phases. This is true for both fixed-wing and rotary-wing aircraft alike where, compared to land-based operations, the ship's flight deck is small and is constantly moving in roll, pitch and heave. In addition, the air flow behind the ship's superstructure and over the flight deck is highly turbulent and contains vortices and shear layers which buffet the aircraft as the pilot manoeuvres over the moving deck and in close proximity to the ship's superstructure. This turbulent flow, also known as the 'airwake', can adversely affect aircraft performance, and will disturb the aircraft's flight path, requiring immediate corrective action from the pilot. Consequently, pilot workload can be high and the margins for error small, so directly affecting the safe operational envelope of the aircraft/ship combination. A reasonably new phenomenon, observed during shipboard testing of aircraft with highly-augmented digital Flight Control Systems, has been the undesirable impact of airwake on the response of the aircraft's Air Data Systems. Therefore, even advanced aircraft with generally low pilot workload are not immune to the effects of airwake. In this project the aircraft of interest is the STOVL F35B Lightning II which is coming into service with the Royal Navy, and the ship is the Queen Elizabeth Class aircraft carrier.
The Heliflight-R motion-base flight simulator at the University of Liverpool is at the cutting edge of flight technology research in academia. The primary modelling and simulation package used to develop flight models for the simulator is Advanced Rotorcraft Technology's FLIGHTLAB software. Flight mechanics models of both maritime rotorcraft and generic fixed-wing STOVL (short take-off & vertical landing) aircraft are integrated into an immersive flight simulation environment that allows the pilot to fly the aircraft to and from the ship. An essential component of the simulation environment is the air flow over the ship and this is created using advanced Computational Fluid Dynamics (CFD); the quality of the airwake modelling and its subsequent integration into the simulation environment is the key driver for this project. The research carried out at the University of Liverpool will support the F35/QEC flight simulation facility at BAE Systems Warton.
Project Outcomes: The overall aim of the project will be to understand how simulation and flight test can be combined optimally by:
1. Providing validation of existing unsteady airwake models using both laboratory-scale flow measurements and/or real-world data measured from the ship at-sea, during industry led Air-Flow Air-Pattern (AFAP) trials. The research will help to direct and specify the measurements taken during these at-sea trials and will use the resulting data to validate and refine existing airwake simulations.
2. Developing tools and techniques to enhance airwake model validation by using novel methods to identify and track significant features in the measured datasets and match those to features in the modelled flow.
3. Developing novel methods of integrating the ship airwake models with a range of air vehicle models (manned or unmanned/fixed or rotary-wing). This will involve the application of novel compression techniques, to reduce the size of the airwake datasets while ensuring maintenance of data fidelity, and advanced data storage, access and real-time look-up techniques.
The Heliflight-R motion-base flight simulator at the University of Liverpool is at the cutting edge of flight technology research in academia. The primary modelling and simulation package used to develop flight models for the simulator is Advanced Rotorcraft Technology's FLIGHTLAB software. Flight mechanics models of both maritime rotorcraft and generic fixed-wing STOVL (short take-off & vertical landing) aircraft are integrated into an immersive flight simulation environment that allows the pilot to fly the aircraft to and from the ship. An essential component of the simulation environment is the air flow over the ship and this is created using advanced Computational Fluid Dynamics (CFD); the quality of the airwake modelling and its subsequent integration into the simulation environment is the key driver for this project. The research carried out at the University of Liverpool will support the F35/QEC flight simulation facility at BAE Systems Warton.
Project Outcomes: The overall aim of the project will be to understand how simulation and flight test can be combined optimally by:
1. Providing validation of existing unsteady airwake models using both laboratory-scale flow measurements and/or real-world data measured from the ship at-sea, during industry led Air-Flow Air-Pattern (AFAP) trials. The research will help to direct and specify the measurements taken during these at-sea trials and will use the resulting data to validate and refine existing airwake simulations.
2. Developing tools and techniques to enhance airwake model validation by using novel methods to identify and track significant features in the measured datasets and match those to features in the modelled flow.
3. Developing novel methods of integrating the ship airwake models with a range of air vehicle models (manned or unmanned/fixed or rotary-wing). This will involve the application of novel compression techniques, to reduce the size of the airwake datasets while ensuring maintenance of data fidelity, and advanced data storage, access and real-time look-up techniques.
