Dude, where's my supersonic jet? | Hacker News Reader

Dude, where's my supersonic jet?

rationaloptimistsociety.substack.com

131 pointsnoleary302 comments

Regarding the “supersonic is now viable because LNG” argument, but for a different reason than usual.

Even if supersonic flight becomes cheaper via new fuels or propulsion, that doesn’t reset the baseline. The same advances (materials, engines, fuel handling, manufacturing) will also apply to subsonic aircraft, where the physics are already far more energy-efficient. So if supersonic gets “cheap,” traditional jets will get much cheaper. Airlines will always arbitrage toward the lowest energy-per-seat-km for most routes, and supersonic flight is structurally disadvantaged there (drag, noise, routing constraints).

Historically, faster transport doesn’t replace slower transport wholesale; it creates a premium tier while pushing the mass market down to a lower cost/energy equilibrium. Concorde didn’t kill widebodies, widebodies got cheaper. My intuition: supersonic may of course exist as a niche (time-sensitive, premium), but its biggest impact would be indirect, accelerating efficiency gains that make conventional aviation even more dominant and cheaper.

And even then, it is only so premium. As you could have a speedy economy seat on the Concorde or a lie flat bed on a widebody by the time Concorde left service. The speed benefit largely goes away if I can travel while sleeping.

Halving travel times would be really good, the problem is that supersonic never had the range to make the difference meaningful.

JFK-London in 3 hours vs 6 is pretty tolerable if you’re more comfortable for the 6 hours. SFO to Shanghai in 7 hours vs 14 would be a lot more compelling but Concorde could not do transpacific range.

I actually prefer a 10+ hrs business class flight over a 6-7 hrs flight. At least you can get a full night of sleep

Depends on the time zone change. From Europe to with Africa sure a 12 hour figggt is great. If I travel business London to singapore i get far worse jet lag than if I fly via the Middle East and break my journey for a few hours.

Past like hour 12 it becomes really draining. I used to fly JFK to HKG and that was an ordeal; I can’t imagine the newer super long haul like London to Perth.

That's the just flight time, but you've also got travel to/from the airport, parking, maybe shuttle bus/monorail, and checking/security/wait time at the airport as well.

So, add an hour for door-door travel to airport, and 2-hr before flight check-in, and now the comparison isn't 3 vs 6hr but 9 vs 12hr, which doesn't sound so worthwhile, although no doubt there are customers for it.

For longer flights it'd be much more attractive, but this is never going to be an affordable service for the masses.

A service where your limo drives out to the aircraft, with all searches and paperwork pre-done, would have about the same time gain as going Mach 1.7 vs. Mach 0.85.

And probably fewer regulatory hurdles (and I don't mean that because they wouldn't be considerable...)

Underrated observation. The low-hanging fruit is all in the office/home-to-takeoff and touchdown-to-office/home blocks on each end, not the time in the air. The commute, checkin, security, airport transit, boarding, and taxiing are the time-sinks worth optimizing.

private jets already solve these problems.

Which already is a bad signal for the article's argument. We already have a way to significantly reduce that travel time and it's a niche.

Could Boom Supersonic or whoever actually survive selling only to a hundred Taylor Swifts? How are they going to keep the lights on for the 30 years those jets fully saturate the market?

That's a real service. Some airports, including LAX and London Heathrow, allow a "tarmac transfer", where the limo goes directly to the plane. [1][2] Cost is $200 to $1000. That could save an hour or more at each end.

VIP Terminal Access: Skip the standard queues and enter exclusive VIP terminals where you’ll receive expedited passport control, security checks, and personalized services, all while enjoying luxury amenities. Avoid long security lines with expedited security processing, ensuring you spend minimal time in the airport.

[1] https://limossist.com/tarmac-transfers/

[2] https://airssist.com/airport-tarmac-transfer-service/

But for the private jet market, the reduction would be huge. They're already paying a premium to save time. The top end will pay an even larger premium to save even more time.

I agree with you that for commercial, anything other than super long haul (which is technically very hard), the time saving advantages are much less compelling.

Cutting 22 hours Sydney to London to 12 would make a big difference though.

There's no real way to make that much time on a plane bearable even if you had a lie flat bed: that's just a ton of time in the air.

Australian international travel would be the premier market if you wanted to travel supersonic (also our coastal cities mean most departures could accelerate immediately).

The irony is that supersonic jets don't have the range to realize the time savings over such long routes.

Having done Dallas<>Sydney a few times, going from 17 hours to ~8.5 hours would be huge.

Highly depends on the person. Over 6 feet tall with screws and rods holding my spine together, even a lie flat is not very comfortable, and not having to spend my first day or two at my destination decompressing before I actually enjoy the trip would be pretty valuable to me. The only way to achieve that is less travel time, but even so I'm not sure reducing the time in air would be enough when you add in travel to and from the airport, plus taxi time on the runway. It wouldn't be nothing, though, and I'd definitely pay for it if it made a difference.

Problem is broad market trends don't care about me personally. There have to be a lot of people like me with both sufficient injuries and sufficient money and there probably are not.

Some planes used to have lounges and bars and such.

Would maybe have helped? I know I'd pay more for that.

Some planes still do e.g. Emirates A380 has a bar, Qantas' has a lounge (though apparently it's not very good).

Is it actually not very good, or did you read an online review by someone who got miffed for some petty reason so they're magnifying the tiniest things?

Hm... I don't know that I buy your argument, since just as you point out, traditional jets are already very optimized. One would assume there's less slack to pick up.

Fuel is a huge component of the cost of operating an airline, sometimes the largest component. LNG is a much cheaper fuel, so I can see it being adopted for mainstream aviation eventually. Existing jets could technically be converted, though the conservative nature of aviation would demand many years of testing before use on commercial flights.

It's also a pathway to incremental decarbonizing of aviation. LNG releases less CO2 per unit energy than oil, and methane can be produced biologically or synthetically which offers a path to total (net) decarbonization.

> Even if fossil LNG is used, it releases less CO2 per unit energy.

However released methane has a significantly worse greenhouse effect than CO2 (80x over 20 years, 28 over 100, 8 over 500 — this decreases because methane has an atmospheric lifetime of 12 years and decays to CO2). So leakage in the LNG chain is a massive problem.

Jet engines don’t release the methane, they burn it, and they’re very efficient. And jets don’t leak fuel, that would be very hazardous.

LNG is not a nice liquid at room temp, so more use means more in transit and more complicated supply chains, meaning more leaks.

Right, but are leakage rates high enough to make this a concern? Every methane molecule leaked is a methane molecule not burnt, so there's already a strong profit maximisation incentive to leak as little as possible (even before considering loftier goals like workplace safety or externally imposed regulation).

> Right, but are leakage rates high enough to make this a concern?

According to a recent IEA report, 30% of the LMG supply chain’s greenhouse impact is methane leaks.

> there's already a strong profit maximisation incentive to leak as little as possible

That runs against the stronger profit maximisation incentive of doing as little maintenance and being as cheap as possible.

A major difference is: there is an economic incentive to not leak methane since a leak is wasted fuel, while the economic incentive for CO2 is to make more of it.

> A major difference is: there is an economic incentive to not leak methane since a leak is wasted fuel

That economic incentive only goes so far given the entire point of the discussion: LNG is cheap. Per the IEA's recent "Assessing Emissions from LNG Supply and Abatement Options":

> Our analysis estimates total GHG emissions from the LNG supply chain are around 350 million tonnes of carbon dioxide equivalent (Mt CO2-eq) (this excludes emissions from combustion of the natural gas at the point of use). Around 70% of this is in the form of CO2 emissions which are either combusted or vented, and the remaining 30% is methane that escapes, unburnt, into the atmosphere.

> ...

> Globally, the average GHG emissions intensity of delivered LNG is just under 20 g CO2-eq/MJ, compared with an average of 12 g CO2/MJ for natural gas supply overall.

Traditional jets have a long inventory and regulation cycle but for example retrofitting a A320 to LNG appears to save 20%:

https://repository.tudelft.nl/record/uuid:63b89022-ac68-426d...

Which still puts it behind the 787 let alone the generation that comes next.. But you aren't going to succeed at making any new inventory without every possible efficiency improvement to drive sales and retirement of older inventory.

Aeronautical engineering isn't that linear. A technology suited to one application may not be helpful in another. It's one of those "hardware is hard" fields.

> Airlines will always arbitrage toward the lowest energy-per-seat-km for most routes

That's a second order effect from fuel being the primary cost, and thus the primary lever to either make more profit or improve competitivity.

If airlines could triple their profits by doubling their fuel burn they'd happily do that.

I agree with your market analysis. Private jets are often referred to as "time machines" given how much time HNW / exec travelers can save. There's a market segment that's willing to pay a high premium for reduced travel time.

For most of my trips, a huge % of the travel time is outside the actual flight time. Trip to the airport, security, boarding, waiting to take off, and reverse on the other side (with addition of potentially getting a rental car). This can be solved without supersonic solutions (e.g. flying private), but adoption is low for business travel – is it too expensive?

Separately, I wonder if a lot of the demand is also obviated by in-air wifi.

> adoption is low for business travel – is it too expensive

Yes. Most companies won't even spring for business/first class, which is 10-20% the cost of a charter. Unless your time is both limited and worth 4 digits per hour, it's not worth it.

You might also look at “semi-private” solutions like JSX, if they go where you want to go. Should significantly cut down on the time outside of the flight itself.

Private jets don't go faster. They can just land closer to your destination and make you skip all the annoying airport stuff.

Want to reduce the time it takes to get somewhere? Reduce the security circus at airports. This will cut off way more of the travel time for the majority of flights, wothout the downsides of supersonic planes.

TSA in the US is a jobs program

You're going to have some security in any case and have since at least the 1970s. And it typically takes me <10 minutes even if I allow some extra time for the potential that it could be longer if it rarely is with pre-check.

Yes but compare it to trains or busses. If I want to take the train/bus I make sure I am at the station 10 minutes before the vehicle departs.

In my experience the good time to arrive before a flight (with luggage to check in) is roughly 1 hour before (and this nearly wasn't enough in some cases).

If we talk about a short flight that can add more than 50% to the flight duration on the ground for (1) putting the luggage somewhere, (2) going through the security funnel and (3) getting to the plane.

