ecoDemonstrator tests suggest tails could get smaller

As we celebrate Earth Day, the news from NASA that empennages on commercial aircraft could be dramatically reduced in size in future could have a significant environmental impact. Initial results from experiments on Boeing’s 757 ecoDemonstrator aircraft suggest that technologies to better control the flow of air over an aircraft’s tail will enable OEMs to produce commercial jets with empennages up to 17 per cent smaller than today cutting fuel consumption significantly.

Speaking about the latest 757 tests, Mike Alexander, lead systems engineer for the flight tests at NASA’s Langley research centre, said: “If we can control the flow of air over the vertical tail on demand, we believe we can provide enough side force during take-off and landing that aircraft manufacturers can safely make the tail smaller.”

The trials, officially and snappily known as the “active flowcontrol enhanced vertical tail flight experiment”, assessed the impact of sweeping jet actuators, 31 of which were installed on the 757’s vertical tail with NASA measuring the impact they had on the aerodynamics of the tail and rudder surfaces.

A total of six roundtrip flights took place from April 9 to- April 15 between Seattle and the Strait of Juan de Fuca under a series of different flight conditions.

And while NASA stated that more analysis is needed, early indicators suggest the 757 experiments validated wind tunnel tests it carried out in 2013 at its research centre in California, which found the size of a future aircraft’s vertical tail could eventually be reduced by as much as 17 per cent while fuel consumption could drop 0.5 per cent.

The ecoDemonstrator 757 was launched last month by Boeing and follows on from the OEM’s previous tests with the 737 and 787 ecoDemonstrator, which included experiments with green diesel in one of the aircraft’s engines in Q4 2014.

The second phase of ecoDemonstrator 757 testing is imminent, with NASA set to begin testing five different wing coatings designed to minimise insect residue from collecting on the aircraft’s wings during flight.

Scheduled to complete 15 days of flying between April 27 and May 15 as part of the research, its results are also sure to be as equally as intriguing to the commercial aviation industry.

Given that the tests could ultimately lead to more fuel efficient aircraft, which in turn would mean big cost reductions, I am sure the results of the latest ecoDemonstrator programme will be eagerly anticipated by operators and MROs alike.

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