Airbus: Formation-Flying Airliners Can Save Fuel

posted on 25th September 2020 by Eddie Saunders
Airbus: Formation-Flying Airliners Can Save Fuel

By Mandolyn Mcbee

The next time you look up at the sky, you may see a flock of airplanes instead of geese. Airbus teamed up with French Bee SAS (BF) and Scandinavian Airlines (SK) to create “Fello’Fly,” a program that will study the benefits of flying airliners in formation.

Airbus is no stranger to introducing new technologies aimed at improving aerodynamic efficiency. In 2012, the company made headlines when JetBlue Airways (B6) became the first airline to fit its A320 fleet with fuel-saving wingtip devices called ‘Sharklets.’ These devices could cut aircraft fuel burn by up to 4%.

Following this shark trend, Airbus partnered with the Fraunhofer Society to develop a paint coating that imitates shark skin. When applied to an aircraft, it could decrease drag by up to 10% and help the airline industry save $1.5bn in fuel costs annually.

Now, Airbus is looking at the behavior of birds for inspiration.

Not Your Typical Formation Flying

A bird’s wingtips generate vortices as they move through the air. These vortices can produce lift for other birds. By flying in a staggered V-formation, an entire flock is able conserve its energy. An airplane’s wingtips also generate vortices and Airbus believes that this behavior can be applied in aviation.

“It’s very, very different from what the military would call formation flight,” says Airbus subidentity UpNext’s Chief Executive Officer Sandra Bour Schaeffer. She mentions that the concept has nothing to do with close formation.

Pilots are trained to not fly into another aircraft’s vortices or ‘wake turbulence.’ Doing so can be dangerous – extremely powerful wake turbulence has the power to flip smaller airplanes.

“They [the Pilots] will be 1 1/2 to 2nm away from the leading aircraft, and slightly offset, which means they are on the side of the vortex,” Bour Schaeffer explains. “It’s no longer the vortex, it’s the smooth current of rotating air which is next to the vortex, and we use this updraft of air.” Taking advantage of this lift is called wake-energy retrieval.

A350 XWB Chosen for Fello’Fly Demonstrations

Airbus has chosen the A350 XWB for its Fello’Fly demonstrations. Initial flight testing with two aircraft began in March 2020. The company boasts that it is “the most modern and efficient aircraft” available. By flying in formation, the A350 XWB can save anywhere from 5% to 10% in fuel burn. That is an “enormous number” according to Bour Schaeffer.

Risk Factors

Formation flying is easier said than done. Airbus must take into consideration the risk factors of having large aircraft fly in close proximity to one another. The company plans to have aircraft meet at a common waypoint for entry into oceanic airspace.

Once past it, the aircraft will fly on the same track while separated by a regulatory 1000ft (305m) difference in altitude. Wake-energy retrieval will then be accomplished when the aircraft are in the correct positions.

“We need to make sure we can do the joining safely,” Bour Schaeffer says. “We will have no compromise on safety, whatsoever.”