NASA Technologies Significantly Reduce Aircraft Noise

Aircraft Noise

More than 70 % reduction in airframe noise achievable

Washington D.C., June 25, 2018: A series of NASA flight tests has successfully demonstrated technologies that achieve a significant reduction in the noise generated by aircraft and heard by communities near airports.

The Acoustic Research Measurement (ARM) flights, which concluded in May, at NASA’s Armstrong Flight Research Center in California, tested technology to address airframe noise, or noise that is produced by non-propulsive parts of the aircraft, during landing. The flights successfully combined several technologies to achieve a greater than 70 percent reduction in airframe noise.

While porous concepts for landing gear fairings have been studied before, NASA’s design was based on extensive computer simulations to produce the maximum amount of noise reduction without the penalty of increasing aerodynamic drag. The landing gear cavity was treated with a series of chevrons near its leading edge, and a net stretched across the opening to alter airflow, aligning it more with the wing.

“The number one public complaint the Federal Aviation Administration receives is about aircraft noise,” said Mehdi Khorrami, an aerospace scientist at NASA’s Langley Research Center in Virginia, and principal investigator for Acoustic Research Measurement. “NASA’s goal here was to reduce aircraft noise substantially in order to improve the quality of life for communities near airports. We are very confident that with the tested technologies we can substantially reduce total aircraft noise, and that could really make a lot of flights much quieter.”

NASA tested several experimental designs on various airframe components of a Gulfstream GIII research aircraft at Armstrong, including landing gear fairings and cavity treatments designed and developed at Langley, as well as the Adaptive Compliant Trailing Edge (ACTE) wing flap, which had previously been flight-tested to study aerodynamic efficiency. The aircraft flew at an altitude of 350 feet, over an 185-sensor microphone array deployed on the Rogers Dry Lake at Edwards Air Force Base in California.

The Landing Gear Noise Reduction technology element addressed airframe noise caused by airflow moving past the landing gear on approach. The experimental landing gear tested by NASA features fairings that are porous along their front, meaning they consist of many tiny holes that, in part, allow some of the air to flow through the fairing, while also deflecting some of the airflow around the landing gear.

Aircraft Noise

While porous concepts for landing gear fairings have been studied before, NASA’s design was based on extensive computer simulations to produce the maximum amount of noise reduction without the penalty of increasing aerodynamic drag. The landing gear cavity was treated with a series of chevrons near its leading edge, and a net stretched across the opening to alter airflow, aligning it more with the wing.
Photo: NASA/Ken Ulbrich

Porous concepts have been studied before, but the unique design developed by NASA resulted from highly detailed computer simulations that led NASA engineers to what they believe is the ideal design for maximum noise reduction without increasing aerodynamic drag.

Another area of focus was landing gear cavities, also a known cause of airframe noise. These are the regions where the landing gear deploys from the main body of an aircraft, typically leaving a large cavity where airflow can get pulled in, creating noise. NASA applied two concepts to these sections, including a series of chevrons placed near the front of the cavity with a sound-absorbing foam at the trailing wall, as well as a net that stretched across the opening of the main landing gear cavity. This altered the airflow and reduced the noise resulting from the interactions between the air, the cavity walls, and its edges.

To reduce wing flap noise, NASA used an experimental, flexible flap that had previously been flown as part of the ACTE project, which investigated the potential for flexible, seamless flaps to increase aerodynamic efficiency. As opposed to conventional wing flaps that typically feature gaps between the flap and the main body of the wing, the ACTE flap, built by FlexSys Inc. of Ann Arbor, Michigan, is a seamless design that eliminates those gaps.

Significant reduction in aircraft noise must be realized in order for air transportation growth to maintain its current trend. The reduction of airframe noise using NASA technology is an important achievement in this effort, as it may lead to quieter aircraft, which will benefit communities near airports and foster expanded airport operations.

