How quiet is the quietest supersonic aircraft?
How quiet is the quietest supersonic aircraft? lead image
NASA’s X-59 is an experimental aircraft designed to fly at supersonic speeds without creating disruptive noise at ground level. If successful, the project could motivate regulators to allow supersonic flights over land again.
In preparation for the first test flights, Doebler and Loubeau simulated the propagation of the X-59 acoustic pressure signature to estimate the noise level on the ground.
The duo took air pressure data from X-59 fluid dynamics simulations and analyzed how the pressure signatures propagated through the atmosphere. They used elevation and atmospheric data from multiple regions around the country to determine the effects of the local environment on the resulting noise level.
“The local ground elevation plays a role in the loudness, as does the weather and climate, especially in the lower few thousand feet,” said author William Doebler.
The researchers found that through combinations of flight speed, altitude, control surface deflections, and atmospheric conditions, the X-59 can generate Perceived Levels on the ground ranging from 72 to 86.7 decibels, encompassing the design target of 75 dB.
After test flights to verify that the simulations are correct, the X-59 will begin flying over selected communities, where residents will be surveyed to gauge their reactions.
“We are trying to locate the loudness that begins to elicit annoyance in hopes that the data can be used to change the rules from a speed limit to a noise limit,” said Doebler. “The goal is to provide data relating noise level to public response to regulators so that they can decide if a loudness limit can be set and at what level it should be.”
Source: “Estimating the noise dose range of the NASA X-59 aircraft in supersonic cruise using PCBoom propagation simulations,” by William J. Doebler and Alexandra Loubeau, JASA Express Letters (2023). The article can be accessed at https://doi.org/10.1121/10.0019501 .
