As Boom Seeks Engine, Airlines Mull Supersonic Use Case

 - September 6, 2022, 5:36 AM
The latest iteration of the Boom Overture features four engines and a contoured composite fuselage. (Image: Boom)

As Boom continues its efforts to convince an engine manufacturer to back its supersonic ambitions by investing in a new powerplant, how exactly airlines expect to capitalize on the promised Mach 1.7 speed remains a central question. The company says it will leverage 50 years of advances in aerodynamics, materials, and propulsion since the development of the Concorde to address the cost challenges the famously loss-making supersonic transport (SST) could never overcome. Critics say the introduction of a fuel-thirsty SST at a time established aerospace companies have turned their research and development efforts squarely toward environmental sustainability amounts to a fundamental miscalculation.

If recent commercial activity serves as any guide, potential operators might have at least lent some credibility to Boom’s claims that the use of 100 percent sustainable aviation fuel (SAF) can eventually render the operation of the Overture transport carbon neutral. In fact, the Overture now has drawn order commitments covering four identified airlines, including what it characterizes as firm orders from United Airlines for 15 and, most recently, American Airlines for 20.

While both orders came with a deposit, analysts question what performance guarantees Boom might have given at this relatively early stage in development, particularly in the absence of a commitment by an OEM willing to invest the funds needed to develop engines suitable for supersonic flight. Although in mid-2020 Boom announced that Rolls-Royce signed an “engagement agreement” to explore the technical requirements for powering the Overture, the UK engine maker told AIN that it reached a decision not to further participate in the program.

“We’ve completed our contract with Boom and delivered various engineering studies for their Overture supersonic program,” Rolls-Royce said in a statement. “After careful consideration, Rolls-Royce has determined that the commercial aviation supersonic market is not currently a priority for us and, therefore, will not pursue further work on the program at this time. It has been a pleasure to work with the Boom team and we wish them every success in the future.”

In a separate statement to AIN, American Airlines didn’t directly address the engine issue but acknowledged the “order” does not constitute a definitive purchase agreement. It also declined to discuss potential markets for the airplane, citing the early stage of the Overture’s development.

“As Boom continues to develop the Overture aircraft, we will work together to better understand where, when, and how it may best fit within our network and operation,” said an American spokesman. “With the aircraft not expected to carry its first passengers until 2029, it’s premature to discuss specific routes. Additionally, the specifics of the purchase are still subject to a finalized purchase agreement with future agreed upon milestones and terms, including customary requirements and conditions.”

Boom’s development schedule shows the rollout of the first prototype in 2025, giving it about three years to line up its suppliers, establish a facility to build the airplane, and assemble the planned four-engine, composite-bodied, 65- to 80-passenger Overture. In January Boom said it chose Piedmont Triad International Airport in Greensboro, North Carolina, as the site for its manufacturing plant, groundbreaking on which it expects by the end of this year. During July’s Farnborough Airshow, Boom revealed the final production design, including a new propulsion system based on four engines rather than two and a revised fuselage shape that features a larger diameter toward the front of the aircraft and a smaller diameter toward the rear. 

Boom’s aggressive development schedule has met with its share of skepticism, even among those who don’t dismiss the idea of introducing a supersonic passenger jet by a startup company at a time Boeing and Airbus don’t see a business case for it. Speaking with AIN following the American Airlines order announcement, Bloomberg Intelligence senior aerospace/defense and airline analyst George Ferguson pointed to Elon Musk’s SpaceX as an example of how a startup can overcome such a massive technological challenge. In fact, he said, a startup might glean a cost advantage over an established organization whose “stodginess” often leads to a resistance to taking chances.

Of course, the Concorde program relied heavily on government funding while Boom needs to succeed on a purely commercial basis. Boom claims to have drawn $600 million of its estimated requirement of between $6 billion and $8 billion to bring the product to market. Ferguson believes the program would absorb more than $10 billion to reach certification.    

But, perhaps more important, airlines will need to make a business case for operating a fuel-thirsty supersonic airplane, something they failed to do in the case of the Concorde. Boom claims the much lighter Overture will prove far more fuel efficient and reckons airlines will need to charge no more per ticket for a transatlantic flight as they now charge first-class passengers on a conventional jet. Ferguson questions the claim. “You need volume, meaning you need to be able to deploy the airplane on a lot of routes and you need to sell a lot of airplanes so you can push down the cost and amortize it over a larger run of airplanes,” he said. “The reason the Concorde died is that people weren't willing to pay up at that level—enough of them—to go across the Atlantic all the time, which again, is a very busy international market.”

