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A glimpse of future flight

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Antenna has been finding out more about some of the most promising technologies scientists and engineers are working on to reduce the impact of aviation on climate change. From greener fuels to more aerodynamic shapes, there are many different ideas being developed to help planes cut emissions.

Every kilo counts

Removing weight from planes is a sure-fire way to cut fuel burn and emissions by reducing the amount of energy needed to propel planes through the sky. Planes are traditionally made from metal - a material that's strong but relatively heavy. In recent years, engineers have developed 'composite' materials that deliver maximum strength for minimum weight by embedding minuscule carbon fibres in plastic. Carbon fibre composites are used to provide strength and save weight for lots of different applications, including sports equipment such as tennis rackets.

Removing your view? Image: Ilja Klutman

Another way engineers are taking the pounds off is by manufacturing aircraft fuselages in larger pieces. A technique called friction stir welding allows engineers to join pieces of metal together into one sheet without rivets or fasteners, which some experts think can make the plane slightly lighter and more aerodynamic.

As every kilogram matters, the latest planes have even swapped copper wiring for lightweight fibre optics in a bid to save as much weight as possible. There's even talk of removing windows and replacing them with much lighter 'virtual windows' - flat television screens showing a view of the outside world.

Morphing materials and radical designs

Watching a plane's weight isn't the only thing to help planes reduce emissions. As planes speed through the skies, they meet a lot of air resistance. By making the plane as smooth as possible - by removing external mechanisms such as hinges that move wing flaps - friction is reduced and less fuel is burned.

Scientists are developing 'morphing materials' that would allow the wing shape to be adjusted by applying electric voltage instead of conventional mechanical hinges.

Blended-wing body plane. Image: The Silent Aircraft Initiative

'We're investigating methods of tailoring the wing throughout different stages of flight - to control how much lift is produced, and reduce drag,' says Peter Giddings, a materials expert at the University of Bath.

Applying an electric voltage to special ceramic fibres within carbon fibre can snap the material between two different configurations to change the curvature of the wing.

Other scientists are looking at radical plane designs to beat air resistance. Engineers from Cambridge University, Massachusetts Institute of Technology (MIT) and the aviation industry are working on the Silent Aircraft Initiative. Their current concept is a 'blended-wing body'. Its broad fuselage maximises lift and minimises drag, significantly improving the aerodynamics of the aircraft.

'The aim of the project was originally to come up with a concept design for a "silent" plane, but in doing so, we also found that the design is up to 25% more fuel efficient,' says Ann Dowling from the University of Cambridge.

Reducing resistance

This infrared image shows friction on a test wing as heat - where the rough texture has been applied on the right, there is less friction and the wing appears darker. Image: Texas A&M University

Another way scientists are looking at reducing air resistance is by altering the wings. While today's airliners usually have swept-back wings, future planes could have wings that point forwards slightly, reducing the flow of turbulent air to make it smoother, or 'laminar'.

'Natural laminar flow' wings could then be covered in a rough texture or nanotechnology 'skin' -similar to shark skin - that would reduce air turbulence even more. This concept could further reduce drag and in doing so would save on fuel and cut emissions.

And it's not the only idea in the pipeline. Engineers are also trying to actively reduce the amount of turbulent air over the wings to achieve 'hybrid laminar flow'. One concept is a system that continuously sucks air through small holes in the surface near the front of the wing and feeds it downstream. However, this suction system still requires extra energy and incurs cost and weight, so engineers are still trying to make it worthwhile. Another idea is making a thin plastic 'skin' for the aircraft that produces an electric current. This would make tiny bumps on the plane's surface that help control airflow.