“This airframe noise reduction produced by NASA technology is definitely momentous, and the best part is that it directly benefits the public,” said ARM Project Manager Kevin Weinert. “While there are obvious potential economic gains for the industry, this benefits the people who live near major airports, and have to deal with the noise of aircraft coming in to land. This could greatly reduce the noise impact on these communities.”

For more information about NASA’s aeronautics research, please visit:

Source: NASA Headquarters, Washington D.C.  and Armstrong Flight Research Center, Edwards, California

NASA Advances Concepts for Next-gen Aircraft

sustainable aviation

Higher efficiency, less noise and fewer emissions!

Cleveland, November 7, 2017: An aviation renaissance, one focused on energy efficiency and economic impact, is on the horizon, and it’s changing how engineers look at aircraft power and design.

Although the aircraft industry continues to adopt innovative technologies, which are making current aircraft more energy efficient, there’s new interest in exploring alternative propulsion systems and energy sources. This new interest presents an opportunity to develop cutting-edge technologies that will dramatically reduce fuel usage, while opening up potential new markets and business opportunities for American companies and carriers.

“I feel we are at a tipping point in commercial aviation,” says Jim Heidmann, manager of NASA’s Advanced Air Transport Technology Project (AATT). “We are exploring and developing game-changing technologies and concepts for aircraft and propulsion systems that can dramatically improve efficiency and reduce environmental impact and accelerate the introduction of new aircraft.”

To provide better efficiency with less noise and fewer emissions, NASA is working with the aviation industry and academia to develop unique vehicle concepts that will use different fuselage shapes; longer, skinnier and more blended wings; innovative materials and components; and highly-integrated propulsion (engine) systems.

NASA aims to accelerate the final testing and validation of these advanced concepts and technologies through its New Aviation Horizons initiative. This initiative outlines the development of a series of experimental planes (X-planes), which will achieve the agency’s aircraft-level metrics for fuel consumption, emissions and noise.

The work has already begun under New Aviation Horizons as NASA is preparing to build and fly the first such X-plane – a low-boom supersonic flight demonstrator.

A turboelectric aircraft configuration is among several candidates for future subsonic transport X-planes that will prove the benefits of these advanced technologies in piloted flight within the next decade.

STARC Contrast: Smaller engines provide more power

One of the most pivotal areas of commercial aviation’s transformation centers around propulsion, and a team of engineers at NASA’s Glenn Research Center in Cleveland is conducting cutting-edge research into high-pressure-ratio compact gas turbine engines, low-emission combustors, electric-enhanced propulsion and boundary-layer ingesting (BLI) engines.

“We believe global competition and international certification standards will drive reduced fuel consumption and more efficient aircraft and propulsion concepts that may use cleaner forms of energy,” said Heidmann. “We also see the potential emergence of alternative modes of commercial transport, such as on-demand and flight service between rarely-traveled locations, both of which would represent new markets and potential beneficiaries of revolutionary propulsion technologies.”

Some of the key propulsion system advances the NASA Glenn team is pursuing converge in an aircraft concept study called STARC-ABL (single-aisle turboelectric aircraft with an aft [at the rear of the aircraft] boundary-layer propulsor).

The STARC-ABL concept, developed by NASA’s Jim Felder and Jason Welstead, is under consideration as one of NASA’s future X-planes. It looks similar to the proven tube-and-wing aircraft you see every day. But, unlike those aircraft, a significant amount of electrical power, approximately three megawatts, is used for turboelectric propulsion, in addition to the electrical operation of subsystems like flight controls, avionics and de-icing.

Imagine a Boeing 737, but with slightly smaller engines. Not a dramatic design departure, but STARC-ABL’s tail features a “T-tail” horizontal stabilizer configuration with a BLI ducted fan on the tail, which is driven purely by electric power derived from generators mounted to the underwing engines.

The wing-mounted engines supply 80 percent of the thrust required during takeoff and 55 percent at cruise, while the tail-mounted, all-electric BLI turbofan accounts for remaining thrust. Researchers predict a potential fuel consumption improvement of roughly 10 percent using this innovative system.


