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A successful Japanese trial of a ramjet engine designed for Mach‑5 aircraft

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Re: A successful Japanese trial of a ramjet engine designed for Mach‑5 aircraft

#171

Post by nine_k »

fancyfredbot wrote: post #163
octaane wrote: post #151

Earlier quoted context omitted.

My take is also a missile, but as an interceptor, not offensive purposes. North Korea has shown that they can deliver a payload to Japan if they want. If the NKs do decide to launch something at Japan, it's not going to be tipped with conventional explosives. It'll be a nuke. Hypersonic interceptor seems the more likely application is this tech to me.

I think that hypersonic interceptors would use a rocket motor and not a ramjet, but I'm not sure. I think this is for offence because I understood the advantage of this engine (compared to a rocket engine) is that you don't carry oxygen so you can carry more fuel and get more range. I think range is much more useful for offence than defence. I am possibly making myself look foolish now as I'm not an expert on either…

Historically, it was: https://en.wikipedia.org/wiki/Sprint_(missile)

Would be handy today.

Re: A successful Japanese trial of a ramjet engine designed for Mach‑5 aircraft

#173

Post by tclarke142 »

throwaway2037 wrote: post #153
emptyfile wrote: post #130

Earlier quoted context omitted.

Well here's an economic application without nuclear tipped warheads. https://en.wikipedia.org/wiki/Meteor_(missile)

The Wiki pages says top speed is about Mach 4. There are already multiple rockets from US, Russia, and China that can achieve the same (or more) but with a solid-fuel rocket motor. What is the advantage of a ramjet here? It just seems way more complex and much less well tested (in labs and in combat). Also, has this missile (Meteor) been used in any combat scenarios? To be clear, the max speed for any fighter jet is…

A ramjet drastically increases range against maneuvering targets. The 'maximum range' quoted for missiles like the AIM-120D (Likely 140-170km) is normally for a front on shot at extremely high altitude (10-15km+) with no evasive actions. With an evading target the No Escape Zone (where a target likely can't kinetically evade the missile) will only be 15-25km.

The Meteor has a longer sustainer and a terminal boost meaning that the No Escape Zone is though to be upwards of 60km. Qatar might have used Meteors to shoot down Iranian Su 24's just a few months ago based on the range they were shot at.

Re: A successful Japanese trial of a ramjet engine designed for Mach‑5 aircraft

#175

Post by nradov »

throwaway2037 wrote: post #153
emptyfile wrote: post #130

Earlier quoted context omitted.

Well here's an economic application without nuclear tipped warheads. https://en.wikipedia.org/wiki/Meteor_(missile)

The Wiki pages says top speed is about Mach 4. There are already multiple rockets from US, Russia, and China that can achieve the same (or more) but with a solid-fuel rocket motor. What is the advantage of a ramjet here? It just seems way more complex and much less well tested (in labs and in combat). Also, has this missile (Meteor) been used in any combat scenarios? To be clear, the max speed for any fighter jet is…

It's not that simple. If the target aircraft is outside the minimum abort range then they can still evade multiple missiles, regardless of whether the shooting platform or the missiles themselves are locked on. Typically they would do so by descending into denser air and beaming the missile to bleed its limited energy. On larger missiles a ramjet can potentially allow it to retain more energy into the terminal phase.

There are a variety of other defenses including countermeasures, signature reduction, EW, and decoys which also complicate the issue.

Re: A successful Japanese trial of a ramjet engine designed for Mach‑5 aircraft

#176

Post by mrguyorama »

nine_k wrote: post #171
fancyfredbot wrote: post #163

Earlier quoted context omitted.

I think that hypersonic interceptors would use a rocket motor and not a ramjet, but I'm not sure. I think this is for offence because I understood the advantage of this engine (compared to a rocket engine) is that you don't carry oxygen so you can carry more fuel and get more range. I think range is much more useful for offence than defence. I am possibly making myself look foolish now as I'm not an expert on either…

Historically, it was: https://en.wikipedia.org/wiki/Sprint_(missile) Would be handy today.

That era of ballistic interceptors all relied on large nuclear warheads to have any effect.

