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.
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.
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.
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.
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?
> (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, possible largely because they wanted to kill off foreign competition).
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?
> 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.
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.
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.
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.
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.
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
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?"
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.
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 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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?
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.
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
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...
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?
>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.
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.
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.
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.
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.
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.
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.
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.
> 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.
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?
> (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, possible largely because they wanted to kill off foreign competition).
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.
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.
> 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.
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.
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.
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.
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
“Roger ramjet he’s our man, hero of the nation!!
https://m.youtube.com/watch?v=E7SqSNQeAFM
As a Canadian who travels to Europe about once per month I am very excited for this :D
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.
Boy, that's an evergreen headline.
that headline uses a subjunctive verb mood "_could_ <verb>" and those titles are seemingly always clickbait
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.
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
What companies are examples of that bait and switch strategy?
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?"
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.
> * when I say time savings I mean dick measuring contest
And in this case smaller is better?
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.
Safety should probably also be considered.
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.
> Dubai to SFO is also a possible route
Is there really that much premium traffic between Dubai and the Bay Area?
I think the more interesting question is /will/ there be that much premium traffic ongoing
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.
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.
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.
ORD -> Vatican
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.
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
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.
It failed because the market dried up due to economic reasons, and they couldn't fill seats.
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.
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.
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.
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.
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.
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.
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?
American execs negotiating memory two months ago in Korea?
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.
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?
I think the SpaceX plan for point to point travel might be even more pie in the sky. Or maybe a tie.
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.
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).
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.
[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.
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?)
Which is why I say the questions are fair and to not use them dismissively. I agree, context matters.
> This is as pie-in-the-sky as it gets.
I saw the "sounding rocket" and thought: Oh, hypersonic missiles money.
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
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...
Probably because there is no plan to develop a commercial plane.
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.
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.
>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.
Another Concorde?
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.
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.
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.
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.
Two news items in one : Japan is getting ready for hypersonic missiles, and Japan’s elite does not give a damn about global warming.
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.
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.
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.
Ahh, but can it run DOOM...?