Ramjets were developed right after the second world war and Mach 4+ was reached in the fifites. It's complicated but not extremely. See Antonio Ferri or Lockheed X-7.
It turned out out solid fuel rockets are operationally more practical for the use cases like air defence, long range missiles that are ballistic instead of cruising in the atmosphere and so on. And jet engines are more efficient for subsonic cruise missiles. Ramjets are still used in some missiles like the long range mach 3 air-to-air Meteor.
There have been air-to-air missiles using rocket-ramjet combinations: they start as a rocket, then once up to speed an inlet opens and they transition to ramjet mode (using the same chamber and nozzle). It extends range. Ramjets are best for maintaining speed rather than accelerating to speed.
...it never went into an actually flying airplane though (apparently there were test flights with Lorin tubes attached to propeller planes, but only to test the Lorin tube behaviour under flight conditions, not as an engine replacement).
The idea and patent itself is over a century old by now:
For many many reasons this engine only has one economic application - delivery of a nuclear payload in a way which is very hard for missile defences to stop.
ICBMs can go faster than this already but as I understand it they go higher allowing for earlier detection and they follow a more predictable trajectory which makes interception more realistic.
I find super fast missiles far scarier than advanced AI. I suppose they maintain the "mutually assured destruction" which might be the main reason there hasn't been a nuclear war since WW2, but it's not a huge comfort.
My take is also a missile, but as an interceptor, not offensive purposes. North Korea has shown that they can deliver a payload to Japan if they want. If the NKs do decide to launch something at Japan, it's not going to be tipped with conventional explosives. It'll be a nuke. Hypersonic interceptor seems the more likely application is this tech to me.
I think that hypersonic interceptors would use a rocket motor and not a ramjet, but I'm not sure.
I think this is for offence because I understood the advantage of this engine (compared to a rocket engine) is that you don't carry oxygen so you can carry more fuel and get more range. I think range is much more useful for offence than defence.
I am possibly making myself look foolish now as I'm not an expert on either rockets or ramjets and I might have incorrectly dismissed defensive applications.
judging by what we saw so far in Russia, Ukraine, and Israel, defensive missiles don't require particularly sophisticated offensive missiles to overwhelm.
yeah, but those are using conventional explosives, only countries like the US and Russia have enough nukes to do the same with nuclear explosives, a country like japan would need a sophisticated missile instead
Not sure I entirely appreciate the use-case vs classical targeting. I'd imagine you're going so fast that you don't really have the opportunity to engage in thought that is particularly useful.
The Wiki pages says top speed is about Mach 4. There are already multiple rockets from US, Russia, and China that can achieve the same (or more) but with a solid-fuel rocket motor. What is the advantage of a ramjet here? It just seems way more complex and much less well tested (in labs and in combat). Also, has this missile (Meteor) been used in any combat scenarios? To be clear, the max speed for any fighter jet is about 2.5 Mach. Once one (or two) of these missiles has locked on, you are done. I read some funny commentary once about how to shoot down a modern fighter jet: Two missiles. They can dodge the first one, but sacrifice so much speed, that the second one can easily find its target.
Missiles versus aircraft is a fight between very high kinetic energy in the missile, and relatively low kinetic energy in the plane, but with the ability to generate more kinetic energy. Missiles don't have a lot of fuel, so they need to generate a lot of kinetic energy to still be effective by the time they reach the target. Typically a missile will accelerate to its top speed in the first few seconds of flight and coast the rest of the way. At very long ranges, all the energy generated when launched has bled off, so there's two common solutions for long-range missiles to generate more energy: a "dual pulse" motor is basically a second rocket motor that fires later in the course; or a ramjet, which can be throttled up and down and is more fuel efficient than a rocket engine.
A ramjet drastically increases range against maneuvering targets. The 'maximum range' quoted for missiles like the AIM-120D (Likely 140-170km) is normally for a front on shot at extremely high altitude (10-15km+) with no evasive actions. With an evading target the No Escape Zone (where a target likely can't kinetically evade the missile) will only be 15-25km.
The Meteor has a longer sustainer and a terminal boost meaning that the No Escape Zone is though to be upwards of 60km. Qatar might have used Meteors to shoot down Iranian Su 24's just a few months ago based on the range they were shot at.
You really need to play combat flight sims (like DCS) to understand why a ramjet AA missile makes a lot of sense ;)
It's not mainly about top speed, but about endurance (e.g. flying under power for the entire flight time of the missile).
The gist ist that traditional BVR AA missiles are only powered at the start of an engagement (and a lot of that power is used to gain height) until their rocket engine runs out of fuel. For a large part of its flight, traditional AA missiles glide without power towards the target, meaning the missile will lose speed from the moment the rocket engines are switched off, and even more for each required maneuver that needs to be performed afterwards (that's why it is a valid strategy for the targeted airplane to evade the missile by forcing it into a turn during its unpowered flight phase - e.g. instead of doing a 180 and flying straight away from the missile, fly a roughly 90 degree course to the incoming missile to force it into a wide turn, which means the missile will lose more energy than it would when remaining on a straight course).
A ramjet powered missile on the other hand flies under power for the entire engagement, it can 'cruise' towards the target and then for the final phase of the engagement speed up and home in on the target (or generally do complex maneuvers) without losing speed, which gives the target airplane much fewer options to evade the attack.
> I read some funny commentary once about how to shoot down a modern fighter jet: Two missiles. They can dodge the first one, but sacrifice so much speed, that the second one can easily find its target.
With a ramjet missile you don't need a second missile to exploit the target's depleted energy. And the two-missile strategy also doesn't really work when the other aircraft fires a single Meteor from a greater distance first ;)
It's not that simple. If the target aircraft is outside the minimum abort range then they can still evade multiple missiles, regardless of whether the shooting platform or the missiles themselves are locked on. Typically they would do so by descending into denser air and beaming the missile to bleed its limited energy. On larger missiles a ramjet can potentially allow it to retain more energy into the terminal phase.
There are a variety of other defenses including countermeasures, signature reduction, EW, and decoys which also complicate the issue.
Is a Mach-5 passenger aircraft actually the goal of this project?
Seems more likely that Japan is designing this engine for a hypersonic cruise missile program, and the passenger aircraft concept is somewhat of a cover.
IMO, there is no point in a Mach-5 Aircraft (other than cruise missiles). There is potentially some point in Mach 2-3 aircraft, (not that we have ever made them commercially viable) but at the boundary to hypersonic, you might as well just switch to a suborbital hop concept.
A suborbital hop gets you to anywhere in the world within ~90min, avoids issues of supersonic overflight and you don't need to worry about the massive engineering issues caused by sustaining hypersonic flight. And as a bonus, the passengers get a hour of weightlessness.
> (not that we have ever made them commercially viable)
Concorde was commercially viable at Mach 2.2 in supercruise (although there's a common misconception that it was not).
However, its overheads were very high, and its applicability was severely limited by fears around the sonic boom (most particularly in the US, which banned supersonic flight overland, possibly largely because they wanted to kill off foreign competition).
Air breathing engines don't need the oxidizer tank, so like the 2/3 of a rocket just goes away before even touching Tsiolkovsky math. That improves payload mass fraction massively.
Also, this doesn't scale down to Mach 3-4 and under. This thing uses scramjet, or supersonic combustion ramjet. It REQUIRES intake air to be at high supersonic speeds for it to work.
> It REQUIRES intake air to be at high supersonic speeds for it to work
This is why I am highly sceptical it can be part of a commercial supersonic passenger jet: how do you get from subsonic -> supersonic without also tacking on some kind of conventional jet engine?
Japan, Italy and UK have a program for a competing F35 design, GCAP. And Japan is focusing mainly on the engines.
Given there will at some point be the need to deliver competing cruise missiles for this platform, and after the crisis of the US not being able to keep demand with Israel's and Ukraine's orders they greenlighted SK and Japan to enter the European defense market, to answer your question yes, this is of course a defense related project.
There's been an industry request to develop native defense components on these matters within the EU following pressures and contrasts with the US (on a report to the EC for the ReArm campaign, EU's biggest playes of aerespace industry made a joint report estimating 60-80% of their components and tech are sourced from the US).
> Is a Mach-5 passenger aircraft actually the goal of this project?
> Seems more likely that Japan is designing this engine for a hypersonic cruise missile program, and the passenger aircraft concept is somewhat of a cover.
Case of China's got them, and can't rely on the Orange Emperor and his heirs to have their backs.
I didn't initially believe these numbers, but if you look at some real life stats, you are probably right.
Nominal SECO for the last starship mission was at ~8 minutes and it took ~20 minutes from deceleration started (well, from air resistance outweighed the forces of acceleration) to landing. So basically 30 minutes of flight is just the "getting up to speed" and "slowing down" part. Both account for some distance traveled, but still. ~45 minutes is probably a good bet.
Do note however that you may have to go around the world "the wrong way" to get some places due to launch constraints. But living in a world where going around the world "the wrong way" is the easier path is interesting. Imagine that.
Unless a suborbital trip is nearly at orbital velocity, it will involve a high, arcing trajectory. This will make the deceleration at the end unacceptably (lethally) high for all but short arcs. Some of the Mercury suborbital missions involved deceleration of 15 gees, if I recall correctly.
And all but rather short ballistic trajectories (well below orbital speed) will come in at a steep angle.
Unless one has seriously variable aerodynamics, the vehicle will have to swerve to nearly horizontal over a distance of about 1 scale height of the atmosphere, which is about 10 km. The exponentially thinning atmosphere goes from "too thin to matter" to "brick wall" over a short distance.
The acceleration for turning is v^2/r; for v = 5000 m/s and r = 10 km this is 250 g.
Acceleration also limits how rapidly one can reenter from beyond Earth orbit. At > LEO velocity, the vehicle has to use (downward) lift to stay in the atmosphere, and if v is too high the required acceleration is too high.
It would still be possible to fly a predominantly ballistic trajectory, yet use rocket propulsion to decelerate whilst still outside the atmosphere. It would require a huge amount of extra fuel compared to a purely ballistic trajectory, but perhaps still less than achieving a full orbit and de-orbiting again for some destinations.
At global distances a fraction orbital trajectory would use less total rocket delta-V.
More practical would be a trajectory that was a series of small suborbital arcs with skipping off the atmosphere (perhaps with some airbreathing propulsion during the skips.) The thermal protection can cool by radiation between the skips.
No, it's an issue for most arcing trajectories. Lift doesn't help much if you're coming in at a steep angle. Reentry from orbit only works well because the entry is almost flat; there even a little lift helps a lot.
