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Hear that sonic boom? NASA F-18 supersonic flights underway over Space Coast
NASA is studying sonic booms at Kennedy Space Center using F-18 Hornet jets with the goal of making quieter sonic booms in the future. Video by Malcolm Denemark
Two NASA-operated F/A-18 Hornets are responsible for this week's spate of sonic booms heard across northern portions of the Space Coast.
Though the former Navy Blue Angels – one a two-seater, the other a single – aren't based here, they have one-of-a-kind accommodations during their stay: Kennedy Space Center's historic 15,000-foot Shuttle Landing Facility.
The fighter-attack aircraft from NASA's Armstrong Flight Research Center in California, their pilots and other teams have converged on KSC to conduct research that could one day lead to supersonic flights in the commercial sector. But first, they'll need data from sonic booms – dozens of them – in an effort to make them quieter for future aircraft.
The Federal Aviation Administration prohibits supersonic, or faster-than-sound, travel over land due to the disturbing nature of sonic booms, which are continuously produced over a flightpath when an aircraft achieves Mach 1.
"We believe at NASA that the standard should not be a speed standard, but a sound standard," said Brett Pauer, sub-project manager of NASA's Commercial Supersonic Technology Project, during a Thursday conference with reporters at KSC's Shuttle Landing Facility. "So we are working towards providing data to other organizations to set the standard."
But why is the experiment, named Sonic Booms in Atmospheric Turbulence, or SonicBAT, focused on supersonic flight?
"In some cases, we can get to places twice as fast," Pauer said. "Do I really want to spend the whole day going out to California? Or can I travel out there and be back in the same day?"
The economic advantages, Pauer said, are also important to NASA, which believes research in high-speed travel can continue to solidify the United States' lead in aviation research, development and exports.
NASA is developing an experimental airplane called the Low Boom Flight Demonstration aircraft, or LBFD, which should achieve those speeds without producing a loud sonic boom. Its maiden flight could occur as soon as 2021.
Previously performed in drier climates, this round of more humid testing at KSC includes dozens of microphones stationed on the ground near the landing facility and even more attached to a TG-14 motorized glider that follows below the F-18's altitude of 32,000 feet.
Then, on a flightpath that heads south just off the coast of Cape Canaveral, the TG-14 cuts its engines to quietly gather data on sonic booms as they approach. It glides above the unstable portions of the lower atmosphere, or turbulence, which can be compared to ground audio for researchers to see how turbulence affects booms.
"We're collecting better weather data to characterize turbulence," Pauer said. "Some of these tests have been done before, but we didn't really have a good measure of the weather."
Researchers hope to gather data on a minimum of 33 sonic booms over the course of the experiment, meaning multiple flights and booms per day. Pilots will take to the skies six days a week excluding Sundays from 10 a.m. to 5 p.m. until August 31, but the experiment could run until September 7 if more than 33 booms are necessary or if weather doesn't cooperate.
"We've had seven flights up until this point and 16 or so booms," said Larry Cliatt, co-principal investigator for SonicBAT, noting that researchers want a range of different turbulences when collecting data. "Everything has been in that moderate range, so we're going to have to change our plan a little bit."
The timing modifications could include flying earlier in the morning to gather data on lower turbulence levels as well as flying later into the evening, which would produce greater turbulence.
But Space Coast residents need not worry – aside from being startling, sonic booms are not harmful or dangerous.
"The booms and sounds are startling," said Peter Coen, NASA's Commercial Supersonic Technology project manager. "There's no possibility of physical damage and there's no possibility of hearing damage."
Pauer said teams can calculate the footprint of sonic booms ahead of time, giving them at least some ability to "keep the boom foot off Titusville and other cities along the coast." That, however, depends on weather.
"It sounds like some of that is happening – we are getting a few booms in Titusville, but we are trying to keep that off based on daily weather," he said.
For Nils Larson, a former Navy pilot and chief test pilot at Armstrong Flight Research Center, flying from the historic landing facility and near the Vehicle Assembly Building has been a change of pace.
"When you're coming back, you can see the VAB over there," he said. "That's pretty cool."
Want to comment on the sonic booms? Officials recommend reaching out to NASA's public affairs office at Kennedy Space Center at 321-867-2468.