When an airliner gets a new winglet or engine nacelle, it’s a big deal for the industry. The pace of change for commercial aircraft design is best described as “molasses.” Manufacturers are wary of risking radical designs which could be disruptive to infrastructure or federal safety standards.
We’ve reported on new electric engine technology that could make it to future Airbus airliners (albeit probably a long way off in the future), and now we’re taking a look at a new ecoDemonstrator design from Boeing that could promise similar efficiency gains. Boeing’s ecoDemonstrator program is an ongoing series of tests using several Boeing aircraft (including the 787 Dreamliner) that are ultimately aimed at developing one or more environmentally-conscious prototypes by the early 2020’s.
A major departure from the “tube and wing” configuration that airliners typically utilize, this new concept is unlike the previous ecoDemonstrator aircraft as it uses a wing mounted high on the fuselage. The key feature on the new wing configuration is a diagonal truss support that connects with the lower fuselage. The support from the truss section allows the main upper wing to be longer and thinner,and therefore, more aerodynamic. The truss itself is a drag penalty, but the wing’s efficiency and lack of heavy load-bearing structure overcomes this with overall fuel savings in the range of 5-10 percent.
Cessna with truss-braced wing in flight.
Wings braced with a truss segment aren’t a new development, as Cessna has been manufacturing truss-braced wing aircraft for the general aviation market for decades. This isn’t Boeing’s first foray into trusses supporting airliner wings, either, having produced a 737-based design that featured folding truss-supported wings for NASA’s 2010 SUGAR (Subsonic Ultra Green Aircraft Research) program.
Fuel costs are the largest variable expense that airlines face, so any efficiency improvements that manufacturers can provide equates directly to increased profits. The new ecoDemonstrator from Boeing would be aimed at regional, point-to-point flights versus long-range flights between major hubs. A future regional aircraft wouldn’t need to be capable of the highest speeds but should be optimized for fuel efficiency over short and medium ranges.
Boeing 757 and 787 Dreamliner ecoDemonstrator aircraft.
Boeing is currently winding down testing of a different ecoDemonstrator aircraft based on the older, out-of-production 757 airliner. That program focused on reducing drag through an innovative coating applied to the leading edge of the starboard wing that repels bugs, as well as the addition of new variable-camber Kreuger flaps on the port wing. The same aircraft also just completed a cross-country flight using a blend of 95 percent jet fuel and 5 percent diesel fuel derived from sustainable sources such as used cooking oil and waste animal fats.
We can continue to expect innovative solutions aimed at decreasing drag, fuel consumption, emissions and noise from aircraft manufacturers like Boeing, Airbus and others. This is critical not only for airlines to remain competitive, but also for human beings to be better stewards of the environment. While airlines are ultimately embracing these technologies because they save money, the outcome of decreasing aviation’s net environmental impact is still very exciting for a future of truly eco-friendly flying.
Photo credit: ecoDemonstrator in transonic dynamics tunnel - Boeing, Cessna in flight - Robert Frola/Wikicommons, ecoDemonstrator aircraft on tarmac - Boeing