GE Aerospace Successfully Develops and Tests New Hypersonic Dual-Mode Ramjet
geaerospace.com
geaerospace.com
Incredibly impressive if true. But below quote makes it sounds like they purchased a company with mostly ready design and made a prototype. Still pretty awesome.
> The successful development and testing of the dual-mode ramjet in such a short period of time was made possible through the collaboration of GE Aerospace’s team of engineers, Innoveering – a company acquired by GE Aerospace in 2022 that specializes in hypersonic propulsion – and GE Aerospace’s Research Center.
Now I want real engineering / everyday astronaut like breakdown of how it works.
We're probably reading a lot from a few sentences but I had a similar impression. Probably more similar to writing a software project for the second time after you throw away your first version - but now with more resources. Like you said still pretty cool.
All aircraft design is basically this. You don't/can't ever really start from scratch, there's an enormous volume of historical aircraft designs and all new planes look very similar to old planes. There are very rarely opportunities to solve problems in new ways.
Airlines are extremely conservative because pilots are expensive and hard to train, which is how we got the whole 737MAX fiasco instead of a clean-sheet, optimized design. Though i wonder why they didn't go for commonality with the 787 similar to how the a330 and a350 are common type ratings.
If Boeing attempted to sell these customers a new type, even if there is some compatibility with some other plane, it creates an opportunity for them to freely compete bids between Airbus and Boeing, and even when Boeing wins that bid, it's a loss to them. (Because they are going to win at a lower price point than if the customer has to account for the switchover cost only for Airbus planes.)
They tried to find the loopholes and thread the needle but failed, at least in the court of public opinion.
What was once GE Appliances was sold to Haier 8 years ago.
If they purchased the design it's because GE Aerospace has the manufacturing and sales arms to actually make it real.
https://www.geaerospace.com/news/press-releases/other-news-i...
They really seem to love to talk about how fast they move except wait:
https://www.geaerospace.com/news/articles/100-year-anniversa...
Per the above in 2019 they had been developing RDE technology for 5 years.
Now developing the tech is different then building a prototype but it's good to take these timetable numbers with a large dose of salt.
It is interesting to see RDE's getting alot of headlines recently. Really cool tech that works off of a principle known for a long time but only just recently hitting an inflection point in terms of development.
Cool video from Scott Manly talking about RDE's: https://www.youtube.com/watch?v=rG_Eh0J_4_s
The waverider program was a huge success, then suddenly funding stops and nothing is heard about it anymore. That was over 10 years ago, and now we have a commercially-developed dual cycle engine in under a year.
It’s my personal opinion that the technology was developed further internally for weapons and surveillance platforms like the SR-71 was back in the day. The technology just has too much potential.
Supersonic has been DoA for a while because post-deregulation airlines are only interested in ever more fuel efficient aircraft. (It’s also why major states like Japan, China and Russia have for the most part failed to build a competitive airliner against the duopoly.)
I don't think that has anything to do with it at all. Building a competitive large airliner requires a huge industrial base. And since it's so safety-critical, it takes a lot of time and expertise to build the reputation needed to unseat the incumbents. China has an aircraft manufacturer, but time will tell if it goes anywhere, since they don't exactly have a reputation for high quality. Russia has built many large aircraft in their Soviet days, but their industrial base has eroded so they probably just don't have the capacity to build competitively-priced aircraft in volume now, plus they're not well-liked by most countries that would want airliners anyway. Japan might be able to do it, but just isn't geared up for building lots of large aircraft so it would be a huge investment to build such an industry almost from scratch.
Fuel efficiency isn't a factor because building an airliner doesn't involve building engines for that airliner, and engines determine an aircraft's fuel economy for the most part. Boeing and Airbus don't make jet engines: those are all made by Rolls-Royce, Pratt & Whitney, and GE.
Russia did design and build a few designs recently - SSJ-100, MS-21, Tu-204/214. Almost all of them used Western parts (such as engines/avionics) to speed the process up because Russian manufacturers are a few decades behind in some critical parts (like engine efficiency). That being said, they're currently trying to ramp up production on a domestic only Tu-204/214 version, but it's slow, probably quite expensive, and super inefficient.
> Japan might be able to do it, but just isn't geared up for building lots of large aircraft so it would be a huge investment to build such an industry almost from scratch.
Mitsubishi had a regional jet design in progress, the SpaceJet, which got cancelled after a few billion in R&D and years in delays.
Ukraine also had decent manufacturing facilities and capabilities with Antonov and Motor Sich, including decent recent designs and subcontracting work for other companies.. but with the war a lot of things were destroyed (like Antonov and Motor Sich factories and facilities), and their focus is mostly on drones and missiles now.
> Fuel efficiency isn't a factor because building an airliner doesn't involve building engines for that airliner, and engines determine an aircraft's fuel economy for the most part. Boeing and Airbus don't make jet engines: those are all made by Rolls-Royce, Pratt & Whitney, and GE.
Fuel efficiency is a major factor. Outside of countries big enough to prop up a domestic airliner industry with enough spare cash to compensate for inefficiency (which is a list of 1 country, China), nobody will buy a jet which is less efficient than an alternative. Airline margins are razor thin.
And not everyone can buy an engine from Rolls-Royce, GE/CFM(their joint venture with Safran that designs manufactures short-haul engines and the future open fan design) and Pratt and Whitney. The Russian UAC cannot. The Chinese COMAC got sold a decade+ old variant for their latest jet out of fear of industrial espionage (the Chinese engine manufacturers have failed at producing reliable and efficient jet engines for any application, usually relying on Russian designs).
TL;DR is that modern airliners are extremely complicated, expensive, and have very long lead times. A new design won't be making any money within the first 10-15 years of its life, which means that only countries with very developed and advanced industrial bases, lots of money, and the desire for strategic airliner autonomy will invest in them.
204/214 are no longer built I think.
but the PS90 turbofan is still the mainstay along with D30 derivatives.
avionics is a separate question ofc
They are now being built again, because it's the only design that wasn't built with the assumption that Western providers (of avionics, specialised parts, engines) will be available and therefore it's the easiest one to manufacture with an entirely Russian supply chain. Still painful because most of that supply chain is decades old and very rusty, but theoretically possible.
No, it's not really a factor, because, as I wrote before: airliner manufacturers don't make jet engines. They can only get engine manufacturers to build them engines, and integrate those into their airframe designs. Of course, actually having access to modern, efficient engines is necessary to be competitive, which as you point out is problematic for Russia and China, but if, for instance, a major Japanese company decided to suddenly get into the jumbo-jet business, this shouldn't be an issue for them, provided the existing engine manufacturers have enough manufacturing capacity to provide them engines in addition to those they provide to Airbus/Boeing. So yes, being fuel-efficient is important to the end customers (passenger airline companies), but for the airframe makers, that's really determined by the engines they have access to, not really by any technical capabilities of the aircraft makers. The problem with lack of supply in large passenger jets isn't the engines (AFAIK), it's really just the Boeing/Airbus duopoly and how quickly they can build new aircraft, which use the engines from those suppliers.
The most fuel-efficient aircraft possible would be an electric one (for the sake of argument lets assume batteries of high enough Wh / kg would exist) flying at much higher altitudes (20km+) than the current fuel and oxygen fired engines.
That definitely involves both engine and aircraft design.
Even for jet engines: an engine from the 50's is not going to cut it in terms of fuel efficiency on ANY airframe compared to current flying machines. Even if you had unlimited budget and time to design the perfect airframe for those engines.
Highly unlikely, it's not even close right now, and nothing in recent progress indicates that soon we might have batteries that are denser and lighter by a factor of 10 any time soon.
At this point the 737 Max 8 and A320 both are sitting around an 18:1 L/D. You can't really go a whole lot higher than that without affecting controllability. Things like winglets give you incremental improvements on the order of single digit percentages.
But weight savings... that's huge. For every pound you shave off, all other things equal, means the engine needs to make less thrust and the aircraft itself needs to carry less fuel.
I don't think it's that simple. You can count jumbo jet makers and their engine suppliers on one hand. It's not like you can go shop for a new line of engines on Craigslist, these things are designed with the plane maker in mind and production numbers planned for a decade+ ahead. Both parties have to work very closely together to produce something with acceptable fuel efficiency.
The most cyberpunk thing I've ever seen is the international aerospace company bunkers at Beijing's airport.
