[HN Gopher] GE Aerospace Successfully Develops and Tests New Hyp...
___________________________________________________________________
GE Aerospace Successfully Develops and Tests New Hypersonic Dual-
Mode Ramjet
Author : NoRagrets
Score : 128 points
Date : 2024-07-12 06:54 UTC (16 hours ago)
(HTM) web link (www.geaerospace.com)
(TXT) w3m dump (www.geaerospace.com)
| paganel wrote:
| To what (I guess future) planes would this engine be assigned to?
| Is there a new US project after the F35?
| zakary wrote:
| Missiles and Drones. There's essentially no viable use case for
| a hypersonic manned jet
| banku_brougham wrote:
| In the world we have built, the answer to "what purpose will
| this new technology serve?" is usually dispiriting.
| TrainedMonkey wrote:
| A huge portion of modern technology was originally
| developed for military applications.
| hoorayimhelping wrote:
| This isn't the world we've built, it's the world we live
| in. We didn't create this world, and we aren't yet powerful
| enough to change the nature of reality, so to blame
| humanity for the necessity of defense is silly. You'll be a
| lot less dispirted if you accept that the world we live in
| isn't a human creation and that we still haven't made it
| out of the struggle to survive.
| prewett wrote:
| There's nothing in the nature of reality that forces us
| to fight each other, unless you mean human nature. But we
| have a choice in whether we choose to be self-serving,
| which inevitably leads to conflict, or we choose to love
| our enemy. Loving your enemy requires dying to yourself,
| usually metaphorically, but it _is_ an option. Humanity
| is _entirely_ complicit.
|
| 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.
| dotnet00 wrote:
| >There's nothing in the nature of reality that forces us
| to fight each other
|
| 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.
| credit_guy wrote:
| > But we have a choice in whether we choose to be self-
| serving, which inevitably leads to conflict, or we choose
| to love our enemy.
|
| 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?
| asdff wrote:
| If people were not pulling the oars, the galley of war
| would never leave the harbor. People have to remember
| there are more of them on the oars than there are those
| who hold the whips, although this is no easy feat when
| the incentives to paint this simple truth as some
| desperate impossibility are so high.
| lpcvoid wrote:
| This will hopefully be used to counter russian and Chinese
| threats in the future.
| preisschild wrote:
| There is a _certain_ military that is happy to test those
| weapons against real russian targets :)
| jabl wrote:
| I think they wouldn't want to use the absolutely newest and
| greatest tech there for fear the Russkies will figure out
| something from the wreckage.
|
| There's plenty of not quite the latest cutting edge stuff
| sitting in storage that could be donated, though.
| spywaregorilla wrote:
| And so the war of 1990s tech vs. 1970s tech in the 2020s
| continues
| Xss3 wrote:
| I think it's likely it'll be used in the sr72.
|
| 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.
| jabl wrote:
| From what I read (on that source of all truth, twitter),
| SR-72 was effectively canceled due to unforeseen technical
| challenges.
|
| But might be that with a functional dual mode ramjet,
| assuming that was the major holdup, perhaps the project could
| be on track again?
| andrewflnr wrote:
| Where are you getting "rotating detonation" from? As far as I
| know that's an unrelated project/problem.
| icegreentea2 wrote:
| Hypersonic dual-mode ramjets are not suitable for 'general'
| applications. What makes them 'dual-mode ramjets' is that a
| single engine can work at both supersonic and hypersonic
| speeds. It's still a ramjet and so needs another means to get
| the engine/vehicle up to supersonic speeds.
|
| 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?).
| bobthepanda wrote:
| How much fuel does it use, I wonder?
|
| 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.)
| lynx23 wrote:
| Supersonic is only dead in civil aviation. The military doesn't
| care about regulations :-)
| shiroiushi wrote:
| >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.
| sofixa wrote:
| > 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
|
| 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.
| lstodd wrote:
| well, ssj and ms10/21 were attempts at partially
| outsourcing, yes.
|
| 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
| sofixa wrote:
| > 204/214 are no longer built I think.
|
| 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.
| shiroiushi wrote:
| >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.
|
| 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.
| anovikov wrote:
| Fuel efficiency is more about plane itself (aerodynamic
| optimisation as well as weight saving) than about
| engines.
| bboygravity wrote:
| It's not.
|
| 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.
| sofixa wrote:
| > (for the sake of argument lets assume batteries of high
| enough Wh / kg would exist)
|
| 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.
|
| https://www.youtube.com/watch?v=VNvzZfsC13o
| tonyarkles wrote:
| > weight savings > engines
|
| 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.
