Why No One Will Build An Engine For Boom’s Supersonic Plane

Last year United Airlines placed an order for Boom Aerospace’s promised Supersonic jets. This summer American Airlines followed suit. Japan Airlines is an investor in the company. And yet most people in aviation think that the plane will never be built.

  • Is it just the skepticism of the status quo? Certainly aviation can be a stodgy industry, and it’s so heavily regulated we don’t see a lot of innovation. (If you start pointing to changes that have happened, you have to recognize how small they are over long periods of time.)

  • Or is there something about the company, or the plan, that’s simply not viable?

The most common refrain you hear is that they do not have an engine for the plane and that’s obviously a big deal. But why is that?

  • Boom promises to announce a manufacturer of an engine for its plane later this year, which is another way of saying they still do not know who is going to manufacture an engine for their plane.

  • GE, Honeywell, Safran, and Rolls Royce have all opted out.

  • Pratt & Whitney and CFM haven’t publicly taken themselves off the table. Engine Alliance makes A380 engines. International Aero Engines makes A320 engines. GE Honda makes regional jet engines. It’s hard to imagine Boom engaging a Russian or Chinese manufacturer at this point. Could they be left with Ukraine’s Ivchenko-Progress?

Credit: Boom Aerospace

If they can’t get a top tier manufacturer like Pratt & Whitney, they’re going to have a credibility problem (well, they already have one). And what they’re trying to accomplish takes real engineering know-how.

Here’s the issue. An engine manufacturer has to believe that the engine is going to sell well, in order to recoup develop costs and turn a profit. In fact it has to sell better than other things they might deploy development resources against.

It should be possible to accomplish what Boom wants to do. Supersonic jets aren’t a new idea, Concorde accomplished it 50 years ago. They’re just trying to engineer something that’s more fuel efficient – both for operating economics (so airlines can make money) and for environment concerns (airlines have made environmental commitments). They’re also trying to make something quieter. Combining with potential regulatory changes they want to be able to do some overland flying in order to serve more markets, and therefore sell more planes.

The problem is that engine manufacturers aren’t just betting on Boom Aerospace technology, they’re betting on a willingness of airlines to actually buy the planes. That doesn’t just mean place orders for the planes, either!

  • No U.S. airline ever purchased a Concorde, though orders were placed by Pan Am, Continental, TWA, American Airlines, Eastern, United and Braniff.

  • There were also orders from Qantas, Air India, Sabena, Air Canada, Lufthansa, and even Middle East Airlines and others which never came to fruition.

  • Only British Airways and Air France took actual deliveries of new aircraft.

  • The only other committed order came from Iran Air, and that was cancelled after the Iranian revolution.

Oddly Braniff did briefly own Concordes for a few hours at a time. They operated service between Dallas and Washington Dulles in conjunction with Air France and British Airways, but to do so they were required to take ownership of the plane for the flight segment in order to operate under their own certificate of airworthiness.

As well as changing flight crews the US approved documentation and procedures had to be present on the flight deck, which meant that the UK/French documentation had to be stored in the forward toilet.

There also had to be a change in the aircraft registration, while being flow on the Dallas – Washington – Dallas routes the “G” or “F” was covered up with white tape. On landing at Washington the ground staff would pull work ladders up to the tail and peel of the F- or G- registration numbers and changed them to an “N” with two letters and the numbers “94″ after that. This was repeated every time the Concordes landed in the US from Europe.

Credit: Boom Aerospace

As long as supersonic travel is more expensive than subsonic, the market will be limited. And limited markets make it tough to recoup development and acquisition costs. Airlines have a hard time making money operating only a couple of planes of a type. The plane needs to be capable of flying long distances, fuel efficiently, and carry large numbers of passengers in order to be economical on a large scale.

Otherwise the market has to be able to support fares significantly higher than for subsonic transport. The ultimate question is: how much is shaving 3.5 hours off of a transatlantic flight worth, and to how many people?

