NASA

November 2, 2012

NASA Dryden F/A-18 to be chasing ‘FaINT’ sonic booms

NASA’s F/A-18B mission support aircraft 852 is pictured flying over the high desert near the Tehachapi Mountains northwest of Mojave, Calif. The aircraft will be flying a series of low-supersonic, high-altitude flight profiles during the Farfield Investigation of No Boom Threshold, or FaINT, flight research project at NASA Dryden.

NASA’s Supersonics Project will embark on its latest effort to soften sonic booms when a NASA F/A-18 aircraft takes to the air in a project called Farfield Investigation of No Boom Threshold, or FaINT, beginning in late October.

As the latest in a continuing progression of NASA supersonics research projects aimed at reducing or mitigating the effect of sonic booms, FaINT is designed to enable engineers to better understand evanescent waves, an acoustic phenomenon that occurs at the very edges or just outside of the normal sonic boom envelope.

For an aircraft flying at a supersonic speed of about Mach 1.2 or less at an altitude above 35,000 feet, the shockwaves being produced typically do not reach the ground, so no sonic boom is heard. This is because shockwaves from an aircraft flying supersonically at higher altitudes are refracted, or bent upwards, as they enter warmer air closer to the ground, due to the fact that the speed of sound increases with air temperature.

But when sonic booms curve upward they create a series of sonic boom waves that are focused along a line. This line is called a caustic line. The side of the caustic line opposite of the sonic boom waves is called the “shadow side,” where the evanescent waves are generated. This is the area that NASA researchers will study during FaINT.

“It’s exciting to help lead a new area in sonic boom flight research,” said Larry Cliatt, principal investigator for the FaINT flight project at NASA’s Dryden Flight Research Center. “We are investigating supersonic technology and research that is relatively raw in the modern sense. When overland supersonic commercial travel is commonplace, it will be efforts like this that helped get us there.”

The planned evanescent wave flights will occur over Edwards Air Force Base, Calif., where special microphone arrays placed on the southern portion of Rogers Dry Lake will again be the NASA Dryden researcher’s sensor of choice.

For the upcoming FaINT flight project, capturing the fleeting sounds of evanescent waves coming off sonic boom shockwaves will be a challenge. Similar to the shadow the sun creates behind a building, if some light were to still leak around the edges it would not get completely dark, but it would get darker the further you move away from the edge. Certain conditions and refractions create a similar “shadow side” of a sonic boom where evanescent waves are generated, sounding similar to distant thunder. These waves quickly fade and disappear, as supersonic shockwaves act similar to boat wakes on water, decreasing with distance.

“The FaINT team has been working hard on the development and design of the FaINT project for the last six months,” said Brett Pauer, FaINT deputy project manager at NASA Dryden. “NASA, along with our seven industry and university partners, are ready to collect data and expand our collective knowledge of sonic boom propagation effects near the shadow side of them,” Pauer said.
Characterizing the effects of both normal and loud sonic booms in order to provide the data necessary for engineers to design future low-boom supersonic aircraft has required an amazing amount of work and tenacity by NASA engineers from the agency’s Dryden and Langley research centers, and industry partners as well.

Related sonic boom research projects preceding FaINT date back several years. Recent efforts include the Superboom Caustic Analysis and Measurement Program, which produced and measured amped-up, super-loud sonic booms, and the Waveforms and Sonic boom Perception and Response project, which gathered data from a select group of volunteer Edwards Air Force Base residents on their individual perceptions of sonic booms produced by aircraft in supersonic flight over Edwards.

The overarching goal of NASA’s sonic boom reduction research is to shrink the sonic boom “footprint” in order to make commercial supersonic flight over land practical.

This research is funded by NASA’s Aeronautics Research Mission Directorate at NASA Headquarters in Washington, D.C.




All of this week's top headlines to your email every Friday.


 
 

 
NASA photograph by Tom Tschida

NASA Armstrong Support Center receives LEED platinum certification

NASA photograph by Tom Tschida Large expanses of windows and curved rooflines highlight NASA Armstrong’s new Facilities Support Center. The 38,000-square-foot structure has been certified that it met the Leadership in Ene...
 
 
NASA/NSERC photograph by Jane Peterson

College students study Earth from NASA’s DC-8 flying lab

NASA/NSERC photograph by Jane Peterson Jonathan Hemingway, an applied meteorology and computational mathematics major at Embry-Riddle Aeronautical University in Florida, assists in installation of the Whole Air Sampler instrume...
 
 
NASA photograph by Jim Ross

NASA Aeronautics makes strides to bring back supersonic passenger travel

NASA photograph by Jim Ross NASA F/A-18 mission support aircraft were used to create low-intensity sonic booms during a resaerch project at the agency’s Armstrong Flight Research Center in Edwards, California. The Wavefor...
 

 
Image courtesy of NASA/SOFIA/EXES/Mathew Richter

NASA begins testing of new spectrograph on agency’s airborne observatory

Image courtesy of NASA/SOFIA/EXES/Mathew Richter EXES, the Echelon-Cross-Echelle Spectrograph, made its first light commissioning flight on April 7, 2014 on NASA’s SOFIA flying observatory. The instrument, shown mounted t...
 
 
NASA photograph by Jim Ross

NASA declares SOFIA Observatory fully operational

NASA photograph by Jim Ross The door to the SOFIA observatory’s 2.5-meter telescope is wide open during a developmental test flight in 2010. On June 2, 2014, during the 224th meeting of the American Astronomical Society i...
 
 
Photograph courtesy of Mars Scientific/Clay Center Observatory

NASA, Virgin Galactic announce payloads for SpaceShipTwo flight

Photograph courtesy of Mars Scientific/Clay Center Observatory Telescopic image of Virgin Galactic’s SpaceShipTwo during a supersonic test flight in 2013. NASA has selected 12 technology experiments to fly on the first commer...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>