Cyient’s senior vice-president - aerospace & defence, Anand Parameswaran and head of aerospace and defence, EMEA, Ian Thompson discuss the evolution of aircraft wings and the innovations that create significant improvements in aerodynamic performance.
The composite materials used in the latest models fresh off Airbus and Boeing’s production lines have come a long way from the simple wooden and fabric twin-wing set up of the Wright brothers’ Flyer. The first ever flight, completed by Orville Wright in 1903, lasted a mere 12 seconds and travelled just 120ft – under the wing span of today’s Boeing 747.
The four primary forces acting on an aircraft are thrust, drag, lift and weight. In today’s aerospace ecosystem, OEMs are focusing on reducing drag and weight across all components with a view to improving performance and efficiency. The basic aerofoil shapes – designed by NASA (and its predecessor NACA) in the 1930s and necessary for generating lift – may not have undergone much recognisable change, but manufacturing processes and materials used have seen huge advances.
Efficiency is a top priority for all airline executives. For airlines to continue increasing profit margins, driving cost efficiencies in both aircraft production and operations is essential, especially in the face of an increasingly mobile customer base demanding cheaper flights. As airline operators turn up the heat on suppliers to deliver more efficient aircraft, OEMs are looking to technology to refine wing design and manufacture, improve aerodynamics and reduce component weight.
Lightening the load
Increasing fuel efficiency is at the core of potential cost savings for operators. The drag of the aircraft is approximately proportional to the amount of fuel burned during the flight. Higher drag equates to more fuel burned, which translates to increased costs for operators. Considering this, designers and manufacturers across the supply chain have centred on the idea of reducing drag in wing design. Aerodynamics and weight are the two main factors at play here. Decreasing weight reduces the lifting force required, and more efficient aerodynamics means less fuel and force is needed to move the plane through the air.
The weight of aircraft wings has been significantly reduced since the introduction of advanced composite materials, superseding the predominantly aluminium structures that had dominated since the 1960s. Additionally, using composites (a combination of several components) has the added benefit of being adaptable to specific design loads, strengths and tensions for varying wing and aircraft models. The recent addition of nanomaterials applied to composites during the manufacturing process has improved this further, as they can make composites even more tailored to specific job functions in the wing. For example, integrating electrical conductive nanoparticles with structural components that are able to protect against lightning strikes, or improving the damage resistance of the outer wing laminate by incorporating high-strength nanoparticles.
The dawn of additive manufacturing (AM) has enabled another key technological advancement: the application of rapid prototyping. Major weight and aerodynamics savings can be achieved thanks to the development of advanced computing, analysis and design techniques that can quickly evaluate how effective a prototype is. AM enables designers to experiment with innovative concepts, that can then be quickly assessed and adapted as necessary. These designs can be perfected at minimal cost in prototype form before being rolled out on a mass scale. These developments are all aimed at manufacturing lighter wing components, with more aerodynamic structures, at lower production costs. These innovations are enabling major fuel and costs savings, that can be passed on to airline operators.
Integrating structural innovations
Technology is also having a secondary effect on the design of aircraft wings, as they increasingly need to support and host new hardware for structural health monitoring purposes. Sensors that monitor key performance parameters during flights are being embedded into the finely tuned wing structure design and production; with additional allowances being made for the physical space they take up and added weight they bring. This is an area where there are still significant improvements to be made. OEMs are turning to AM and rapid prototyping to solve this, refining the product to optimise dimensions and integrate the new technology without compromising the highly-tuned wing structure. Having worked closely with a number of OEMs and tier 1 suppliers over the past decades, we have been driving this technological development and weight reduction.
Recent design innovations at the wingtips have also seen significant improvements in the aircraft’s aerodynamic performance. Raked wingtips (used mostly on Boeing models) or winglets (used mainly on Airbus models), lessen the effects of the ‘wake’ – the swirling vortex of air left behind the wing as it passes through the air at high speed. These are normally fixed at the tip of wings and consist of small upward-pointing extensions. The aircraft’s passage is rendered smoother and more efficient by reducing air disturbance. The overall effect of the wingtips is essentially the same as drastically increasing the wingspan of the aircraft, minus the added weight. Applied to new aircraft design and even retrofitted to old models, these alterations at the wingtip have driven significant drag and fuel efficiencies. For example, when Boeing applied them to the 767 aircraft the rate of fuel burn was improved by 4-5%, saving 500,000 US gallons of jet fuel and 4,790 tonnes of CO2 per plane per year.
The aircraft wing has undergone a dramatic transformation since the Wright Brothers’ first flight in 1903. The top priority for OEMs in today’s marketplace is utilising innovative technologies and designs to improve aerodynamic performance and reduce the weight of wing structure components. If this can be achieved, airlines will see the benefits of huge fuel efficiencies and tangible cost savings.