It can be nuclear powered, so you don't have CO2 emmisions /S
You just need to add heat to the air at the point where the diameter is the lowest.
The russians are maybe using this idea for one of their new cruise missles named Burevestnik, although for them the nuclear emmisions are likely a positive side effect.
I kind of think today's air travel is in an uncanny valley.
I'd prefer either: just as uncomfortable or even more so but very fast, like multiple mach numbers fast. I live in the Midwest and go to the West Coast often, and it usually takes 5 hours -- I'd cram into a less comfortable seat for 2 hours instead to get there at mach 2.5.
OR... airships. Big cushy seats. A lounge with fast wifi and desks. A coffee shop. You can walk around. The trip takes all day, or overnight with a sleeping cabin. Trains could fill this niche too, but airships could go overseas.
I actually learned about what a ramjet is after looking up the definition of “scramjet” when watching the _Top Gun: Maverick_ movie with my son. This is at the beginning of the movie when he is flying the Dark Star plane designed in conjunction with Skunk Works from Lockheed Martin. Well, we are obviously a ways away from Mach 10 reached in the film by the SR-71 Blackbird descendant, the new technology pushing Mach 5 and into high hypersonic is pretty impressive.
> A scramjet is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to compress the incoming air forcefully before combustion, but whereas a ramjet decelerates the air to subsonic velocities before combustion using shock cones, a scramjet has no shock cone and slows the airflow using shockwaves produced by its ignition source in place of a shock cone - Wikipedia
As I understand, the problem with anything over Mach 4 (or 5), the metal begins to disintegrate. It is fine for a one way missile, but not a reusuable aircraft. Without some alien tech (see 1990s game "X-Com 2"), I cannot believe that we can build a reusuable aircraft that can reliably and safely fly for long periods over Mach 5.
Ramjets are limited in the speed they can operate because slowing the air to subsonic speed in the engine causes it to become hot, and the temperature increases rapidly with speed (the kinetic energy of an incoming air parcel is proportional to the square of the vehicle's speed, and most of that energy is being converted to heat.)
I always thought it was an underutilized design that could be improved for practical applications.
Improved enough, it could become cheaper and more environmentally-friendly than current aviation whereas regular supersonic jets are never going to achieve that.
>At that elevation at Mach‑5, air around the nose and leading edges can reach temperatures exceeding 1,000 degrees Celsius (1,832°F), a challenge...
It is not the conical nose or leading edges that are the show stopper problem(s). There the shockwave generally does not touch the craft. The internal shockwaves that touch the walls of the engine ducting are. The heat loading and heat soak ability on those shockwave impingement sites will limit the duration of hypersonic travel.
Hypersonic travel through the atmosphere is easy, a problem solved in the 1950s. Be conical and carry your oxygen internally. Hypersonic travel that is air-breathing is an entirely different class of problem and I don't think it is anywhere near to being solved.
The only silver lining is that at hypersonic speeds you don't need to be propulsive for very long to get anywhere.
Supposedly the SR-72 has figured this out. Just rumours at this point, but apparently they’ve cracked the hypersonic air breathing puzzle on a usefully sized aircraft.
Interesting, but assuming they can get the engine to work as intended, the question still remains how the passenger jet would get up to Mach 5 so the engine can start working. A solid-fuel rocket booster that would then drop off?
"It was initially proposed that a wire-mesh basket holding coal be mounted behind a nose air intake, protruding slightly into the airflow and ignited by a gas burner. [...] The air passing through the ramjet would take the gases from the burning coal ..."
I'm no aircraft engineer, but I guess it would use traditional jet engines to get up to some low Mach 1+ speed until the ramjet gets enough air to bite on.
My bet is that this hasn't been done yet simply because it wouldn't be economical (the technology itself is a century old and has been tried over and over again), and that the 'civilian ramjet aircraft' is just a feel good story for what will end up as purely military usage, and most likely not in an airplane, but in missiles (there are a couple ramjet engine missiles in use already, like the European Meteor).
I can't see how this would work for civilian purposes - since you need to counter the higher temperatures from higher altitudes. ceramic tiles (heat protection) - then u r heavy. this is based on noob aeronautics reasoning btw.
> At that elevation at Mach‑5, air around the nose and leading edges can reach temperatures exceeding 1,000 degrees Celsius (1,832°F), a challenge the U.S. Air Force has struggled to overcome with its own hypersonic jets.
> To handle that level of heat, engineers constructed an advanced thermal‑protection system that maintained the aircraft's interior near normal operating temperature, allowing the onboard avionics and control electronics to function normally.
People say this like it's a simple engineering problem.
No. By itself, a new hypersonic engine can't make 2-hour flights between Japan and the US a reality. We are not even close to being able to build an aircraft that can do that - we don't even have the materials for that. What seems "easier" (as in "less impossible") is a hypersonic glider design that enters a suborbital trajectory and does shuttle-like aerobraking while it glides to its destination, before reengaging propulsion prior to landing on an airstrip (because passenger planes need to be able to abort landings and do multiple attempts). Not sure how reverse thrust would work there - variable geometry rocket bells?
I've always wanted someone to bring back the Avro Arrow to use the Iroquois engine for freight, but I don't think anyone has the knowledge to even pull it off anymore.
The avro was an excellent plane for the time. It would have been a good plane for the Cold War. It was a plane well suited for Canada's threat environment. The missiles that replaced it sucked.
However, the Avro wasn't anything any of the other great powers couldn't do back then or today and it was ruining Canada financially.
The only question I have about the Avro is: "Could foreign sales have rescued the plans and Ottawa's budget?"
I think not. In an era of hyper-protectionism where the Brits built an air cooled nuclear reactor [1] rather than buy Canadian heavy water, it's inconceivable that Canada would have found buyers.
[1] resulting in the largest nuclear disaster until Chernobyl. Keep in mind, at the time, English Canada largely thought of itself as British and even decades later fumed at the new flag lacking the Union Jack. And yet the Brit's didn't but their heavy water.
The engine noise can still be conducted through the body of the plane. With the kind of ramjet being talked about, I think that's still likely to be significant even at very high altitude.
This effect would help mitigate the noise heard by people outside of the plane (but I suspect that noise is negligible compared to the sonic boom), but in the plane the sound would mostly be propagated though the fuselage of the plane, not through air, so it's not going to help.
Cool science. But the article fails to take even a cursory stab at contextualising the plan against the economic, environmental and political backdrop - doesn’t even mention that there’s already been one failed supersonic commercial flight programme. This is as pie-in-the-sky as it gets.
I think a lot of the Concorde failure is tied to its status as a British-French project. Trans-Pacific flights are much longer and there's a lot of money in PEK -> LAX than in JFK -> LHR.
Qantas wanted to offer London to Sydney, but they couldn't fly supersonic over land. Mainland China or Japan to Australia is a feasible route for high-margin, low-capacity supersonic flights.
If you could make the flight from Beijing to California take less than 5 hours that seems like a premium product many ultra wealthy people would spring for. Dubai to SFO is also a possible route.
I was pretty sure the whole Concorde thing failed because people don't like it when you sonic boom an entire city dozens of times a day. And that all attempts to reduce the sonic booms necessarily resulted in flight times that aren't significantly faster than traditional subsonic flights, rendering the entire thing moot.
It was impractical due to physics, not some weird racism. You simply can't push a supersonic shockwave over inhabited areas, and the only way to not do that is to fly subsonic over land. Even if the oversea leg is supersonic, the tickets were much more expensive for not very much shorter flights. It wasn't a valuable proposition for most people.
1) The flight markets are different now. There's been a large increase in both transatlantic and transpacific flights, especially the latter. These change the economics of considering only these types of flights, flying only over uninhabited regions.
2) The technology has changed. We're much better at dealing with sonic booms now. You can't get rid of them entirely, but you can reshape them. You can't send everything "up" but the longer of a tail you can make the more the sound dissipates by the time it hits the ground. There's lots of research around this and as you can imagine, incredibly important for the military. You can't fly fast spy aircraft if they are just announcing their position while flying around. Sure, there are satellites, but those are predictable by the enemy, you'll always need aircraft to do this.
However, there are markets where you don't have to fly supersonic over land, the distance is long enough for the speed to matter, and there is massive amount of demand. The only problem is, such markets require a longer range than what the Concorde was capable of. Notably, all the very frequently traveled trips over the Pacific.
Concorde’s sonic boom was astonishingly loud. The night flights would go supersonic outside the Bristol Channel at around 9pm to 10pm. It was still audible over 60 miles away and sounded like a muffled barn door slamming outside.
Far louder though — it would wake all the pheasants up just as they’d gone to roost.
England in the '80s didn't give a shit about little people. Had it been really profitable, Concorde would have continued operations. It just did not make sense economically, particularly once they stopped making new airframes.
There is a lot of money in NYC-LHR, that's why Concorde continued to fly that route and profitably too, once they realized how high they could yank the prices and still fill the plane.
Also, Concorde's maximum range was 4,488 mi, which was calibrated to allow trans-Atlantic but not much more. Trans-Pac was not an option and even Australia to North Asia would be a stretch.
There is money in NYC-LHR (it brings BA alone $1B in revenue annually) but the market for supersonic basically vanished. In the 70s when Concorde started flying, it was certainly a step up. However, the market niche basically disappeared when the lie flat seat was developed; for a lot cheaper, you could have a sleep for six hours in a really cushy lie flat, or you could spend a crapton more to be in a much louder, more cramped cabin for only about three hours less. If you were halving a 12-16 hour journey instead, there would still be a market left, but Concorde just didn't have the ability to do so.
You can also essentially work remotely in an airplane now. I haven’t tried videoconferencing, but I easily do all my other software work on trips. So a couple extra hours might even be a benefit: more time with no distractions to wrap up that slide deck, maybe a 1:1 or two, get your free drinks from premium/business class, doze off to a movie, wake up for an early start at your destination.
Shorter, no, but having a private cabin with a shower, and a lounge with a bartender on the plane, not to mention Starlink, would make those 12 hours a lot more bearable vs 12 in an economy seat.
AFAIK: Showers are only available to first class customers flying via the major Gulf carriers. I checked Google flights for business class and first class tickets between Tokyo and London. Business is about 5,000 USD and first class is about 10,000 USD. Assuming that we are talking about first class here (to satisfy your shower requirement), what kind of developer is hacking code at 10,000 meters in first class... except... hmm... Mitchell Hashimoto?
Mitchell Hashimoto's got tres commas in his bank account and his own jet. He doesn't need to take commerical, or even first class. If we backsolve, say $10,000 is a once a month purchase, and $10,000 for a hotel and you stay a month. Say your other living expenses are $10,000/month, so we're shooting for spending $20,000/month. With the recommended shaving off 3% the nest egg, (20,000 * 12) / 3% gets us $8 million in the bank.