| notahacker wrote:
| the major engine OEMs aren't investing enormous amounts
| in optimising for a startup airframe program though, so
| at best you're getting a derivative of the engine on the
| equivalent sized Boeing/Airbus program with roughly the
| same fuel efficiency but worse expectations in every
| other relevant area (expected reliability, competitive
| local maintenance markets, type-rated crew availability,
| commonality with existing fleet, residual values etc, and
| probably worse aerodynamics and structural weight) due to
| the airframe program's relative immaturity
| twelve40 wrote:
| > company decided to suddenly get into the jumbo-jet
| business, this shouldn't be an issue for them
|
| 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.
| ethbr1 wrote:
| > _Chinese COMAC got sold a decade+ old variant [engine]
| for their latest jet out of fear of industrial espionage_
|
| 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.
| notahacker wrote:
| > 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
|
| 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.
| teractiveodular wrote:
| The SSJ's track record of three hull losses, including
| one on a demo flight that killed 45 sales reps and
| prospects, probably isn't helping.
| notahacker wrote:
| Tbf that one was counted as pilot error IIRC, but never a
| good idea to kill your customers. The few non Russosphere
| SSJ customers pretty much all going bust except for
| CityJet who dropped them from their fleet citing
| reliability issues probably didn't help either
| throwaway4good wrote:
| Both China and Russia are building alternatives to
| Boeing/Airbus commercial airliners. But are in two
| completely different situations.
|
| 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.
| throwaway4good wrote:
| And the Chinese have a modern engine under development
| that can be used in a commercial airliner:
|
| https://en.wikipedia.org/wiki/ACAE_CJ-1000A
| TheOtherHobbes wrote:
| China might. Russia has decided to move its economy in a
| different direction.
| throwaway4good wrote:
| Even at war and cut off from the world the Russian
| economy is growing. Driving by buoyant commodity prices.
|
| They have tech for civilian aviation in their massive
| military industry. And just the sheer size of the country
| guarantees the demand.
| dralley wrote:
| The economy is growing because of massive government
| expenditures on defense. The same thing happened with
| Nazi Germany. It's not sustainable.
|
| "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.
| HPsquared wrote:
| Silicon Valley was built on defense spending.
| brnt wrote:
| Nobody is interested in 1970's airliners though.
| HPsquared wrote:
| In that part of the world, if those are the only ones
| available...
| brnt wrote:
| Then it aint no Silicon Valley.
| signatoremo wrote:
| Not at the same scale. At the peak of the Vietnam War,
| the US spent less than 10% of GDP on the war. Most of the
| time it was only half of that (for comparison it's less
| than 3% at the moment).
|
| 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.
| racional wrote:
| The figure I've seen for Russia's spend is 40% of its
| _budget_ , not its GDP. More like about 10 percent of
| GDP.
|
| Still an insane amount, for a war that has been obviously
| insane from the very beginning. But a different number,
| in any case.
| cpursley wrote:
| It's 6% which is not a dealbreaker for a country with one
| of the lowest GDP to Debt ratios (assuming the war does
| not stretch for another 5 years).
|
| https://carnegieendowment.org/russia-
| eurasia/politika/2023/0...
| dralley wrote:
| They have low debt but little ability to borrow. Once
| they run out of reserves they won't be able to sustain
| these levels of funding.
| cpursley wrote:
| Why would they need to borrow when they can continue to
| sell commodities (which the EU and US continue to buy,
| btw)? Besides, there's no indication that they are
| running out of reserves. Wasn't one of Putins first moves
| to get off of foreign debt?
| dralley wrote:
| Those commodities won't even come close to covering their
| spending spree. And their reserves are running dry very
| quickly. Likely by the end of this year.
| treflop wrote:
| Even if it was, many of the products that came out were
| not defense products.
|
| 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.
| phonon wrote:
| Russia's GDP is a bit more than half of California's.
|
| 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...
| cpursley wrote:
| The reason they dipped in terms of planes is directly
| related to sanctions and western countries pulling out
| based on the article you shared. Worth noting, the
| foreign parts Sukhoi Superjet 100 (a very good regional
| jet) are in the process of being fully "Russified" and
| the MC-21 is actually a true domestic plane vs the
| Chinese C-919:
|
| - 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/e
| ds2...
| sofixa wrote:
| > Worth noting, the foreign parts Sukhoi Superjet 100 (a
| very good regional jet)
|
| 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.