Sure I get why things are shaped the way they are, but if I wanted to cut travel time I would first have a long deep look at that.

If you are flying to/from popular destination like Europe in August, you can stuck for two hours just in the luggage drop queue. Extra hour for security check queue and one more for border/customs check queue. Another 20 minutes just to walk to the gate.

Depends on the airport and your luck, of course.

I admit I just avoid Europe at that time of year, although I'd note that Eurostar from the UK to the Continent can be pretty bad too at any time of the year.

You are missing an important factor in the baseline here, the cost of time.

Right now, a cheap 7 hour each way round trip between NYC and London is ~500$.

Halve it to 3.5 hours each way with a supersonic plane, saving a total of 7 hours.

Now, the real question is then, what's one hour of your time worth to you or whoever is paying for your flight?

If improvements to subsonic aircrafts bring down the price to 200$ instead of $500, people would still be willing to pay 200$ + 7 * $HOURLY for a faster flight.

Even with a low-ish estimate of $HOURLY = 50, it would make sense to take the supersonic fight if the price was $500, which it could conceivably be brought down to, and the market has already validated to be willing to pay.

Business passengers aren't out here paying for their own tickets. Their employers are paying for those tickets, so the question is whether or not companies care about the time their salaried employees spend in the air, when those employees can be just as productive on the business-class wifi.

Assuming they're even micro-managing employee productivity to the degree that they really care about working on a plane. Personally, I never purchased plane wi-fi even when I could have expensed it.

Most employers book the most convenient flight for their employees, and not really care much but saving a few hundred dollars.

That's a reasonable argument for businesspeople, but it doesn't apply for the greater public. Because chances are that except in a minority of situations, they are on holidays and during that saved time they wouldn't be working at all anyways.

People who could perfecty afford a $2,000 plane ticket still fly with $400 ones (as long as they are within reasonable standards), for example because they have a desired budget for a given trip, and the expensive option would blow it away, so they don't mind the extra time.

Have you ever picked a slightly more expensive nonstop flight instead of one with a layover for a vacation?

This is similar. 3.5 hours vs 7 hours is a pretty good difference.

You can take a 3.5 hours flight in the morning and have energy to see a city the whole day after that. Maybe not after a 7 hour flight unless you are a pretty experienced and motivated traveler who can sleep the entire flight and have the mental energy to enjoy new things after that.

That depends entirely on how much "slightly more expensive" is. For the vast majority of the travelling public, they'll choose the cheaper option and we know that because that's what they choose already.

If that was the case, most nonstop flights between non-major cities would not exist at all.

Most major airports are at their physical limit in terms of both airfield and gate traffic and are charging extremely high gate fees. I'm not in airline logistics but I would bet my bottom dollar that is the true constraint in having more traffic fly into hubs.

I do actually think you're right, but the counterpoint is that airlines have slowed down all their flights to save money, and no one has come in offering a faster flight in exchange for more money.

Maybe the delta just isn't enough to matter? Or maybe people aren't willing to pay for it.

I’d say the tech isn’t there yet.

Remember we’re still pretty early in the history of aviation.

We know the tech is there. It used to take 45 minutes to fly from LAX to SFO. Now it's 70 minutes. That's not a tech problem, it's a logistics/fuel problem. But if people really valued the difference, they would offer a 45 minute flight for more money.

Or when I leave from Boston to go to the San Francisco, and we leave an hour late but we still arrive on time, it's because they were able to go faster. We certainly have the tech to go faster.

So why can't I buy a BOS->SFO flight that is one hour shorter for more money? Probably because of a lack of willingness to pay.

> Or when I leave from Boston to go to the San Francisco, and we leave an hour late but we still arrive on time, it's because they were able to go faster. We certainly have the tech to go faster.

Catching favorable winds and burning more fuel. It is in the airlines best interest to have the plane in position for the next flight, so they will burn the fuel when they need to. However, committing to a tighter schedule would cause a lot of problems if they were late too often, kinds of problems that means they would make less money than with the current schedule.

> However, committing to a tighter schedule would cause a lot of problems if they were late too often, kinds of problems that means they would make less money than with the current schedule.

There is always a price where this isn't the case. My overall point is that that price is still too high and people aren't willing to pay, and we don't really know if that's the case (but maybe the airlines probably do).

They aren’t going to make that flight time very often so even if it was offered at a premium, they just could not deliver that product consistently.

Even most businesspeople aren't really that hyper-scheduled on trips--especially the ones that can't book whatever class they want.

And to your latter point, I can afford higher-class tickets but it comes back to what I could do with the money instead like a nice dinner. I don't tend to have a budget per se but I do recognize tradeoffs.

With Starlink and better wifi, the time on board can also be used better. So if you end up on the internet answering mails and so on, you can do that on the plain or in the hotel-room.

Also, the same plane can now make twice as many revenue flights.

7 hour to London is actually 10 hours when you factor in the commute to the airport, security, planing, flight, deplaning, shuttle to hotel.

Cutting it to 3.5 hours isn't a 50% overall decrease, because those 3.5 will turn into 6.5 of real time.

So the marginal value of faster flight goes down the shorter the trip is, and these supersonic airplanes can't do the super long Pacific flights because physics.

It's a much smaller niche than is often imagined. But it's still a niche, I guess.

the argument breaks down when the cost of these flights will be at minimum in the range of $10000

Read the article

unrealistic expectations or double decker economy where you can't even sit down. I believe that overvalue their time - there's a lot of things you can do during flights including sleeping and SpaceX providing near gigabit of Ethernet over the Atlantic further reduces the need for these solutions. VR is also being heavily used to review designs 'in person', anyone that genuinely needs to be at the right place at the right time probably has a private jet already.

I might be an outlier as someone who is never in a rush to live their life.

Supersonic is more interesting over the Pacific than the Atlantic. An uncomfortable 7-hour flight becoming a less uncomfortable 4-hour flight isn't really news. A miserable 14-hour flight becoming a tolerable 8-hour flight is, both for passengers and possibly even for the burden on staff. IIRC the old Concorde just didn't have the range, but any improvement in the underlying tech could change that.

I think we’ll eventually have some technology to make this realistic.

Supersonic flights powered by jet/rocket engines might not be it for all we know. IMO we are still pretty early in the history of aviation as a technology.

If you are already mentioning rocket propulsion, then you should know that Gwen Shotwell foresees Starship flying E2E (point to point on Earth) flights with paying passengers, competing with airlines. One hour to anywhere on the planet.

Hopefully we discover some sort of gravity physics/tech that makes chemical rockets obsolete!

I don't see Starship being useful for civilian transport use cases, but for military operations sure! But there's not much to distinguish a starship from a nuke launch during a war, so it remains to be seen whether that risk is worth it.

> One hour to anywhere on the planet.

Anywhere they can take off from, which is a decent distance from a population center. The last (forty?) mile problem bites again.

I can imagine Starship landing on a sea launchpad (in coastal cities), and the last 30 miles can be taken by a speedboat in half an hour. The sea usually isn't as traffic-jammed as land communications, and boats, unlike high-speed trains, don't require that much infrastructure.

Which is nonsense. Not only will rockets never have airplane reliability and safety for basic physics reasons, but that rocket profile looks exactly like an ICBM and nobody wants to let that confusion happen.

Airplane flight trajectories look exactly like a V1 missile, and even modern tomahawks could be made to fly such a profile. Or it could be a subsonic B-1B instead of a Boeing 747. Solutions to IFF have decades of development.

That is not quite true. The advantages of LNG are much more important for high supersonic jets (Mach 2.5 and higher) than for subsonic jets. There are disadvantages too, and they are quite significant for all jets, but altogether the tradeoff is worth it at high speed long endurance supersonic jets.

Here's why. LNG offers 2 main benefits. The first is the higher energy density (53.6 MJ/kg vs 43 MJ/kg, so 25% more [1]). Airplanes are subject to the rocket equation, even if they are not rockets. The rocket equation says that the mass of the fueled vehicle is the mass of the vehicle at the end of the trip times the exponential of delta-v divided by the exhaust velocity. For airplanes, it is not exhaust velocity, but "effective exhaust velocity", because they borrow a lot of reaction mass from the atmosphere (the air used as oxidizer, and more importantly, the bypass air). The effective exhaust velocity is very high for subsonic airplanes, and much lower for high supersonic airplanes. The delta-v for subsonic airplanes is lower than the delta-v for supersonic airplanes because of the lower drag (although not as much lower as one would expect, because they need a higher attack angle). Overall, the benefit from the high energy density LNG is much more pronounced for high supersonic jets.

The second benefit is the use of the cryogenic LNG to cool off the engine. For very high speed engines, this is huge. So huge that the famous (but never materialized) SABRE engine was supposed to use liquid hydrogen, which is stored at much lower temperatures.

The disadvantage of LNG is, surprisingly, not the need for cryogenic storage. It is the lower volumetric energy density. It is 22% lower than that of jet fuel. The rocket equation does not care about volumes, only about mass, but larger volumes means bigger airplanes, so more drag.

So, for subsonic airplanes the advantages of LNG are not all that important, while the bulkier tanks are a pretty big downside. For high supersonic jets, the advantages of LNG are so high that they simply open up possibilities that are not there with jet fuel. The fact that the LNG is cheaper is a nice thing to have, but it's really not that important, since the economics of high supersonic jets are more impacted by the construction cost and very high maintenance cost than by the fuel cost.

[1] https://en.wikipedia.org/wiki/Energy_density#Chemical_reacti...

Are you sure the numbers are correct?

Wikipedia lists LNG as 53.6 MJ/kg and 22.2 MJ/L and jet fuel as 43MJ/kg and 35MJ/L.

53.6 / 43 = 1.247

22.2 / 35 = 0.634

Energy density by mass is higher than jet fuel. But it is higher by less than jet fuel's energy density by volume is higher than LNG. And LNG requires heavier tanks.

So all in all, if it's not absolutely needed because of the cooling advantages, LNG can store less energy in the fuel tanks.

You are absolutely right. My 22% was a mistake, the correct number is indeed 36.5% lower volumetric energy density. But that strengthens my argument, doesn't it?

yes i agree with you on it being unfeasible for most applications.

> Historically, faster transport doesn’t replace slower transport wholesale; it creates a premium tier while pushing the mass market down to a lower cost/energy equilibrium.