So at $8 million in the bank, you could take a $10,000 plane trip, stay for a month, spend $10,000 on a hotel, take a $10,000 flight back. Still upper end of net worth, but nowhere near Mitchell Hashimoto territory.
Everyone thought SSTs were going to be the next big thing. Both the US and USSR had projects. The 747 got a hump so it could easily be converted to a freighter once it was made obsolete by supersonic passenger planes.
Despite two superpowers making the attempt, and plenty of time for more tries since then, Concorde is the only one that came even remotely close to something commercially viable.
I’m sure there’s a market for California to China in five hours. But is it enough to support a whole new type of aircraft? Fuel burn is going to be enormous. Maintenance on something so cutting edge will be extremely expensive. Tickets would probably cost more than a private room on a widebody.
There are no economies of scale to be had here. If there are only a handful of plausible economically-profitable routes, all of the expenditures on R&D, testing, certification, and production facilities can only be amortized across a handful of aircraft.
Once you’ve built a dozen or two of them and a handful of extra engines and spare parts… what then? There’s no point in keeping the production lines open.
From an airline’s perspective, they have to now have an entire separate chain of employees (pilots, mechanics) dedicated to another airframe that barely makes up a fraction of their fleet. That’s a lot of overhead for two or three routes.
Those are some pretty big structural disadvantages that need to be overcome in order to make a boutique supersonic route appealing.
Scheduled service is not viable but there is a bountiful supply of billionaires willing to one up each other with lavish expenditures. Having the fastest class of private jet is worth something to them. This is what's going to be the market for Boom if they don't fold.
One analysis I read by a marketer that makes good sense is that the speed was worth paying for LHR to JFK but not really on the return given the clock changes and speed.
Getting to NYC before the clock time you left London was a cool trick. It allows you to make a morning meeting in NYC without coming in the night before.
But flying subsonic leaving NYC after dinner and arriving in London for breakfast works fine. Getting to London faster in 3.5 hours travel time but 8.5 hours later clock time means losing a day in the air effectively.
If it stays in the realm of the ultra wealthy I don't see how it will succeed in the end. Commercial aircraft are really expensive to design and qualify, and you need to have a lot of sales to justify a new model. Ultra wealthy people are willing to pay more, but they also demand luxuries that take up a lot of space.
The only reason Concorde did as well as it did, economically speaking, is the respective governments footed the bill for development.
> respective governments footed the bill for development
I just looked up development costs on Wiki: "£12–16.7 billion in 2025". Yikes. And "the market forecast was 350 aircraft", but only 20 were built. What a waste.
Yeah. But to be fair, it was the first supersonic airliner, so they were feeling around a bit in the dark when it came to estimating demand. They would have all looked like geniuses if enough demand to build 700 air frames had materialized.
I remember when the aircraft first went into service. Everybody thought subsonic air travel, at least over the ocean, would become a thing of the past.
My point is mostly that since the 80s there's a lot more trans-pacific flight from the Middle-east and Far-east to the United States. When the Concorde was developed this wasn't really a worthwhile market to consider for ultra-premium air travel.
I could absolutely see Emirates doing a super-luxury super-sonic flight to the West Coast of the US. Once you're in the States you can take a PJ.
Emirates just dominates long-haul flights to Dubai overall. Other (mostly flag carrier) airlines handle other airports in the region. Qatar Airways through Doha is also a big player in flights between the US/Europe and Asia.
It's not tied to anything other than there not being enough people who care enough to spend the sort of money required.
The people who have that kind of money are going to be more interested in flying in a jet share doing mach .96 leaving when they want to leave, going where they want to go, when they want to go, how they want to go, with who they want to go with.
You get treated like a criminal for forgetting your shampoo bottle is 2 ounces too big for some dipshit TSA agent's liking, and meanwhile the ultrawealthy are shuttling around physical assets worth millions of dollars in their private jets and customs barely does more than stamp their passport.
Yeah, this is something that changed from Concorde times (and possibly even sped up its very demise): the market for reliable, high-quality private planes has grown massively. It's now pretty easy to shuttle between the big cities in almost complete privacy through secluded airports.
> You get treated like a criminal for forgetting your shampoo bottle is 2 ounces too big for some dipshit TSA agent's liking,
Enforcement is super uneven, and etc, but IME, they just open your bag, find the thing, and then offer you the choice of tossing it or going back to check your bag. Depending on how much you paid for your shampoo and how much a checked bag would cost you and if you have time to do all that and then wait in line again, I expect most people toss it.
Concord was very old technology. I am quite sure a clean sheet now
1. Would have much lower sonic booms thanks to recent research (quite a bit of it by NASA on wing geometry) and more importantly computer simulation available now
2. The engines would be far more fuel efficient
3. The flights would be able to have better efficiency in the subsonic regime as well. Just see what winglets and the like have done to fuel economy .
I fly 14 to 18 hour routes maybe 4-5 times a year on business paying 5x the economy cost and it still sucks. Breaking the flight with a connection (IMO) sucks more. My management flies such routes every month. There is a lot of revenue headroom in that fare gap for something that flies maybe 3x-4x as fast which military aircraft already do.
What will hold back the idea is conservatism among the business managers in aircraft manufactures and incumbent airlines who will "draw lessons" from a 50 year old experiment
not really. In supersonic regime Concorde engines were pretty good, and you'd not beat them today by much.
Concorde was using afterburners to accelerate to supersonic and this is where it burned a lot of fuel. Designing engines which would give you good thrust at subsonic speeds without afterburners and would still perform well in supersonic is still much unsolved. Just look at the best military engines today - they all under Mach 2 and can't give even 3000 miles range.
And without increasing efficiency we can't really get much beyond the Concorde's 4500 miles. I.e. unfortunately there seems to be no current tech (or coming right tomorrow morning) that will allow Trans-Pacific.
It looks more feasible to me that Starship suborbital SFO-to-Shanghai will come well before a new Concorde on that route. Especially considering that Starship's ballistic trajectory is more fuel efficient on such long distances than supersonic plane flight.
It'd be far more efficient than the 50 year old tech, but so is the baseline tech they're comparing it with, and the market has optimised heavily for price competition (and has a lot more private jets doing exactly the route and time executives with Concorde money want) and needs speed somewhat less when it's a lot easier to stay in touch with a business whilst inflight. Ultimately there's not much to draw lessons from that suggests it's going to sell enough aircraft to recover the investment of building and certifying it (even comparatively simple niche aircraft like the A380 struggled there), which is why even Boom is now reinventing itself as a provider of turbines for AI datacentres to try to fund its development costs...
Whenever you look at supersonic or hypersonic commercial aircraft plans you should assume one of two things.
A. It's a bait and switch by a founder who wants to pivot to weapons/military aircraft but wants to be able to hire high grade talent without paying the "we're gonna kill people" premium, can pivot once a good chunk of the workforce is complacent with a paycheck. You laugh but this happens SO FUCKING MUCH.
B. It's for business jet scale operations for billionaires. There are >3000 billionaires and however many corporate aviation departments and if you can build a super/hypersonic private jet that's not horribly expensive to operate the "time savings"* for that class of person will demand they buy one.
* when I say time savings I mean dick measuring contest
Defense contractors don't pay premium wages. Rather the opposite. Many employees specifically want to work in the field in order to contribute to the national security mission.
I'm being a bit obtuse here to make the point, it's more complicated than that. The reality is if you create a defense startup you end up hiring defense employees which comes with its own set of issues.
That said, go look at salaries right now in the defense space.
From my experience with working for defense/aerospace companies as well as civilian b2b ones in the US, the general situation is that defense/aero companies pay less but demands less of a grind. People usually take the lower pay (usually 70% of equivalent role in commercial sector) for the better culture
For pure generic full-stack-whatever devs yes. For EEs, embedded, FPGA, RF, etc you can pull waaaaay more in the defense world, especially if you're willing to do cleared work.
I’m not in the industry, but I would say Hermeus would be a perfect example. Ostensibly building a commercial airliner, but if you look closely it feels like a military oriented startup from the inside out.
Can't give any examples but I have definitely heard the same about a lot of aerospace startups through the grapevine. As for OP's point about private jets, Boom supersonic is your classic example.
I can't name names but 3 of the startups I've worked at.
Places I haven't worked:
Skydio
Applied Intuition
Saildrone
Planet Labs
Boom
Scale AI
Also worth noting that sometimes it's on purpose, sometimes the founders are all "we're gonna save the world" then AFWERX enters the chat with a big fucking check and the founders yell "Nevermind! Guess we're the baddies now! How many slaughterbots did you say?"
Vastly more favorable today than it was when Concorde flew.
1) Rich people are WAY richer, and time is even more valuable
2) Businesses have some very important employees and "2 day trip" vs "3-4 day trip" is worth $50-100k
3) Larger population of people able to pay $20-30k for a flight than ever before.
The biggest practical impact is there's probably going to be a private jet version instead of just a commercial one, and there will likely be transpacific demand exceeding transatlantic. Also government/military use.
You are not thinking high enough the food chain. I mean heck you have tenured SV engineers cracking $1mm with RSUs. It’s not rare in finance for folks to be hitting $3-5mm with bonus. So that’s what $19k comp a day. If that individual is making $5mm they are more than likely making a multiple of that for the organization.
Even these days, a lot of retailers operate fleets of private jets even for district or regional managers, because it saves somebody like Walmart a lot of paid hours to fly someone from rural town A to rural town B rather than potentially deal with the hassle of an overnight booking at an airport hub.
I still don't quite get it given I have never worked high enough or in a big enough corp. What kind of mission a person earning $19k a day have to do at the destination to justify the cost? I imagine to earn this much their main responsibility is to lobby / influence someone important (at dinners, golfing and such). Otherwise, if there are no outsiders involved the whole thing could be just done online. If it's about lobbying though - does it have to be done immediately and 3-4 times a week?
Another example that comes to my mind is a highly skilled expert in repairing some important machinery, e.g. ship engines or factory lines.
Again thinking too small. Large business dealings are still done in person, who is going to give another entity $50mm or more without meeting in person, having dinner and getting to know the counter party. It’s not about lobbying so much as time in person counts.
Who said anything about 3-4 times a week? There are plenty of businesses with high earners where time matters and I could see flights like these being profitable. Boards meet quarterly typically and they are often preferred to have in person.
Well yea great but why do they have to be there so quickly that not even a private jet is good enough?
What kind of multi million dollar deal blows up because a dude arrives 18 hours later? And what are they doing when they get there that couldn’t have been done online?
