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.

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.

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

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.

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.

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.

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).

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.

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.

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.

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.

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.

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

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.

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.

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

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.

TSA in the US is a jobs program

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.

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

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.

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.

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.

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

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.

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

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.

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".

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.

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.

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

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.

> ”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).

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...)

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.

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%.)

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.

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

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.

> 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.

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.

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).

Deep Vein Thrombosis?

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

> 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.

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.

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.

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.

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).

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

> Give those passengers a supersonic plane

Meaning a big price increase for us normal passengers?

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

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.

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

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

Absolutely no one cares what Claude has to say about anything. Are you completely incapable of forming and sharing an independent idea?

Pasting LLM output is against HM guidelines.

> i asked claude

nobody cares about the output of your favorite industrial quantity slop generator. try using your brain next time.

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.

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.

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.

Standing room only flights.

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.

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

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.