If that were true, we’d all be taking trains and boats everywhere. We aren’t.

The difference between a supersonic jet and and a subsonic jet is about 2x. Between NY and London that's a 3.5 hour flight vs a 7 hour flight (plus the overhead of security, traveling to and from the airport, boarding, taxiing, etc. which brings down the proportional cost).

By comparison, a boat would take 7-8 days. The disparity in time saved between supersonic and subsonic flight is pretty trivial in comparison to the time saved between a boat and a subsonic plane.

Presumably there are no flights from Paris to Munich then?

There are. A flight is about an hour and a half, a train is about 5 hours. Far more people fly between the two every day than take a train.

A 5x disparity is still a lot more than a 2x disparity. In fact, considerably less than 2x given the overhead time of traveling to the airport, security, boarding, etc.

How many people would pay 8x the ticket price for a 45 minute flight from Paris to Munich (The Concorde was ~8x the ticket price of economy subsonic flight tickets)?

Isn't the flight cheaper as well?

Surprisingly, at least in theory, and probably in practice with better technology, supersonic travel can be as efficient or even more efficient than subsonic flight. Supersonic travel opens up higher altitudes, higher altitudes means less air resistance.

The ultra high altitudes of LEO satellites showcase the steelman example, traveling effortlessly through the vanishingly thin atmosphere at hypersonic speeds with extreme efficiency even though the fuel expenditure to get them there was high.

For more reasonable hypersonic travel, at 100k feet, the “wind” force at 3375mph is only as much as you would feel at 400 mph at sea level… so you can exert the force needed to fly at 400mph, but for that same energy you are going 3375mph.

Of course there is a lot of tech needed to take advantage of these efficiencies, but it’s not a matter of faster = less efficient. As for economies, a jet that can fly LA to NY in 70 minutes, with an hour of turn at each end, could make 10 trips a day, potentially cutting the number of aircraft needed to cover a given route or route rotation by a factor of 4.

Obviously this is not currently practical on so many levels, but there is nothing fundamentally stopping us from achieving that level of service, given enough knowledge and technical capability.

If we ever want to achieve that level of understanding and competence, we will have to work on it when it seems impractical. Remember, it was in a single persons lifetime between flying precariously in glorified kites and supersonic flight.

It seems like there's not enough interrogation of how much time supersonic could actually save you. 3 hours of flying from LA to Seattle, 2.5 with climb and approach removed. If you cut it in half, 1h15m saved. On the flip side, how long does it take to get to the airport, park, though security, board, deboard, massive buffer time because flights are expensive and you don't know what might delay you, god forbid you have baggage to check and pick up. Flying at twice the speed might reduce the time to fly by less than 20%. Taking small on-demand supersonic flights from regional airports as suggested is definitely not a solution btw, because it's a pipe dream.

He used 24 hour LA to Dubai as an example?

Why would you pick a 3 hour flight?

LA to Dubai is just over 16 hours flight time, so either way, he's not comparing realistic flight times anyway.

1. The in-flight time from LA to Dubai is not 24 hours. A direct flight between the two cities is more like 15. If he was on a "24 hour flight", it was a flight with a stopover, which just goes to show the point about air travel time being bloated by non-flight time.

2. Concorde rather infamously could barely make the transatlantic trip from New York to London, because supersonic flight is expensive. Boom's currently nonexistent aircraft is planned to have about the same range. Neither could make the flight from LA to Dubai, which is a distance close to double their maximum ranges.

And NY to London really isn't bad. I have to do Zero Dark Thirty for London flights with a change in Newark but EWR-LHR itself isn't really much different from when I fly from BOS to SFO.

At a minimum, I'd want to be able to fly from the East Coast to continental Europe to avoid a red-eye but the biggest win would be trans-Pacific.

Yeah, in my opinion the point that "wouldn't it be nice if this was faster?" becomes a real issue is the point that you would feasibly need to get your day's sleep en route with today's airliners, because it's difficult to sleep for more than a few hours at a stretch on a flight even with business class conveniences (and that's before getting into the degraded quality of sleep). If I could catch a flight that's fast enough to let me hold off on sleep altogether until I get to my destination, then that's worth paying a premium even for economy seats. Unfortunately, that's also the point that a supersonic airliner becomes unworkable for airlines, because the fuel-to-passenger ratio just stops making sense. You can try to make it work with refuelling stops along the way, but that really eats up the theoretical time savings and adds its own operational overhead too.

I think we need an energy breakthrough with a denser and still cost-effective fuel before really getting into the era of supersonic transport. Maybe at some point someone will dust off the nuclear-powered aircraft designs of yore...

RE 1. - the example still stands. Travel time is best understood as falling into buckets. Roughly:

- < 1h - can go there for lunch, or as part of running some errands;

- 2-3 hours - can fly over, have a full day of work at remote location (or sight-seeing), and get back home for supper;

- 4-8 hours - can fly over, do something useful, fly back overnight or next morning;

- > 8 hours - definitely a multi-day trip.

(There are more buckets still, if you consider long-distance travel by sea or land, and then more when considering how people perceived travel in historical times.)

As long as the travel time stays in the same bucket, reducing (or increasing) it doesn't matter much to the travelers. However, going up or down a bucket is a huge qualitative change, and one people - especially the business travelers - are more than happy to pay premium for.

So back to our supersonic planes, cutting down the LA-Seattle travel time from 3 hours to 1.5 hours (and accounting for airport overhead), doesn't affect the kind of trips people take. Cutting down travel from LA to Dubai from your 15 hours to 5 hours means it suddenly makes sense for corporate executives to fly over in person for single-day meetings, where previously it wouldn't.

This is also why it's the business customers that are always the target for such ideas - regular people are much more price sensitive than corporations, and are fine with long and hard flights if it means they can afford them. Meanwhile, paying an extra $10k to get the executive on an important meeting might actually be worth it for a large company.

Replying to point 1 (especially with this argument) while completely ignoring point 2 makes very little sense to me.

Even with airport overhead, there's plenty of routes a supersonic plane could drop from 4-8h bucket to 2-3h bucket, and that is still something business flyers would pay for.

Like which ones? Bear in mind that despite carefully worded PR, Boom has very much not somehow surmounted the laws of physics to eliminate the sonic boom that caused the Mach 2+ Concorde to be banned from going supersonic over land.

NASA seems to think it's possible though. https://ntrs.nasa.gov/api/citations/20160007348/downloads/20...

Yea, but only for speeds up to Mach 1.3… theoretically. Not Mach 2.0 flights. And they only demonstrated the effect up to Mach 1.1.

Saving only one hour on a transcontinental (US) flight doesn’t seem all that impressive.

See the pesky thing is that if you actually read the paper you've been linking as opposed to just running with "NASA said it's possible", you'll notice that like I alluded to, at Mach 1.3 (theoretically!) "boomless flight" is much slower than Concorde's Mach 2+ cruise that the company certainly wants you to think of when you do your back-of-the-napkin supersonic flight time savings maths. And that's on top of requiring optimal atmospheric conditions, so not even a guarantee to begin with.

The laws of physics funnily enough are not something you can "move fast and break" or PR-speak your way around.

No one is flying supersonic over land at least in the US. Going over the oceans is where it would happen.

That's because there was a dumb ban in place, with an executive order [1] and bill that just cleared to lift it [2]. The ban was "dumb" because it's indirect, trying to control loudness by limiting speed, which is an incorrect [3] assumption based on old tech of the time.

[1] https://www.whitehouse.gov/presidential-actions/2025/06/lead...

[2] https://www.govtech.com/transportation/bill-authorizing-supe...

[3] https://boomsupersonic.com/boomless-cruise

The ban was specifically to hinder the Concorde, so it made sense to base it on supersonic flight rather than noise in case the Concorde would have managed to mitigate its noise level one way or another.

Reference? There was an "Anti-Cordorde Project" [1] but its purpose was to ban all supersonic flight, for environmental reasons. Concorde being the only in regular service, thus the targeted name.

[1] https://en.wikipedia.org/wiki/Anti-Concorde_Project

I don't trust it. They will get approval and then when sonic booms disrupt nature from coast to coast they will say "it's just because the weather/it only affects a small number of people/the 3rd party contractor who supplied the data was wrong, they are gone now/the benefits outweigh the downside/think of all the jobs". Basically they'll say anything other than "oopsie we were wrong, no transonic flight for you".

Bear in mind that despite carefully worded PR, "Boomless cruise" is 1) not guaranteed to be "boomless" 2) is much slower than would make all the rigmarole of supersonic flight worth it even when it is "boomless".

I'm not sure how that matters. A sonic boom in a phenomenon not an SPL reading. The goal should be to have a direct metric for how loud/how much it disturbs things is. "boomless" and "speed" aren't a direct metric. If someone makes a sonic boom that's quiet enough, that's fine too.

I'm not sure how to respond to this because it's really just ignoring what I said entirely (maybe due to a lack of context?) and instead responding to things that I didn't say. "Supersonic for supersonic's sake" makes no sense.

The author of this slop seems to believe Boom's pitch deck that they can use AI to only boom into space and thus do supersonic overland. The only thing his article suggests though is that you could do it under certain atmospheric conditions, and more likely this is just cover for "do it all the time and blame the computer when we rattle peoples' windows".

Saying it requires or uses AI seems to be just... modern marketing bullshit. But the technique itself seems sound enough. NASA studied the phenomenon already: https://ntrs.nasa.gov/api/citations/20160007348/downloads/20...

But if you actually, you know, read that NASA study, it mentions that the maximum practical speed (from theory) for “boomless” flights is less than Mach 1.3, and they only demonstrated “boomless” flights at Mach 1.1.

That would result in far, far less time savings that what is posited by the commentary on HN. Compared to Cessna Citation X, for example, that would reduce time in the air by just 15%.

Total travel time savings would be even less… so a private Citation X at M0.95 would still be beat a commercial M1.1 flight in door to door travel time.

Right but Mach 1.0-1.3 is all that "Boom Supersonic" is claiming to hit, though, so the paper is in line with the marketing pitch. The speed advantage of "up to Mach 1.3" might not be worthwhile, no, but that's orthogonal to the claims of "boomless" supersonic.

