BBC Future

Edge-of-space planes to free-up congested skies

About the author

Will Whitehorn is the former president of Virgin Galactic and a Fellow of the Royal Aerospace Society.

  • No fly zones?
    As air travel increases and more and more freight is moved by planes, the world’s flight paths come under increasing pressure. (Copyright: Getty Images)
  • Humble beginnings
    In the 1930s, a transatlantic flight cost the equivalent of $90,000; now we can cross the ocean for a few hundred dollars. (Copyright: Getty Images)
  • Jumbo giants
    The pressure for more seats has led plane makers to build giants like the Airbus A380, using carbon fibres and new engine technology to boost efficiency. (Copyright: Getty Images)
  • High-flying concept
    The Skylon is two aircraft in one; one which can fly at the edge of space using a reaction engine, and like a normal airliner in the atmosphere. (Copyright: Skylon)
  • Blended wings
    Future airliners, like this concept from Boeing, will blend wings into fuselages to create more lift – meaning planes may be able to fly much higher. (Copyright: Nasa/Thinkstock)
  • Edge of space
    Virgin Galactic tested a vehicle which could fly at the upper reaches of the atmosphere – an idea which could take long-haul travel out of this world. (Copyright: Virgin Galactic)
  • Winds of change
    The need for greener energy has led to massive windfarms; but the spinning blades can confuse radar systems, putting pressure on some flight paths. (Copyright: Getty Images)
  • Worker drones
    Drones are already being used for military and surveillance tasks, but could they also be used to do agricultural work such as spraying crops? (Copyright: AFP/Getty Images)
More and more aircraft have to share airspace, and this will only get worse as our cities grow. In the next part of our Building Tomorrow series, former Virgin Galactic president Will Whitehorn says we have to rethink everything from how high we fly to how air traffic is managed.

Making predictions about the future of aviation is dangerous; after all so many have got it wrong before. Few in aviation’s golden age could have foreseen how cheap flying would become; in 1939 a trans-Atlantic airline ticket cost up to $90,000 in today’s money and nobody predicted the transatlantic passenger liner would ever be replaced. Airships were supposed to be the way of the future, not aircraft.

Experts believed the aviation industry would die because of environmental concerns and falling passenger numbers. But despite these concerns it has not collapsed. In some sectors, business and leisure travel are booming. Airports are getting busier, even in a Europe grappling with downturn and austerity. All the major regions are improving and we are seeing real growth in Africa for the first time, with new African carriers appearing. New generations of aircraft like the Boeing 787 and the Airbus A380 are far more efficient than older aircraft – 70% more fuel-efficient than aircraft of 40 years ago, according to the International Air Transport Association (IATA). Transport’s impact on the environment is lessening, and nowhere will the impact be greater than in aviation.

By the year 2050, the world’s population may have risen to 10 billion, with 75% of them living in cities. These cities will be ever-more connected by air, dependant on the movement of people and goods between them. It is too late to turn our backs on air travel, so how do we make it more efficient, and stop the skies becoming completely congested?

New materials and new engine technology will continue to make aviation more efficient. Plane designs will make more use of carbon composites and, in the future, carbon nanofibres. Air traffic control and airport management will also be revolutionised as digital technology makes aircraft easier to manage. This could result in long-haul travel which is markedly more efficient. Lighter aircraft can be bigger and carry more freight and passengers.

New fuels

In years to come they can be flown remotely, too. In the case of freighters, this means no crew – so there is an extra weight saving by getting rid of the life support systems and the windows. Passenger aircraft might not be remotely flown – we will still feel safer with a human in the cockpit – but automated air traffic could double the capacity of the flight paths around the world and only airport capacity would constrain us. The stuff of science fiction? Not exactly. British Aerospace flew an aircraft remotely to Inverness in Scotland this summer in a Civil Aviation Authority-supported experiment. Allowing UAVs to monitor and spray crops is already regulated and sanctioned in both North and South America.

Another will be the fuel itself. The best bio fuel for aviation is probably butanol, an alcohol which behaves very like the kerosene that the jet engines of today use. Jet engine efficiency  has come on in leaps and bounds, but the fuels they use are still polluting hydrocarbons which come out of the ground. Butanol can be produced by bacteria in biomass and if an economically efficient method can be found to industrialise that process then your flight of the future could literally be fuelled by alcohol.

The number of aircraft flying on our skies, however, also depends on the infrastructure to safely manage it. The US, for instance, currently has some of the most antiquated air traffic management in the developed world as a result of Congress failing to back reforms proposed by the Federal Aviation Authority  after a very famous air traffic controllers strike more than 25 years ago.  However, when change does come it will be dramatic.

New forms of air traffic management, using digitised TV and mobile signals bounced off aircraft will replace the 1940s-era radar system still in use by  air traffic control, and allow planes to land more efficiently, using less fuel in the process. Although no air traffic system is using such signals at the moment, the Technology Strategy Board of the UK government is now funding an experiment to look at the practicalities of using the BBC’s Freeview – a free-to-air digital TV signal – for just such a purpose.

One of the solutions to cut down on polluting fuels is the use of wind energy. But the rise in wind farms has its own unintended effects. Air traffic control systems are being interfered with, both offshore and across moors and hills. The movement of the turbine blades creates, essentially, a phantom signal that even modern radars find hard to differentiate from a real moving aircraft. In places such as Scotland, where the projections for wind farms are amongst the densest in the world, this could cause problems for existing flight paths. As the need for wind power increases, a solution will have to be found.

Jet-rocket hybrid

Eventually, mankind will see long distance travel - London to Sydney, for example - taking place outside the Earth’s atmosphere. By today’s standards, it will be cost relatively little to get tourists into space. Not only is Virgin Galactic, based in the US, developing a spaceplane that could one day fly between these cities, but other concepts are being investigated. 

In countries such as Britain and Japan, there is research into engines and rival vehicles which could make space travel a long-haul passenger’s reality. In the UK, a company called Skylon has just attracted £60m ($110m) of government funding to develop a futuristic type of engine known as a “reaction engine”.  This could behave like a very efficient jet engine in the atmosphere, but also be able to function outside the atmosphere like a rocket. If that breakthrough comes, a vehicle could circumnavigate the world in a couple of hours.

However, these flights are likely to run from dedicated spaceports and it will be some time before mixed-mode airports that can operate both spacecraft and aircraft become possible. The early space systems will probably involve gliding back to Earth – which may mean our airports will have to be redesigned to make them useable by these different designs.

The futuristic visions of the 1950s and 60s imagined neighbourhood airports and helicopters in our back gardens - but space travel is more likely. The harsh reality of economics in a world with a huge demand for fuel have has meant it is too expensive to fight gravity and the atmosphere to blast off for the work commute.  Our composite wing vehicles, instead, will take us to the edge of space, efficiently, and allow us to glide effortlessly to our destinations, continents away.

Will Whitehorn has recently been made a Fellow of the Royal Aeronautical Society

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