| Toutouxc wrote:
| > A big issue with these metrics is that they use the
| official exchange rate for RUB to USD exchange rate
|
| Isn't the main point of PPP-based metrics that they DON'T
| use the official exchange rate?
| mlyle wrote:
| > 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,
|
| 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.
| willcipriano wrote:
| California spends 50k per homeless person[0] and can only
| house them when Xi Jinping[1] comes to town.
|
| [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.
| MaxPock wrote:
| How much steel and electricity does California produce ?
| conradev wrote:
| COMAC's C919 is flying domestically and their next goal
| is EASA type certification
|
| I imagine it will be more geopolitics than anything else,
| but the EASA says 2026 is "too soon".
| sofixa wrote:
| > 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.
| holoduke wrote:
| Airbus is heavily depending Russian titanium. Even with the
| current tensions they decided to keep buying Titanium from
| Russia. Money is the only reason why players are not having
| inhouse solutions. Give it time and reason and any country
| can get a fuel efficient engine.
| lobsterthief wrote:
| It takes an insane amount of expertise and endurance
| testing to produce a safe, reliable jet engine. These
| companies have been doing so for 60+ years at this point.
| There's a lot of knowledge and investment that has
| allowed them to produce these things at any kind of scale
| at this point.
|
| 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.
| vl wrote:
| Boeing used to make engines and even had their own
| airline. They were split due to anti-trust regulations.
|
| Airline became United, and engine manufacturer - Pratt &
| Whitney!
| sofixa wrote:
| This was a century ago, when aircraft engines were radial
| ones with propellers, and weren't all that different or
| complex than truck or tank engines (outside of layout and
| materials for weight optimisation).
|
| 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.
| nine_k wrote:
| I wonder where Embraer fits in your picture.
|
| 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.
| sofixa wrote:
| > The Ukrainian aircraft industry was indeed interesting,
| but it was all about cargo planes
|
| 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.
| whalesalad wrote:
| This is hypersonic. Way faster, way more heat just from moving
| through air. We will not see passenger aircraft going
| hypersonic for a long time. It will be hard enough to make a
| hypersonic aircraft that doesn't melt itself during flight.
|
| The main reason supersonic flight is dead is the sonic boom.
| Until that issue is resolved they are banned over land,
| unfortunately.
| af78 wrote:
| | The main reason supersonic flight is dead is the sonic boom
|
| 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.
| rsynnott wrote:
| The sonic boom made Concorde's economics harder, but they'd
| have been hard anyway. It confined it to largely only being
| useful for that transatlantic route, and that was
| borderline economically viable for airlines. However, as
| there was really only one route where it was useful, there
| were not many Concordes flying and the fixed costs were
| considerable. Eventually Airbus pulled the plug, and ended
| maintenance, and that was the end of that. It was probably
| spurred on by a high-profile disaster, but even without
| that, the writing was on the wall; if you were an airline
| Concorde looked economically viable, but without subsidy by
| the state or by Airbus or both, it never had been.
|
| 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.
| lstodd wrote:
| This I agree with. There were not enough viable routes.
| Same thing happened with TU-144 - no destinations.
| twelve40 wrote:
| Sad for both. Saw Concorde at Le Bourget. Both were
| miracles of engineering in their day.
| filereaper wrote:
| Genuinely trying to understand.
|
| 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?
| adgjlsfhk1 wrote:
| a couple things:
|
| 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
| twelve40 wrote:
| smaller, and SR71 could cruise at 85000 feet
| rsynnott wrote:
| > Didn't the SR71 fly between LA and NY at above
| supersonic speeds? Don't military jets fly at supersonic
| speeds above land?
|
| 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?
| ceejayoz wrote:
| The F-22 can also cruise at supersonic speeds without
| afterburners. https://en.wikipedia.org/wiki/Supercruise.
| rsynnott wrote:
| _Can_, but does it routinely outside of
| training/deployment situations? Like if you're just
| moving one from one side of the US to the other, you're
| probably going subsonic.
| kube-system wrote:
| > 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.
| kube-system wrote:
| > Don't military jets fly at supersonic speeds above
| land?
|
| 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.
|
| https://www.youtube.com/watch?v=G8G-mgKycUM
| denton-scratch wrote:
| Thd only time I've ever heard a sonic boom was as a kid,
| on holiday in the south of France. They would regularly
| fly Mirage jets over the beach resorts. I suspect these
| flights were for when Gen. de Gaulle was in residence at
| the Chateau d'If.
| dghughes wrote:
| >The sonic boom made Concorde's economics harder...
|
| 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.
