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HAMBURG—Lufthansa Technik is studying how its fuel burn reducing AeroShark riblet film can be engineered to cover a greater proportion of the aircraft.
The work is taking place as the company is seeing its retrofit product gaining traction, after hiccups when it was initially offered to carriers. The application’s current fuel efficiency improvement and return on investment are comparable to those for a similar result with an engine upgrade.
AeroShark relies on prism-shaped riblets. Air friction creates turbulence on the aircraft’s surface and riblets move that turbulence 50 micrometers away, effectively reducing drag and therefore improving fuel efficiency. The first supplemental type certificate (STC) was obtained for the Boeing 747-400 in November 2019 but the pandemic, shortly after, caused most four-engine commercial aircraft to be parked or retired, thus impeding AeroShark’s entry into service.
AeroShark is in service on 27 aircraft—mostly 777-300ERs and 777Fs, as well as four 777-200ERs and one 747-400. “On a 777, the film currently covers 40% of the surface of the aircraft,” Jens-Uwe Mueller, Lufthansa Technik’s product sales lead for AeroShark, says. “We hope to increase that proportion to 80%.”
Installing the adhesive film involves placing the riblets in various angles, thus following the airflow. From doors 1, the film already covers the entire aircraft length. Clockwise, it covers from 1:30 to 10:30 on the fuselage, and the nacelles. On a 777-300ER, the AeroShark riblet film thus covers more than 900 m2 (9,700 ft.²), including 50 m2 for each nacelle.
The crown area is trickier, Mueller says. “Because of the aircraft’s slightly nose-up attitude in cruise flight, the film would have less influence in this area,” he says. “Moreover, we would have to certify the fact the film does not negatively impact the airflow on the stabilizer. And it is even harder to install on the crown.”
Because some surfaces already see laminar air flow, and because certain areas are not allowed to be modified (such as external sensors that are calibrated for defined airflow conditions), AeroShark will never cover 100% of an aircraft’s surface, he added.
On average (depending on fuselage length), the film adds 150 kg (330 lb.) on a 777. On a 10-hr. flight, Lufthansa Technik estimates fuel savings to a significant 1%. Return on investment comes after 2-3 years, depending on aircraft utilization, fuel price and installation costs, which themselves vary with labor costs at the modification center, Mueller says.
As it is designed for the cruise phase, AeroShark is more suitable for long-haul flights than short hops. Hence the 747 and the 777 being the first applications. Lufthansa Technik started with older-generation widebodies because of the company’s greater experience with modifications. Moreover, current delivery delays tend to force carriers to operate older aircraft longer than anticipated.
Lufthansa Technik is now designing an Airbus A330 version. The A321XLR could be an interesting target for future developments, Mueller says. An AeroShark modification could potentially squeeze out an extra bit of range, which could open up even more routes for the new type.
Lufthansa Technik has received more than 50 orders since product launch and customers include ANA, Austrian, EVA Air, Latam, Lufthansa, Lufthansa Cargo, and Swiss.
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