The modern, hard problem is avoiding using a nuke, because detonating a nuclear warhead above your own country is Bad

Re: A successful Japanese trial of a ramjet engine designed for Mach‑5 aircraft

#177

Post by hdndjsbbs »

gottorf wrote: post #22
hdndjsbbs wrote: post #21

Earlier quoted context omitted.

I think a lot of the Concorde failure is tied to its status as a British-French project. Trans-Pacific flights are much longer and there's a lot of money in PEK -> LAX than in JFK -> LHR. Qantas wanted to offer London to Sydney, but they couldn't fly supersonic over land. Mainland China or Japan to Australia is a feasible route for high-margin, low-capacity supersonic flights. If you could make the flight from Beijin…

> Dubai to SFO is also a possible route Is there really that much premium traffic between Dubai and the Bay Area?

My point is mostly that since the 80s there's a lot more trans-pacific flight from the Middle-east and Far-east to the United States. When the Concorde was developed this wasn't really a worthwhile market to consider for ultra-premium air travel.

I could absolutely see Emirates doing a super-luxury super-sonic flight to the West Coast of the US. Once you're in the States you can take a PJ.

Re: A successful Japanese trial of a ramjet engine designed for Mach‑5 aircraft

#178

Post by belviewreview »

flohofwoe wrote: post #128
belviewreview wrote: post #86

Interesting, but assuming they can get the engine to work as intended, the question still remains how the passenger jet would get up to Mach 5 so the engine can start working. A solid-fuel rocket booster that would then drop off?

I may be wrong but I think a ramjet doesn't need Mach 5 to ignite, Mach 3 to 6 is just where it is most efficient at high altitudes. E.g. early German experiments during WW2 based on the Lorin tube ( https://en.wikipedia.org/wiki/Ren%C3%A9_Lorin ) only had to get to 320 km/h to start working: https://en.wikipedia.org/wiki/Kronach_Lorin

Ok, but the question still remains, how is it going to get up to the required speed? And in a way that is practical for a passenger plane?

Re: A successful Japanese trial of a ramjet engine designed for Mach‑5 aircraft

#179

Post by trhway »

flohofwoe wrote: post #128
belviewreview wrote: post #86

Interesting, but assuming they can get the engine to work as intended, the question still remains how the passenger jet would get up to Mach 5 so the engine can start working. A solid-fuel rocket booster that would then drop off?

I may be wrong but I think a ramjet doesn't need Mach 5 to ignite, Mach 3 to 6 is just where it is most efficient at high altitudes. E.g. early German experiments during WW2 based on the Lorin tube ( https://en.wikipedia.org/wiki/Ren%C3%A9_Lorin ) only had to get to 320 km/h to start working: https://en.wikipedia.org/wiki/Kronach_Lorin

>https://en.wikipedia.org/wiki/Kronach_Lorin

coal burning ramjet!

"It was initially proposed that a wire-mesh basket holding coal be mounted behind a nose air intake, protruding slightly into the airflow and ignited by a gas burner. [...] The air passing through the ramjet would take the gases from the burning coal ..."

Re: A successful Japanese trial of a ramjet engine designed for Mach‑5 aircraft

#180

Post by throwaway2037 »

laughing_man wrote: post #87
hdndjsbbs wrote: post #21

Earlier quoted context omitted.

I think a lot of the Concorde failure is tied to its status as a British-French project. Trans-Pacific flights are much longer and there's a lot of money in PEK -> LAX than in JFK -> LHR. Qantas wanted to offer London to Sydney, but they couldn't fly supersonic over land. Mainland China or Japan to Australia is a feasible route for high-margin, low-capacity supersonic flights. If you could make the flight from Beijin…

If it stays in the realm of the ultra wealthy I don't see how it will succeed in the end. Commercial aircraft are really expensive to design and qualify, and you need to have a lot of sales to justify a new model. Ultra wealthy people are willing to pay more, but they also demand luxuries that take up a lot of space. The only reason Concorde did as well as it did, economically speaking, is the respective governments…

    > respective governments footed the bill for development
I just looked up development costs on Wiki: "£12–16.7 billion in 2025". Yikes. And "the market forecast was 350 aircraft", but only 20 were built. What a waste.
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