Greensboro, North Carolina will be the home of Boom Supersonic’s Overture final assembly line. The company announced plans to develop a 65 acre plot into the “Superfactory” where it plans to complete construction of its flagship aircraft. The initial footprint will offer 400,000 square feet of workspace for the aircraft builds.
Selecting the site for Overture manufacturing is a significant step forward in bringing sustainable supersonic air travel to passengers and airlines.– Blake Scholl, founder and CEO of Boom Supersonic
Work on the $500 million investment is expected to begin later this year, with the facility online in 2024. Holding to announced timelines is not, however, one of Boom’s strong suits.
Company executives continue to suggest a 2025 rollout of the first aircraft and 2026 first flight. And while the company continues to claim that development of Overture is informed by things discovered during the assembly of XB-1, the two aircraft have many, many differences.
Overture will fly with new engines. Boom announced a partnership with Rolls Royce to research potential options, but a formal design and selection has not been made. At least not publicly. History suggests getting from engineering to delivery of new engine technology takes a few years.
Even if it is just “moving the knobs” to an existing engine core design, as CEO Black Scholl suggested four years ago, rather than inventing something that’s never been certified before, the testing and certification processes are not trivial.
Nor are those steps particularly easy for a clean-sheet aircraft design. The A350 and A380 went from first flight to commercial service in 18-24 months, with another 12 months for assembly of the first frame to become the test aircraft. The 787 also took about two years to go from first flight to commercial service, along with a longer buildout timeline. The A220 (then known as CSeries) took almost three years to make the jump from flight to commercial service.
All of those came from companies with long histories in aircraft manufacturing and certification. Boom will be doing it all for the first time.
Where’s the money??
Then there are the questions around funding the effort. Boom’s public data suggests ~$150 million from funding rounds over the years. Assume that the deals from JAL and United Airlines also contributed a small amount of cash, but not much. A couple US Government contracts also help, but the company would seem to be well short of the cash required to build this facility.
So where will Boom find $500 million to invest in a new manufacturing facility? And that’s only a small part of the likely billions required to develop a new aircraft program through certification to commercial entry into service. CEO Blake Scholl previously suggested $6 billion should be enough, though others believe the number to be higher.
Read more: Behind the scenes with Boom Supersonic
Getting XB-1 into the air – presumably coming later this year, with ground tests now underway in Colorado – should help the company attract new investors. But Boom will have to demonstrate that the market for the planes measures into the hundreds, not just dozens.
How many planes?
What is the true demand for supersonic commercial aircraft? Boom does not publicly share a target, but to justify the investment in full scale production the build rate would need to be significant. Researchers are less convinced.
A joint report published by researchers from Massachusetts Institute of Technology (MIT) and the International Council on Clean Transportation (ICCT) suggests “environmental limits will sharply constrain the potential supersonic market.” The MIT/ICCT study sees a market for just 240 supersonic aircraft by 2035, assuming zero restrictions on noise or fuel burn operating conditions.
With noise or emissions concerns that demand drops by 95% or more, essentially disappearing.
The study also projects fuel burn to be 7-9x per seat mile than a subsonic aircraft in 2035. Boom’s position has always been that its planes would be developed to support 100% Sustainable Aviation Fuel (SAF), sidestepping the conversation about emissions.
What about the “boom”
Which leads to another set of challenges. Since the early days of the program the company has touted a route map showing hundreds of cities that could be connected at higher speeds. During the site selection announcement Boom’s President and Chief Business Officer Kathy Savitt suggested that supersonic travel would open up new destinations as markets because people would be willing to visit them if the travel time were shorter.
But the company also would need to see significant regulatory changes for overland supersonic flight to become a regular occurrence. Thus far no regulators appear inclined to shift that stance.
Indeed when US regulators announced new proposed supersonic noise regulations in April 2020, they explicitly indicated that overland supersonic travel would not be approved.
At that time a Boom representative indicated “Overture is designed to fly at supersonic speeds only over water, and our business case does not require any changes to existing regulations, in the US and elsewhere, on overland supersonic flight.” This position is not supported by the theoretical route maps shared nor the discussions of how many city pairs could be served.
How much fuel?
The combination of increased fuel consumption and higher cost per gallon for SAF could lead to fuel costs 25 times higher per seat-mile than subsonic flight, should an airline choose to power Overture with 100% SAF. Assuming any airline can source enough SAF by 2030 to operate a fleet of supersonic jets.
Even at the most optimistic end of projected production growth, the industry will barely have enough SAF to meet subsonic emissions targets in 2030. Adding aircraft that burn significantly more fuel per seat won’t help.
Such optimism also might not be well placed. Boom expected to at least partially fuel its XB-1 demo program with SAFs from partner Prometheus Fuels. That is no longer the plan, however, with the desired fuels presumably unavailable. Instead the company will purchase carbon offsets for the handful of test flights.
Emissions are complicated
Finally, even burning 100% SAFs, the emissions impact from a supersonic jet might not be as climate-friendly as the marketing pitch would have you believe. The MIT/ICCT report suggests that, because of the way the SAFs burn and the higher altitude at which Overture would fly, “a small fleet of supersonic aircraft, providing between 0.1% and 0.6% of the total number of seat-km of the projected subsonic fleet, could cause ozone depletion equivalent to up to 8% of the total impact of CFC emissions” at their peak.
Ultimately, the mid-term radiative forcing of commercial aviation could increase by two-thirds, despite covering less than 1% of all traffic in ASKs and flying with SAFs. If, however, we assume SAFs remain cost-prohibitive and relatively unavailable for supersonic flight the radiative forcing is not as bad, but CO2 emissions go back up.
There is no true good environmental news about operations that require that much more fuel per seat-mile flown, regardless of how the fuel is produced.
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