Subscribe free to our newsletters via your
. 24/7 Space News .




AEROSPACE
NASA Investigates the 'FaINT' Side of Sonic Booms
by Gray Creech for Dryden Flight Research Center
Edwadrds AFB CA (SPX) Nov 08, 2012


A FaINT project researcher adjusts one of the microphones in a linear array nearly 1 .5 miles long laid out by the project team to record and measure sonic booms. Image credit: NASA/Tom Tschida. For a larger version of this image please go here.

Sonic booms created by aircraft flying faster than the speed of sound certainly aren't known for being faint, but rather for their loud, make-you-jump startle effect for those who experience them. However, sonic booms have a quieter, fainter side, too.

NASA's Supersonics Project is embarking on its latest effort to characterize or define that fainter side of sonic booms as a NASA F/A-18 aircraft takes to the air in a project called Farfield Investigation of No Boom Threshold, or FaINT.

As the latest in a continuing progression of NASA supersonics research projects aimed at reducing sonic boom levels, 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 are studying during the FaINT project to learn more about how to reduce the level of sonic booms.

"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.

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.

"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.

Related sonic boom research projects preceding FaINT date back several years. Recent efforts include the Superboom Caustic Analysis and Measurement Program (SCAMP), which produced and measured amped-up, super-loud sonic booms, and the Waveforms and Sonic boom Perception and Response (WSPR) 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.

.


Related Links
Aeronautics
Read About WSPR, Another Low Boom Research Project
Aerospace News at SpaceMart.com






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle








AEROSPACE
Boeing to clinch $2.4 billion Indian deal: report
New Delhi (AFP) Nov 5, 2012
Boeing looks set to win military contracts worth $2.4 billion from India for its Chinook and Apache helicopters, a report said Monday. Dow Jones Newswires, quoting an unidentified Indian Air Force official, said commercial negotiations would begin soon for the purchase of 15 Chinook CH-47F heavy-lift helicopters and 22 AH-64D Block III Apache helicopters. The transaction would mark a big ... read more


AEROSPACE
Moon crater yields impact clues

Study: Moon basin formed by giant impact

NASA's LADEE Spacecraft Gets Final Science Instrument Installed

Astrium presents results of its study into automatic landing near the Moon's south pole

AEROSPACE
More Driving And Imaging At 'Matijevic Hill'

Curiosity Team Switches Back to Earth Time

Survey of 'Matijevic Hill' Continues

Mars Longevity Champ Switching Computers

AEROSPACE
Voyager observes magnetic field fluctuations in heliosheath

New NASA Online Science Resource Available for Educators and Students

'First' Pakistan astronaut wants to make peace in space

Space daredevil Baumgartner is 'officially retired'

AEROSPACE
China to launch manned spacecraft

Tiangong 1 Parked And Waiting As Shenzhou 10 Mission Prep Continues

China to launch 11 meteorological satellites by 2020

China makes progress in spaceflight research

AEROSPACE
Crew Prepares for Spacewalk After Progress Docks

Crew Preparing for Cargo Ship, Spacewalk

Russian cargo ship docks with ISS: official

Packed Week Ahead for Six-Member Crew

AEROSPACE
Ariane 5 is poised for Arianespace's launch with the EUTELSAT 21B and Star One C3 satellites

Ariane 5 orbits EUTELSAT 21B and Star One C3 satellites

Arianespace's heavy-lift Ariane 5 flight is cleared for liftoff with EUTELSAT 21B and Star One C3

NASA's Vehicle Assembly Building Prepared for Multiple Rockets

AEROSPACE
Physicists confirm first planet discovered in a quadruple star system

Planet-hunt data released to public

New Study Brings a Doubted Exoplanet 'Back from the Dead'

New small satellite will study super-Earths for ESA

AEROSPACE
HTC and Apple reach global settlement

Nanocrystals and nickel catalyst substantially improve light-based hydrogen production

Apple still perched high, but seems vulnerable

Radar Production Readiness Review For Indonesia National Air Space Surveillance Program Completed




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement