And 3 J85-15 jet engines designed in the 1950s (?)
I remember reading about these J85 engines in an issue of Popular Mechanics roughly 20 years ago. This engine was designed to be cheap and small enough to fit in a carry-on suitcase circa 1955. They are best known for powering the F5 "low-budget fighter" from 1959.
Crazy that a new aircraft is launching with such new tech, but still rocking engines that were fundamentally designed around 10 years after the dawn of jet aircraft.
> Crazy that a new aircraft is launching with such new tech, but still rocking engines that were fundamentally designed around 10 years after the dawn of jet aircraft.
Their goal is to prove the design's aerodynamics WRT sonic boom, not the engines.
As I understand it, engine sourcing has been one of Boom's challenges. Rolls Royce was originally working on an engine for them, but cancelled it in '22. Boom announced their own engine design last year but I'm assuming that's not ready.
Apparently newer engines aren't designed for supersonic flight so I'm guessing options are limited for testing this airframe.
I believe they are thinking that one is a solved problem (Jet Engine) and the other is a novel problem (Airframe with reduced supersonic noise). There has been some work done on the sonic boom problem, but not nearly as much as the jet engine problem.
They will probably just iterate from an existing engine design rather than trying to re-invent one. Just because no one is manufacturing them doesn't mean the designs are not there to be used.
Jet engine is a "solved" problem for like 4 Western companies (GE, Pratt-Whitney, Rolls-Royce, Safran) plus some Russian and Chinese state-owned enterprises that mostly do military work. These organizations guard their secret sauces vigorously. Designing a cutting edge jet engine from scratch (i.e. with competitive fuel efficiency) is NOT a trivial task.
>> Jet engine is a "solved" problem for like 4 Western companies (GE, Pratt-Whitney, Rolls-Royce, Safran) plus some Russian and Chinese state-owned enterprises that mostly do military work.
There's actually quite a few companies that make small turbojets especially for military purposes and up to a certain point, you can even DIY your own from spare parts (there are some Youtubers that have done that). That's the first tier and includes companies like Williams, usually producing <5,000 lbf engines.
Then you have companies like Garrett/Honeywell that can make engines that output tens of thousands lbf like the TFE731 for mid-range jets and fighter jets. These can power big jets but not very fuel efficiently; that's the second tier.
The next tier up is the high bypass turbofans producing tens of thousands lbf used for commercial aviation and afterburner engines for last gen fighter aircraft are a completely different story. The GP is right there are only a few players in the game. Due to scaling laws, at this point it becomes less about the design and more about the metallurgy and material science. Magic like single crystal alloys are critical here and are very closely guarded secrets because the knowledge unlocks everything from ICBMs to gaseous centrifuges to nuclear reactors.
Ha jet engine that can be certified maintained and is efficient is barely solved by GE. That’s it nobody else can make a modern commercial aircraft engine that isn’t a total money pit.
They are at least a generation behind GE and the company is on life support so I don’t see them closing the gap. Pratt now Collin’s has engines too but their commercial engines are 3-4 generations behind.
Although I think it's not going to be as easy as picking one up at the corner store, I do not think supersonic flight (which occurs every day on thousands of airframes) will compare to the level of complexity of landing a human being on an irradiated airless rock 238,900 miles above the earth's surface and returning them safely.
Edit: There are private groups that own supersonic aircraft and maintain them. EG:
They can get a hold of existing models and diagrams to produce their own copies since the patents have long since passed and been declassified for decades.
One of the key features of Overture is its planned use of e-fuels.
I think this is almost crucial. Airlines are not going to line up to buy non-renewable, fuel-guzzling, net CO2-gushing supersonic jets for use over the next couple decades.
Isn't it completely irrelevant for their development how the fuel is produced? My understanding is that E-fuels are exactly the same as "normal" fuels. They are just produced in a carbon neutral way. You can fly a 50 year old Concord on e-fuels.
Airlines are almost certain to face significant carbon regulation or carbon taxes in the next couple of decades. In turn, lots of engines will be effectively banned.
Of course, this is nothing new: noise abatement effectively banned a whole lot of engines, too.
I don't think it requires giving up on "affordable global flight". It might be a bit more expensive -- getting aircraft to be tens of decibels quieter cost something, too.
Externalities -- whether they're noise imposed on a community or climate impacts -- aren't generally addressed by the market on its own.
Indeed, we have a new regulatory regime coming into play for airplane emissions slowly-- with first effects in 2028.
I mean, it's already happening all over the world. It's not just Germany.
The UK already taxes carbon in aviation fuel. It's about to implement a carbon pricing mechanism for jet fuel obtained in jurisdictions without it.
The EU is implementing carbon taxes, and a mandate for Sustainable Aviation Fuel. In 25 years, it will be illegal across the EU27 to use aviation fuel that is not at least 70% Sustainable Aviation Fuel.