Again, time is money. It’s not about arriving later but the efficiency of time. Many different attributes to consider from sleep, to time optimization or more simply a lot of folks don’t particularly enjoy the long travel and it’s worth the premium. The kind of trips I am thinking about are business related, may only last a day or two with zero buffer before or after.
In business face time still matters. Less than prior to COVID but it still matters. Most boards prefer to meet in person.
If a fund can get into the Anthropic Series A vs. not get into the Anthropic Series A based on a flight to meet with the team, that is worth buying the supersonic plane even if you scrap it after.
All your critiques are things we heard about Starlink too. "Oh, you're just reinventing Globalstar[0], which already failed. What makes you think this time will be different?" The question isn't wrong, per say, but most of the time it is used dismissively rather than in earnest. There's thousands of products you use today that were invented and ahead of their time. Hell, Google itself is famous for this. A great example being Google Glasses. When they first came out you could get punched in the face[1], but now there's Meta Glasses, Snap's, and dozens of others. The landscape changes, and fast. Just because others failed before doesn't mean others later won't.
It's not bad to ask these questions, but it is easy to be too dismissive. People love to tear things down, but not build them up. The two go hand in hand, but there needs to be a more measured approach. Frankly, projects can fail for many reasons. Too often it is simply bad luck. You either learn from the past or you repeat it.
I’m in favour of projects like these - even on spending taxpayer money on them. I think it’s super cool and I would love to see it. Yeah, I also think it’s extremely unlikely.
However, when you’re doing journalism, you should contextualise for your readers. TFA doesn’t even try to do the bare minimum.
> I’m in favour of projects like these - even on spending taxpayer money on them.
Even a few hits is extremely valuable. I mean the US's investments in CERN and ARPA sure lead to way more economic activity and resultant tax money than they ever spent. By many orders of magnitude (I mean the US still is committing like a billion a year, that's nothing in government money. Let alone considering how many multi-trillion dollar companies there are?)
> However, when you’re doing journalism
Which is why I say the questions are fair and to not use them dismissively. I agree, context matters.
And the time wasted on transfers. I used to regularly fly from airports in NY, London, SF, Singapore, LA, Sydney, etc. I would block out the opportunities to work or rest, and the reality was that only the plane time was valuable for either. It was painful to see all the other blocks of non productive time, particularly the allowances for congestion and disruption between downtown and the airports. I would have paid thousands a flight to be able to check in/clear security at my hotel and then get driven to a holding bay at the airport, and then on to the gate, in a vehicle suitable for both work and rest.
This is a solved problem in civilized countries. The time between arriving at an airport and boarding your plane in Japan is ~10 minutes, most of it walking. Because they don't spend an hour fucking around with clownshow security, and because boarding doesn't take forever, as people don't try to stuff ten pieces of carry-on luggage into five overhead bin spaces.
Customs always takes time, though, even in the happy (no extra questions, no bag searches) path.
---
Do you want to know the secret to fast security lines?
Either reduce the work security does, or open more lines and hire more agents[1], until they can meet the throughput requirements. Both seem to be anathema to an American airport.
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[1] This also works to reduce lines and improve quality and cleanliness in other aspects of society. It's not that Japanese people don't produce any garbage, or dirt, it's that their public infrastructure is regularly and meticulously cleaned and maintained.
Not necessarily for extremely long haul flights. The airport side of things takes about the same amount of time regardless. For a transpacific flight, you’re looking at maybe 3-4 hours at the airport and 10+ hours in the air. Shaving down the airport side would be nice but a faster plane could save a lot more time.
Really? Obviously it varies by country, but there’s no customs/immigration when leaving the US, and security usually takes <5 minutes with PreCheck. Sometimes immigration takes a while on the other side, but it’s quick at airports with biometric gate systems. You still hear people talk about airport buffer time in units of hours, but I think that’s increasingly out of date.
Yes, ymmv (a lot). But alas buffer time is getting higher, not lower.
Yes, TSA is a big part of the problem. It's less "how long it took" and more "how long can it take". I've personally experienced those days where "TSA decided to go slow" and a couple hours disappears. The 5 minute days just make that worse.
Yes, the airport matters. If you're at some small regional it's no big deal. JFK or Atlanta etc is another thing entirely.
Yes, domestic or international matters. Yes, flying business class makes it faster. Yes signing up for "special status" makes things faster.
But airports are typically some drive away from city center (both ends, in traffic). Security and immigration both take time (often significant time.) Door to door time is easily 6 hours more than flight time.
I have _yet_ to hit a time where TSA can make multiple hours disappear. Precheck w/ touchless ID lines are virtually empty at most airports, the actual security screen itself is quite fast given almost nothing needs to be removed from your bag these days. I still tend to arrive early, but I don't mind getting work done at the airport, especially at a lounge - though I've arrived very close to departure other times and still make it to the gate with plenty to spare.
On international returns, both Global Entry or MPC lines are virtually empty when I arrive (SFO)
The worst part is international arrivals in foreign countries, where immigration can soak up a lot of time, and you have no choice but to stand in line. Luckily I don't have to fly internationally too many times a year.
So how long before the actual flight departure will you be at the airport?
If I catch a train that is 10 minutes before the train departs on a metropolitan train station in Europe.
With planes in my experience arriving two hours before the actual departure is not uncommon at bigger airports, since there are more insecurities involved like how crowded security checks are, where your gate is, etc.
In the US, generally one hour no matter whether it's domestic or international. In Germany, like three hours because security and immigration is insanely slow and inefficient. In the UK and other countries I'm less familiar with, two is usually fine.
If I come earlier, it's with the expectation that I'll waste some time hanging out in a lounge.
(Train situation is similar in the US, in places where we actually have those. Generally fine to show up right before departure.)
First time I heard the word "ramjet" was as a kid watching the Goliath episode of Knight Rider. Definitely not a documentary, but the word stuck.
Then the Blackbird showed up in some plane book, and that was that.
Ramjets back in the news. Kid me is having a great morning.
So nostalgic. AI, self-driving, ramjets — they packed it all in. And the thing that dates it isn't any of that, it's that nothing is a touchscreen. The future used to be chunky buttons.
Next generation of. The Type 25 HVGP just entered service few months ago. That one is just a two-stage Scud, but the Block 3 or NG or Type 35 or whatever of that could have this tech.
Building a ramjet that is more efficient than rockets while travelling at several times the speed of sound is the easy part. The hard part is getting up to that speed first, because they give basically no thrust at low speeds. So you always need a two component engine and fuel system, with each component being useless at either launch or in-flight. Basically a similar reason why only the military uses VTOL planes. The military has no problem strapping a rocket booster on a ramjet missile.
And once you do all that, you will need to also handle the massive atmospheric heating from friction, so that the whole thing does not melt during flight.
Again, not that problematic for missiles due to shorter flight times and single-use ablative heatshields being viable.
Ramjets were developed right after the second world war and Mach 4+ was reached in the fifites. It's complicated but not extremely. See Antonio Ferri or Lockheed X-7.
It turned out out solid fuel rockets are operationally more practical for the use cases like air defence, long range missiles that are ballistic instead of cruising in the atmosphere and so on. And jet engines are more efficient for subsonic cruise missiles. Ramjets are still used in some missiles like the long range mach 3 air-to-air Meteor.
There have been air-to-air missiles using rocket-ramjet combinations: they start as a rocket, then once up to speed an inlet opens and they transition to ramjet mode (using the same chamber and nozzle). It extends range. Ramjets are best for maintaining speed rather than accelerating to speed.
EDIT: I see this was referenced above (Meteor).
This is why Ukraine is so excited to get up to 150 Gripens (with Meteor loadout) from the Swedes.
> Ramjets were developed right after the second world war
Development already started during WW2 as one of many German last-ditch experiments, for instance:
https://en.wikipedia.org/wiki/Kronach_Lorin
...it never went into an actually flying airplane though (apparently there were test flights with Lorin tubes attached to propeller planes, but only to test the Lorin tube behaviour under flight conditions, not as an engine replacement).
The idea and patent itself is over a century old by now:
https://en.wikipedia.org/wiki/Ren%C3%A9_Lorin
For many many reasons this engine only has one economic application - delivery of a nuclear payload in a way which is very hard for missile defences to stop.
ICBMs can go faster than this already but as I understand it they go higher allowing for earlier detection and they follow a more predictable trajectory which makes interception more realistic.
I find super fast missiles far scarier than advanced AI. I suppose they maintain the "mutually assured destruction" which might be the main reason there hasn't been a nuclear war since WW2, but it's not a huge comfort.
My take is also a missile, but as an interceptor, not offensive purposes. North Korea has shown that they can deliver a payload to Japan if they want. If the NKs do decide to launch something at Japan, it's not going to be tipped with conventional explosives. It'll be a nuke. Hypersonic interceptor seems the more likely application is this tech to me.
I think that hypersonic interceptors would use a rocket motor and not a ramjet, but I'm not sure.
I think this is for offence because I understood the advantage of this engine (compared to a rocket engine) is that you don't carry oxygen so you can carry more fuel and get more range. I think range is much more useful for offence than defence.
I am possibly making myself look foolish now as I'm not an expert on either rockets or ramjets and I might have incorrectly dismissed defensive applications.
Historically, it was: https://en.wikipedia.org/wiki/Sprint_(missile)
Would be handy today.
That era of ballistic interceptors all relied on large nuclear warheads to have any effect.
The modern, hard problem is avoiding using a nuke, because detonating a nuclear warhead above your own country is Bad
judging by what we saw so far in Russia, Ukraine, and Israel, defensive missiles don't require particularly sophisticated offensive missiles to overwhelm.
yeah, but those are using conventional explosives, only countries like the US and Russia have enough nukes to do the same with nuclear explosives, a country like japan would need a sophisticated missile instead
You can fire a lot of decoys and one nuke.
> I find super fast missiles far scarier than advanced AI
But what about super fast missiles with advanced AI?
I find fast missiles with AI to be pretty scary. Heck a slow drone with AI targeting chasing me is bad enough...
> I find fast missiles with AI to be pretty scary
Not sure I entirely appreciate the use-case vs classical targeting. I'd imagine you're going so fast that you don't really have the opportunity to engage in thought that is particularly useful.
You only need to draw a fake moustache on yourself to fool it, or something.
like a backpack from which a cardboard version of a soldier springs out, with the operator being shielded with an aluminum foil pane
Well here's an economic application without nuclear tipped warheads.
https://en.wikipedia.org/wiki/Meteor_(missile)
The Wiki pages says top speed is about Mach 4. There are already multiple rockets from US, Russia, and China that can achieve the same (or more) but with a solid-fuel rocket motor. What is the advantage of a ramjet here? It just seems way more complex and much less well tested (in labs and in combat). Also, has this missile (Meteor) been used in any combat scenarios? To be clear, the max speed for any fighter jet is about 2.5 Mach. Once one (or two) of these missiles has locked on, you are done. I read some funny commentary once about how to shoot down a modern fighter jet: Two missiles. They can dodge the first one, but sacrifice so much speed, that the second one can easily find its target.
Missiles versus aircraft is a fight between very high kinetic energy in the missile, and relatively low kinetic energy in the plane, but with the ability to generate more kinetic energy. Missiles don't have a lot of fuel, so they need to generate a lot of kinetic energy to still be effective by the time they reach the target. Typically a missile will accelerate to its top speed in the first few seconds of flight and coast the rest of the way. At very long ranges, all the energy generated when launched has bled off, so there's two common solutions for long-range missiles to generate more energy: a "dual pulse" motor is basically a second rocket motor that fires later in the course; or a ramjet, which can be throttled up and down and is more fuel efficient than a rocket engine.
A ramjet drastically increases range against maneuvering targets. The 'maximum range' quoted for missiles like the AIM-120D (Likely 140-170km) is normally for a front on shot at extremely high altitude (10-15km+) with no evasive actions. With an evading target the No Escape Zone (where a target likely can't kinetically evade the missile) will only be 15-25km.
The Meteor has a longer sustainer and a terminal boost meaning that the No Escape Zone is though to be upwards of 60km. Qatar might have used Meteors to shoot down Iranian Su 24's just a few months ago based on the range they were shot at.
You really need to play combat flight sims (like DCS) to understand why a ramjet AA missile makes a lot of sense ;)
It's not mainly about top speed, but about endurance (e.g. flying under power for the entire flight time of the missile).
The gist ist that traditional BVR AA missiles are only powered at the start of an engagement (and a lot of that power is used to gain height) until their rocket engine runs out of fuel. For a large part of its flight, traditional AA missiles glide without power towards the target, meaning the missile will lose speed from the moment the rocket engines are switched off, and even more for each required maneuver that needs to be performed afterwards (that's why it is a valid strategy for the targeted airplane to evade the missile by forcing it into a turn during its unpowered flight phase - e.g. instead of doing a 180 and flying straight away from the missile, fly a roughly 90 degree course to the incoming missile to force it into a wide turn, which means the missile will lose more energy than it would when remaining on a straight course).
A ramjet powered missile on the other hand flies under power for the entire engagement, it can 'cruise' towards the target and then for the final phase of the engagement speed up and home in on the target (or generally do complex maneuvers) without losing speed, which gives the target airplane much fewer options to evade the attack.
> I read some funny commentary once about how to shoot down a modern fighter jet: Two missiles. They can dodge the first one, but sacrifice so much speed, that the second one can easily find its target.
With a ramjet missile you don't need a second missile to exploit the target's depleted energy. And the two-missile strategy also doesn't really work when the other aircraft fires a single Meteor from a greater distance first ;)
It's not that simple. If the target aircraft is outside the minimum abort range then they can still evade multiple missiles, regardless of whether the shooting platform or the missiles themselves are locked on. Typically they would do so by descending into denser air and beaming the missile to bleed its limited energy. On larger missiles a ramjet can potentially allow it to retain more energy into the terminal phase.
There are a variety of other defenses including countermeasures, signature reduction, EW, and decoys which also complicate the issue.
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Is a Mach-5 passenger aircraft actually the goal of this project?
Seems more likely that Japan is designing this engine for a hypersonic cruise missile program, and the passenger aircraft concept is somewhat of a cover.
IMO, there is no point in a Mach-5 Aircraft (other than cruise missiles). There is potentially some point in Mach 2-3 aircraft, (not that we have ever made them commercially viable) but at the boundary to hypersonic, you might as well just switch to a suborbital hop concept.
A suborbital hop gets you to anywhere in the world within ~90min, avoids issues of supersonic overflight and you don't need to worry about the massive engineering issues caused by sustaining hypersonic flight. And as a bonus, the passengers get a hour of weightlessness.
> (not that we have ever made them commercially viable)
Concorde was commercially viable at Mach 2.2 in supercruise (although there's a common misconception that it was not).
However, its overheads were very high, and its applicability was severely limited by fears around the sonic boom (most particularly in the US, which banned supersonic flight overland, possibly largely because they wanted to kill off foreign competition).
The individual aircraft could be operationally viable on certain routes, but the whole program was not commercially viable.
Air breathing engines don't need the oxidizer tank, so like the 2/3 of a rocket just goes away before even touching Tsiolkovsky math. That improves payload mass fraction massively.
Also, this doesn't scale down to Mach 3-4 and under. This thing uses scramjet, or supersonic combustion ramjet. It REQUIRES intake air to be at high supersonic speeds for it to work.
> It REQUIRES intake air to be at high supersonic speeds for it to work
This is why I am highly sceptical it can be part of a commercial supersonic passenger jet: how do you get from subsonic -> supersonic without also tacking on some kind of conventional jet engine?
And you’d need the conventional jet to survive
Japan, Italy and UK have a program for a competing F35 design, GCAP. And Japan is focusing mainly on the engines.
Given there will at some point be the need to deliver competing cruise missiles for this platform, and after the crisis of the US not being able to keep demand with Israel's and Ukraine's orders they greenlighted SK and Japan to enter the European defense market, to answer your question yes, this is of course a defense related project.
There's been an industry request to develop native defense components on these matters within the EU following pressures and contrasts with the US (on a report to the EC for the ReArm campaign, EU's biggest playes of aerespace industry made a joint report estimating 60-80% of their components and tech are sourced from the US).
> Is a Mach-5 passenger aircraft actually the goal of this project? > Seems more likely that Japan is designing this engine for a hypersonic cruise missile program, and the passenger aircraft concept is somewhat of a cover.
Case of China's got them, and can't rely on the Orange Emperor and his heirs to have their backs.
> you might as well just switch to a suborbital hop concept.
One is not exclusive to the other.
Skylon was expected to use air breathing engine up to Mach5+ and switch to rocket engine beyond it.
You can probably do the same for a suborbital airliner if you are insane enough.
90 minutes is a full low Earth orbit cycle. For a suborbital hop it should be about half of that at maximum for any 2 points on Earth.
I didn't initially believe these numbers, but if you look at some real life stats, you are probably right.
Nominal SECO for the last starship mission was at ~8 minutes and it took ~20 minutes from deceleration started (well, from air resistance outweighed the forces of acceleration) to landing. So basically 30 minutes of flight is just the "getting up to speed" and "slowing down" part. Both account for some distance traveled, but still. ~45 minutes is probably a good bet.
Do note however that you may have to go around the world "the wrong way" to get some places due to launch constraints. But living in a world where going around the world "the wrong way" is the easier path is interesting. Imagine that.
90 minutes is a low earth orbit period.
A suborbital craft won’t be travelling at that speed.
Like, you could do a partial orbit & then drop down over the destination. But it would need much more delta-v & an orbital class heat shield.
It was proposed as nuclear warhead delivery method though: https://en.wikipedia.org/wiki/Fractional_Orbital_Bombardment...
Unless a suborbital trip is nearly at orbital velocity, it will involve a high, arcing trajectory. This will make the deceleration at the end unacceptably (lethally) high for all but short arcs. Some of the Mercury suborbital missions involved deceleration of 15 gees, if I recall correctly.
If the capsule/rocketplane has some lift & preferably steerable aerosurfaces then you can compensate the purely ballistic deceleration somewhat.
But yeah, if it is going down almost vertically then this will not be enough.
And all but rather short ballistic trajectories (well below orbital speed) will come in at a steep angle.
Unless one has seriously variable aerodynamics, the vehicle will have to swerve to nearly horizontal over a distance of about 1 scale height of the atmosphere, which is about 10 km. The exponentially thinning atmosphere goes from "too thin to matter" to "brick wall" over a short distance.
The acceleration for turning is v^2/r; for v = 5000 m/s and r = 10 km this is 250 g.
Acceleration also limits how rapidly one can reenter from beyond Earth orbit. At > LEO velocity, the vehicle has to use (downward) lift to stay in the atmosphere, and if v is too high the required acceleration is too high.
It would still be possible to fly a predominantly ballistic trajectory, yet use rocket propulsion to decelerate whilst still outside the atmosphere. It would require a huge amount of extra fuel compared to a purely ballistic trajectory, but perhaps still less than achieving a full orbit and de-orbiting again for some destinations.
At global distances a fraction orbital trajectory would use less total rocket delta-V.
More practical would be a trajectory that was a series of small suborbital arcs with skipping off the atmosphere (perhaps with some airbreathing propulsion during the skips.) The thermal protection can cool by radiation between the skips.
That would be very cool to witness! SABRE sounds like it would be an ideal engine for that application.
That was only an issue because they were fired pretty much straight up; They only went 500km down range.
You can also reduce peek deceleration forces by using aerodynamic lift to stretch out the reentry over a longer period.
No, it's an issue for most arcing trajectories. Lift doesn't help much if you're coming in at a steep angle. Reentry from orbit only works well because the entry is almost flat; there even a little lift helps a lot.
From a science and engineering point of view, I root for this.
From an environmental point of view, I hope this won't materialise for some time.
It can be nuclear powered, so you don't have CO2 emmisions /S
You just need to add heat to the air at the point where the diameter is the lowest.
The russians are maybe using this idea for one of their new cruise missles named Burevestnik, although for them the nuclear emmisions are likely a positive side effect.
I kind of think today's air travel is in an uncanny valley.
I'd prefer either: just as uncomfortable or even more so but very fast, like multiple mach numbers fast. I live in the Midwest and go to the West Coast often, and it usually takes 5 hours -- I'd cram into a less comfortable seat for 2 hours instead to get there at mach 2.5.
OR... airships. Big cushy seats. A lounge with fast wifi and desks. A coffee shop. You can walk around. The trip takes all day, or overnight with a sleeping cabin. Trains could fill this niche too, but airships could go overseas.
Go faster or go roomier.
I actually learned about what a ramjet is after looking up the definition of “scramjet” when watching the _Top Gun: Maverick_ movie with my son. This is at the beginning of the movie when he is flying the Dark Star plane designed in conjunction with Skunk Works from Lockheed Martin. Well, we are obviously a ways away from Mach 10 reached in the film by the SR-71 Blackbird descendant, the new technology pushing Mach 5 and into high hypersonic is pretty impressive.