Literally, bunkers. Barbed wire. Structural access control gates. Tiny one-room building.
I assumed that was the only privileged link back to HQ for information connectivity.
And to add to that, the desire for strategic airliner autonomy tends to be inversely proportional to domestic companies' chances of non-trivial international sales. There will be a few airlines and lessors that passed on the Russian SSJ-100 out of longstanding concerns about Russian supply chains (even though it had an Italian marketing JV so you didn't necessarily have to deal with them directly) that will be patting themselves on the back for making the correct decision, and presumably the Russian state picked up the tab for all the losses Sukhoi made on the programme.
COMAC relies on international suppliers, probably hoping that will make it easier for them to be allowed to fly outside China and then over time they can use more and more domestic suppliers. Whereas the Russians are completely cut off from international suppliers and travel, and have to resurrect their airliner projects which have been more or less dormant since the Soviet times.
I think both will be succesful over time; they have huge internal markets that can sponsor quite a bit of development cost.
They have tech for civilian aviation in their massive military industry. And just the sheer size of the country guarantees the demand.
"Buoyant commodity prices" is also known as inflation. They have high inflation despite having a federal interest rate of 18%, which is sky high. Not great signs for their economy.
Russia currently spend about 40% of the GDP on Ukraine war ( coming off my memory, may not be 100% accurate). That can’t be sustainable and they will have long lasting impact.
Still an insane amount, for a war that has been obviously insane from the very beginning. But a different number, in any case.
https://carnegieendowment.org/russia-eurasia/politika/2023/0...
Nazi Germany spent defense money to build defense products. The war was going to end eventually.
Like spending too much money on remote work products during a pandemic that will eventually end. It’s going to blow up.
Civil aviation there is a few hundred planes (about the size of Southwest--in total), and is heavily government subsidized.
https://www.reuters.com/business/aerospace-defense/russia-sp...
- https://aviacionline.com/2022/05/sukhoi-tests-100-russian-av...
- https://www.youtube.com/watch?v=E32TCdBgkoY
Also, Russia just surpassed Japan to become #4 in terms of GDP PPP (the number that matters), was recently reclassified as a high-income county and is expected to experience relatively high GDP growth, and that's even under the heaviest sanction regime on the planet x3 and after getting cut off from SWIFT:
https://www.worldbank.org/en/about/leadership/directors/eds2...
A very good based on what measurement? Operators have complained about extremely poor reliability, and there have been a high amount of crashes.
> and the MC-21 is actually a true domestic plane vs the Chinese C-919:
The MS-21 isn't domestic, it uses Western avionics and engines. There's a russified version which is supposed to be launched in 2025-2026, but it's unknown if that would happen considering it's using the Aviadvigatel PD-14 engines which are still undergoing design refinement and testing. It could literally be years before the engines are ready, so when the jet enters service is anyone's guess.
> Also, Russia just surpassed Japan to become #4 in terms of GDP PPP (the number that matters), was recently reclassified as a high-income county and is expected to experience relatively high GDP growth, and that's even under the heaviest sanction regime on the planet x3 and after getting cut off from SWIFT:
A big issue with these metrics is that they use the official exchange rate for RUB to USD exchange rate, which is entirely theoretical since it's impossible to trade the two due to the sanctions. The real exchange rate is probably much worse for the RUB, so these metrics based on the official theoretical one are highly misleading.
Isn’t the main point of PPP-based metrics that they DON’T use the official exchange rate?
You can get a lot of GDP growth if you focus your entire economy on making war materiel. It's not exactly durable growth and it doesn't really increase your citizens' quality of life.
Russia's industrial development outside of refurbishing Soviet stockpiles for war is extremely limited. Ditto for its civilian development: come on, 20% of citizens are still waiting for indoor plumbing.
GDP PPP is a useful number in comparing relatively-like economies, but here it breaks down completely.
[0]https://www.cbsnews.com/sanfrancisco/news/california-homeles...
[1]https://wpde.com/news/nation-world/san-francisco-cleans-up-b...
GDP is sort of a nonsense metric for "ability to get things done". A huge portion of that GDP are things like rents extracted via intellectual property so it doesn't tell you anything about ability to manufacture anything.