Next Step: Collaboration leads to solutions

While NASA is preparing for initial ground tests of a subscale STARC-ABL concept later this fall at NASA’s Electric Aircraft Testbed (NEAT) at Plum Brook Station in Sandusky, Ohio, several vehicle-level development challenges remain: How to balance aerodynamic efficiency, appropriately optimize the engines and aft BLI fan, validate the BLI benefits, store energy, compensate for additional weight, and meet safety and operational requirements.

To further investigate the challenges surrounding the hybridization of commercial aircraft, NASA is looking to industry and academic expertise for solutions.

NASA recently awarded 12-month contracts to Boeing, teamed with Georgia Tech, and Liberty Works, with ES Aero, to develop preliminary single-aisle, 150-seat aircraft designs using promising electric-enhanced propulsion and vehicle configuration concepts.

“During the 12-month cycle, we’ll work with the teams to take a deep dive into their hybrid and turboelectric aircraft concepts,” said Amy Jankovsky, NASA’s AATT subproject manager. “These concepts will provide in-depth, detailed analyses of the propulsion and electrical systems, and we will recommend technology development paths for their concepts.”

The year-long study will also reveal new development approaches and any unforeseen technological hurdles, as well as any safety and flight certification challenges that could get an aircraft like STARC-ABL or other next-generation, hybrid or turboelectric aircraft concepts aloft within 20 years.

And while those proposed industry concepts could look like STARC-ABL, the real objective is to transform commercial aviation by using new propulsion technologies that meet NASA’s aircraft-level requirements of energy use, life-cycle carbon, landing-and-takeoff emissions and noise.


Ready for Takeoff: Development, testing, flight

Final reports from the industry study will outline hybrid-electric and conventional single-aisle aircraft concept designs, technology roadmaps for the major electrical systems and aircraft subsystems, and the evaluation of the concepts’ performance against NASA aircraft metrics.

“As we move forward, we’d like to further develop the powertrains for these and any other concepts that may prove viable by building and testing them at NEAT and other NASA facilities,” said Jankovsky. “We’ll identify key performance parameters for components such as motors, generators and power electronics, and any wind tunnel, altitude and other ground tests and flight demonstrations that are appropriate.”

Ultimately, NASA hopes to contribute to a next-generation aircraft that will substantially reduce fuel burn, noise and emissions. Many researchers feel we are only a few steps away from a major aviation revolution, and that a commercial aircraft using NASA-developed, hybrid-electric or turboelectric propulsion technology could be flying to an airport near you in the not too distant future.

Source: NASA, Glenn Research Center

Climate Change – NASA: June 2017 was Fourth-warmest on Record

IASA e.V. - Climate Change

10 warmest months of June occurred between 2005 and 2017

Washington, July 14, 2017:

June 2017 was the fourth warmest June in 137 years of modern record-keeping, according to a monthly analysis of global temperatures by scientists at NASA’s Goddard Institute for Space Studies (GISS) in New York.

Last month was 0.69 degrees Celsius warmer than the mean June temperature from 1951-1980. It is surpassed by June 2016 (+0.79 °C) and June 2015 and 1998 (+0.78 °C) and only insignificantly warmer than June 2005 (+0.68 °C).

Except for June 1998, the 10 warmest months of June occurred between 2005 and 2017.

The monthly analysis by the GISS team is assembled from publicly available data acquired by about 6,300 meteorological stations around the world, ship- and buoy-based instruments measuring sea surface temperature, and Antarctic research stations.

The modern global temperature record begins around 1880 because previous observations didn’t cover enough of the planet. Monthly analyses are sometimes updated when additional data becomes available, and the results are subject to change.

IASA e.V. - Climate Change

A global map of the June 2017 LOTI (land-ocean temperature index) anomaly, relative to the 1951-1980 June average. Source: NASA

For more information on NASA about Climate Change and GISS’s monthly temperature analysis, please visit:

Source: NASA

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