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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

#71

Post by kevin_thibedeau »

stouset wrote: post #48
wat10000 wrote: post #36

Earlier quoted context omitted.

Everyone thought SSTs were going to be the next big thing. Both the US and USSR had projects. The 747 got a hump so it could easily be converted to a freighter once it was made obsolete by supersonic passenger planes. Despite two superpowers making the attempt, and plenty of time for more tries since then, Concorde is the only one that came even remotely close to something commercially viable. I’m sure there’s a mark…

You’re hinting at another huge part of the issue. There are no economies of scale to be had here. If there are only a handful of plausible economically-profitable routes, all of the expenditures on R&D, testing, certification, and production facilities can only be amortized across a handful of aircraft. Once you’ve built a dozen or two of them and a handful of extra engines and spare parts… what then? There’s no poin…

Scheduled service is not viable but there is a bountiful supply of billionaires willing to one up each other with lavish expenditures. Having the fastest class of private jet is worth something to them. This is what's going to be the market for Boom if they don't fold.

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

#72

Post by godelski »

vitally3643 wrote: post #57
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…

I was pretty sure the whole Concorde thing failed because people don't like it when you sonic boom an entire city dozens of times a day. And that all attempts to reduce the sonic booms necessarily resulted in flight times that aren't significantly faster than traditional subsonic flights, rendering the entire thing moot. It was impractical due to physics, not some weird racism. You simply can't push a supersonic shoc…

1) The flight markets are different now. There's been a large increase in both transatlantic and transpacific flights, especially the latter. These change the economics of considering only these types of flights, flying only over uninhabited regions.

2) The technology has changed. We're much better at dealing with sonic booms now. You can't get rid of them entirely, but you can reshape them. You can't send everything "up" but the longer of a tail you can make the more the sound dissipates by the time it hits the ground. There's lots of research around this and as you can imagine, incredibly important for the military. You can't fly fast spy aircraft if they are just announcing their position while flying around. Sure, there are satellites, but those are predictable by the enemy, you'll always need aircraft to do this.

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

#73

Post by Snafuh »

bob1029 wrote: post #53
amanaplanacanal wrote: post #49

Earlier quoted context omitted.

I think the SpaceX plan for point to point travel might be even more pie in the sky. Or maybe a tie.

I think it's more practical. They've already got humans flying.

Good luck getting a launch and landing pad anywhere close to a population centre.

Logistics around the flight would be a big asterisk behind the flight time.

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

#74

Post by switchbak »

Seattle3503 wrote: post #13
HNisCIS wrote: post #9

Earlier quoted context omitted.

Whenever you look at supersonic or hypersonic commercial aircraft plans you should assume one of two things. A. It's a bait and switch by a founder who wants to pivot to weapons/military aircraft but wants to be able to hire high grade talent without paying the "we're gonna kill people" premium, can pivot once a good chunk of the workforce is complacent with a paycheck. You laugh but this happens SO FUCKING MUCH. B.…

What companies are examples of that bait and switch strategy?

I’m not in the industry, but I would say Hermeus would be a perfect example. Ostensibly building a commercial airliner, but if you look closely it feels like a military oriented startup from the inside out.

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

#75

Post by argimenes »

brandelune wrote: post #70

Two news items in one : Japan is getting ready for hypersonic missiles, and Japan’s elite does not give a damn about global warming.

The world's elites have factored in global warming already. It's a cost they are happy to shift onto their descendants.

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

#76

Post by steveBK123 »

hdndjsbbs wrote: post #21
darkteflon wrote: post #6

Cool science. But the article fails to take even a cursory stab at contextualising the plan against the economic, environmental and political backdrop - doesn’t even mention that there’s already been one failed supersonic commercial flight programme. This is as pie-in-the-sky as it gets.

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…

One analysis I read by a marketer that makes good sense is that the speed was worth paying for LHR to JFK but not really on the return given the clock changes and speed.

Getting to NYC before the clock time you left London was a cool trick. It allows you to make a morning meeting in NYC without coming in the night before.

But flying subsonic leaving NYC after dinner and arriving in London for breakfast works fine. Getting to London faster in 3.5 hours travel time but 8.5 hours later clock time means losing a day in the air effectively.

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

#77

Post by switchbak »

nubinetwork wrote: post #51

I've always wanted someone to bring back the Avro Arrow to use the Iroquois engine for freight, but I don't think anyone has the knowledge to even pull it off anymore.

I’d love to have a big die cast model of one, but that’s about as close as we’ll ever get to the Avro flying again.

I don’t think you’d be pushing much freight on an Arrow (though I’d love to fly one!).

An XB-70 with modern engines? Now that would be interesting.

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

#78

Post by darkteflon »

godelski wrote: post #64
darkteflon wrote: post #6

Cool science. But the article fails to take even a cursory stab at contextualising the plan against the economic, environmental and political backdrop - doesn’t even mention that there’s already been one failed supersonic commercial flight programme. This is as pie-in-the-sky as it gets.

> This is as pie-in-the-sky as it gets. All your critiques are things we heard about Starlink too. "Oh, you're just reinventing Globalstar[0], which already failed. What makes you think this time will be different?" The question isn't wrong, per say, but most of the time it is used dismissively rather than in earnest. There's thousands of products you use today that were invented and ahead of their time. Hell, Google…

I’m in favour of projects like these - even on spending taxpayer money on them. I think it’s super cool and I would love to see it. Yeah, I also think it’s extremely unlikely.

However, when you’re doing journalism, you should contextualise for your readers. TFA doesn’t even try to do the bare minimum.

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

#79

Post by ranyume »

argimenes wrote: post #75
brandelune wrote: post #70

Two news items in one : Japan is getting ready for hypersonic missiles, and Japan’s elite does not give a damn about global warming.

The world's elites have factored in global warming already. It's a cost they are happy to shift onto their descendants.

>Their descendants

I'm sad to tell you, they're already looking for places on earth to buy land to build their nest after they decimate or help decimate humanity.

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

#80

Post by switchbak »

superkuh wrote: post #5

>At that elevation at Mach‑5, air around the nose and leading edges can reach temperatures exceeding 1,000 degrees Celsius (1,832°F), a challenge... It is not the conical nose or leading edges that are the show stopper problem(s). There the shockwave generally does not touch the craft. The internal shockwaves that touch the walls of the engine ducting are. The heat loading and heat soak ability on those shockwave imp…

Supposedly the SR-72 has figured this out. Just rumours at this point, but apparently they’ve cracked the hypersonic air breathing puzzle on a usefully sized aircraft.
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