NASA tested three technologies of noise reduction during takeoff and landing aircraft. It happened during a series of flight experiments called Acoustic Research Measurement (ARM). They managed to reduce the amount of noise from aircraft by 70%.
The Agency of Aeronautics focused on reducing the noise of the engines and airframe, which occurs due to the wind passing by the fuselage and other aircraft parts. For testing, three pilot projects were installed on the research aircraft Gulfstream III, which was flying at an altitude of about 100 meters above the array of the 185 microphones, located on the dry lakebed of Rogers, not far from Edwards air force base in California.
Most of the complaints society on planes applies to noise. The purpose of NASA is to significantly reduce its level to improve the quality of life near airports
— Mehdi Horr, head of acoustic research
The main culprit for noise during takeoff and landing defined by the chassis of the aircraft, so two of the three enhancements relate to it. NASA reviewed the design of the fairing, and added on the front surface pores. This allows outdoor air to pass through the fairing, and the rest to bypass it. This project was based on computer simulations that you were able to find a ballance between noise reduction and air resistance.
Improvement was made and the cavity that hide the wheels. When the landing gear is down, air freely gets out there and creates a lot of noise. Experts from NASA achieved the best removal of air, creating the air duct. And also added “chevrons”, which reduce the total amount of air entering in the cavity.
The last decision is the new technology creating a flap, is used to adjust the height. The technology is called Adaptive Complied Trailing Edge (ACTE). And represents a flexible and seamless detail that leaves no gaps on the surface of the wing.
After a test flight, NASA stated that use of technology has allowed to reduce the level of noise from aircraft landing has more than 70 percent. Project Manager ARM remained satisfied with this result:
Noise reduction is of great importance, and the best part is it will benefit the community