| kitd wrote:
| Even without the sonic boom, it was _painfully_ loud on
| takeoff and final approach. It used to fly over us near
| Heathrow and the ground would shake as it went over at a
| few thousand feet.
| rsynnott wrote:
| Concorde B, apparently, would've fixed that (though not
| the sonic boom, of course).
| lstodd wrote:
| Green and nimby bullshit as usual. I lived at a summer home
| in 80s which was near a (soviet) air force base for many
| summers, and listened to sonic booms daily. In no way it
| was even disturbing.
| jjk166 wrote:
| It's a little more complicated then that. The main impetus
| for the development of the Concorde was actually fuel
| efficiency - once you get high enough above the sound
| barrier supersonic flight is more fuel efficient than
| subsonic flight, all else being equal. Back in the 50s, as
| fuel costs became more and more of a concern for airlines,
| this seemed like the obvious future: you get your
| passengers to their destinations faster, you spend less on
| fuel, and you can make more flights per day. So Super Sonic
| Transports (SSTs) looked great on paper. SSTs need to use
| turbojet engines, which all passenger jets in the 50s were
| using anyways.
|
| 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.
| 15155 wrote:
| Cruise missiles have different efficiency goals than commercial
| airliners.
| Beretta_Vexee wrote:
| It's a hypersonic thruster, i.e. 5 or more times the speed of
| sound. Far too fast for civil aviation. It's probably even too
| fast for "safe" manned flight. This is the speed at which the
| air ionizes around the vehicle. It's like flying inside a
| fireball.
|
| 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.
| dralley wrote:
| If you define "hypersonic weapon" as merely traveling at or
| beyond Mach 5, then practically every medium range ballistic
| missile since the V-2 qualifies. There is nothing special
| about a missile that can hit hypersonic speeds.
|
| 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.
| FuckButtons wrote:
| Kinzhal isn't really a true hypersonic weapon. They just
| strapped an iskander tbm to a su34, which is why the pac3
| patriot interceptors can actually shoot them down, they were
| developed to intercept tbms.
| ahoka wrote:
| It's like the US was yeeting Lance missiles from F-106s and
| insisting that it's a hypersonic weapon and it's ahead of
| everyone else. Pathetic.
| alephxyz wrote:
| well you still get the marginal benefit of having a mobile
| launch platform that travels at mach 1, which makes it a
| bit easier to avoid static air defenses if you know where
| they are. (assuming your adversary can't track and destroy
| your aircraft before they get a chance to launch them)
| pfdietz wrote:
| > It's a hypersonic thruster, i.e. 5 or more times the speed
| of sound. Far too fast for civil aviation. It's probably even
| too fast for "safe" manned flight. This is the speed at which
| the air ionizes around the vehicle. It's like flying inside a
| fireball.
|
| 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.
| jandrewrogers wrote:
| > 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.
|
| 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.
| dghughes wrote:
| Half for a cheeky answer.
|
| 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.
| GartzenDeHaes wrote:
| > which could enable high-speed flight and longer range across
| numerous multi-mission aircraft
|
| This is DoD language, so more secret drones I would think.
| thrillgore wrote:
| People are forgetting why they are really building this
| hypersonic rocket: Nuclear stockpile.
| 15155 wrote:
| Why would you not just use a ballistic missile for nuclear
| delivery?
|
| What advantage does an air-breathing engine have in this
| capacity over MIRVs and decoys?
| dotnet00 wrote:
| Supersonic has also been dead because passenger supersonic
| flight is banned over the continental US (and probably similar
| restrictions exist in Europe). In the US the regulations will
| be getting reviewed depending on the results of studies on
| building supersonic jets that make less noise (after which it'd
| be down to if they can be made efficient enough to be
| profitable).
| kevin_thibedeau wrote:
| You don't need to make an airliner. There are enough
| billionaires in the world to support a small industry of
| supersonic private jets. All of the marketing hype about
| supersonic for the masses is a figleaf to avoid being pilloried
| over tech that only serves the ultra wealthy.
| banku_brougham wrote:
| Sorry for the naive question: Back in my day they called it
| "Supersonic", why do we call it "Hypersonic" now? Are there
| trademark issues?
| throwaway4good wrote:
| Supersonic = +1 mach, hypersonic = +5 mach.
| dghughes wrote:
| But toothbrushes are ultrasonic. I can never find mine.
| Beretta_Vexee wrote:
| https://www.grc.nasa.gov/www/k-12/airplane/mach.html
|
| 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.
| icegreentea2 wrote:
| This distinction is important, but in the contexts of this
| engine, hypersonic is important because it roughly aligns
| with a performance boundary for conventional ramjets.
