QuickTake Q&A

Why Am I Not Flying on a Supersonic Jet?

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Inside Boom's Supersonic Flight Ambition

Sitting out a flight delay in a congested airport terminal can inspire some Walter Mitty-style dreaming about a better way to travel. It’s fair to wonder why we don’t fly any faster now than six decades ago, when the Boeing Co. 707 was the pinnacle of aviation technology. From 1976 to 2003, deep-pocketed passengers could fly the Atlantic at twice the speed of sound on a Concorde. But costs and noise complaints killed off that first supersonic jet. Now NASA, Lockheed Martin Corp., General Electric Co. and a number of startups see new designs and technology that could make supersonic flight a commercial reality.

1. How fast do these new supersonic planes fly? 

All of the supersonic aircraft projects under development will break Mach 1, or the speed of sound, which at sea level is about 760 miles per hour (1,223 kilometers per hour). The slowest aircraft under development plans to cruise at Mach 1.5 while the speediest will zip along at Mach 2.2. Back in the day, the Concorde would jet across the Atlantic at around Mach 2, connecting New York and London in about 3 1/2 hours--around half the time of a subsonic flight.

2. Would these be supersonic airlines or private jets?

Both —- entrepreneurs see promise in both fields. One school of thought says private aviation is the most logical forum for a supersonic jet. That’s where companies such as Aerion Corp. and Spike Aerospace Inc. are focused. But Boom Technology Inc. is working on a larger aircraft for airlines, seating 45 to 55 passengers, to fly Mach 2.2, and Spike has recently begun pondering the potential of stretching its design to seat 40. Spike’s S-512 jet will fit as many as 22 and cruise at Mach 1.6. Aerion’s AS2 is also a private jet, scheduled to fly about Mach 1.5.

3. Are these just Concordes updated with new technology?

No. Long before its 2003 retirement, the Concorde aircraft operated by Air France and British Airways had become infamous for its gas-guzzling ways, a core inefficiency that led to high fares. To pass muster today, a supersonic aircraft will need to be environmentally friendly on emissions, stable at subsonic speeds, reasonably affordable to operate and able to fly as often as today’s aircraft without onerous maintenance. And when it’s above the sound barrier, it will need to be much quieter than the window-rattling boom that announced the Concorde’s presence.

4. Won’t those sonic booms produce complaints on the ground?

At least at first, the new planes, like the Concorde, will reach supersonic speeds only over oceans. Most of the startups are working on their technology and not expending much effort to lobby regulators about easing the 44-year-old U.S. ban on civil supersonic flight over land. Elsewhere, regulators prohibit “nuisance” noise but not supersonic flight, per se. Thus, if you keep the sound of your booms low enough over Europe, Asia and other parts of the world, you can zip along as speedily as you please. The general view among many in the field is that as supersonic air travel matures, sonic booms will be mitigated to a point where they become quiet enough that the Federal Aviation Administration will gradually allow supersonic flight across the U.S.

5. How do you tamp down the boom?

NASA, among other organizations, is investigating new aircraft shapes and materials to prevent sound waves from merging into a sonic boom. The goal is to keep these waves dispersed across a wide area of points behind an airplane so that the resulting sound is about as loud as a luxury car humming along a freeway or the background conversation in a busy restaurant. In its research, NASA is targeting a sound level of 60 to 65 A-weighted decibels (dBa), about as loud as that fancy Audi on the highway. Concorde had a perceived noise level several times louder, at 90 dBa.

6. Does flying supersonic feel any different?

No -- it’s very similar to current commercial flights. On the Concorde, pilots would typically make an announcement once they’d throttled up to supersonic speed as there was no way to tell otherwise. One difference might be less turbulence, since during the cruise phase most supersonic aircraft will fly somewhat higher — 40,000-60,000 feet — than their subsonic peers.

7. Will supersonic flying be atrociously expensive?

Probably. But so were high-definition televisions when those were new. Over time, following the path of other industries, topping the sound barrier could become accessible to more people, especially those in fields where time truly is money and speed counts. Boom’s co-founder and CEO, Blake Scholl, says the company’s initial goal is for tickets to cost about the same as current business-class fares for comparable routes.

8. Why would supersonic flight work financially this time?

The industry is making a huge wager on technology — all the materials science, computing horsepower, dynamic modeling techniques and turbofan engine design that didn’t exist in the 1960s when the Concorde was developed.

9. Who’s bankrolling these plans?

Boom and Boston-based Spike say they have funding through their flight tests and both are taking customer orders now. Aerion is backed by Texas billionaire Robert Bass. Aerion is working on engine technology with GE, a pillar of the aerospace industry, while Airbus SE has also signed on as an Aerion partner. Boom is using a GE engine for its demonstration aircraft, which is scheduled to fly in 2018. Other companies such as General Dynamics Corp.’s Gulfstream and France’s Dassault Aviation SA have undertaken or continue to do research on supersonic aircraft.

10. When do we take off?

Don’t pack your bags just yet. In a 2016 report, NASA said it anticipates the introduction of business jets and small airliners with capacity to carry as many as 90 passengers between 2025 and 2035. NASA is budgeting $390 million through 2023 to build a demo supersonic airplane and test it over populated areas. And while Boom, Spike, Aerion and others are keen to begin producing commercial supersonic aircraft, plenty of hurdles remain -- not just the noise issue but also per-seat costs, engine emissions and regulatory certification requirements. Spike began flight-testing its SX-1.2 subsonic demonstrator in October with plans to work to supersonic tests in 2019 and a full-size S-512 supersonic jet, seating 18, for delivery in 2023. A larger, 40-passenger version could be developed around 2030. Boom plans to fly its XB-1 demonstrator next year, with a full-scale, 55-passenger version ready for delivery “in the early 2020s.” Boom says it has orders for 76 aircraft from five (undisclosed) airlines.

The Reference Shelf

  • Boom Technology’s FAQ on supersonic flight.
  • NASA’s summary of its supersonic flight research.
  • British Airways history: “Celebrating Concorde.”
  • A Bloomberg article on NASA’s research into quieter supersonic flight and another on how airlines weigh the bottom line on supersonic flight.
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