Now the article randomly pulls Mach 1.7 out of seemingly nowhere, and I have no idea where that came from or how that is justified. But the company isn't making that claim as far as I can tell ( https://boomsupersonic.com/boomless-cruise the "FAQ" section even specifically says: "Boomless Cruise is possible at speeds up to Mach 1.3, with typical speed between Mach 1.1 and 1.2.")

Wasn't that just an act of spite because Europeans were the first to deliver commercial supersonic flight? I'm sure it will be reversed if the US becomes the leader.

Being on the actual plane is the most uncomfortable part of the entire experience, for me at least.

Others may disagree, but I'd rather cut an hour from the flight than the entire commute/parking/security/airport waiting. (Assuming conditions on the actual plane were the same.)

Funny, for me it's the opposite. It's uniquely relaxing to be locked in with nothing but a book or some movies (I purposely avoid connecting to the internet during a flight.)

My biggest dilemma is whether to sit in the aisle or window. The former you can get up whenever you want but are bumped by passers by and neighbors exiting the row. Versus being the one doing the disturbing.

And if you can afford business class - where supersonic would be priced - then I mean... The meals are restaurant quality and the full recline?! I hardly want to disembark! The biggest discomfort is the dry sinuses.

But in getting to/from the plane you are cattle moving through a logistical labyrinth with countless possibilities for something to go wrong.

I don't love being on a plane for a very long stretch, even in business class. And IMO food is very mid-tier restaurant. But I don't necessarily disagree with your comment. Even with transport and airport conveniences that a relatively modest amount of money can buy, there's plenty that can go wrong and you can avoid all the other people to only a certain degree.

>And if you can afford business class [...] The meals are restaurant quality and the full recline?! I hardly want to disembark!

Let's settle down. This kind of biz class experience is almost certainly unique to international travel. Flying "business class" from ATL to SFO might get you a plate of microwave slop and an extra 15deg of incline on almost all domestic jets. Once in a blue moon you'll get a modern plane with the diagonal seats. One less person in the row, though.

Paying for business class domestically is almost always a sham by my experience.

ATL to SFO would almost certainly top out at first class, not business class. This is true of most all domestic routes. First class on international also just gets you the 15 degrees and 1 or 2 fewer chairs per row, it's business that gets you the lie downs and such.

The food will probably still be worse than a first class international flight though. Not as many people paying as much and not enough air time to really force all of them to want to eat airplane food in the first place.

> First class on international also just gets you the 15 degrees and 1 or 2 fewer chairs per row, it's business that gets you the lie downs and such.

This is not my experience at all. First class is better than business class on international (and domestic, of course, though relatively few domestic routes have true three cabin service [counting all the slightly different economy levels as one cabin]).

For ATL<->SFO the directs are Delta, Frontier, and United:

Frontier doesn't have a business class nor long haul international flights (they are an ultra-low cost carrier).

Delta calls their highest tier "Delta One" their business class offering. It's mostly available in mid & long haul international flights, though there are a few select domestic routes with it IIRC. A tier below is First, which is available for both domestic and international flights. https://en.wikipedia.org/wiki/Delta_Air_Lines#Cabin:~:text=D...

United's highest is called "Polaris", representing their international business class. Confusingly, they have "United First and United Business" as the next class. I.e. it's the same class but on domestic flights they call it "United First" and on international flights the same seat would be sold as "United Business" despite having Polaris for that already. Regardless of that oddity, the First class can't be higher than itself named Business class even compared directly instead of with the actual business class Polaris - it's the same seat. https://en.wikipedia.org/wiki/United_Airlines#Cabins:~:text=....

Other airlines label and order things differently of course. E.g. American has Flagship First above Flagship Business above First/Business (shared much like United on that 3rd class) and maybe that's where your experience is. To my knowledge though, no such airlines operate the ATL<->SFO route originally described though.

Can you find any three-cabin service where First class is the middle tier of cabin? (In a two-cabin service, whether the one that's not economy is called Business or First is not helpful in determining whether business or first is higher; we both agree they're better than economy.)

Here are airlines offering three-cabin services on a single aircraft where First is the highest tier:

Air France - La Première (First), Business, Economy

American Airlines - First, Business, Economy

Cathay Pacific - First, Business, Economy

Emirates - First Class suites, Business Class, and Economy

Etihad - First Class private suites, Business, Economy

Japan Airlines - First, Business, Economy

Lufthansa - First, Business, Economy

Happily, here's one from Delta as I described above https://i.imgur.com/wwYQXy1.png. Sadly (for me, at least), I've never flown above "First" on such a configuration from Delta though :). Like you had noted, they call it 4 cabin classes... but the economy classes ("Main" & "Comfort") are both treated as a single cabin in terms of service and the difference in economy seats is an inch or two of leg room. So it's really a 3 cabin of: business, first, economy.

Again, hbosch said ATL<->SFO... and you aren't going to be flying Air France or Japan Airlines for that route. My list, as far as I'm aware, was exhaustive for that route. It was not a cherry picked search of airlines which do it that way or global claim of what all other airlines do, only a response to the particular claim. On other routes/airlines the statement could, or rather "would", certainly have been true. Honestly, I think those airlines have it the right way around, but, having flown the exact route and the same airlines internationally, it did not match my experience for the route - which agreed with the labeling for all airlines for that route according to the links above. Unless, perhaps I'm missing that American or similar does actually have a ATL<->SFO to be compared with?

Where is the label of “first” anywhere in that image or in Delta marketing on that flight?

It literally says "first" in the upper right hand corner of the image indicating the red seats, which are clearly not as nice as the purple seats, aka Delta One?

That is a composite image, with screenshots from two different pages (and I'm virtually certain from two different flights), not a legend of the seating chart and a seating chart.

I can't find an ATL-SFO flight offering Premium Select and in fact couldn't find a domestic Premium Select flight at all, but on flights where I can find Premium Select, such as BOS-AMS on May 10, 2026, here is the fare selection screenshot from that flight, and the seating chart screenshot, including the legend on a single page:

https://imgur.com/a/Nz1FxOT

Notably, neither of those use red for "First Class" and there's no confusion between trying to use a legend from one page/flight as a key to understand a seating chart on a different page/flight. In fact, they both use red for "Premium Select" and booking Premium Select on that flight gives you a fare class of "A", which is specific to Premium Select (and NOT to First Class/Delta One, which share J, C, D, I, and Z, because Delta One is just a branding of First Class, rather than a cabin distinct from first class).

Delta fare class codes: https://www.nerdwallet.com/travel/learn/delta-fare-classes

I'm not saying that there was a specific intent to deceive with that prior imgur link, but I think the end effect was deceptive.

I was specifically thinking of my experience flying Emirates to the UAE :)

Other threads are discussing what range is actually practical or worthwhile. The article is very optimistic saying Australia can be a weekend trip. For me it's much more beneficial to cut a 16 hour flight in half than a 6 hour one. I don't really mind an itinerary 9 hrs or less, which includes all US domestic travel. But of course it will be different for a business commuter vs the occasional getaway.

> And if you can afford business class - where supersonic would be priced - then I mean... The meals are restaurant quality and the full recline?! I hardly want to disembark! The biggest discomfort is the dry sinuses.

Lay-flat chairs and business class are nice and a massive upgrade for long flights but better than being off the plane? Nope.

> restaurant quality

The food is mid-tier at best, I would not return to a restaurant that served food like what they serve in business class. It's only amazing when compared to the alternatives and the fact you get treated like half a human for a minute.

> full recline

Ehh, I find them claustrophobic and they only really "lay flat" if you aren't 6'+. They are approximately 1 billion times better than normal airplane chairs but you are still in an airplane.

100% agree with you. Actually being on the plane is fine, I don't have many complaints there. Yes, there are various compromises around space and comfort, but they're all understandable given the cost/efficiency concerns.

Getting through the airport is just a huge pain in the ass though. At least some airports now let you keep your shoes on again, hopefully soon we'll have scanners that don't need you to remove electronics (I tend to bring too much of this and it's always a pain), or even let you keep liquids again (!).

Look for the "Smiths" brand scanners and go in that line if possible. Those don't have to remove items from the bag.

Unless you pay the sort of money (or more) that supersonic flight would realistically cost. Even without going private, business/first seating (along with expedited service through security, airport clubs, and arranged private car to your hotel) deal with a lot of the issues that many economy travelers have with air travel.

Nah, its quite opposite for me. It becomes real chore with small kids on non-short flights, but the thing is - I travel normally only for vacations. Time spent in airports is literally vacation wasted on bureaucracy without even moving, since in ideal situation I would spend 1 minute giving them big luggage, if at all, and stepping in the plane just about to take off. Flying is actually moving me towards the goal, feels more acceptable.

Overall when I started traveling I loved all of it, exciting, new. Now I hate this part as a whole, necessary evil of wasted life to get what I actually want where I actually want.

I expected that others would have opposing experiences and tried to reflect that in my comment. People are different sizes, flying different class, frequenting different airports, traveling with families or solo, for longer or shorter periods of time, more or less luggage, etc. So of course it won't be universal.

My main point is that all time is not created equal, that it matters WHERE you shave the minutes/hours off, not just what percent of overall travel time is removed. And while we disagree on how to apply this, we seem to agree on that main point.

I try to find absurd humor in counting the different steps that I had to go through from leaving my house to getting on the plane. Or analyzing the legibility & usability of the systems. Or just being proud of myself for being able to be so patient and let it all go. Sometimes you can even strike up a good conversation with a stranger. But with kids, oof, yeah... :-)

being on the plane is the easy part. put bags up top -- and check the big ones so this is a simple process -- and then buckle-up and snooze.

it's the everything-else part of air travel that is fucking awful.

40+ minutes of security theater even with NEXUS and other fast-passes, lost bags, massive PITA airports, delays, and the hoards of dumb fuckin rubes who have no idea how to travel and need to haul their comically huge carry ons that somehow got through sizing + emotional support chihuahua -- a far cry from even the worst subways I've been on.

I feel the need to praise the (relatively) new SFO terminal 1 somewhere. The design is a breath of fresh air.

Always my smoothest airport experience by far. No checked bag, Clear + Pre Check, fill your water bottle after security, get a coffee at Ritual, buy a banh mi for the plane, use a pretty clean bathroom, sit in one of those swivel chairs, get on the plane.