Example: California woman sends her kids to daycare a few weeks after birth and goes back to her job (high GDP), Russian woman stays home with her children (no GDP). Now wait 50 years until you only have neglected iPad kids raised by busy parents left, how many planes you building now? And the ones you manage to build? Maybe they start falling out the sky, doors coming off the hinges, that sort of thing. Maybe the engineers don't have enough of a backbone to stand up to their boss because they never really experienced secure attachment, and some people die.
I imagine it will be more geopolitics than anything else, but the EASA says 2026 is “too soon”.
Certifying a new jet from scratch is usually a multi-year endeavour, so why would it be geopolitics?
The C-Series, latest jet to be certified, took a good 2.5 years from first flight to type certification.
And the C919 hasn't started EASA certification yet.
I used to work at Pratt & Whitney, and trust me a LOT goes into this. We also worked with some of the Rolls-Royce guys. There’s a reason Boeing and others don’t even attempt it.
Airline became United, and engine manufacturer - Pratt & Whitney!
Modern jet engines are technological marvels of engineering with extreme complexity. And there are massive advancements like turbojets, turbofans, high bypass turbofans, geared turbofans, open fan every few decades.
Any engine manufacturer from the 1930s could and did manufacturer plane engines. Nowadays it's so complex and capital intensive there are 3.5-4 companies remaining with modern efficient designs.
The Ukrainian aircraft industry was indeed interesting, but it was all about cargo planes. An-225 was a magnificent device, but it could not serve as an airliner. Neither could An-124. BTW both were designed back in the USSR times.
Not exclusively, they had the An-148/158 regional civilian airliners (and related An-178 military cargo jet). They definitely had catching up to do (the An-148/158 didn't perform really well, in large part due to issues with the supply chain which was part Ukrainian, part Russian, and the war(s) between the two complicated things a lot), but there was a good base on which to build.
> I wonder where Embraer fits in your picture.
They're the only ones that can do it, but probably won't because they don't have the capital and there's the example of Bombardier which bankrupted themselves trying to make a new short to medium haul airliner.
Part of why they had to do it is because they had so many testing issues and delays with their new design that people were not willing to bite the bullet on an unproven design.
Nope, it's not unheard of in aviation because a plane, or an engine, has a multi-decade life, over which there will be a lot of maintenance and spare parts needed.
GE and Rolls-Royce used to sell jet engines at a loss, banking on maintenance and spare parts making up the losses.
And of course, the punitive tariffs were later removed because Boeing weren't actually impacted by the C-series, dumping or not.
The main reason supersonic flight is dead is the sonic boom. Until that issue is resolved they are banned over land, unfortunately.
Is it? The Concorde would fly at subsonic speeds over land and move to supersonic over the Atlantic. Given the reduced flight time at supersonic speeds I thought economic considerations prevailed.
In a world where there had been many viable Concorde routes, this could all have worked out a lot differently, Concorde B might have happened (which would have allowed a Pacific crossing), and maybe we'd still see supersonic airliners.
Didn't the SR71 fly between LA and NY at above supersonic speeds? Don't military jets fly at supersonic speeds above land?
What makes this allowable in terms of sonic booms? Is it that they're much smaller and the their booms don't cause as much of a "wake" on the ground?
1. smaller lighter, and higher flying reduce the sonic boom size
2. way fewer planes
3. the military gets some latitude to ignore the rules that everyone else has to follow
I think not routinely in either case? Most supersonic aircraft can't actually sustain supersonic speeds for a significant period; the Concorde and Tu-144 are, as far as I know, the only aircraft ever designed with supersonic flight as the effective _default_ mode of operation. For both planes, _getting_ to supersonic was rather expensive, and required the use of afterburners, so an ideal flight profile would involve ramping up to supersonic once, and then staying that way for the rest of the flight.
The SR71 was, unusually, _capable_ of sustained long-range supersonic flight, but I can't imagine it was routinely used above land when not actually on missions; why would it be?
Everything a military plane does is a mission, and the SR-71 absolutely did supersonic training missions over the US.
And as I understand, the military can and still does do supersonic training missions over land, but they do it at higher altitudes and in locations where it isn't disruptive to population centers.
It can happen, but it is disruptive at best. It isn't something you'd want happening around a populated area on a routine basis in peacetime. And it typically is not, unless under emergency circumstances.