When American announced their order they said they made a non-refundable deposit but didn’t specify what that means. It could have been $1. They didn’t even produce a graphical rendering of the plane in American Airlines livery. And American didn’t spend the day promoting this on social. For some reason they made the move (claiming to have ordered more planes than United, even) but didn’t go all-out even with the P.R. Their pilots’ union even came out against the move, and they represent the people who theoretically would get to fly the thing!

It’s possible to build a supersonic plane, but inefficiencies and regulation killed the Concorde. Boom can presumably develop a plane, and a top engine manufacturer can produce an engine for it. But will it sell to airlines who see themselves able to operate enough of the planes, to enough places, with enough frequency – given a market that will pay a premium for the option – in order to buy enough planes and engines where the whole thing works out as a business?

That’s what Boom seems to be having a hard time convincing engine manufacturers to make a bet on, and while they’ve raised about $250 million in funding over the past 8 years they don’t have the resources to guarantee an engine manufacturer profitability.

Engines can cost billions of dollars to design and tens of millions of dollars apiece to purchase. It’s a huge bet for an engine manufacture, which Boom isn’t in a position to fund, and a need to sell large numbers of engines just to break even. If a manufacturer can’t sell several hundred engines they won’t recoup their development cost, after recouping production costs, let alone turn the project profitable.

It’s as much about skepticism of the market as skepticism of the plane, or put another way, to the extent that it’s about the plane it’s not whether the plane is possible, or an engineering marvel, but whether the plane will be good enough, to be so compelling, that airlines cannot turn down placing orders and taking actual delivery in large numbers.

About Gary Leff

Gary Leff is one of the foremost experts in the field of miles, points, and frequent business travel - a topic he has covered since 2002. Co-founder of frequent flyer community InsideFlyer.com, emcee of the Freddie Awards, and named one of the "World's Top Travel Experts" by Conde' Nast Traveler (2010-Present) Gary has been a guest on most major news media, profiled in several top print publications, and published broadly on the topic of consumer loyalty. More About Gary »

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  1. I’m more skeptical. If Boeing or Airbus were developing this plane, the engine manufacturers would develop the engine. But they’re not, and Boeing and Airbus don’t want the competition, so they quietly send word to the engine manufacturers that they don’t want this thing to succeed, at least until Boom has sold out to us. Then you can develop it.

    I hate to be conspiratorial, but there’s at least a decent chance that the above is correct.

  2. Until a company can design supersonic travel that is competitively priced, supersonic concepts will be nothing but vaporware.

    Airplanes don’t run on fuel… They run on MONEY!

  3. Dalo: GOOD ONE! I wonder how many readers understood your comment. We are showing our ” experience ” The stories about the brothers trying to by parts from GE are legendary.

  4. Everything about this aircraft is wrong. It’s entire design is old thinking. I won’t get into the technical issues but, having been in aerospace R&D program management, I have one observation. When you see a major rethink in design such as the recent engine and operating specification changes, someone is missing something. And, that something ain’t something small. It reminds me of Tesla’s early deployment of charging stations: seemingly positioned by a cell phone engineer rather than a driver.

  5. A few minor, albeit important, clarifications:

    CFM is a JV between GE and Safran, P&W is not involved.

    Engine Alliance is a JV between P&W and GE – they make one engine, the GP7200, one of the engine options on the A380.

    GE Honda only makes the HF120 for the HondaJet (GE does all the production) – they do not make regional jet engines.

  6. “The ultimate question is: how much is shaving 3.5 hours off of a transatlantic flight worth, and to how many people?”. Even given that this actually characterizes what the ultimate question is, then it is heavily supported by data from Concorde flights to be a very large number.

    A more accurate phasing would take note that Boom, unlike Concorde, is aiming for transoceanic routes generally, and in that respect there are dozens of routes.

    The discussion also neglects to mention that the Boom engine could be used for other planes/UAVs.

    Booms problems appear to be more sublte. Part of it may be their unwillingness to grant a exclusive to one powerplant supplier — at least for a period. On this and other issues, Boom needs a new CEO. The current management is too engineering-heavy.


