Flying efficiency – Bristol Composites Institute Blog

One of the larger activities currently happening at the Bristol Composites Institute is CerTest. This EPSRC (UK Engineering and Physical Sciences Research Council) Programme Grant, with £6.9million of funding, started in July 2019 and will run for 5 years.

CerTest is led by Bristol Composites Institute Co-director, Professor Ole Thomsen at the University of Bristol, with academic collaboration partners at the University of Bath, University of Exeter, and University of Southampton.

The aim of the research in this multidisciplinary project is to develop new approaches to enable lighter, more cost and fuel-efficient composite aero-structures. This vision will be realised through four flexible but highly interlinked research challenges:

Multi Scale Performance Modelling
Features and Damage Characterisation
Data-rich High Fidelity Structural Characterisation
Integration and Methodology Validation

The four research challenges will result in a new approach for integrated high-fidelity structural testing and multi-scale statistical modelling through Design of Experiments (DoE) and Bayesian Learning.

The efficient exploitation and optimisation of advanced composite aero-structures is fundamentally prohibited by current test, simulation and certification approaches, and CerTest seeks to break this impasse by holistically addressing the challenges that are preventing step-changes in future engineering design by reshaping the ‘Testing Pyramid’.

The CerTest project is supported by seven key industry partners who provide important steer and valuable market insight along with several funded studentships. Airbus, Rolls Royce, BAE Systems, GKN Aerospace, NCC, the Alan Turing Institute, and CFMS meet with the CerTest team at least twice a year and are keen to see the research succeed.

The project is further supported by an Independent Advisory Board of experts from international and UK based academia, industry and regulators that provide further guidance and support to ensuring CerTest reaches its full potential and realises its goals and objectives.

This is one of the largest collaborations the Bristol Composites Institute has ever undertaken, and a lot of groundwork has gone into supporting the collaboration, flow and sharing of data between the partners. The current CerTest team has 37 members and counting.

group of co-workers standing in front of a building — The CerTest team at an internal meeting held at the National Composites Centre.

Further information

For more information and updates, visit the CerTest website.

We interviewed the lead investigator of the SABRE project, Dr. Benjamin Woods.

What is the SABRE project?

SABRE stands for ‘Shape Adaptive Blades for Rotorcraft Efficiency’. The four-year, €6 million, EU-funded project brings together a consortium of six research institutions from across Europe to develop ground-breaking new helicopter blade designs capable of changing shape in real-time to reduce noise, fuel burn and CO2 emissions.

Can you tell us what motivated this work?

In a word, sustainability. Reducing emissions from current flying technology is imperative if we want a credible chance to tackle climate change, hence developing new technologies that are more efficient and drastically reduce fuel burn is key to becoming more sustainable.

How are you proposing to achieve better flying efficiency for helicopters?

yellow helicopter on the ground

Current designs for helicopter blades are rife with inefficiency. The problem with helicopters is that blades will experience cyclic changes in airflow as they rotate. These differences in airflow velocity are detrimental to the performance of the rotor. This is a well-known issue and current rotor designs can change the overall pitch (orientation) of each blade as it spins around the helicopter to partially mitigate this issue. Unfortunately, the pitching solution is not ideal as it pitches the whole blade.

Instead, we are proposing to develop different morphing concepts that will enable us to quickly and accurately control the shape of each blade and hence the airflow, during each rotation.

What are these morphing concepts?

There are many key design parameters that should be considered when creating rotor blades. For example, you should ask ‘how much curvature is there in the aerofoil?’, ‘how does the length of the aerofoils vary over the blade?’, ‘how much twist is there in the blade?’. These are the types of features that engineers play with to optimise rotorcraft performance, with compromises being required due to the wide range of operating conditions. Those are the things that we would love to be able to change – but in real-time – to allow us to fully respond to the different operating conditions without the need to compromise. We are looking at exactly those factors.

Six promising morphing blade concepts are being investigated. Two concepts can actively change the blade twist. Another two can actively change the aerofoil curvature (camber). One concept can increase the length of the aerofoil, and the last concept can alter the blade dynamic response.

Active camber, active chord, active tendons. active twist, and negative stiffness passive energy balancing. — Morphing concepts investigated by SABRE

What have you found out so far?

Using one concept at a time resulted in a fuel burn reduction of up to 5%, but when we looked at multiple concepts in different parts of each blade to attack different elements of physics, that’s when we saw significant reductions of up to 11%. There is certainly scope for further reductions, and with the right combination of technologies, fuel burn could be reduced by as much as 20%.

What are your next steps?

It will be a while before this technology becomes mainstream. Development times of up to 30 years are “completely standard” for novel technologies in civil aerospace because the safety requirements are so rigorous. However, SABRE’s research could have applications elsewhere – more specifically, with renewable wind energy. This will likely be part of my next investigation.

Find out more

For more information, visit the SABRE Project website.

Tag: Flying efficiency

CerTest – Certification for Design: Reshaping the Testing Pyramid