I live in south-east Canada in the province of PEI and I hope no supersonic aircraft are made. Right now all commercial air traffic from NA flies right over my house. Especially every evening the rumble of high flying jets can he heard. It's not loud but it's certainly noticeable for something 10,000m above me.
In the 90s and 2000s you would have had 747s and a340s doing that nonstop without Anchorage or Honolulu, so if anything that would have made concorde B have an even shorter shelf life.
But shortly after Concorde's design was locked in high bypass turbofan engines were developed whose fuel efficiency was way higher than turbojets, and indeed much higher than the jump to supersonic flight could achieve. Now it was a choice between speed and fuel efficiency. This really could have gone either way, but when Boeing got out of the SST game they lobbied for overland supersonic flight to be restricted because of sonic booms, which eliminated the potential domestic market. Concorde was reduced from the future of air travel to an offshoot for a niche market.
Still it was profitable. People were willing to pay a premium for faster travel, it just wasn't a big enough success to warrant further development. The aircraft aged, unable to take advantage of many of the improvements that came to subsonic jets, and there was no replacement in sight. The Concorde was increasingly expensive to operate compared to more modern aircraft, not because of fuel but because of maintenance and staffing. Between a high profile Concorde crash in 2000, then the reduction in aircraft travel after 9/11, and the security increases which essentially tacked on 2 hours to every trip by air, the Concorde ceased to be viable.
The first use that comes to mind is a hypersonic cruise missile or unmanned bomber.
Intercontinental missiles are also hypersonic, but their re-entry vehicles are gliders with limited maneuvering capabilities.
The Russians have developed and used hypersonic air-to-ground missiles in Ukraine, the Kinzhal. It is very difficult to intercept a missile at these speeds, and almost impossible if the missile is maneuverable. This has re-launched research into this type of missile and propulsion system.
Russia is ahead in this field. The USA, China and France have carried out various experiments (mach 5 to 25), but do not really have combat-ready hypersonic weapons.
One of the great difficulties of hypersonic flight is that you generally need one engine and one stage per flight regime. The majority of demonstrators operate according to the following scheme:
- a rocket or aircraft propels the vehicle to supersonic speed, so that it can start its engine.
- The vehicle accelerates to Mach 5. The vehicle starts its hypersonic engine and detaches from the supersonic stage.
- Climb to the edge of space.
- Descent and acceleration.
- Detachment from the hypersonic engine and final gliding approach. The fireball moving off at mach 20 kind of approch.
The engine shown here would enable to have just one engine for supersonic and hypersonic flight, greatly simplifying the vehicle. The fact that it's an engine and not a rocket is important, as it means that the thrust is much longer and can potentially last for the whole flight. At these speeds, it's largely the engine's thrust that makes maneuvering possible, and this is what distinguishes these vehicles from the hypersonic glider/reentry vehicle found on intercontinental missiles.
The real difference is maneuvering, but most of Russia's "hypersonic weapons" cannot actually do this. Hence why Ukraine has shot down nearly every Khinzal that has been fired at Kyiv and about half of the Zircon missiles too, using technology that has existed for decades. IIRC one of the Khinzal missiles was even knocked out by a PAC-2 missile, which wasn't designed for that purpose.
Maybe AvanGuard is more competent and less overrated/overhyped than their other efforts, but there's no particularly good reason to believe that. Meanwhile the last time the US successfully tested a hypersonic weapon it was immediately greenlit for serial production, and I don't think that's because they are freaking out so much as that the US sandbags our capabilities while some of our competitors inflate theirs. You claim the Russians are ahead, but they keep putting their hypersonic engine researchers in jail. I don't buy it.
Ionization occurs at considerably higher temperature.
The hypersonic regime is described as when vibrational excitations of air molecules begin to significantly affect the specific heat. After that, dissociation sets in, and only after that does ionization become significant. Temperature ranges, as I understand it, are (for air at 1 bar):
Vibrational excitations: > 800 K
Dissociation of oxygen: > 2500 K (nearly complete ~4000 K)
Dissociation of nitrogen: > 4000 K (nearly complete ~9000 K)
Ionization: > 9000 K
Lower pressure will reduce the temperatures at which dissociation and ionization become significant.