|
| 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.
| pfdietz wrote:
| The reason one cannot push the ramjet any higher is the
| air, slowed to subsonic speed, is simply too hot. If it's
| sufficiently hot the materials of the engine cannot
| withstand it, and even combustion stops being effective
| (because the temperature drives reactions in reverse,
| preventing heat production.)
| denton-scratch wrote:
| That ball of ionized air is opaque to radar, making the
| rocket hard to detect. Or, so I read somewhere.
|
| 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.
| magicalhippo wrote:
| These lecture notes[1] goes into some details of what makes
| hypersonic aerodynamics different.
|
| 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...
| carabiner wrote:
| This should be upvoted more, but I know HN prefers the binary
| explanations over the accurate ones in aerospace.
| "Hypersonic" isn't strictly defined like supersonic.
| Hypersonic phenomena begin to manifest at around 3 mach.
| Toutouxc wrote:
| No offense, but you can type "hypersonic" into your favorite
| search engine and be reading the explanation on Wikipedia,
| literally in less than five seconds.
| TrainedMonkey wrote:
| > A dual-mode ramjet was developed and tested in less than 11
| months
|
| 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.
| vasco wrote:
| > 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.
|
| 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.
| colechristensen wrote:
| >more similar to writing a software project for the second
| time after you throw away your first version - but now with
| more resources
|
| 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.
| bobthepanda wrote:
| even if you have a novel design your customers are rarely
| interested.
|
| 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.
| throwaway81523 wrote:
| Says hypersonic ramjet in the title, so the initial
| applications may be missiles rather than aircraft. It
| does talk about aircraft use in the article.
| 05 wrote:
| Because Southwest pilots are not 787 type rated.
| t0mas88 wrote:
| Some airlines fly the 777 and 787 mixed by the same
| crews. It's not a full different type rating in that
| case.
| Tuna-Fish wrote:
| The problem Boeing had was that there is a massive amount
| of 737:s, and a correspondingly massive pool of crew
| qualified for those planes. Customers really wanted not
| just a plane that was compatible with something, but
| specifically compatible with the 737. And this was a
| problem because the 737 is too old of a design.
|
| 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.)
| s1artibartfast wrote:
| It was a classic example of an over constrained problem.
|
| They tried to find the loopholes and thread the needle
| but failed, at least in the court of public opinion.
| nimbius wrote:
| i for one look forward to experiencing this next generation of
| ramjet technology firsthand in my next three-star motel room
| air conditioner, the most common and widespread use of ramjet
| technology in the United States today.
| schmidtleonard wrote:
| I just got a new battery-powered air duster that says "TURBO
| FAN" on the side. It's about 100,000 horsepower short of an
| actual turbo fan, but it's a good duster and I enjoy the
| enthusiasm.
| SAI_Peregrinus wrote:
| There are some RC aircraft turbofans available, very loud
| and fuel hungry but not quite 100,000 HP over your air
| duster.
| Scene_Cast2 wrote:
| Oh interesting. I've only seen turbojet and turboprop
| variants (with a single stage centrifugal compressor) for
| sale.
| fooblaster wrote:
| https://www.chiefaircraft.com/radio-control/turbine-gas-
| glow...
|
| wild
| inasio wrote:
| I heard a rumour that you can find repurposed project Orion
| technology in 2-star motel ACs
| kube-system wrote:
| If this is a joke about GE's appliances -- that version of GE
| is long in the past. GE has pretty much been dismantled and
| is just an aerospace company at this point.
|
| What was once GE Appliances was sold to Haier 8 years ago.
| dmoy wrote:
| I thought it was a joke about how noisy hotel HVAC is (at
| least in cheaper hotels)
| api wrote:
| When companies reach a certain size they basically become
| banks, either funding smaller teams under their umbrella to do
| things or purchasing and integrating them into a larger
| portfolio.
|
| If they purchased the design it's because GE Aerospace has the
| manufacturing and sales arms to actually make it real.
| wooplanes wrote:
| I've been saying this for years, but I'm extremely skeptical the
| DARPA hypersonic programs just ceased.
|
| 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.
| pmayrgundter wrote:
| The SR-72 is thought to be a real hypersonic from Lockheed
| flying since 2017. Extended reportage here:
|
| https://youtu.be/QlMX6TYdU7I
| class3shock wrote:
| Another similar thing from the end of last year:
|
| 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
| zaps wrote:
| Exclusive photo of the project's lead engineer:
|
| https://gifyu.com/image/Stgkj
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