Aerodynamic efficiency target of Boeing Eco Demonstrator 757 flight tests

By Tony Borroz

The Boeing Airplane Company's ecoDemonstrator 757 (Photo: Boeing)

Boeing is at it again, continuing its on-going ecoDemonstrator test program by ramping up a series of flight tests with a modified 757 airliner. The lengthy tests will assess new methods to advance efficiency, cut noise and lower carbon emissions.

The flight tests, a continuing part of Boeing's ecoDemonstrator series, are being conducted in collaboration with the TUI Group and NASA using the ecoDemonstrator 757 for the tests. Boeing is actually using the single aircraft to conduct three separate tests simultaneously, on three separate aerodynamic surfaces. The experiments being conducted with TUI focus on aerodynamic efficiency. The two other investigations in conjunction with NASA will focus reduced fuel use and carbon emissions.

We covered an earlier phase of Boeing's ecoDemonstrator initiative back in November when the company was using its new 787 Dreamliner as the test bed, but this latest round of examinations uses a specially-outfitted version of the company's older workhorse, the 757. These 757 flights continue the extensive ecoDemonstrator program's multi-year effort to improve environmental performance.

The aircraft's left wing is being used by Boeing to evaluate technologies to reduce the environmental effects on natural laminar flow. Anything that disrupts the smooth flow of air across the plane is bad, and doubly so if this flow disruption occurs on the wing. For example, the ecoDemonstrator 757 will test a Krueger shield aimed at protecting the leading edge from insects. Yes, bugs. It might seem like an insignificant worry, but think of how bugs and other debris can collect on your car's windshield on a long cross-country trip. Multiply that several-fold due to a bigger surface area and higher speed, and you can see how this can add up to many gallons of costly jet fuel wasted.

The right wing is also concerned with lessening the effects of insect fragments. Working in conjunction with NASA's Environmentally Responsible Aviation (ERA) Project, Boeing will evaluate two technologies on the ecoDemonstrator 757. These are two different bug-phobic coatings, used to lessen the residue left by bug strikes on the leading edges of aircraft wings. NASA and Boeing's goal is to facilitate more drag-reducing laminar flow over the remainder of the wing by cleaning up the airflow over the leading edge.

The third test is happening at the same time, but this one is up on the vertical tail. Active flow control is being evaluated by NASA and Boeing to improve airflow over the rudder and maximize its aerodynamic efficiency. Based on previous wind-tunnel testing, active flow control aims to increase the rudder's efficiency by up to a whopping 20 percent. If these tests pan out, that could mean either less fuel used, higher speeds, or, even better, it may allow for a smaller vertical tail design in the future.

The other part of this latest round of Boeing's ecoDemonstrator program looks at reducing carbon emissions and is partnered with the TUI Group. TUI is a European company that is the world's largest integrated tourism group and includes six airlines. TUI says it's preparing for a low-carbon future by decreasing its environmental impact and encouraging its customers and suppliers to do the same.

The really great thing about Boeing's ecoDemonstrator program is that the results and advancements will not end up buried in the company's archives or sit disused in a warehouse. Apart from Boeing proprietary technology, the knowledge gained in the collaboration between Boeing and NASA from the ecoDemonstrator research will be publicly available to benefit the entire aerospace industry. In other words, if NASA and Boeing come up with a smart way of keeping bugs off of the wings of airplanes, that technology could be seen on Airbus offerings.

"Having a relevant test bed, like Boeing's ecoDemonstrator, to help mature technology concepts is extremely important to NASA's Environmentally Responsible Aviation (ERA) Project," said NASA's ERA project manager, Fay Collier. "Our researchers have been working hard to develop technologies to reduce airplane fuel consumption, noise and emissions. Being able to prove those concepts in flight tests gives them a better shot of getting into the commercial fleet."

And this round of testing is nowhere near the end of the ecoDemonstrator program. Boeing has been working on it since 2011, and it shows no signs of slowing down.

Source: Boeing