If you live in the right areas - mostly the western US - try JSX. Runs about equal to maybe 20% more than commercial domestic first class. Regional jets, all 1+1 seating, fly out of (effectively) an FBO, show up 20 minutes before domestic and 40 before international flights. Light screening, no terminal, no carryon (all bags brought off immediately at end of flight for collection planeside). Free WiFi on board and 120V power outlet at every seat.

>40+ minutes of security theater

This is such an exaggeration. Usually it's like 3-5 minutes.

The whole experience nowadays is horrible. The airplane is a bus, the airport is a shopping mall. Passengers are just cattle.

When you can fly e.g. London to Barcelona for something like $59 (if you time your ticket purchase right), it is a bus, for the price of a long-range bus ticket.

(There is even a big aircraft company named "Air Bus", or something, did you hear about them?)

I've flown business class, it's still a bus, a nicer bus where you are treated marginally better, but it's a bus. Maybe private planes would change things (I've never been on one) but I can't imagine airplanes as being anything but a means to an end that I wanted to spend the least amount of time on.

Of course it's a bus, what do you expect? If you want it to be like the 1950s golden age, you can get that, but for a price.

Seattle to Beijing is like 12+ hours now that Russian airspace is closed. There is a lot of time to save.

So save it using a Chinese airline who can fly through Russian airspace?

Chinese airlines aren’t allowed to use Russian airspace for any flight to/from the USA approved after 2021 or so, which, because of COVID, is basically most of them. You could maybe fly to Vancouver and get a quicker connection.

My last trip was on Hainan, which didn’t over fly Russia.

The one note about Astro Mechanica towards the middle is referring to long haul flights from smaller airfields because they'll have a smaller private jet sized plane. It was not referring to short haul flights, nor was the rest of the article.

I don't believe the economics for that will at all work out the way they are pitching, but it has no relation to how much supersonic makes sense for a domestic short haul.

LA to Seattle is not worth it. The real gains are in London to NYC, or Tokyo to LA, or maybe Rio de Janeiro to Miami.

South America to Miami and vice versa will absolutely be a market for supersonic flight. It may be slow to takeoff (hah), but as soon as the South American elite pick up on it, it'll 100% be utilized to its maximum potential, especially during events like Art Basel.

I am guessing this is really aimed at the 1%, who don't have to get to the airport 3 hours before a flight.

Rory Sutherland commented that, insteading of spending billions on high speed trains, why not spend a few million on making the experience nicer. Better carriages, more staff, nicer stations.

I don't think you have to be a member of the 1% to get to the airport an hour before a flight. Precheck is like $20 per year.

If you're a member of the 1%, you can pay to use the private terminals and have a completely different airport experience while flying commercial.

This isn't a very common product in the US, but it is available at most big airports elsewhere.

I find it especially useful during arrivals. Typically there'll be a sedan to pick me up next to the plane, many airports will have co-ordinated with the airline, my luggage will have been loaded separately and the crew will make sure I'm the first off the plane. After exiting the aircraft, I'm driven to a private terminal for possible border formalities and there'll be a car waiting for me right outside with my luggage already loaded.

At some airports, you might save hours off a trip like this. Prices run between crazy at places like heathrow and a few hundred dollars at less fancy airports.

It's for much longer distances.

There are flights between St Petersburg and Moscow. About 10 daily. It's about 1 hour. Together with everything you described, it's more like 4 hours. A high-speed train is also 4 hours. So the only people who choose to fly are those who have a connection or those who couldn't get a train ticket because those are always in high demand.

> Concorde burned 52% of its fuel just taxiing and taking off

and later in the article:

> Remember, Concorde burned 52% of its fuel just taxiing down the runway.

Setting aside that these are completely different claims, the author does not cite this claim at all and it fails my personal gut check. Where is this information coming from?

https://news.ycombinator.com/item?id=24283386

They did burn a crazy amount of fuel on getting up to supersonic speeds though.

It used about half of its fuel for taxiing, takeoff, climb, and acceleration to cruising speed. Maybe that's where the number came from originally and it got mangled in translation.

When I looked into this in another context (not supersonic jets), while "a lot" of fuel was used just getting the jet up to speed going down the runway, "most" of the fuel was going from 1 foot off the ground to N0,000 feet.

(I was curious if there was any opportunity for some sort of system to power take-off from the ground, be it catapults like on air craft carriers or just power-transmission for electric planes, and the numbers I found were that while a surprising amount of fuel was used by the time the plane lifted off, it was more like 5% than 50%.)

Yes, it sounds like the repetition of a mangled version of the SR71 stories. Burning 45 tonnes of fuel on the runway would be completely insane.

Checking various links on taxiing burn yields about 2 tonnes which is a lot more realistic and reasonable (a previous HN comment indicates the 767 burns about a tonne taxiing: https://news.ycombinator.com/item?id=24283386 concorde burning twice that sounds fair)

The OP might have gotten confused reading articles like https://simpleflying.com/concorde-fuel-consumption/ stating concorde burned half its tank from the gate to cruise (mach 2 at FL600)

> ”the 767 burns about a tonne taxiing”

This seems incredibly inefficient. Is there a future for hybrid aircraft, which would feature both traditional turbofans and large batteries for energy storage?

Batteries would eliminate the need for an APU and power the aircraft during taxi, allowing the engines to be started just before actual takeoff, and shut down immediately after landing.

Either the batteries could power wheel motors directly during taxi, or the aircraft could mix turbofans with e-fans (which could also allow energy recovery during descent and help power the aircraft during cruise, reducing fuel consumption further).

> This seems incredibly inefficient. Is there a future for hybrid aircraft, which would feature both traditional turbofans and large batteries for energy storage?

I would assume the extra weight would make it not really worth the added cost and complexity.

Honestly it sounds like the "right" way to do it would be electric ground vehicles pulling the planes into position, as with tugboats in water. Plane never need carry batteries into the sky and saves a literal ton of fuel.

IIRC towing to and from the runway has two major issues:

- standard towing tractors are really slow when towing, nowhere near taxiing speed, so you need a fleet of heavier duty "fast tow", possibly dedicated (depending on price)

- more traffic around the runway, which creates more airport complexity

Taxibot does exist tho, and is certified, and used in a few airports. Though I think it's only hybrid not electric.

Bigger issue is that the engines need to be idled for a while anyway to get up to proper temps, etc. you don’t want to start the engines and jam them into full takeoff thrust 5 seconds later.

The software in modern engines wouldn’t let you do that anyway. The engine startup process can be quite long - several minutes in a 737 MAX - while the engine’s ECU brings things to proper temperatures etc.

But with e-taxi, the startup cycle could be performed while taxiing, potentially saving airlines time on pushback as well as fuel/maintenance cost savings.

True, the engines need to be warmed up and the hydraulics need to be pressurised, but given e.g. airbus recommends single engine taxi without APU (SETWA) warming up the engines probably doesn't take that long in the grand scheme of things. Definitely not the 15~25mn of taxi. From the sources I can find, "normal" warmup takes 2~5mn depending how long ago the engine was shut down, unless outside temps are exceptionally low, and you can do that while reaching the end of your taxi.

> but given e.g. airbus recommends single engine taxi without APU

This is wrong, unless you have a source for it

Because jet engines are notoriously simple devices to begin with.

Electric taxiing (on APU) has been in development for over a decade, but it's mostly intended for single aisles (the shorter the flight the more the taxi overhead), and the relatively low fuel prices has led to these projects mostly dying off: L3 shuttered their effort in 2013, Honeywell and Safran's EGTS joint venture was dissolved in 2016, and wheeltug... apparently still lives (with no support from either boeing or airbus), though it was initially supposed to enter service in 2018.

Fuel saving would be only one of the benefits.

Airlines would also significantly reduce engine operating hours, reducing engine wear and thus maintenance costs. I’ve been on flights out of Heathrow that seem to spend almost as much time taxiing as they do in the air (due to weather or ATC delays or whatever), so for short-haul operations this seems really significant.

Local air quality is also a concern for airports: the air in the neighbourhoods around Heathrow often stinks of jet exhaust, sometimes you can smell it from miles away. Presumably, much of those emissions come from taxiing aircraft.

The limiting factor for most turbine engines isn’t really operating hours, but “cycles”, which is to say starts and stops. From a maintenance perspective it’s not terribly important whether you start the engine at the gate or the runway.

Also, as far as maintenance goes, engine hours are weighted by operating power. So, an hour at idle doesn’t count as much as an hour at cruise power. One of the reasons airlines started using not-full power on takeoff when conditions allow it is because of “power by the hour” maintenance contracts, which incentivize that.

> ”engine hours are weighted by operating power”

Interesting - I didn’t know this!

Airport tugs might be a better fit to improve ground operations efficiency?

I think they've looked at that kind of thing but not found if practical so far. One innovation has been airbus jets taxiing with just one engine which cuts fuel use a lot as it mostly goes to just spinning the engines.

eTAXI is just one such solution

https://www.safran-group.com/videos/e-taxi-safran-unveils-it...

> This seems incredibly inefficient.

Very inefficient but good for safety: if an engine is failing, you hopefully might discover that while taxiing rather than when you are in the death zone 25 meters up in the air.

Not an expert, but intuition suggests this probably isn’t true.

If an engine is going to fail spontaneously it’s almost certainly going to happen at high thrust, not while at idle or very low thrust values during taxi.

Your intuition is wrong.

Engines experience issues when changing speeds (especially start-up) not when at steady thrust output.

Fair enough. But delaying engine start-up until the aircraft has nearly finished taxiing wouldn’t have any effect on the way the engine operates during start-up. It just means it would spend less time at idle or near-idle speeds during taxi.

American coverage of the Concorde has to try and make out that it was technically bad, otherwise they would have to face up to the fact that their country squashed the possibility of supersonic travel, through political bullying and protectionism of their own aircraft industry

And also through supersonic travel being annoying as hell and super expensive.

Though, given the investment into the Concorde led to Airbus and all of their planes, disrupting Boeings dominance of that industry, I think they might have gotten the last laugh.

Roughly that figure (45%) was used to get to Mach 2.0 at 60,000 feet, about 45 minutes after takeoff from LHR (normally over the Bristol channel) to JFK.

Takeoff and climb / accel to Mach 1.7 was done with re-heat (afterburners), which did use a lot of fuel. After that, normal power (no re-heat) was used to get to Mach 2.0 and cruising (supercruise).

The article is just generally sloppy.