  7. @C_M, No, honestly there’s very little chance that your analysis is correct there. Boeing and Airbus really aren’t worried at all about Boom’s vaporware. If either one of them thought SST was actually viable, they could have easily purchased any of the myriad of startups claiming to be working on them quite easily. Or just designed one themselves. Gary’s analysis is spot-on. Designing a new jet engine up to modern standards costs billions up front. No engine manufacturer is going to design a clean-sheet engine unless they know they can sell thousands of them. Suffice it to say that there is no evidence that demand exists – or will exist in the foreseeable future – for even hundreds of SSTs, let alone thousands. Even in the era of Concorde where many thought SST was sure to be the future, ultimately only 20 airframes were ever built.

    There’s frankly just almost no reason at all to believe that thousands of people per day are going to pay far more than business-class fares in order to save 3 or 4 hours crossing the Atlantic vs. just taking a far more efficient normal jet with a flat-bed seat.

  8. Hmm, pilots against a technology that reduces block hours, who would have thought. Even worse, it might require EU/UK based crew to do out and back of LHR/EWR/LHR with no layover. Why would pilots possibly disagree? It boggles the mind.

  9. dalo and Mike, count me as another reader. Of course the J79 could never be a consideration. Its non-afterburning SFC sits around 1 and its afterburning SFC sits above 2. It’s a brute force instrument and it’s way too fuel inefficient for commercial aviation.

    Separately, commenters to various articles have suggested that hyper-sonic flight will leap-frog over super-sonic flight. You’re talking two completely different types of engines. As Gary suggests, engine manufacturers have to pick where they are going to put their R&D money.

    Recent reports suggest that there have been changes to the aircraft’s A-level and B-level specs. If correct, I would be inclined to believe that major aerospace partners are measuring their commitment to the program. This is compounded by the following.

    L3, where to start? Traditional airframe design creates sonic booms during super-sonic flight. As so many have noted, with the presence of sonic booms, super-sonic flight has heretofore been restricted to trans-oceanic routes. This reduces the utility and economic viability of such an aircraft. Even if the aircraft became a reality, as a “program,” I doubt it would be a financial success.

    The FAA has stated that an aircraft may travel super-sonic in U.S. airspace if the aircraft’s sonic boom is below a certain threshold sound level at ground level. I believe but am not completely certain that the threshold level is 37 decibels.

    Since the mid-1990s, NASA, Gulfstream, and certain other aerospace firms have been jointly involved in airframe fundamental research. The objective is to lower the sound level of sonic booms. In short, you want an airframe contour that creates detached shock waves that are self-canceling/diffusing. (Think Bose noise-canceling headsets.) Currently, the best designs are producing sound levels of 43 to 48 decibels.

    The renderings of the airframe seem to be consistent with a 1960s Concorde-like design and not consistent with a noise-attenuated airframe design. The engine nacelles seem strapped on as opposed to being conformal, which is an efficiency issue as well. Sure, it will fly. But, no, it will not meet the FAA’s sound threshold when flying super-sonic. And, no, it will not be as fuel efficient as it could be. So, the aircraft will have limited utility. I think major aerospace partners look at these design issues and further measure their commitment to such a program.

    These are the easiest talking points.

    This is not a conspiracy. I think the company fails all by itself.

  10. To call the aviation industry “stodgy” is disingenuous. The *commercial* aviation industry is ruled by regulations written in blood. Other people’s blood. Over decades of experience, some of it tragic. There is careful consideration of the past baked into any new advancement—and for good reason. When one flies at/above fatal altitudes and airspeeds, the risk is genuine and immutable. To expect a major aircraft engine manufacturer to traipse into this endeavor willy-nilly is a huge ask. It will not happen without incredible (read-unattainable) amounts of money, much of it thrown down a very deep hole never to be seen again.

  11. Which then limits it to trans-oceanic routes. Which then limits the aircraft’s marketability. There’s something to be said about harmonizing an airline’s fleet.