Speed does not make hypersonic missiles difficult to intercept. They are considerably less maneuverable than slower missiles due to the limits of material physics. The primary advantage of hypersonic weapons is that it reduces the available reaction time of the target such they may not be able to respond effectively or mount a defense. Any "difficulty of intercept" is predicated on there not being enough time to execute the intercept after the missile is detected. US air defense systems have very low reaction latencies by design, as demonstrated in Ukraine.
I am unclear why anyone thinks Russia is ahead in this field, beyond their penchant for marketing ballistic missiles like Kinzhal as "hypersonic". The US has been building and testing hypersonic weapon systems longer than most people have been alive. Unlike Russia, the US requires hypersonic missiles to have precision terminal guidance, which is an extremely difficult engineering problem within the atmosphere. It took decades for the US to figure out how to reliably deliver terminal guidance for hypersonics.
The air is part of the fuel and onboard fuel hydrogen or some other thing to burn is the other half.
Really at >Mach 5 you'll be there fast. At Mach 5 NY to London in 54 min. Mach 10 it's 12 minutes.
This is DoD language, so more secret drones I would think.
What advantage does an air-breathing engine have in this capacity over MIRVs and decoys?
We speak of hypersonic flight when we approach or exceed Mach 5. At this speed, the heat is such that the ionized air forms a plasma around the vehicle. To put it simply, you're flying in the middle of a white hot blowtorch.
This dramatically alters flight characteristics. Some prototypes approach or exceed mach 20. At this speed you're closer to a meteorite burning up in the atmosphere than to any form of aircraft.
In a conventional ramjet, you basically have some static/static-ish structures in your inlet that uh.... "rams" into the air. This entire structure slows down the supersonic airflow to subsonic speed, and causes the pressure/temperature of the air to rise to allow for combustion.
The problem is that ramjets become less and less efficient and feasible as Mach number increases, and around Mach 6 (so technically past the hypersonic boundary), you basically can't push them any harder, and so you need a supersonic ramjet (scramjet).
In a scramjet, you only slow down the airflow to low supersonic speeds (instead of all the way to subsonic), and you feed that compressed supersonic flow into your combustion chamber.
I believe expectation for scramjets in general is that you'd only really get to Mach 10-12 or so, since above that speed rockets start providing more favorable performance.
I don't know at what speed a rocket has to be going, before the kinetic impact of 200Kg of solid metal exceeds the energy of 200Kg of explosives.
Similarly to how the supersonic regime is different enough from the subsonic regime that it's useful to distinguish the two, the hypersonic regime is different enough that it warrants its own name.
There's no exact definition, but typically around Mach 3-5 things start to behave differently enough.
[1]: https://archive.aoe.vt.edu/mason/Mason_f/ConfigAeroHypersoni...
It's a waste of money though as the Ukraine war showed that the Russian Kinzhal missile have limited utility and can be intercepted.
Naval drones and long-range drones are not only cheaper but also more effective.
In fact, each person is a microcosm of that dynamic. Each time we sacrifice a little bit of someone else's well-being for our own, we are engaging in a small bit of that warfare. Cut someone off in traffic because you're in a hurry; cheat a little to get ahead; don't clean up your public mess because laziness/rushed. It's all essentially that same dynamic.
The reality that we are each capable of disagreeing with each other and having conflicting priorities, combined with the limited resources we have access to, is the nature of reality that forces us to fight each other.
Sounds very poetic, but how exactly does this apply to the case of Ukraine being invaded by Russia? Do you propose that the Ukrainians should love the invaders? If that should happen, then the Poles and the Romanians should also love the Russians when their time to be invaded comes?
There's plenty of not quite the latest cutting edge stuff sitting in storage that could be donated, though.
Apparently they had to completely rethink and refocus the project part way though due to new technology becoming available.
That tech is probably this rotating detonation dualmode ramjet.
But might be that with a functional dual mode ramjet, assuming that was the major holdup, perhaps the project could be on track again?
As sibsling notes, maybe it could go into SR-72 or similar penetrating ISR platform is a reasonable guess. It might go into some sort of missile carrier (the carrier gets the expensive reusable dual-mode ramjet, so it can launch missiles with cheaper disposable scramjets directly at hypersonic speed?).