> .. my recent trip from Abu Dhabi to LA. 24 hours door-to-door. We have the technology to reduce that to under 10.

The direct flight (by Emirates) takes 16h15 mins, so that leaves 7h45 mins not in flight. If we want to bring that down to 10 hours just by making the flight supersonic then that would require a flight time of 2h15, corresponding to a (ridiculous) speed well over Mach 4.

Not ridiculous if you’re flying above the atmosphere. SpaceX has proposed point-to-point rocket-powered hypersonic flights that connect New York to Paris in around 30 minutes.

Obviously the real problem with this idea is environmental: emissions would be substantial and nobody wants an extremely noisy rocket port near their city.

Musk has proposed lots of things.

How do you imagine that? First thing coming to mind is the loudness of rocket starts and powered landings. Even for airports that would be too loud. At least with current regulations. So you'd probably waste time getting to some dedicated facility, far out in the midst of nowhere to care about, and getting out of a similar hole on the other side of the trip. And again regulations regarding the closure of airspaces and seas for starts and landings, as it's currently done. Which seems rather incompatible with the current system of commercial flight ops, as it's currently done. Other relevant regulations coming to mind are evacution procedures/general survivability provisions for conventional commercial flights, which are mandatory by law.

However I turn that idea, no matter from which point I'm looking at it, I'm not seeing it going anywhere.

Whenever I hear people talk about rocket flights I think of the Stephen King short story "The Jaunt". Humans develop near-instant transportation but you have to be unconscious while travelling. A kid avoids being sedated and is driven insane by whatever interdimensional stuff he sees in transit.

Likewise for every fit 20-something being launched at Mach 5 you'd have 10 octogenarians dying of cardiovascular complications.

And furthermore you would be able to start only in good weather window for takeoff and landing and Gs on Gemini flights (which were doing the same thing) weren't comfortable either.

In fairness, Astro Mechanica and Hermeus claim to have a pathway to Mach 5. Not saying I expect to see it, particularly not for regular people flights to the Middle East, but believing in it is kind of the premise of the article.

(I must admit I was more curious about Astro Mechanica's engine tech before they also threw in the intention to operate Uber for business jets...)

The claim in the article, "Concorde burned 52% of its fuel just taxiing down the runway", is completely wrong and kind of ruins my confidence in the article. A Concorde used less than 1% of its fuel taxiing down the runway, not 52%.

Source: Air France Flight 4590 Accident Report states that the plane had 95 t of fuel on board when the aircraft started out and used 800 kilos of fuel during taxiing (page 17) and 200 kilos after taxiing before takeoff (page 159). https://www.faa.gov/sites/faa.gov/files/2022-11/Concorde_Acc...

(Since there's a bunch of discussion about how to reduce taxiing consumption, I'll point out that one tonne of aviation fuel is about $700, so there's not much money to be saved by creating battery-powered tugs or whatnot.)

As far as takeoff, "at the start of cruise 20% of the total fuel burnoff will have been consumed while only 9% of the total distance will have been covered." From "Operation Experience on Concorde", a paper by the Design Director. While 20% is a lot, it is much less than 52%. https://www.icas.org/icas_archive/ICAS1976/Page%20563.pdf

9% of the distance but 100% of the altitude. That statement completely ignores the hardest part of the flight (with respect to building potential energy) of getting at altitude.

> (Since there's a bunch of discussion about how to reduce taxiing consumption, I'll point out that one tonne of aviation fuel is about $700, so there's not much money to be saved by creating battery-powered tugs or whatnot.)

Probably the biggest win in aviation emissions would be converting all the ground support vehicles to electric. They’re currently classified as off-road vehicles, so don’t have to adhere to the same emission standards and normal cars and trucks. Additionally, they already spend a lot of time parked at the gate, which makes charging convenient and means that workers are never “waiting” for the vehicle to charge.

Equating speed of travel with innovation is lame: a lot of work has been done in recent decades on making airplane engines more efficient, which makes air travel more economical both in terms of cost as well as C02e emissions per passenger (the Jevons paradox implications of that can be taken as read).

The whole post comes off a bit as someone who doesn't really understand the passenger air travel industry very well, and isn't particularly interested in changing that.

tbf whilst the lower cost travel we've got accurately represents what the market wants, it isn't exactly unusual to find industry insiders that want flight to be faster (they're just a little less likely to gush about how startups are "cleverly" working with regulators or describe Douglas as the last successful US airframer...)

One could say Douglas is the only successful US commercial airline manufacturer. (Last remaining, after Boeing bought MD but inherited MD's culture)

The technology of air travel may seem counter intuitive when your frame of reference is the Moore's Law.

But in practice, what happened with semiconductors is the exception, not the rule.

We are still often making wild predictions about the future of technology based on some kind of exponential take-off, it may turn out to be a lot more constrained by physics and energy density.

Supersonic commercial air transport is one such technology, possible and proven, yet not viable.

Mars colonies or interstellar travel could be in a similar bucket.

It’s already booked 130 orders.

I really don't believe this. Even the Boom website says that most of these are "options" to purchase, but I'm guessing the "firm" orders are basically just non-binding letters of intent that effectively say "Sure, if you build it with these specs, we'll buy some at price X. Unless we change our mind."

And I'm further guessing that the terms include dates that Boom has zero chance of hitting. The author estimates that these won't be in commercial service before 2033, but I think that's still optimistic. My understanding (could be wrong, not an expert) is that new regular airliners take many billions and 10+ years to design, build, and certify, and that's without the complications of supersonic and brand new engine designs.

The Boom stories have been circulating on HN for a decade now [1], and they originally were claiming two years to have a manned prototype, which was obviously untrue. I guess they are like the Tesla of the sky in that regard.

1. https://news.ycombinator.com/item?id=11329286

tbf United and JAL did put in a non-trivial deposit, but yeah, the orders won't be binding on them (I remember having an exchange on here with one of their investors on here about that). Frankly I think they've done well to get where they are, but where they are is a basic demonstration of their supersonic boom suppresion technology on a small testbed aircraft (a few years behind schedule!), and having to design their own engine because they can't get one of the major OEMs to work with them.

Notably Boom's big pivot a month ago was to start selling their supersonic designed engines to data centers for power.

I struggle to imagine this is a very efficient design, that something designed for going mach 1.something breathing significant air is ideally suited for being at sea level not moving running a generator. Just feels like the stupid timeline having it laughs at us all again. https://boomsupersonic.com/press-release/boom-supersonic-to-...

Update: also, I was surprised in the first place because I thought the big challenge for boom was they were trying & failing to get engines. They eventually got Kratos to sign up but I thought it'd mostly be a Kratos engine... https://ir.kratosdefense.com/news-releases/news-release-deta...

That is not a pivot I would have expected. Aviation turbines are not good utility turbines. If you just need to beef up your turbine engineering, drone turbines are probably the place to go. Less competition from GE etc.

I don't think they expected it either, but it's building expertise in that general area, the question is if that expertise will transfer back over to supersonic jet engines, or if they're different enough that they can't.

It's a VC fundraising oriented pivot I think.

I just don't see any pressing need for supersonic jet travel now that in-flight Wi-Fi, hi-res HMDs for your laptop and the Nintendo Switch all exist. And I think that trying to justify it in terms of "we have to end the stagnation and go back to a regime where plane speeds increase YoY" is silly: either it provides a compelling service for its high cost (there's no getting around that air drag and fuel consumption increases quadratically with speed) or it doesn't, and personally I don't think it will.

There is such a huge market of ways to improve flights that are between "what we have now" and "high price supersonic" that aren't currently being done; indicating that there's not a terribly large market for it.

Those who could easily afford supersonic can already afford other luxuries; the only one it gives is time; but if time is of the essence you can save it elsewhere by chartering your own jet.

> chartering your own jet

Honestly, this seems like the place to start with supersonic technology. The very wealthy are price-insensitive and would be ok paying 3-4x as much to get somewhere 2x faster. A good place to prove the technology, infrastructure, and market opportunity before cost-optimizing to try to get interest from mass-market travellers.

a good reason to tax the wealthy so hard that they can't own private jets <3

The thing is, if you can charter your own jet, you can make it travel on your schedule and suddenly cutting travel time in half isn't quite as important (even rich people sleep sometime).

It's a weird niche that is unlikely to be filled for awhile, if ever - partially because the era of the supersonic jet was before the Internet, which now gives even normies telepresence that is "good enough" if not perfect.

There's a powerful and outspoken modern cult that worships technological progress, but only for values of "progress" that meet a certain wow-factor/"shininess" threshold.

The idea that such progress could ever falter is anathema to such a cohort (which, in their defense, have lived their whole lives in the most technologically anomalous period of the entirety of human history), making them susceptible to scams like Boom.

Instead, I'd implore people to consider that true progress is the ability to do more with less, and not merely the ability to do more with more.

Would expect nothing less from someone self-styling as "rational optimist".

Because these are not solutions, they're just fluff. If they were actual solutions these people would kill them because they'd diminish the power their real overlords have.

Just look at the whole circus around the hyperloop instead of just building high speed trains.

> Instead, I'd implore people to consider that true progress is the ability to do more with less, and not merely the ability to do more with more.

Being able to do more with less is equivalent to being able to do much more with only little more.

And yet all that the aforementioned progress-cultists care about is being able to do a little more, even if it costs much more. The rate of return based on the effort invested is precisely the issue here.

AI has some of the most stupidly high rates of return on effort and energy used out of all modern inventions, so I'm not sure what your point is.

“ Blake’s pitch to airlines is enticing: “You’re already flying this route with a 300-seat plane where 80+ people in business class generate most of your profit. Give those passengers a supersonic plane, cut the flight time in half, and charge the same price.”

It's been a while since I've flown. Are ~20% of seats really business class?

Look at a 777-300 on [United](https://www.united.com/en/us/fly/company/aircraft/boeing-777...) - 60/290 biz/econ (~20%), but the biz seats take up probably 40% of the plane.

Estimate 4k for one-way biz ticket and 500 for economy, then that's about 240k from the front and 145k from the back. Actually, I'd expect them to optimize based on space, so if 40% of the plane is biz, then 40% of revenue should come from biz. Perhaps the most profitable routes with this config are 60% revenue from biz; other routes might be more like 2.5k-3k one-way biz.