> A scramjet is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to compress the incoming air forcefully before combustion, but whereas a ramjet decelerates the air to subsonic velocities before combustion using shock cones, a scramjet has no shock cone and slows the airflow using shockwaves produced by its ignition source in place of a shock cone - Wikipedia
As I understand, the problem with anything over Mach 4 (or 5), the metal begins to disintegrate. It is fine for a one way missile, but not a reusuable aircraft. Without some alien tech (see 1990s game "X-Com 2"), I cannot believe that we can build a reusuable aircraft that can reliably and safely fly for long periods over Mach 5.
Ramjets are limited in the speed they can operate because slowing the air to subsonic speed in the engine causes it to become hot, and the temperature increases rapidly with speed (the kinetic energy of an incoming air parcel is proportional to the square of the vehicle's speed, and most of that energy is being converted to heat.)
The original submission didn't mention ramjet.
I always thought it was an underutilized design that could be improved for practical applications.
Improved enough, it could become cheaper and more environmentally-friendly than current aviation whereas regular supersonic jets are never going to achieve that.
>At that elevation at Mach‑5, air around the nose and leading edges can reach temperatures exceeding 1,000 degrees Celsius (1,832°F), a challenge...
It is not the conical nose or leading edges that are the show stopper problem(s). There the shockwave generally does not touch the craft. The internal shockwaves that touch the walls of the engine ducting are. The heat loading and heat soak ability on those shockwave impingement sites will limit the duration of hypersonic travel.
Hypersonic travel through the atmosphere is easy, a problem solved in the 1950s. Be conical and carry your oxygen internally. Hypersonic travel that is air-breathing is an entirely different class of problem and I don't think it is anywhere near to being solved.
The only silver lining is that at hypersonic speeds you don't need to be propulsive for very long to get anywhere.
Supposedly the SR-72 has figured this out. Just rumours at this point, but apparently they’ve cracked the hypersonic air breathing puzzle on a usefully sized aircraft.
Interesting, but assuming they can get the engine to work as intended, the question still remains how the passenger jet would get up to Mach 5 so the engine can start working. A solid-fuel rocket booster that would then drop off?
It is a safe bet that the first applications will be missiles and there won't be any passengers to worry about.
Interns provide the guidance.
I may be wrong but I think a ramjet doesn't need Mach 5 to ignite, Mach 3 to 6 is just where it is most efficient at high altitudes.
E.g. early German experiments during WW2 based on the Lorin tube (https://en.wikipedia.org/wiki/Ren%C3%A9_Lorin) only had to get to 320 km/h to start working:
https://en.wikipedia.org/wiki/Kronach_Lorin
>https://en.wikipedia.org/wiki/Kronach_Lorin
coal burning ramjet!
"It was initially proposed that a wire-mesh basket holding coal be mounted behind a nose air intake, protruding slightly into the airflow and ignited by a gas burner. [...] The air passing through the ramjet would take the gases from the burning coal ..."
Yes, not because it would be any better than the alternatives, but because this was one of countless "last ditch" efforts.
Ok, but the question still remains, how is it going to get up to the required speed? And in a way that is practical for a passenger plane?
I'm no aircraft engineer, but I guess it would use traditional jet engines to get up to some low Mach 1+ speed until the ramjet gets enough air to bite on.
My bet is that this hasn't been done yet simply because it wouldn't be economical (the technology itself is a century old and has been tried over and over again), and that the 'civilian ramjet aircraft' is just a feel good story for what will end up as purely military usage, and most likely not in an airplane, but in missiles (there are a couple ramjet engine missiles in use already, like the European Meteor).
I can't see how this would work for civilian purposes - since you need to counter the higher temperatures from higher altitudes. ceramic tiles (heat protection) - then u r heavy. this is based on noob aeronautics reasoning btw.
> At that elevation at Mach‑5, air around the nose and leading edges can reach temperatures exceeding 1,000 degrees Celsius (1,832°F), a challenge the U.S. Air Force has struggled to overcome with its own hypersonic jets.
> To handle that level of heat, engineers constructed an advanced thermal‑protection system that maintained the aircraft's interior near normal operating temperature, allowing the onboard avionics and control electronics to function normally.
Hindenburg 2.0 waiting to happen
We have a lot of experience with heat shields from cosmic reentries now, though. This is probably doable.
> Hindenburg 2.0 waiting to happen
Fortunately there's no hydrogen in that plane.
People say this like it's a simple engineering problem.
No. By itself, a new hypersonic engine can't make 2-hour flights between Japan and the US a reality. We are not even close to being able to build an aircraft that can do that - we don't even have the materials for that. What seems "easier" (as in "less impossible") is a hypersonic glider design that enters a suborbital trajectory and does shuttle-like aerobraking while it glides to its destination, before reengaging propulsion prior to landing on an airstrip (because passenger planes need to be able to abort landings and do multiple attempts). Not sure how reverse thrust would work there - variable geometry rocket bells?
How long of a weightlessness period does this entail?
Maybe not complete weightlessness, because at 80-90 km the atmospheric drag is still noticeable. But it should be enough of a unique experience.
I would say windows would be a non negotiable design requirement, as well as external HDR cameras for the middle seats.
As a Canadian who travels to Europe about once per month I am very excited for this :D
Wait 20 years to save a few hours :)
Speed Racer unavailable for comment.
What would a ticket cost like? 50k? Aren't those people in their own fancy private jet with whiskey, massages and party?
Or have their own room in first class... Maybe time trade off isn't worth it for most of the people who can afford it at that point.
I've always wanted someone to bring back the Avro Arrow to use the Iroquois engine for freight, but I don't think anyone has the knowledge to even pull it off anymore.
The avro was an excellent plane for the time. It would have been a good plane for the Cold War. It was a plane well suited for Canada's threat environment. The missiles that replaced it sucked.
However, the Avro wasn't anything any of the other great powers couldn't do back then or today and it was ruining Canada financially.
The only question I have about the Avro is: "Could foreign sales have rescued the plans and Ottawa's budget?"
I think not. In an era of hyper-protectionism where the Brits built an air cooled nuclear reactor [1] rather than buy Canadian heavy water, it's inconceivable that Canada would have found buyers.
[1] resulting in the largest nuclear disaster until Chernobyl. Keep in mind, at the time, English Canada largely thought of itself as British and even decades later fumed at the new flag lacking the Union Jack. And yet the Brit's didn't but their heavy water.
I’d love to have a big die cast model of one, but that’s about as close as we’ll ever get to the Avro flying again.
I don’t think you’d be pushing much freight on an Arrow (though I’d love to fly one!).
An XB-70 with modern engines? Now that would be interesting.
Boy, that's an evergreen headline.
that headline uses a subjunctive verb mood "_could_ <verb>" and those titles are seemingly always clickbait
I imagine passengers will be exposed to very high noise levels during flight.
I don't have a good intuitive feel for that.
At 25km altitude, with 1% of normal atmosphere, maybe you're close enough to vacuum that it can get really quiet?
The engine noise can still be conducted through the body of the plane. With the kind of ramjet being talked about, I think that's still likely to be significant even at very high altitude.
This effect would help mitigate the noise heard by people outside of the plane (but I suspect that noise is negligible compared to the sonic boom), but in the plane the sound would mostly be propagated though the fuselage of the plane, not through air, so it's not going to help.
PG celebrates Boom's pivot to power generator supply.
Cool science. But the article fails to take even a cursory stab at contextualising the plan against the economic, environmental and political backdrop - doesn’t even mention that there’s already been one failed supersonic commercial flight programme. This is as pie-in-the-sky as it gets.
I think a lot of the Concorde failure is tied to its status as a British-French project. Trans-Pacific flights are much longer and there's a lot of money in PEK -> LAX than in JFK -> LHR.
Qantas wanted to offer London to Sydney, but they couldn't fly supersonic over land. Mainland China or Japan to Australia is a feasible route for high-margin, low-capacity supersonic flights.
If you could make the flight from Beijing to California take less than 5 hours that seems like a premium product many ultra wealthy people would spring for. Dubai to SFO is also a possible route.
I was pretty sure the whole Concorde thing failed because people don't like it when you sonic boom an entire city dozens of times a day. And that all attempts to reduce the sonic booms necessarily resulted in flight times that aren't significantly faster than traditional subsonic flights, rendering the entire thing moot.
It was impractical due to physics, not some weird racism. You simply can't push a supersonic shockwave over inhabited areas, and the only way to not do that is to fly subsonic over land. Even if the oversea leg is supersonic, the tickets were much more expensive for not very much shorter flights. It wasn't a valuable proposition for most people.
1) The flight markets are different now. There's been a large increase in both transatlantic and transpacific flights, especially the latter. These change the economics of considering only these types of flights, flying only over uninhabited regions.
2) The technology has changed. We're much better at dealing with sonic booms now. You can't get rid of them entirely, but you can reshape them. You can't send everything "up" but the longer of a tail you can make the more the sound dissipates by the time it hits the ground. There's lots of research around this and as you can imagine, incredibly important for the military. You can't fly fast spy aircraft if they are just announcing their position while flying around. Sure, there are satellites, but those are predictable by the enemy, you'll always need aircraft to do this.
However, there are markets where you don't have to fly supersonic over land, the distance is long enough for the speed to matter, and there is massive amount of demand. The only problem is, such markets require a longer range than what the Concorde was capable of. Notably, all the very frequently traveled trips over the Pacific.
Concorde’s sonic boom was astonishingly loud. The night flights would go supersonic outside the Bristol Channel at around 9pm to 10pm. It was still audible over 60 miles away and sounded like a muffled barn door slamming outside.
Far louder though — it would wake all the pheasants up just as they’d gone to roost.
England in the '80s didn't give a shit about little people. Had it been really profitable, Concorde would have continued operations. It just did not make sense economically, particularly once they stopped making new airframes.
It failed because the market dried up due to economic reasons, and they couldn't fill seats.
There is a lot of money in NYC-LHR, that's why Concorde continued to fly that route and profitably too, once they realized how high they could yank the prices and still fill the plane.
Also, Concorde's maximum range was 4,488 mi, which was calibrated to allow trans-Atlantic but not much more. Trans-Pac was not an option and even Australia to North Asia would be a stretch.
I think they are agreeing with you re: the range.
There is money in NYC-LHR (it brings BA alone $1B in revenue annually) but the market for supersonic basically vanished. In the 70s when Concorde started flying, it was certainly a step up. However, the market niche basically disappeared when the lie flat seat was developed; for a lot cheaper, you could have a sleep for six hours in a really cushy lie flat, or you could spend a crapton more to be in a much louder, more cramped cabin for only about three hours less. If you were halving a 12-16 hour journey instead, there would still be a market left, but Concorde just didn't have the ability to do so.