People |
ORCID iD |
| Mark White (Primary Supervisor) | |
| Neale Watson (Student) |
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/P510567/1 | 01/10/2016 | 30/09/2021 | |||
| 1794920 | Studentship | EP/P510567/1 | 01/10/2016 | 31/03/2021 | Neale Watson |
| Description | This work has performed an extensive experimental and computational study of the air flow over the UK Royal Navy's Queen Elizabeth Class (QEC) aircraft carriers, including how the air flow will affect aircraft flying operations, particularly rotorcraft. Maritime fixed- and rotary-wing aircraft routinely perform launch and recovery manoeuvres to and from ships at sea, often in challenging environmental conditions. Pilots performing such manoeuvres must contend with ship motion, sea spray, and an unsteady airwake generated by the air flow shedding off the ship's superstructure. The main aim of the research was to investigate the use of modelling and simulation to improve understanding of the flying environment over the flight deck of the QEC. The unsteady air flow over the QEC was created using Computational Fluid Dynamics (CFD) and incorporated into flight simulators at the University of Liverpool (UoL) and at BAE Systems, Warton. Experimental data to confirm the validity of the computed air flow was obtained from a small-scale experiment in which a 1.4 m long (1:200) scale model of the QEC was submerged in a water channel and Acoustic Doppler Velocimetry (ADV) was used to measure the unsteady flow around the ship. The results show generally very good agreement between the model-scale experiment and CFD. Piloted flight simulation trials were conducted using the UoL's HELIFLIGHT-R full-motion flight simulator in which a test pilot conducted simulated deck landings of a representative Sikorsky SH-60B Seahawk helicopter to the flight deck of the QEC under a range of wind conditions. Results for aircraft performance and pilot workload were obtained. These trials demonstrated how flight simulation could be used to support flight trials and helicopter clearance activities, but also notes that real-world trials data are needed to compare with the simulations before the techniques can be beneficially deployed. A non-piloted simulation technique was also deployed in which the unsteady forces and moments imposed by the air flow onto the helicopter fuselage were quantified; the results were correlated with the pilot workload ratings from the piloted simulation trials. The results have demonstrated how modelling and simulation can be effectively used to inform real-world flight trials. The simulations reaffirmed how important it is that helicopter flight models respond to the very different velocity components that are imposed on different parts of the aircraft by the highly unsteady three-dimensional air flow. Fixed-wing flight models, however, are not typically designed to capture the unsteady moments created during hover in a highly turbulent flow at low speeds. A new aerodynamic model of a fixed-wing aircraft has been developed which uses strip theory to create the overall forces and moments acting on the aircraft when hovering in a ship airwake. The results show the effect of the QEC airwakes on a hovering fixed-wing aircraft and provide recommendations for the number of strips required to accurately capture the effect of the flow. |
| Exploitation Route | The outcomes of this funding are already being used in industrial applications. The methods used and validated in this work have been implemented in the piloted flight simulation of the F-35B with the HMS Queen Elizabeth by BAE Systems to aid in the integration of both platforms prior to flight trials at sea. Other airwake analysis tools developed as part of this funding are also currently being used to aid design of several military frigates across the world. The method of experimental flow measurement developed as part of this work is currently being used for UK MOD to identify flow features over the flight deck of HMS Queen Elizabeth. The Virtual Airdyn is currently being used by industry to assess the effect of unsteady airwakes on the helicopters operating to ships. The funding outcomes has opened new avenues of further research into the modelling and simulation of the ship-air interface using CFD, particularly, the effect of the inlet conditions/position of the hangar lifts and flight deck obstacles on the flow field over the aircraft carrier. Other identified areas of research that may be taken forward by others is the development of an STOVL model for piloted flight simulation to determine the effect of the ship's airwake on fixed wing aircraft. |
| Sectors | Aerospace, Defence and Marine |
| Description | The findings in this work have been used by BAE Systems to develop the modelling and simulation of the launch and recovery of the F-35B ship-borne aircraft to HMS Queen Elizabeth in preparing for First of Class Flight Trials, the first time this had ever been done, increasing the economic competitiveness of the United Kingdom. |
| First Year Of Impact | 2016 |
| Description | Presentation of work aboard the aircraft carrier HMS Prince of Wales |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Industry/Business |
| Results and Impact | Invited aboard HMS Prince of Wales to present my research which aided the intergation of aircraft with the ship itself. |
| Year(s) Of Engagement Activity | 2020 |
| Description | UK Parliament STEM For Britain Event, |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Policymakers/politicians |
| Results and Impact | Poster presentation of work to UK MPs in Portcullis House |
| Year(s) Of Engagement Activity | 2020 |
| URL | https://stemforbritain.org.uk/ |