But biz will be half empty or more at full price, so it gets filled with upgrades of coach tickets to reward frequent fliers or full-fare users. The average has to be lower. The biz price may also be optimistic. United EWR-LHR is more like your $2.5k-$3k. Delta has an ATL-LHR option for first/business class with a bed that's more like $8k-$10k, and their Premium Select, which is more like United's business class, is $2.5k. Interestingly, they offer more beds than big seats.

I remember pricing out the Concorde years ago, before it was grounded. BA's first class subsonic was $8k, Concorde was $12k. (2001 dollars) If you're paying those rates anyway, it might be worth it to go faster, if you don't mind the relatively small seat and limited food service. Coach was $400-$600.

Also by no longer providing service to non-business class customers they save a lot of money on personnel, services, logistics.

Of course the disadvantage, is no more air service for non-business class customers (that being most of us).

The math doesn't scan out on that, it sounds good for pitches and articles but is kind of nonsense once you think about it imo. It's going to cost way more than just 2x to run the supersonic jet along the same route per flight just in fuel and maintenance and you're cutting out all the low fare passengers they cram in the back so they need to make up even more money than just the fuel costs and running additional flights per day doesn't address the issue because the cost per trip is increasing so running more trips just keeps incurring those same costs.

It won't change the economics of the current class of aircraft. They will still need to have business class seats to pay for the economy cabin.

You will probably end up with 5 or 6 tiers of service instead:

Supersonic: Business + First

Subsonic: Economy + Eco+ + Business + First

Supersonic First will be a Veblen good that has a high price floor (like $30k). Business for time sensitive business passengers, and it's actually an Economy Plus seat for ~$15k.

It's very hard to resist marketing some service differences, particularly when you have two classes of users with different needs (speed vs. prestige).

The pitch quoted from the post I was responding to essentially said it was going to siphon all the business class fliers from normal flights: "Give those passengers a supersonic plane, cut the flight time in half, and charge the same price." There's no way businesss travellers would choose subsonic travel if supersonice was the same price for half the time.

We agree I think that there wouldn't be a similar price between the sub and supersonic travel options. The economics of running the routes can't work out to a similar price to existing offerings.

> Give those passengers a supersonic plane

Meaning a big price increase for us normal passengers?

Even with those conveniences IMO that only dulls the tedium of the flight and no matter how comfy the travel is I'm still losing about a whole day at least of just flying across the Atlantic going from the US to Europe and back for a vacation which is pretty valuable with US leave allowances. At the very least there's the market for business travel where workers don't lose whole days to travel.

In the age of ubiquitous video conferencing, does it really make sense for business travel?

My work just did a big moderately disruptive shuffling of all the teams to try to localize as many members of each squad as possible in one location and the trend since COVID stopped being as deadly has been a massive wave of RTO so management seems to believe there's benefit in in person meetings or at least professes and acts like they do. I can't assign all of the huge RTO pushes to just management justifying and propping up their office real estate portfolios.

Sure, business travel is definitely still a thing. But every company I’ve ever worked at has sort of accepted that travel days are lost anyways because people come in from all over the country, get in at different times, have delayed flights, etc. My point being that I’m skeptical that companies are going to start paying 2x, 3x, 4x the cost so that their employees can get there a few hours faster, especially when, at least in my experience, it’s hard to get them to even pay for seats with extra legroom.

And also the negative externalities. Plane noise is irritating, sonic booms are far worse and spread farther.

IMHO digital entertainment doesn't make up for being stuck in a cramped cabin for up to 19 hours (the longest international flight) around people (with varying levels of considerateness, contagiousness, and personal hygiene). Not to mention the increased risks of DVT and radiation exposure.

I travel each year to see family abroad, a minimum 2-leg trip totaling at least 27 hours. I can't sleep on planes so I arrive exhausted and am useless and cranky for the first 2 days after this trip. I would happily pay 2x the fare to cut that trip in half.

Deep Vein Thrombosis?

If you're flying half-way around the world, sleeping on the plane or a shorter flight isn't going to help much. I've done it twice and the jet lag is killer for the first 2-3 days regardless of how well you sleep on the plane (I usually sleep very well).

If you can afford supersonic travel, then you could also afford first class. And supersonic travel will probably be like flying economy. The concord was pretty crammed compared to today’s first class.

> I

You are not the only consumer of air travel. Supersonic is not for you, it is for elites willing to spend 4x the ticket price for half the flight time. Concorde tickets were $6000 for D.C. to London in the mid 1990s, so about $12,500 today, and that was for an economy-style seat. It was very popular among a certain segment.

East Coast US to Europe in 3-4 hours versus 7-8, West Coast US to Asia in 5-6 hours versus 10-12.... makes it more like a domestic flight.

My dad got upgraded to a Concorde once (for reasons I don't know) from First Class on (I assume) Pan Am. His reaction was basically meh. Got into London at rush hour and he really wasn't that impressed.

Not a word on the environmental impact. We need to be flying less, not faster.

And yes, I know flying only makes roughly 5% of world emissions. It also turns out that these are some of the most avoidable emissions. We should be cutting them first.

We're all of us speeding towards a cliff that ends in environmental disaster.

And if you point that out, you get downvoted to invisibility on Hacker News and elsewhere.

I spent a lot of my 20s and early 30s as an environmental activist. I'm now in my mid 40s. One of the biggest things I've learned is that the vast majority of people will never make that trade. We are going to heat up the Earth. And then we are going to deal with the consequences.

Necessary link to Maciej Cegłowski's talk "Web Design: The First 100 Years:" https://web.archive.org/web/20230210133927/https://idlewords...

Because the technologies we had were good enough. It turned out that very few people needed to cross an ocean in three hours instead of six hours. On my way to this conference, I flew from Switzerland to San Francisco. It took eleven hours and cost me around a thousand dollars. It was a long flight and kind of uncomfortable and boring. But I crossed the planet in half a day!

Being able to get anywhere in the world in a day is really good enough. We complain about air travel but consider that for a couple of thousand dollars, you can go anywhere, overnight.

The people designing the planes of tomorrow got so caught up in the technology that they forgot to ask the very important question, “what are we building this for?”

I dont know i agree. Trans-antlantic flights kind of suck. If i was doing tourist things (and the cost point was right) i would definitely prefer a 3 hour flight. Not sure i would pay double for it, but i do think there is a market for this.

You'll pay double (or more) for it. You can have a much better experience today if you fly business.

Well that's the question right? What is the price point. All products have a price where people won't buy it.

But i suspect even if its double, that would still be enough to attract business class peeps, which might make it economically viable.

The issue concord had was also that a lot of people would rather a luxury seat on a conventional airliner rather than be squished in on a supersonic airliner.

I kinda doubt that dynamic changes.

One big reason supersonic can be economic now is the increase in wealth in Asia since the 80s.

Transpacific flights from California have no sonic boom population issues for 90% of the flight, and there’s already a large market of people spending $10k on business travel.

Reducing travel time from 12hrs to 4hrs would be a product with a lot more demand than 7hrs to 3hrs to Europe.

I'm excited for progress in supersonic flight because fast things can be qualitatively different. I first remember hearing this idea from Linus Torvalds, talking about developing Git. He said he works differently, not just faster, when merges are instant and easy.

Since hearing that, I see the effect in other areas of life, and transportation is one. I travel differently when the flight is 3 hours as opposed to 7 or more. Shorter trips, less luggage, less advance planning, less exhaustion, etc.

At first it will be available only at a premium, but that's how innovation usually goes. When the market finds something people love, capital seeks opportunities to lower the cost and increase the quantity. The real price of travel by aviation has declined dramatically over the last 50 years, for example.

I've got friends and family all over the world... I would for sure go visit more often if it wasn't so darn long just to get there and back.

With all those fantastic claims defining "the future", it feels more like PR hunt for venture capital in those start-ups than a serious article.

I just wanted to point out that Boom Aerospace is now mainly focused on delivering a Gas Turbine for power generation [1].

In an interview with CNBC Mr. Scholl talked about this pivot [2].

1. https://boomsupersonic.com/press-release/boom-supersonic-to-... 2. https://www.youtube.com/watch?v=ELl2uUAfGBw

> Blake embodies the “bits to atoms” shift underway in America. Before founding Boom, he was designing internet coupons for Groupon.

What is this? I can't find easily the meaning of "bits to atoms." Is this meaning that US is going away from digital "exports"?

From virtual goods to physical goods I assume.

Never heard before either so you're not alone.

EDIT: the reference to America is, again I assume, the trend to bring manufacturing back to the US from mainly China.

No the meaning is that there's a wave of hardware innovators who started as software innovators. Musk (Paypal) is the most obvious example. The Boom CEO featured here is another. There's a fair bunch more, I agree with the author that a weirdly high % of founders of cool hardware / deeptech companies have a software engineering background. Like, you'd expect that space to be dominated by mechanical engineers, electrical engineers and physicists etc but somehow it isn't.

Because people who led software companies (which have insanely high margins) have access to the vast capital needed for serious heavy hardware development. They then hire the engineers they need to succeed.

Yep. I suspect they're also better at getting warm intros to and selling their vision to Silicon Valley CEOs than your average aerospace engineer with a dream.

> You’re already flying this route with a 300-seat plane where 80+ people in business class generate most of your profit. Give those passengers a supersonic plane, cut the flight time in half, and charge the same price.

What does that end up doing to the cost of a seat in coach?

Left unstated is that the Concorde was designed at a time when aviation gas EDIT jet fuel ENDEDIT was priced at pennies per gallon.

That said, it might still be flying if its recertification flight hadn't happened on 9/11.

I'm relatively certain that neither Concorde nor any passenger jets burn aviation gas. It may be physically possible, but would be extremely ill advised given the lead additive

I'm pretty sure they weren't referring to 100LL, but either way even back in the 90s Jet-A was around USD 0.50 per gallon, in the 60s it was nearly 1/5th of even that.

Fair. Edited my comment to note that both sorts of fuels were in that price range, but didn't look up the specific fuel specification used by the Concorde.

Some version of Aviation Turbine Fuel (the other ATF) is used in passenger jets, which is either Jet A or Jet A-1 for colder, non-American flights. It is a kerosene-based fuel which does not contain any lead.

https://en.wikipedia.org/wiki/Jet_fuel

I'd guess not. It was aging, maintenance was getting ever more expensive, Airbus didn't really want to support it anymore, and it faced ever more competition from better first-class amenities on regular planes, and from the internet reducing the need for fast business travel. It was modestly profitable in its heyday once the capital costs were written off, but it didn't have a lot of headroom.

