Feature This week, a bipartisan bill was introduced that would allow supersonic flight over the continental US for the first time in 52 years, as long as they’re quiet.
The Supersonic Aviation Modernization Act would allow America’s aviation watchdog to issue licenses allowing flights over land “at a Mach number greater than one so long as the aircraft is operated in such a manner that no sonic boom reaches the ground in the United States,” the legislation states [PDF].
In February, Trump advisor and SpaceX CEO Elon Musk named it as one of the federal regulations he wanted to do away with. Now, a group of Republican politicians has taken up the cause.
The bill was introduced to the Senate by Senators Ted Budd (R-NC), Thom Tillis (R-NC), Mike Lee (R-UT), and Tim Sheehy (R-MT); and to the House of Representatives by Troy Nehls (R-TX), and Representative Sharice Davids (D-KS). If successful, it’ll give the Federal Aviation Administration (FAA) a year to comply and allow the next generation of supersonic commercial aircraft into American skies once again.
The backing of Budd and Tillis for the legislation is understandable. Boom Supersonic, which is building an 80-person commercial supersonic passenger jet, chose the US state the two senators represent, North Carolina, to build the Overture Superfactory it’ll use to manufacture the aircraft. In January, Boom’s single-seat XB-1 test aircraft, piloted by Tristan “Geppetto” Brandenburg, broke the sound barrier six times without a noticeable sonic boom. Boom boasts a number of big-name VCs and tech luminaries as funders, including AI poster child Sam Altman and LinkedIn founder Reid Hoffman.
NASA, too, has skin in the game, as it has been funding research into quiet supersonic flight for decades and last year fired up the engines on its X-59 supersonic test vehicle. The Register spoke to the pilot James “Clue” Less at the time, and he said the technology works and that the agency expects the first full flight later this year.
“The race for supersonic dominance between the US and China is already underway and the stakes couldn’t be higher,” said Senator Budd in a canned statement.
“The Supersonic Aviation Modernization Act paves the way to lift decades-old restrictions, allowing for faster air travel. This is a critical step to ensure America leads the next era of aviation.”
China is certainly making progress in the area. Beijing-based Lingkong Tianxing Technology is developing a ramjet-powered passenger aircraft that would travel at Mach 4, although it will need to be launched from a carrier rocket, which will bring it to an altitude of about 20 km (it’s designed for vertical takeoff), before achieving those speeds. It predicted the first test flight will be in 2026, with commercial flights kicking off in 2030, according to China Daily.
More prosaically, in March the Middle Kingdom’s state-owned commercial aviation biz published a paper describing the C949, a proposed supersonic passenger aircraft capable of carrying 24 to 48 people 50 percent further than Concorde at Mach 1.7 with a sonic boom of less than 90 decibels, but it’s not proposed to fly until 2049 at the earliest.
Nevertheless it’s clear there’s interest in commercial supersonic passenger travel, with Boom joined by Spike Aerospace and the now defunct Exosonic startup in the US. But that pesky sonic-boom ban is holding things up, claim Boom and others.
Why the FAA is going softly softly
The history of sonic booms over the continental US is contentious, mired in technology, politics, and the immense forces involved in supersonic flight.
America was the first nation to break the sound barrier back in 1947 with the purpose built Bell X-1 Glamorous Glennis, and by 1960 the US military had other fighters and bombers capable of Mach 2 – the Lockheed F-104 Starfighter and Convair B-58 Hustler respectively.
In the 1960s Britain, France, the US, and the Soviet Union all started work on commercial supersonic flight.
Getting up close and personal with Concorde, Concordski, and Buran
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The results were mixed. France and the UK decided pursuing separate projects was too expensive and joined forces on Concorde, which first went supersonic on October 1, 1969. The former Soviet Union technically beat them to it, taking its Tupolev Tu-144 past Mach 1 that June, but the aircraft was small, very noisy on the inside, and poorly designed, which it fatally demonstrated at the Paris Air Show, as you can see below.
Youtube Video
Boeing had been noodling with supersonic passenger jets since the 1950s but things stepped up a notch when the UK, France, and the-then USSR got involved and US President John F Kennedy funded a competition among aircraft manufacturers to come up with a prototype to match the Europeans.
The FAA held tests of sonic booms would do to Americans and their environment. In 1961 and 1964, the citizens of St Louis and Oklahoma City were deliberately subjected to repeated sonic booms in Operations Bongo and Bongo II. In the latter case, the test was originally scheduled to have aircraft generate eight sonic booms a day overhead for six months, but this was cut to four months after windows were broken and residents complained.
Congress cut off funding for the project in 1971 and Boeing dropped it. But the testing also gave legislators an excuse to ban supersonic flight altogether two years later, which limited the Concorde’s usefulness and commercial potential.
But after more than half a century of research by NASA and others, it seems we now understand supersonic flight well enough to silence the sonic boom such travel generates. The trick is to fly high and mount the engines on the top of the aircraft, according to the space agency.
Boom has augmented this by figuring out how to direct the sound waves from a sonic boom so that they refract away from the ground when they hit the warmer air at lower altitudes. They call it “boomless cruise” and claim the XB-1 proved the concept, as you can see below.
Youtube Video
“Supersonic flight without an audible sonic boom should obviously be allowed,” enthused Blake Scholl, CEO of Boom Supersonic on the news of the legislation.
“The ban on supersonic has held back progress for more than half a century. I urge Congress to pass the Supersonic Aviation Modernization Act supersonically, so we can all enjoy faster flights and maintain American leadership in aviation.”
Then again, he would, wouldn’t he? ®