You can also essentially work remotely in an airplane now. I haven’t tried videoconferencing, but I easily do all my other software work on trips. So a couple extra hours might even be a benefit: more time with no distractions to wrap up that slide deck, maybe a 1:1 or two, get your free drinks from premium/business class, doze off to a movie, wake up for an early start at your destination.
12 hours on a plane is 12 hours on a plane. And there's currently no amount of ticket money that can make that shorter.
Shorter, no, but having a private cabin with a shower, and a lounge with a bartender on the plane, not to mention Starlink, would make those 12 hours a lot more bearable vs 12 in an economy seat.
Wasn’t Concorde like 20-50% more expensive than a normal first class ticket for the same itinerary?
So any hacker considering a SST flight should also be able to afford the first class cabin.
If it ever actually gets off the ground, Boom Supersonic is allegedly targeting a $5000 business class trip for transatlantic.
Mitchell Hashimoto's got tres commas in his bank account and his own jet. He doesn't need to take commerical, or even first class. If we backsolve, say $10,000 is a once a month purchase, and $10,000 for a hotel and you stay a month. Say your other living expenses are $10,000/month, so we're shooting for spending $20,000/month. With the recommended shaving off 3% the nest egg, (20,000 * 12) / 3% gets us $8 million in the bank.
So at $8 million in the bank, you could take a $10,000 plane trip, stay for a month, spend $10,000 on a hotel, take a $10,000 flight back. Still upper end of net worth, but nowhere near Mitchell Hashimoto territory.
Sure, but it would also make it much more expensive than a supersonic flight…
Everyone thought SSTs were going to be the next big thing. Both the US and USSR had projects. The 747 got a hump so it could easily be converted to a freighter once it was made obsolete by supersonic passenger planes.
Despite two superpowers making the attempt, and plenty of time for more tries since then, Concorde is the only one that came even remotely close to something commercially viable.
I’m sure there’s a market for California to China in five hours. But is it enough to support a whole new type of aircraft? Fuel burn is going to be enormous. Maintenance on something so cutting edge will be extremely expensive. Tickets would probably cost more than a private room on a widebody.
You’re hinting at another huge part of the issue.
There are no economies of scale to be had here. If there are only a handful of plausible economically-profitable routes, all of the expenditures on R&D, testing, certification, and production facilities can only be amortized across a handful of aircraft.
Once you’ve built a dozen or two of them and a handful of extra engines and spare parts… what then? There’s no point in keeping the production lines open.
From an airline’s perspective, they have to now have an entire separate chain of employees (pilots, mechanics) dedicated to another airframe that barely makes up a fraction of their fleet. That’s a lot of overhead for two or three routes.
Those are some pretty big structural disadvantages that need to be overcome in order to make a boutique supersonic route appealing.
Scheduled service is not viable but there is a bountiful supply of billionaires willing to one up each other with lavish expenditures. Having the fastest class of private jet is worth something to them. This is what's going to be the market for Boom if they don't fold.
And currently we live in a vastly more unequal world ecomomically than when the Concorde and similar were developed, there is money to throw around
One analysis I read by a marketer that makes good sense is that the speed was worth paying for LHR to JFK but not really on the return given the clock changes and speed.
Getting to NYC before the clock time you left London was a cool trick. It allows you to make a morning meeting in NYC without coming in the night before.
But flying subsonic leaving NYC after dinner and arriving in London for breakfast works fine. Getting to London faster in 3.5 hours travel time but 8.5 hours later clock time means losing a day in the air effectively.
If it stays in the realm of the ultra wealthy I don't see how it will succeed in the end. Commercial aircraft are really expensive to design and qualify, and you need to have a lot of sales to justify a new model. Ultra wealthy people are willing to pay more, but they also demand luxuries that take up a lot of space.
The only reason Concorde did as well as it did, economically speaking, is the respective governments footed the bill for development.
Yeah. But to be fair, it was the first supersonic airliner, so they were feeling around a bit in the dark when it came to estimating demand. They would have all looked like geniuses if enough demand to build 700 air frames had materialized.
I remember when the aircraft first went into service. Everybody thought subsonic air travel, at least over the ocean, would become a thing of the past.
> Dubai to SFO is also a possible route
Is there really that much premium traffic between Dubai and the Bay Area?
The Middle East (was) a pretty common stopover for India flights, since India's not that well connected to the US due to a lack of capacity.
My point is mostly that since the 80s there's a lot more trans-pacific flight from the Middle-east and Far-east to the United States. When the Concorde was developed this wasn't really a worthwhile market to consider for ultra-premium air travel.
I could absolutely see Emirates doing a super-luxury super-sonic flight to the West Coast of the US. Once you're in the States you can take a PJ.
A couple of searches suggests only Emirates operate a direct route between SFO and Dubain, so it wouldn't seem so.
Emirates just dominates long-haul flights to Dubai overall. Other (mostly flag carrier) airlines handle other airports in the region. Qatar Airways through Doha is also a big player in flights between the US/Europe and Asia.
I think the more interesting question is /will/ there be that much premium traffic ongoing
Honestly not so much in my experience. It was busy, but mostly because of Emirates longhauls. Dubai to NYC and back is extremely busy though.
ORD -> Vatican
It's not tied to anything other than there not being enough people who care enough to spend the sort of money required.
The people who have that kind of money are going to be more interested in flying in a jet share doing mach .96 leaving when they want to leave, going where they want to go, when they want to go, how they want to go, with who they want to go with.
You get treated like a criminal for forgetting your shampoo bottle is 2 ounces too big for some dipshit TSA agent's liking, and meanwhile the ultrawealthy are shuttling around physical assets worth millions of dollars in their private jets and customs barely does more than stamp their passport.
Yeah, this is something that changed from Concorde times (and possibly even sped up its very demise): the market for reliable, high-quality private planes has grown massively. It's now pretty easy to shuttle between the big cities in almost complete privacy through secluded airports.
> You get treated like a criminal for forgetting your shampoo bottle is 2 ounces too big for some dipshit TSA agent's liking,
Enforcement is super uneven, and etc, but IME, they just open your bag, find the thing, and then offer you the choice of tossing it or going back to check your bag. Depending on how much you paid for your shampoo and how much a checked bag would cost you and if you have time to do all that and then wait in line again, I expect most people toss it.
Concord was very old technology. I am quite sure a clean sheet now
1. Would have much lower sonic booms thanks to recent research (quite a bit of it by NASA on wing geometry) and more importantly computer simulation available now
2. The engines would be far more fuel efficient
3. The flights would be able to have better efficiency in the subsonic regime as well. Just see what winglets and the like have done to fuel economy .
I fly 14 to 18 hour routes maybe 4-5 times a year on business paying 5x the economy cost and it still sucks. Breaking the flight with a connection (IMO) sucks more. My management flies such routes every month. There is a lot of revenue headroom in that fare gap for something that flies maybe 3x-4x as fast which military aircraft already do.
What will hold back the idea is conservatism among the business managers in aircraft manufactures and incumbent airlines who will "draw lessons" from a 50 year old experiment
>2. The engines would be far more fuel efficient
not really. In supersonic regime Concorde engines were pretty good, and you'd not beat them today by much.
Concorde was using afterburners to accelerate to supersonic and this is where it burned a lot of fuel. Designing engines which would give you good thrust at subsonic speeds without afterburners and would still perform well in supersonic is still much unsolved. Just look at the best military engines today - they all under Mach 2 and can't give even 3000 miles range.
And without increasing efficiency we can't really get much beyond the Concorde's 4500 miles. I.e. unfortunately there seems to be no current tech (or coming right tomorrow morning) that will allow Trans-Pacific.
It looks more feasible to me that Starship suborbital SFO-to-Shanghai will come well before a new Concorde on that route. Especially considering that Starship's ballistic trajectory is more fuel efficient on such long distances than supersonic plane flight.
It'd be far more efficient than the 50 year old tech, but so is the baseline tech they're comparing it with, and the market has optimised heavily for price competition (and has a lot more private jets doing exactly the route and time executives with Concorde money want) and needs speed somewhat less when it's a lot easier to stay in touch with a business whilst inflight. Ultimately there's not much to draw lessons from that suggests it's going to sell enough aircraft to recover the investment of building and certifying it (even comparatively simple niche aircraft like the A380 struggled there), which is why even Boom is now reinventing itself as a provider of turbines for AI datacentres to try to fund its development costs...
Whenever you look at supersonic or hypersonic commercial aircraft plans you should assume one of two things.
A. It's a bait and switch by a founder who wants to pivot to weapons/military aircraft but wants to be able to hire high grade talent without paying the "we're gonna kill people" premium, can pivot once a good chunk of the workforce is complacent with a paycheck. You laugh but this happens SO FUCKING MUCH.
B. It's for business jet scale operations for billionaires. There are >3000 billionaires and however many corporate aviation departments and if you can build a super/hypersonic private jet that's not horribly expensive to operate the "time savings"* for that class of person will demand they buy one.
* when I say time savings I mean dick measuring contest
Defense contractors don't pay premium wages. Rather the opposite. Many employees specifically want to work in the field in order to contribute to the national security mission.
I'm being a bit obtuse here to make the point, it's more complicated than that. The reality is if you create a defense startup you end up hiring defense employees which comes with its own set of issues.
That said, go look at salaries right now in the defense space.
From my experience with working for defense/aerospace companies as well as civilian b2b ones in the US, the general situation is that defense/aero companies pay less but demands less of a grind. People usually take the lower pay (usually 70% of equivalent role in commercial sector) for the better culture
For pure generic full-stack-whatever devs yes. For EEs, embedded, FPGA, RF, etc you can pull waaaaay more in the defense world, especially if you're willing to do cleared work.
But if you need clearance to do your work, how can it be bait-and-switch? You need to hire people who are able and willing to obtain a clearance.
Two different discussions, but I've had an earthy crunchy employer ask me to put in for one once.
And have work that allows employees to keep their existing clearances active.
What companies are examples of that bait and switch strategy?
Google tried to become a national security contractor, and the backlash among the engineers was very intense.
Google already does national security work.
https://cloud.google.com/distributed-cloud-air-gapped
https://www.defence.gov.au/news-events/releases/2025-12-19/d...
I’m not in the industry, but I would say Hermeus would be a perfect example. Ostensibly building a commercial airliner, but if you look closely it feels like a military oriented startup from the inside out.
Can't give any examples but I have definitely heard the same about a lot of aerospace startups through the grapevine. As for OP's point about private jets, Boom supersonic is your classic example.