Jet fuel cost about $1/gallon when Concorde retired. Five years later, it would hit $3/gallon. I have to imagine that would have ended it if nothing else had by that point.

I don't think the Internet has reduced the need for fast business travel. I think business travel has grown along with the Internet.

The Russian Tu-144 first went supersonic on 5 June 1969, four months before Concorde, and on 26 May 1970 became the world's first commercial transport to exceed Mach 2

In 1973, it became the first supersonic passenger transport to crash into a town during an airshow.

"The last successful US airplane manufacturer was Douglas Aircraft, founded in 1921."

Nice (misleading) buried lede re: Boeing I suppose.

I just think regular flying shouldn't suck so so so hard and I'd be happy to spend 24 hours flying. Economy is an absolute nightmare these days, premium economy is where economy should be.

I'd love to be able to afford business or beyond but I honestly don't even want to try it because I know I won't want to go back.

> Three reasons: noise, regulation and cost.

So the environmental impact isn't even worth mentioning?

The environmental impact won't prevent their use unless something like a carbon tax is present, where environmental impact directly results in cost. People "need" to travel, in a convenient way, regardless. Same with ICE cars. They'll go away when they're superseded by both cost and convenience. The environment doesn't really matter to the mass population that travels.

I've had an EV (Tesla model 3) for almost 3 years now. I'm kind of flabbergasted at how good it is. I don't think you could pay me to go back to an ICE. Or you'd have to pay me a lot!

I think more and more people are having this experience. It's just not cheap enough yet, and hasn't penetrated the used market far enough yet. But I think it's just a matter of time.

I believe that fits under “regulation” from the perspective of people building these things.

At first I thought this was a reference to https://en.wikipedia.org/wiki/Leonard_v._Pepsico,_Inc.

Concorde was extremely loud. I remember it flying over. But its main sin was being a European product not an American one.

That said the US used to have the space shuttle and that has gone the same way.

> “Supersonic 2.0,” where anyone can catch a quick, affordable supersonic flight almost anywhere on earth.

There is a proven middle ground, where you can pay the current price or x the price for 2x the speed.

This was the bit that caught my eye:

> Blake’s pitch to airlines is enticing: “You’re already flying this route with a 300-seat plane where 80+ people in business class generate most of your profit. Give those passengers a supersonic plane, cut the flight time in half, and charge the same price.”

And now most of the profit for the 300-seater is gone. What does this do to flight pricing for those who were flying economy?

Yup, it's a bad pitch. Let's say the economy airplane without the business seats can now accommodate 400 economy seats. You now need two air crews and twice as much maintenance (or more) to transport 480 people (~60% increase) with a smaller percentage of those passengers being business class fares.

What really kills this though is the value proposition for the business class passengers. I think I'd rather pay extra to sit in a comfortable seat for 16 hours, where wifi is now a standard feature, than cram into a smaller (likely noisier) seat for 8 hours. The cases where that 8 hours matters - especially when you can work from the seat if you have to - are fleetingly few. In the 70s, you couldn't do much in an airplane seat so it was wasted time. This is no longer the case and is steadily getting better.

Depends on how well the wifi actually works. I flew Lufthansa from Europe to the US and paid for wifi that didn't actually work of most of the flight. If I could have just gotten there quicker, I would have paid for that instead.

> a smaller (likely noisier) seat

Reminds me of that description of the Tu-144 as "so loud you couldn't hear the person next to you screaming".

Standing room only flights.

Which one, the "strapped to an upright stretcher" variant, or just hold on to a handle or a metal pole like in a bus?

Most being the operating word here. Economy class tickets still make a profit if the airline wants it, just see the vast majority of regional flights which have zero business class seats. Southwest for instance has single-class layouts.

Some airlines "take" the marginal economy seat loss on larger planes because those are the ones they can fill with business class seats and make an even larger profit.

Even then it's a complex math on whether economy is hurting those flights' profit margins since those people buy things in-flight such as Wi-Fi and extra bags. Base fare is not the only way airlines make money.

Boom

I swear boom spends more on puff pieces than any other aerospace company. They continuously make claims they will do things by certain dates that are unrealistic.

They claim they will be delivering airplanes to United that would be in service in 2029:

https://boomsupersonic.com/united https://www.cnbc.com/2021/06/03/united-will-buy-15-ultrafast...

However new aircraft take 5-9 years to certify and they have not yet even built one! Not to mention new engines take a similar amount of time and they are supposedly building their own brand new engine, which is a substantially harder task.

Now they are claiming the first "test" flight will be in 3 years despite the fact that they still don't have a plane or an engine built. I hope someone over their let United know they are going to be a little late. Their website hasn't amended to article to say they were wrong.

I wonder if we can look to history to see how long it takes between when they say they will fly something and when it actually flies? Oh right, we can!

https://en.wikipedia.org/wiki/Boom_XB-1

"The original design was unveiled at Centennial Airport in Dove Valley, near Denver, Colorado, on November 15, 2016,[6] and it was initially intended to make its first subsonic flight in late 2017"

"The XB-1 performed its first flight test on March 22, 2024, flown by test pilot Bill Shoemaker from Mojave Air and Space Port.[1]"

They were only 7 years off but we all make mistakes.

Astro Mechanica

- LNG isn't used because weight needed for fuel tanks that will keep it cold enough to stay liquid cancels out any benefits. For anyone interested in a famous failure of a similar idea: https://en.wikipedia.org/wiki/Lockheed_CL-400_Suntan - I don't know what analysis they are doing that makes them think reducing the number of passengers and going to supersonic is possible while maintaining current ticket prices... but it's not. - Engine and plane makers are not allowed to run airlines. Anyone unfamiliar with the field can look up United Aircraft. - Their engine does sound like it's trying to do some cool things. I kinda suspect it's just a fun way to pass the time on the governments dime given all the other unrealistic stuff they are talking about though.

Hermeus

These folks are legit. Don't know if they will be successful but outsourcing the jet engine and focusing their work on the ramjet and the integration of the two makes alot of sense.

I was a bit disappointed with the Boom XB-1. They originally announced - designed to maintain a speed of Mach 2.2, with over 1,000 nautical miles. I thought cool. Then 7 years late they fly and - Mach 1.1 and no long–range. Then rather than develop it they say it's retired, we'll take orders for Overture now.

I wonder what's going on there?

Why make planes faster when you can make them more uncomfortable and upsell more items mid-journey?

Also don't forget saftey as one of the things holding this back. It's pretty major.

The 1973 sonic boom regs were there to protect the US airline industry, not citizens.

Except the title, a large part of this article seems to have been written by an LLM.

Crazy that you are the only comment that noticed this. I stopped reading at,

> Translation: Building airplane engines is hard

There are many hints previous to that, but that gave it away for me. If I want LLM output I’ll request it from the model myself, thanks.

> using AI software to measure atmospheric conditions

What is this even supposed to mean?

To me this comes across as "I'm not sure if you'll be impressed by a supersonic jet that can surpress sonic booms, so I shoehorned AI into the description to jazz it up." It makes me wonder why the author doesn't think the former is impressive enough on its own.

Every data model is now AI.

Why are we not focussing on rocket based travel so we can finally do 90 mins from Seattle to London :)

Spacex and blue origin has already demonstrated heavy payload transport, why can we just move to this than work on supersonic

"Noise problem solved" from the "Rational Optimist Society"

Sorry can't help but chuckle at this....

[flagged]

We need supersonic airports, not planes. Spending 2h to board a plane for a 1h flight is just wrong

1h flights are just wrong period. Just build a train.

Does your opinion change if the flight speed is 2500km/hour for most of the flight?

? No, because (1) the distance is still short and (2) 2500km/h flight is uneconomical so it's never going to happen anyway.

I used to take the train from Orlando down to Miami (well... Ft Lauderdale) and it was about 3 hours, vs a simple 1 hour flight, or a 3 hour drive. The train ride was worse on holidays though, sometimes it took 6 hours or even way longer. I think I'd much rather be on the plane overall.

good train > plane > bad train

Driving is cheaper than all of those options when its more than one person, at least here in Florida. The more people involved in your travel, the cheaper driving starts to get.

Some pretty bad traffic in Miami. Last month it took me an hour to go 10 miles on a Thursday afternoon.

Hehe, my wife is from there, for the first few years she lived in Orlando I would crack jokes about how bad it is down there, noticed she was getting offended so I pulled back, but the last three times we've gone down there she swears up and down Miami drivers are the worst. Of course Orlando has I-4 as well, which is, its own special place.

Get a comma ai and it's just not a bother.

I regularly take the train between Moscow and Kazan. It's 12 hours, you can get on in the evening, have dinner on the train and then get a decent 8 hours of sleep before getting up, having some coffee and arriving.

It's much longer than the equivalent flight, but also much more comfortable. There's something annoying about airports - with the train I can get to the station 15-20 minutes before departure and it's fine.

Once the train rides get much longer than 12 hours it shifts, but there's a sweet spot right around there.

Correct, you weren’t riding a bullet train.

There are these really fast trains that exist in a dozen countries.

China has 30,000 miles of high-speed rail.

Well duh x) because the "train" is dogshit, that's exactly my point. If instead of a 28 lane highway there was a dirt road, or instead of an intl airport and jets there was a grassy field and biplanes, nobody would drive or fly respectively, either x)

Sometimes it’s not that easy or cheap to build a railway. You have mountains, seas, wetlands etc. But I agree that high-speed trains should be the default option.

Even if you don't, you have property owners whom you'll need to either convince to sell or you'll have to get eminent domain to cross their land. Across multiple jurisdictions depending on distance covered, any one of which could delay your project by months or years with procedural objections or hearings. You'll need environmental impact studies and accomodations for the entire route. And for high-speed rail you'll need to build underpasses/overpasses at every road crossing. And once you build a rail line you're pretty committed to that route. Air travel avoids all of that.

just for sake of clarity - people need to remember it took about 2 years to get the finest plane ever built i.e SR-71 (Blackbird) in the air.

there's thing we lost we i.e skills, grit, creativity we might never recover from

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