Lean, Green, Eco-Friendly Flying Machines

If there was one dominant theme of the 2011 Paris Air Show, it was the industry’s desire to conform to public concerns about environmentally friendly actions and reducing its carbon footprint.

The halls and chalets were dominated by environmentally friendly proposals, ranging from hybrid aircraft to biofuels to more efficient technology, all suggesting innovative ways in which the aerospace industry could achieve eco-efficiency on a large scale.

Airbus dominated the aircraft movement with its A320 Neo aircraft, which promises to consume 15% less fuel than its A320 predecessor, whereas companies like EADS pledged to cut the carbon emissions of its fleet by 50% by 2050.

Boeing boasts of green arrival

Boeing almost pre-emptively launched what was to be the emerging theme of the show, landing its 747-8 Freighter at Le Bourget airport, having become the world’s first commercial jetliner to complete a transatlantic crossing using biologically derived fuel.

Each of the jet’s four GE engines were powered by a blend containing 85% Jet-A fuel and 15% camelina-based biofuel, heralded as a significant move towards eco-efficient flights by Boeing 747-8 vice president and general manager Elizabeth Lund.

“This historic flight is a boost to aviation’s efforts to reduce carbon emissions and improve efficiency in all phases of our industry,” added Lund.

Biofuels show strong progress

While Boeing made a grandstand entrance, considerable progress was noted in the use of biojet fuels, with Gevo claiming particular success with their fuel based on a renewable source of isobutanol.

The fuel itself is derived by converting renewable isobutanol to jet fuel using chemical synthesis, and the fuel itself acts in the same manner as petrochemical jet fuel.

Gevo president and COO Christopher Ryan said: “We have planned production capacity of approximately 110m gallons of isobutanol a year by 2013 for use in jet fuel.

“We continue supply discussions for biojet with numerous airlines seeking a cost competitive, low carbon alternative to petroleum derived jet fuel.”

The company demonstrated results to the alcohol jet review committee of ASTM at the Paris Air Show, with the next step in obtaining the company’s biojet specification to collaborate with engine manufacturers to complete commercial engine testing.

Solar Impulse lighting the way

The star attraction of the Paris Air Show, however, was undoubtedly the Solar Impulse, flown over from its Swiss base with due care and attention. The project, undertaken at the École Polytechnique Fédérale de Lausanne, aims to be the first fixed-wing aircraft to circle the Earth using only solar power.

The premise of the aircraft is its ability to take off using its own power and remain airborne for up to 36 hours using solar power that it collects and stores.

After it was introduced to the public in Dubendorf, Switzerland, in June 2009, the aircraft completed a short-hop test flight in December 2009 piloted by Markus Scherdel.

Further progress was made in 2010, with an extended 87 minute flight test completed in April and the first solar-powered flight, recharging batteries during the flight, in May.

The aircraft has continued to extend its limits since. In July that year, the Solar Impulse completed the world’s first manned 26 hour solar-powered flight, reaching a maximum altitude of 28,500ft.

In May 2011, the Solar Impulse completed its first international flight before departing in the following month for Le Bourget airport, home of the Paris Air Show. The flight wasn’t without its hitches, however, as the first attempt was abandoned due to poor weather conditions.

Green taxiing achieves take-off

Also unveiled at the show was the green taxiing system, produced by a joint venture including Honeywell Aerospace and Safran. The system promises to significantly improve operational performance of airlines whilst reducing their environmental footprints.

This is achieved by rapidly decreasing pollutant emissions of aircraft while taxiing, using energy supplied by the auxiliary power unit to power electric motors installed at the wheels and landing gear of the aircraft. The mechanisms use these electric motors to taxi rather than jet fuel, reducing emissions.

Short-haul aircraft use an estimated 5m tons of fuel a year while taxiing, and the new system proposes to reduce this figure by up to 4%. Honeywell Aerospace president and CEO Tim Mahoney said: “Today, the cost of fuel and those caused by emissions are high on the list of concerns for each airline.

“Thanks to taxiing of green power that will ensure mobility of aircraft on the ground, airlines could save hundreds of thousands of dollars per aircraft per year.”

Reducing the strain

Further options to reduce fuel consumption of aircraft were offered by both General Electric and Nexcelle, who presented their respective technologies at the show.

GE Aviation used the Paris Air Show to unveil the company’s silicon carbide (SiC) based power conversion products for use in air platforms, offering superior performance over conventional silicon devices due to their ability to operate at higher junction temperatures and voltages. This performance allows other, supporting components to be significantly reduced in size and weight, critical for applications aboard aircraft.

“By using GE developed SiC technology, we have the potential to reduce the weight of an aircraft by up to 400lbs while also delivering higher performance,” said GE aviation electrical power president Vic Bonneau.

Alternatively, Nexcelle unveiled a scale model of its new integrated propulsion system, used to reduce aircraft fuel consumption and improve performance whilst also enhancing maintenance.

The system itself boasts a low drag front end and a fan cowl which is structurally integrated to the engine. The integrated mounting system reduces engine distortion and enhances on-wing performance, benefiting the fuel efficiency of aircraft utilising the system.