Tech

September 18, 2013

NASA Dryden engineers capture dramatic supersonic shockwave images

Supersonic shockwaves are clearly visible in this dramatic schlieren image of a NASA Dryden F/A-18 aircraft flying at a speed of Mach 1.1, and an altitude of 44,000 feet during a GASPS flight.

 

Elusive schlieren images of supersonic shockwaves emanating from NASA F-15 and F/A-18 aircraft flying at supersonic speeds were captured during recent pilot proficiency flights.

The images were gathered by a twin telescope and digital camera system on the ground at NASA’s Dryden Flight Research Center to manually test the Ground-to-Air Schlieren Photography System, or GASPS, that was developed by MetroLaser, Inc. under a NASA Small Business Innovation Research project. Schlieren photography is a technique that enables imaging of airflow, with special illumination making changes in air density—in this case the density of the shockwaves—apparent.

“Our team was able to photograph truly spectacular images showing the shockwaves of full-scale supersonic aircraft in flight,” said Ed Haering, Dryden’s GASPS principal investigator.

This dramatic schlieren image of supersonic shockwaves streaming from NASA Dryden’s F-15B aircraft was captured while it was flying at Mach 1.38 at 44,000 feet altitude during a GASPS flight.

“For new quiet supersonic aircraft designs, computer simulations and wind tunnel tests are used to model how to minimize the loudness of the sonic booms, but the simulations and wind tunnel tests have challenges in accurately modeling the flow around engine inlet and tail regions,” Haering explained. “We can use these images to validate our computer simulations and wind tunnel tests, giving us confidence that we can properly design supersonic civil aircraft of the future. Then we will be able to fly over land at about double the speed of current civil aircraft without bothering people on the ground,” he added.

Engineers used a thumb trigger to manually snap digital images when the aircraft passed in front of the sun. Later tests will most likely use aircraft GPS tracking transmitted to the GASPS system on the ground to automatically activate their shutters for more precise imaging.

Previous schlieren photography used an elaborate series of lenses, bright backlighting, and other devices to capture supersonic shockwaves on film as darker or lighter streaks against high-contrast backgrounds like the edge of the sun. Versions of this ground-to-air technique used in the 1990’s required extremely precise alignment of the optics as well.

In contrast, the GASPS project uses just a telescope and a digital camera, leaving the difficult aspects of the work to be performed post-flight using image processing software. This improved method greatly relaxes the precision needed, with the post-mission digital processing of the imagery employed to visualize the shock wave patterns.

With the sun as the light source, supersonic shockwaves are clearly visible in this spectacular schlieren image of NASA Dryden’s F-15B Research Testbed aircraft as it streaks by at Mach 1.2 at an altitude of 40,000 feet during a GASPS flight.

Schlieren imaging provides a clearer understanding of the location and relative strength of supersonic shockwaves. This represents another tool in the growing toolbox of techniques used by NASA researchers designed to characterize sonic booms.

This latest project continues a long series of sonic boom reduction research by NASA.  The 10th anniversary of the NASA/Northrop Grumman F-5E Shaped Sonic Boom Demonstration (SSBD) project’s first reduced sonic boom flight was Aug. 27, marking another milestone in NASA and industry’s path to lower sonic booms. A new NASA aeronautics book, “Quieting the Boom: the Shaped Sonic Boom Demonstrator and the Quest for Quiet Supersonic Flight,” by Lawrence R. Benson details the project. The book was recently posted on-line as a NASA eBook at http://www.nasa.gov/connect/ebooks/nasa-ebook-quieting-the-boom/.

The GASPS project is supported by the NASA Aeronautics Research Mission Directorate’s High Speed Project, which is working to reduce the intensity of sonic booms in order to make commercial supersonic flight over land practical.




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


 
 

 

Headlines November 24, 2014

News: Hagel said to be stepping down as defense chief under pressure - Defense Secretary Chuck Hagel is stepping down under pressure, the first cabinet-level casualty of President Obama’s Democratic majority in the Senate and a beleaguered national security team that has struggled to stay ahead of an onslaught of global crises. Afghan mission for U.S....
 
 

News Briefs November 24, 2014

Fog forces five U.S. choppers to land in Polish field Officials say that that fog forced five U.S. Army helicopters to make an emergency landing in a Polish field and spend the night there, the second such incident since September. The U.S. Army said 15 soldiers were moving equipment to their base in Germany Nov....
 
 
Air Force photograph by Samuel King Jr.

Navy’s first F-35C squadron surpasses 1,000 flight hours

Air Force photograph by Samuel King Jr. An F-35C Lightning II aircraft piloted by Lt. Cmdr. Chris Tabert, assigned to Strike Fighter Squadron (VFA) 101, flies the squadron’s first local sortie. The F-35C is the carrier va...
 

 
boeing-SC-787

Boeing South Carolina begins final assembly of its first 787-9 Dreamliner

Boeing has started final assembly of the 787-9 Dreamliner at its South Carolina facility. The team began joining large fuselage sections of the newest 787 Nov. 22 on schedule, a proud milestone for the South Carolina team and a...
 
 
Lockheed Martin image

Ball Aerospace equips Orion mission with key avionics, antenna hardware

Lockheed Martin image Ball Aerospace & Technologies Corp. is providing the phased array antennas and flight test cameras to prime contractor Lockheed Martin for Orion’s Exploration Flight Test-1 (EFT-1), which is an u...
 
 

Salina, Kansas, recalls anniversary of shuttered base

It has been 50 years this month since the announcement that Schilling Air Force Base was closing rattled Salina residents. The Salina Journal, which carried news of the closure in its Nov. 19, 1964, editions, reported that the economic disaster then spared no part of the community – real estate, retail, civic involvement, church attendance,...
 




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>