Time to break free
For almost a half-century there’s been a clear speed limit on most commercial air travel: 660 miles per hour, the rate at which a typical-size plane traveling at 30,000 feet breaks the sound barrier and creates a 30-mile-wide, continuous sonic boom.
The ground-level disturbances that result—shattered windows, cracked plaster, maddened farm animals—have kept supersonic travel mostly off-limits since 1973, when the Federal Aviation Administration banned its use over US soil.
The ground-level disturbances that result—shattered windows, cracked plaster, maddened farm animals—have kept supersonic travel mostly off-limits since 1973, when the Federal Aviation Administration banned its use over US soil.
Sonic boom to hum
That may be changing. In August, NASA says, it will begin taking bids for construction of a demo model of a plane able to reduce the sonic boom to something like the hum you’d hear inside a Mercedes-Benz on the interstate.
The agency’s researchers say their design, a smaller-scale model of which was successfully tested in a wind tunnel at the end of June, should cut the six-hour flight time from New York to Los Angeles in half. NASA proposes spending $390 million over five years to build the demo plane and test it over populated areas. The first year of funding is included in President Trump’s 2018 budget proposal.
The agency’s researchers say their design, a smaller-scale model of which was successfully tested in a wind tunnel at the end of June, should cut the six-hour flight time from New York to Los Angeles in half. NASA proposes spending $390 million over five years to build the demo plane and test it over populated areas. The first year of funding is included in President Trump’s 2018 budget proposal.
Subtle differences
Lockheed helped create NASA’s design, using fluid dynamics modeling made possible in the past decade or so by increasingly powerful computers.
Together, Lockheed and NASA tested and mapped how subtle differences in aircraft shapes affect the supersonic shock waves they create.
Together, Lockheed and NASA tested and mapped how subtle differences in aircraft shapes affect the supersonic shock waves they create.
As loud as that luxury car
NASA is targeting a sound level of 60 to 65 A-weighted decibels (dBa), Coen says. That’s about as loud as that luxury car on the highway or the background conversation in a busy restaurant.
Iosifidis says that Lockheed’s research shows the design can maintain that sound level at commercial size and his team’s planned demo will be 94 feet long, have room for one pilot, fly as high as 55,000 feet, and run on one of the twin General Electric Co. engines that power Boeing Co.’s F/A-18 fighter jet.
Iosifidis says that Lockheed’s research shows the design can maintain that sound level at commercial size and his team’s planned demo will be 94 feet long, have room for one pilot, fly as high as 55,000 feet, and run on one of the twin General Electric Co. engines that power Boeing Co.’s F/A-18 fighter jet.
Let bygones be bygones
By comparison, the Concorde, that bygone icon of the Champagne-sipping, caviar-scarfing supersonic jet set, had a perceived noise level several times louder, at 90 dBa.
The plane’s advent in the 1970s helped lead Congress to pass the overland ban in the first place; its takeoffs and landings generated hundreds of noise complaints and wouldn’t come close to meeting today’s regulations.
Partly because of the ban, the Concorde wound up being a money pit for Air France and British Airways and was mothballed in 2003.
The plane’s advent in the 1970s helped lead Congress to pass the overland ban in the first place; its takeoffs and landings generated hundreds of noise complaints and wouldn’t come close to meeting today’s regulations.
Partly because of the ban, the Concorde wound up being a money pit for Air France and British Airways and was mothballed in 2003.
The fourth major obstacle
Don’t pack your bags for a supersonic trip just yet. The fourth major obstacle may be Washington, because the language of the 1973 ban will require the FAA or Congress to explicitly undo it even if technology renders it obsolete.
If only everything goes as planned
If everything goes as planned, NASA will test the demo plane over as many as six communities beginning in 2022, Coen says. That’s the first step toward appealing to lawmakers and regulators to lift the ban.
This time, he says, is different, because the toughest technical challenge has been solved. “We’ve got a lot of support in NASA and the administration and in Congress for making this happen. I’m pretty excited about our prospects.”
This time, he says, is different, because the toughest technical challenge has been solved. “We’ve got a lot of support in NASA and the administration and in Congress for making this happen. I’m pretty excited about our prospects.”
Comments
Post a Comment