    If the company accepts noise, they will still need to equip the aircraft with a super-cruise-type engine. If they can demilitarize an existing super-cruise engine, a la the J85, fine. But, again, to Gary’s point, engine manufacturers need a sense that such a demilitarized engine would be as successful as the J85 before they commit.

    I tend to agree with other commenters who suggest a leap-frog to hyper-sonic commercial travel. How does this solve the noise problem? How would such ships fly trans-continental? For design reasons, hyper-sonic aircraft must fly at substantially higher altitudes and sonic booms are better able to dissipate. When the hyper-sonic Aurora was flying in the 1990s, its sonic booms were unnoticed to all but ultra-sensitive seismic sensors. At the time, USGS/CalTech technicians could track “something” traveling at tremendous speed. They just didn’t know what “something” was.

    Along this line, here’s a simple question: where is Richard Branson putting his money?

  12. @Aviators99: “They recently stated that they are no longer interested in making it quieter.”

    Source please.

  13. The only way Boom pulls this off at this point is by using engines that already exist. If they keep the size and weight of the plane small and light enough they could probably use the Rolls Royce Pearl 700 which produces 18250 lbs of thrust. 4 of those tweaked just right could keep it fuel efficient and cost effective. Basically engines in the large fast private jet sector may be able to pull off the speeds and fuel efficiency they are seeking.

  14. Simply not viable to commence a certification project and new engine development. Even off the shelf with “tweaks” would be a massive undertaking in a climate where SFC and efficency is king and both airframers and carriers are hurting financially. Even taking the Olympus and subjecting it to current materials tech, geometry and controls system updates would be a massive undertaking. I love the idea but it is fundamentally flawed.

  15. Reading this article leads me to think that what is needed for a modern day supersonic passenger aircraft is an adaptive cycle engine, such as the ones GE and Pratt & Whitney are developing for the F-35 and NGAD. These are touted as offering improved characteristics over existing low-bypass turbofan jet engines in terms of being able to trade performance for economy (and vice versa) as required and would potentially be an ideal fit for an aircraft that wants to rapidly accelerate and then cruise at supersonic speeds whilst minimising overall fuel consumption.

    Given that only one of these engines is likely to be selected, there exists the possibility that there will be an unwanted engine looking for an application, however, whether either of these engines would actually meet the requirements of commercial airlines who would operate said supersonic aircraft is another matter. Some more R&D would undoubtedly be required and I would imagine there’s an issue around military secrecy too which would complicate the process further.

    I know that we have had these aircraft in the past, but it feels to me like in some ways Boom Aerospace are slightly too far ahead of the curve in terms of engine design, not to mention mitigation of sonic booms (as NASA is currently about to be investigating), for this to actually go anywhere.

  16. The Boeing SST was designed to be more economical than the 747. It would have dropped off passengers at Heathrow, refueled and dropped off passengers at JFK when a 747 was deplaning at Heathrow. Why? A cruising speed of 1800 mph. That fixes the numbers. It is all about the dollars per passenger seat mile. QED.

  17. I summed it up in 2 words… too expensive. No one is going to buy this money suck project to make no money… no one… enjoy…

  18. I wish them well but this is quite the challenge. Not technically – to make it work as a business. Don’t quite understand the arguments about regulation – physics and economics are the biggest hurdles. The Concorde was an amazing machine, very well done. But not enough people were willing to spend on the premium to make it economically viable in the long run. Economics built the coffin for the Concorde and put most of the nails in it. The sad crash in 2000 put in the final nail. I wish these guys the best but the cost of what it will take to do what they want to do – and the thin return on the investment – will I think doom anyone’s willingness to commit to build a motor.

  19. Do not underestimate just how many incredibly rich people there are now post-pandemic. The only thing they can’t buy is ‘more time’. Supersonic civilian air travel is, without question, going to return. Sadly, it is likely to be limited to the general aviation market. Here’s to hoping that Boom can get their commercial airliner off the ground!

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