I can't name names but 3 of the startups I've worked at.
Places I haven't worked:
Skydio
Applied Intuition
Saildrone
Planet Labs
Boom
Scale AI
Also worth noting that sometimes it's on purpose, sometimes the founders are all "we're gonna save the world" then AFWERX enters the chat with a big fucking check and the founders yell "Nevermind! Guess we're the baddies now! How many slaughterbots did you say?"
> * when I say time savings I mean dick measuring contest
And in this case smaller is better?
Vastly more favorable today than it was when Concorde flew.
1) Rich people are WAY richer, and time is even more valuable 2) Businesses have some very important employees and "2 day trip" vs "3-4 day trip" is worth $50-100k 3) Larger population of people able to pay $20-30k for a flight than ever before.
The biggest practical impact is there's probably going to be a private jet version instead of just a commercial one, and there will likely be transpacific demand exceeding transatlantic. Also government/military use.
What are some examples of employees so important you would pay $100k to get them somewhere immediately?
You are not thinking high enough the food chain. I mean heck you have tenured SV engineers cracking $1mm with RSUs. It’s not rare in finance for folks to be hitting $3-5mm with bonus. So that’s what $19k comp a day. If that individual is making $5mm they are more than likely making a multiple of that for the organization.
Even these days, a lot of retailers operate fleets of private jets even for district or regional managers, because it saves somebody like Walmart a lot of paid hours to fly someone from rural town A to rural town B rather than potentially deal with the hassle of an overnight booking at an airport hub.
I still don't quite get it given I have never worked high enough or in a big enough corp. What kind of mission a person earning $19k a day have to do at the destination to justify the cost? I imagine to earn this much their main responsibility is to lobby / influence someone important (at dinners, golfing and such). Otherwise, if there are no outsiders involved the whole thing could be just done online. If it's about lobbying though - does it have to be done immediately and 3-4 times a week?
Another example that comes to my mind is a highly skilled expert in repairing some important machinery, e.g. ship engines or factory lines.
Again thinking too small. Large business dealings are still done in person, who is going to give another entity $50mm or more without meeting in person, having dinner and getting to know the counter party. It’s not about lobbying so much as time in person counts.
Who said anything about 3-4 times a week? There are plenty of businesses with high earners where time matters and I could see flights like these being profitable. Boards meet quarterly typically and they are often preferred to have in person.
Well yea great but why do they have to be there so quickly that not even a private jet is good enough?
What kind of multi million dollar deal blows up because a dude arrives 18 hours later? And what are they doing when they get there that couldn’t have been done online?
Again, time is money. It’s not about arriving later but the efficiency of time. Many different attributes to consider from sleep, to time optimization or more simply a lot of folks don’t particularly enjoy the long travel and it’s worth the premium. The kind of trips I am thinking about are business related, may only last a day or two with zero buffer before or after.
In business face time still matters. Less than prior to COVID but it still matters. Most boards prefer to meet in person.
If a fund can get into the Anthropic Series A vs. not get into the Anthropic Series A based on a flight to meet with the team, that is worth buying the supersonic plane even if you scrap it after.
American execs negotiating memory two months ago in Korea?
I think the SpaceX plan for point to point travel might be even more pie in the sky. Or maybe a tie.
Point to point rocket travel was never a good faith pitch, it was a hype thing (and your pension money are going into the fraud soon).
I think it's more practical. They've already got humans flying.
Good luck getting a launch and landing pad anywhere close to a population centre.
Logistics around the flight would be a big asterisk behind the flight time.
> This is as pie-in-the-sky as it gets.
I saw the "sounding rocket" and thought: Oh, hypersonic missiles money.
Probably because there is no plan to develop a commercial plane.
It's not bad to ask these questions, but it is easy to be too dismissive. People love to tear things down, but not build them up. The two go hand in hand, but there needs to be a more measured approach. Frankly, projects can fail for many reasons. Too often it is simply bad luck. You either learn from the past or you repeat it.
[0] https://en.wikipedia.org/wiki/Globalstar
[1] https://www.cnet.com/tech/services-and-software/google-glass...
I’m in favour of projects like these - even on spending taxpayer money on them. I think it’s super cool and I would love to see it. Yeah, I also think it’s extremely unlikely.
However, when you’re doing journalism, you should contextualise for your readers. TFA doesn’t even try to do the bare minimum.
Safety should probably also be considered.
We had Concorde - it was too expensive to operate safely.
We just didn‘t have enough billionaires back then. Today the Thiels and Musks and Bezos will be able to afford this.
Agree that this is a matter of economic viability rather than technology. Presumably somebody could just go back and resurrect the Roles Royce IP
There would be the nice side benefit of maybe having all these guys in one place, upon an experimental aviation platform.
The actual time to skim off IMO is all the airport procedures.
This is already a solved problem for the class of customers they are going after.
And the time wasted on transfers. I used to regularly fly from airports in NY, London, SF, Singapore, LA, Sydney, etc. I would block out the opportunities to work or rest, and the reality was that only the plane time was valuable for either. It was painful to see all the other blocks of non productive time, particularly the allowances for congestion and disruption between downtown and the airports. I would have paid thousands a flight to be able to check in/clear security at my hotel and then get driven to a holding bay at the airport, and then on to the gate, in a vehicle suitable for both work and rest.
This is a solved problem in civilized countries. The time between arriving at an airport and boarding your plane in Japan is ~10 minutes, most of it walking. Because they don't spend an hour fucking around with clownshow security, and because boarding doesn't take forever, as people don't try to stuff ten pieces of carry-on luggage into five overhead bin spaces.
Customs always takes time, though, even in the happy (no extra questions, no bag searches) path.
---
Do you want to know the secret to fast security lines?
Either reduce the work security does, or open more lines and hire more agents[1], until they can meet the throughput requirements. Both seem to be anathema to an American airport.
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[1] This also works to reduce lines and improve quality and cleanliness in other aspects of society. It's not that Japanese people don't produce any garbage, or dirt, it's that their public infrastructure is regularly and meticulously cleaned and maintained.
[dead]
Not necessarily for extremely long haul flights. The airport side of things takes about the same amount of time regardless. For a transpacific flight, you’re looking at maybe 3-4 hours at the airport and 10+ hours in the air. Shaving down the airport side would be nice but a faster plane could save a lot more time.
Really? Obviously it varies by country, but there’s no customs/immigration when leaving the US, and security usually takes <5 minutes with PreCheck. Sometimes immigration takes a while on the other side, but it’s quick at airports with biometric gate systems. You still hear people talk about airport buffer time in units of hours, but I think that’s increasingly out of date.
Yes, ymmv (a lot). But alas buffer time is getting higher, not lower.
Yes, TSA is a big part of the problem. It's less "how long it took" and more "how long can it take". I've personally experienced those days where "TSA decided to go slow" and a couple hours disappears. The 5 minute days just make that worse.
Yes, the airport matters. If you're at some small regional it's no big deal. JFK or Atlanta etc is another thing entirely.
Yes, domestic or international matters. Yes, flying business class makes it faster. Yes signing up for "special status" makes things faster.
But airports are typically some drive away from city center (both ends, in traffic). Security and immigration both take time (often significant time.) Door to door time is easily 6 hours more than flight time.
I have _yet_ to hit a time where TSA can make multiple hours disappear. Precheck w/ touchless ID lines are virtually empty at most airports, the actual security screen itself is quite fast given almost nothing needs to be removed from your bag these days. I still tend to arrive early, but I don't mind getting work done at the airport, especially at a lounge - though I've arrived very close to departure other times and still make it to the gate with plenty to spare.
On international returns, both Global Entry or MPC lines are virtually empty when I arrive (SFO)
The worst part is international arrivals in foreign countries, where immigration can soak up a lot of time, and you have no choice but to stand in line. Luckily I don't have to fly internationally too many times a year.
>> I have _yet_ to hit a time where TSA can make multiple hours disappear.
Lucky you :). And I hope you stay lucky! Alas your experience is not universal.
So how long before the actual flight departure will you be at the airport?
If I catch a train that is 10 minutes before the train departs on a metropolitan train station in Europe.
With planes in my experience arriving two hours before the actual departure is not uncommon at bigger airports, since there are more insecurities involved like how crowded security checks are, where your gate is, etc.
In the US, generally one hour no matter whether it's domestic or international. In Germany, like three hours because security and immigration is insanely slow and inefficient. In the UK and other countries I'm less familiar with, two is usually fine.
If I come earlier, it's with the expectation that I'll waste some time hanging out in a lounge.
(Train situation is similar in the US, in places where we actually have those. Generally fine to show up right before departure.)
First time I heard the word "ramjet" was as a kid watching the Goliath episode of Knight Rider. Definitely not a documentary, but the word stuck. Then the Blackbird showed up in some plane book, and that was that. Ramjets back in the news. Kid me is having a great morning.
“Roger ramjet he’s our man, hero of the nation!!
https://m.youtube.com/watch?v=E7SqSNQeAFM
Roger Ramjet! Now I've got that theme stuck in my head. Pretty sure that's where "ramjet = unstoppable" got hardwired in me.
Yes it looks a lot more cheesy now than I remember as a kid
https://youtu.be/SpEO-jIKhE8?si=89Qw1_AOXYow9PfR
But ramjets have been promised to us for years
So nostalgic. AI, self-driving, ramjets — they packed it all in. And the thing that dates it isn't any of that, it's that nothing is a touchscreen. The future used to be chunky buttons.
Two news items in one : Japan is getting ready for hypersonic missiles, and Japan’s elite does not give a damn about global warming.
Next generation of. The Type 25 HVGP just entered service few months ago. That one is just a two-stage Scud, but the Block 3 or NG or Type 35 or whatever of that could have this tech.
The world's elites have factored in global warming already. It's a cost they are happy to shift onto their descendants.
>Their descendants
I'm sad to tell you, they're already looking for places on earth to buy land to build their nest after they decimate or help decimate humanity.
It seems to me that hypersonic engines are the fusion power of aeronautics. Always 10 years away.
Building a ramjet that is more efficient than rockets while travelling at several times the speed of sound is the easy part. The hard part is getting up to that speed first, because they give basically no thrust at low speeds. So you always need a two component engine and fuel system, with each component being useless at either launch or in-flight. Basically a similar reason why only the military uses VTOL planes. The military has no problem strapping a rocket booster on a ramjet missile.
And once you do all that, you will need to also handle the massive atmospheric heating from friction, so that the whole thing does not melt during flight.
Again, not that problematic for missiles due to shorter flight times and single-use ablative heatshields being viable.
Another Concorde?
[flagged]
Ahh, but can it run DOOM...?