China has the world's largest emissions trading program. Civil aviation will be included next year.
Australia has a carbon tax, and will soon have mandates on civil aviation emissions.
Brazil does not yet have a carbon tax, but in the past year there has been legislation proposed, and it looks likely to be coming sometime soon.
The US EPA just announced regulations that will not force, but will certainly make it cost prohibitive to sell lots of gasoline cars ten years from now. Civil aviation is a likely next target.
The sun's variation in intensity over the solar cycle has a typical 0.2C difference... and even then, 5 years later you get the 0.2C "back".
If you're saying "another Maunder Minimum":
- There is no consensus that is going to happen; or even a majority view that it will.
- It sure doesn't look like the Maunder minimum caused significant cooling overall (perhaps at most 0.4C, so not much more than a normal solar cycle). Yes, Europe's temperatures swung more than this.
>The sun's variation in intensity over the solar cycle has a typical 0.2C difference... and even then, 5 years later you get the 0.2C "back".
On what are you basing this statement? The climate models I've looked into were wrong about the effect of clouds and ignore types of energy from the sun.
>- There is no consensus that is going to happen; or even a majority view that it will.
If I am walking towards someone in a rocking chair, they may be moving towards me or away from me at any point, but overall I will get closer. Similarly, if solar cycle causes a variation of .2C back and forth, it doesn’t eliminate a non-oscillating trend.
When weighing what is likely to happen, fringe beliefs don’t matter much. I would not bet on a Maunder minimum to save us, because A) it is not a big enough effect even if it happens, and B) it is probably not going to happen.
You've edited your comment-- I'm glad you've reconsidered including the below which violate the site guidelines:
> Oh please, spare me the polemics.
> Do you stand to benefit financially, directly or indirectly, from climate change?
But: I think most of us stand to lose significantly from climate change.
They announced they're building their own because the regular engine OEMs showed little interest. Even if required modifications to historic or military turbojets are minor, there's a lot of expense in certifying them for use for a new type of passenger aircraft, and modern economical turbofans were not designed for supersonic flight...
(Almost?) exclusively on military planes which have different return on investment needs than commercial aircraft that need to be efficient first and foremost (ask Convair and BAC/Sud Aviation how many airlines valued speed over efficiency).
If China is anything to go by, immensely more so, and you are not significantly helped even if you had all the documents and industry secrets required to design and build a modern engine!
Yeh, although on https://boomsupersonic.com/flyby/inaugural-first-flight-xb1-... they say 'Supersonic intakes: XB-1’s engine intakes slow supersonic air to subsonic speeds, efficiently converting kinetic energy into pressure energy, allowing conventional jet engines to power XB-1 from takeoff through supersonic flight.' - so perhaps the engine design problem is not as tricky as it would otherwise be.
All current supersonic aircrafts do that. The only kind of jet engine that can take supersonic intake air is scramjet(supersonic combustion ramjet), which is more like a space age gas torch, not a turbine engine. Shockwaves are going to blow off turbine blades if not done or something along that.
From what I've read GE spent roughly 10 years and 10 billion dollars to develop their monocrystalline turbine blade manufacturing materials and process.
"After careful consideration, Rolls-Royce has determined that the commercial aviation supersonic market is not currently a priority for us and, therefore, will not pursue further work on the program at this time. It has been a pleasure to work with the Boom team and we wish them every success in the future."
Guess it was a cost thing. Wasn't worth their time. Not enough customers probably.
Not sure of the relative timing, but the new CEO is super focused on profitability/cash flow. In comparison to what he described as a ‘burning platform’ when he took over. So supersonic would have needed a brilliant business case to have survived his strategy.
Falcon 9's Merlin engine is really just based on a NASA reference design for a simpler low cost rocket engine. Raptor is new tech, but that was long after SpaceX had proven itself and had the capital and talent to invest in building something like that.
It makes total sense to use flight proven engines like this off the shelf at first.
High tech manufacturing at scale is often equally as challenging as development work. Starting with a proven design let's teams focus on leveling up their manufacturing capabilities prior to introducing the double complexity of manufacturing a part that just made it out of CDR.
A bit of a tangent, but this is the genius of Musk's Merlin engine. Simple design utilizing RP9 allows the manufacturing staff to hit their stride before introducing the raptor (methalox).
>> Augmented reality vision system: Two nose-mounted cameras, digitally augmented with attitude and flight path indications, feed a high resolution pilot display enabling excellent runway visibility. This system enables improved aerodynamic efficiency without the weight and complexity of a movable nose.
(Cough) Don't tell the passengers it is all because the pilot literally cannot see the runway during landing.
ILS generally still requires manual visual approaches from the minimum altitude to the ground. Only ILS Cat III-C is a true autoland that can take the aircraft down all the way to the ground.
Even then, aircraft certification requirements even for Cat III-C capable aircraft requires that pilots be able to conduct a visual approach because the ILS system can fail.
