Flight to sustainability

Since supplies of fossil oil cannot last forever, LNG is becoming increasingly important as a cheap and lasting energy source. Researchers believe that in the 2040-50 timeframe, a hyper-efficient commercial aircraft stacked with fuel-saving emissions-minimising features, might well be operated on LNG.

Two factors are likely to dominate any debate about the future of commercial aviation—the soaring cost of jet fuel and the need to slash aviation-related greenhouse gas (GHG) emissions. Fortunately, the solution to both is practically the same—greater fuel efficiency.

In May 1952, the age of modern travel burst on the world scene when the British Overseas Airways Corporation (BOAC) operated a de Havilland Comet from London to Johannesburg. It was the world’s first passenger jet service. Sixty years since then, surprisingly little has changed. Airframes have certainly become more aerodynamically efficient, jet engines are quieter and ‘cleaner’ and most airlines are noticeably cost-conscious. The fuel-guzzling Comet has given way to the fuel-sipping Boeing B787. However, efficiency gains have been incremental rather than spectacular. And the same tube-and-wing design of the Comet continues to be employed in every commercial aircraft. Why is a truly revolutionary airliner so long in coming?

It’s All About Risk!

Blame it on the aversion to risk. One might think that after so many years of experience, it should be relatively simple to design a new jet. But historically, most airliner projects have been subject to huge cost and time overruns. For instance, the 1970 launch of the Boeing B747, the world’s first wide-body jet, almost drove Boeing bankrupt. It is a different matter that the B747 went on to become one of its most successful products.

Currently dominated by narrow-body aircraft, the global airline industry is expected to generate a demand for perhaps 20,000 planes over the next two decades. Stung by high oil prices, carriers everywhere have been pestering manufacturers to come up with new 120- to 230-seat airliners that can drastically reduce fuel bills. However, as the big two, Airbus and Boeing, enjoy an enormous backlog of their most popular models, the A320 and B737 respectively, why would they want to stick their necks out? After much dithering, Airbus last year announced the A320neo, while Boeing after even more indecision, responded with the B737 Max. Both re-engined aircraft, which are expected to rule the market for the next 20 to 25 years, promise double-digit fuel burn reduction. The manufacturers believe it makes little sense to attempt a clean-sheet design now since several emerging technologies will only fructify after 10 to 15 years.

NASA’s Lofty Ambitions

Strategies to ensure that aviation becomes more sustainable environmentally as well as financially begin at the conceptual stage. For instance, there is NASA’s Environmentally Responsible Aviation (ERA) study on advanced concepts for airliners under which it has roped in big guns such as Boeing, Lockheed Martin and Northrop Grumman. Researchers are focusing mainly on reducing weight, drag, energy consumption, emissions and noise. And their targets are not modest. The aim of these ‘N+3’ research programmes, three generations on from today’s Boeing B737 and B777, is to identify technologies and advanced configurations that could by 2035 reduce fuel burn by a whopping 70 per cent from a CFM56-powered B737. As gains of this magnitude can hardly be expected from current tube-andwing designs, researchers are venturing into radically different configurations. They are also considering the use of hybrid-electric propulsion, multi-role wing leading edge and protective outer skin that would mean lighter structures. If 2035 seems a long way off, the same technologies tailored to today’s designs may also prove fairly effective. NASA hopes to select a design to produce a B737-sized subscale test vehicle by 2016. It could help prove the technologies required for a fuel-efficient new passenger aircraft by 2025