While Boom estimates the Overture could serve as many as 600 markets around the world, Ferguson sees that most, apart from perhaps transatlantic routes between North American cities and Heathrow Airport, as difficult to justify economically. “By far, the most lucrative international market for all the U.S. airlines is the North Atlantic,” he stressed. “And Heathrow is traditionally the most important hub for U.S. business travel. So when this airplane comes out, it will probably arrive in Heathrow first from New York and, if you’re American Airlines, Chicago and maybe Texas.”

The economic calculus in regions such as Asia, however, makes its use there even more problematic, noted Ferguson. “You start to have challenges with price points you can get people to pay in Asia and the range. Because anything going supersonic is burning a lot more fuel.”

In a recent interview with AIN, Boom founder and CEO Blake Scholl acknowledged that coastal cities will benefit most from the Overture’s supersonic speed, but because the airplane would fly 20 percent faster than a conventional jet over land at Mach .94, the airplane will serve far more cities than most imagine when considering the purely transatlantic service the Concorde provided. Toward that end, the company has developed proprietary route optimization software that calculates the most favorable mix of time spent over water versus over land for greater time savings.

Having drawn a sales commitment from Japan Airlines, Scholl would disagree with the characterization of Asia as “problematic.”

“Imagine if Sydney, Australia were as easy to get to as Hawaii is today; imagine Seattle to Tokyo and an almost impossibly fast four and a half hours,” urged Scholl. “And what that means is that a business trip from the U.S. to Asia, which today takes a minimum of three calendar days, we can do in just 24 hours.”

The Overture’s performance specifications show a range of 4,250 nm, requiring a refueling stop for many transpacific routes. Boom notes, however, that while the Overture could fly 65 percent of all “viable” routes nonstop, the company has designed the refueling process to take only 30 minutes and accounts for stops in its claims that the airplane will fly from origin to destination in half the time of a conventional jet.

Scholl also addressed the question of seating capacity, which, he said, roughly matches a typical business class seat count of 65.

“So 65 seats makes it possible for airlines to achieve great load factors, not just here and there, but in hundreds of routes around the planet,” he said. “We think we're going to need hundreds, if not thousands of these aircraft, and it's going to touch tens of millions of lives every year. We found that 91 percent of business class passengers would buy a supersonic ticket tomorrow.”

Still, Ferguson doubts Boom’s claims that airlines could profitably fly the airplane while charging typical first-class fares and questions whether enough people will pay a premium cost for such time savings.

“If you look at how the world works today, the sweet spots are moving up in the number of passengers you can get behind the two pilots,” he noted. “Regionals are having trouble operating now because they can’t find the pilots and it just doesn’t make economic sense. And then, if you’re United and American and you peel the premium people out of your transatlantic flights, then what is your triple seven or 787? Is that all high-density leisure? What is that? Because the mix of passengers in those airplanes is what makes them profitable.”

Meanwhile, an aircraft’s profitability also depends on its ability to meet what will no doubt become ever more stringent environmental regulations. While the likes of Airbus turn their attention to new propulsion technologies based on hydrogen power, for example, the Overture will burn SAF, and a lot of it. Under the assumption that refiners will eventually produce and supply SAF in a zero-carbon manner, Boom insists that the Overture’s operation will also be carbon neutral, notwithstanding assertions by fuel producers that 100 percent SAF can reduce carbon emissions by up to only 80 percent.

“We need to go all the way to net zero and we challenge ourselves to do it from day one,” said Scholl. “How? By building the aircraft, just the first one, that's a hundred percent compatible with sustainable aviation fuel, no blends, no additives required.

“And this means that we can actually operate net zero. So we're not just making this a feature of the airplane. It's part of our airline agreements as well. Last year when United announced this order of Overture aircraft, they announced that from day one it'll be operated on sustainable aviation fuel on a net-zero carbon basis. And you're going to find that going forward, that's going to be a hallmark of every customer agreement we announce.”