An aircraft that has literally no recourse when ILS Cat III-C capability goes down (either on the aircraft side or the airfield side) does not seem like a good idea, especially because in this case large categories of emergencies are positively correlated with avionics failure.
For example an engine failure may cause power loss to avionics, so your fancy AR webcam feed is more likely to go down in that situation just when you need to make an emergency landing.
Not impossible to overcome of course - you certainly can ensure your avionics have its own isolated (and multiply redundant) power source so that it does stay up in the event of many kinds of emergencies, but personally I'd need to really see the homework on that before I'd feel safe flying in that kind of setup.
But whether or not it can do an ‘Autoland’ currently is irrelevant because as the parent said:
> Even then, aircraft certification requirements even for Cat III-C capable aircraft requires that pilots be able to conduct a visual approach because the ILS system can fail.
Whether or not it can do an ‘Autoland without the pilot being able to check’ while satisfying the regulator’s inevitably vastly more stringent rules is what matters.
To be fair, they do need an alternate with a better visibility. But if the computers are not working, you're not in for a good time in a modern airliner anyway.
Maybe not a 'good time', but a safe one.
Commercial airliners have standby instruments and a VHF radio that works on a battery. Which is all you need to get it on the ground in one piece.
You cannot operate fly-by-wire aircraft without computers, that's what I meant. Redundancy is name of the game, I see no problem in using cameras if they're made redundant.
Yes and no. Line of sight was one reason, but aerodynamics was another. Pointing the nose into the wind (ie slightly down) is more efficient during landing and takeoff. Boom is avoiding the concept because it would cost tens of millions to develop and test such a configuration.
Large moving parts on an airframe seem to be avoided in general these days. There’s a similar story with swing wings (which I think Boom also considered before ultimately rejecting).
Edit: I replied to the wrong comment. Hermes chose to start with the same engine as Boom - The J85. I'm assuming Boom chose it for similar reasons.
I like their explanation of the choice from a recent tour:
(Youtube transcript)
"So these are out of production, the J 85s. So we didn't work with GE at all. It was all just us working with, we were really working with the maintenance, repair and overhaul shops for them. That's really where the expertise and knowledge lies. These engines were, I think originally designed in the fifties. There's not a lot of electronics on board. There's no firmware we have to work through.
And really, it's a pretty elegant but hydro mechanical system for all the controls. So really it was about understanding the configuration of it and you can kind of chase down all the different tubes and everything to understand how it works. And then there's a suite of documentation out there. So it was really on us to learn how it worked."
J85s are old technology. They're a turobjet, not a turbofan, nor do they have any electronics on board. This makes them highly inefficient engines. They're cheap, there are plenty lying around from old 4th gen fighters, and plenty of old guys who know how to work on them.
I suspect they used these just to get the XB-1 airborne, making progress while they find a better engine.
Where would the LLM get the training data? It's not as if supersonic jet designers commonly post easy-to-ingest design data online.
Besides, most countries couldn't build a modern jet engine even if they had the exact engineering drawings of an existing one available. From fashioning single-crystal turbine blades to establishing a supply chain capable of the quality controls needed, the amount of hours spent is unreal.
As a corollary to AI taking up easy jobs like CRUD apps and spreadsheets, will human work be pushed to making things like silicon chips, nuclear reactors, jet engines and space elevators?
Because you have to be able to take them on the plane, obviously. /s
But seriously I think 'fitting in a suitcase' wasn't the design goal, per se, but an approximate description of the design goals. The engine was designed to go in a missile.
That’s interesting actually - and a lot of 1950s era ‘small enough to fit in a suitcase’ descriptions (computers, nuclear warheads, jet engines…) make more sense if you realize they are a euphemism for ‘small enough to fit in a missile’. Makes me wonder what ‘small enough to fit in a cigar box’ was a euphemism for.
That's a euphemism for cigar boxes; smuggled cigars get through borders with a little rake-off at each inspection. The fact that they are actual cigars on the top layers allows all the boxes to get past slightly bent but nonetheless patriotic guards.
Eh, maybe. The suitcase itself is also, more simply, literally just something designed to be a reasonable amount of stuff that a human could carry. Many early portable PCs (e.g. Osborne) targeted a suitcase form factor just because it was a reasonable form factor for people to carry around.
And the comparison is something colloquially convenient. "The device was the size of a suitcase" is just more illustrative than "the device was 50 liters in volume"
And 3 J85-15 jet engines designed in the 1950s (?)
I remember reading about these J85 engines in an issue of Popular Mechanics roughly 20 years ago. This engine was designed to be cheap and small enough to fit in a carry-on suitcase circa 1955. They are best known for powering the F5 "low-budget fighter" from 1959.
Crazy that a new aircraft is launching with such new tech, but still rocking engines that were fundamentally designed around 10 years after the dawn of jet aircraft.