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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

#31
post #2

People say this like it's a simple engineering problem. No. By itself, a new hypersonic engine can't make 2-hour flights between Japan and the US a reality. We are not even close to being able to build an aircraft that can do that - we don't even have the materials for that. What seems "easier" (as in "less impossible") is a hypersonic glider design that enters a suborbital trajectory and does shuttle-like aerobrakin…

How long of a weightlessness period does this entail?

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

#32
post #20
post #18

Earlier quoted context omitted.

From my experience with working for defense/aerospace companies as well as civilian b2b ones in the US, the general situation is that defense/aero companies pay less but demands less of a grind. People usually take the lower pay (usually 70% of equivalent role in commercial sector) for the better culture

For pure generic full-stack-whatever devs yes. For EEs, embedded, FPGA, RF, etc you can pull waaaaay more in the defense world, especially if you're willing to do cleared work.

But if you need clearance to do your work, how can it be bait-and-switch? You need to hire people who are able and willing to obtain a clearance.

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

#33

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…

There is a lot of money in NYC-LHR, that's why Concorde continued to fly that route and profitably too, once they realized how high they could yank the prices and still fill the plane. Also, Concorde's maximum range was 4,488 mi, which was calibrated to allow trans-Atlantic but not much more. Trans-Pac was not an option and even Australia to North Asia would be a stretch.

I think they are agreeing with you re: the range.

There is money in NYC-LHR (it brings BA alone $1B in revenue annually) but the market for supersonic basically vanished. In the 70s when Concorde started flying, it was certainly a step up. However, the market niche basically disappeared when the lie flat seat was developed; for a lot cheaper, you could have a sleep for six hours in a really cushy lie flat, or you could spend a crapton more to be in a much louder, more cramped cabin for only about three hours less. If you were halving a 12-16 hour journey instead, there would still be a market left, but Concorde just didn't have the ability to do so.

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

#34
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?

Google tried to become a national security contractor, and the backlash among the engineers was very intense.

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

#35
post #22

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?

The Middle East (was) a pretty common stopover for India flights, since India's not that well connected to the US due to a lack of capacity.

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

#36

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…

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 market for California to China in five hours. But is it enough to support a whole new type of aircraft? Fuel burn is going to be enormous. Maintenance on something so cutting edge will be extremely expensive. Tickets would probably cost more than a private room on a widebody.

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

#37
post #28

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.

Vastly more favorable today than it was when Concorde flew. 1) Rich people are WAY richer, and time is even more valuable 2) Businesses have some very important employees and "2 day trip" vs "3-4 day trip" is worth $50-100k 3) Larger population of people able to pay $20-30k for a flight than ever before. The biggest practical impact is there's probably going to be a private jet version instead of just a commercial on…

What are some examples of employees so important you would pay $100k to get them somewhere immediately?

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

#38
post #4

The actual time to skim off IMO is all the airport procedures.

Not necessarily for extremely long haul flights. The airport side of things takes about the same amount of time regardless. For a transpacific flight, you’re looking at maybe 3-4 hours at the airport and 10+ hours in the air. Shaving down the airport side would be nice but a faster plane could save a lot more time.

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

#39
post #32
post #20

Earlier quoted context omitted.

For pure generic full-stack-whatever devs yes. For EEs, embedded, FPGA, RF, etc you can pull waaaaay more in the defense world, especially if you're willing to do cleared work.

But if you need clearance to do your work, how can it be bait-and-switch? You need to hire people who are able and willing to obtain a clearance.

Two different discussions, but I've had an earthy crunchy employer ask me to put in for one once.

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

#40
post #30

I imagine passengers will be exposed to very high noise levels during flight.

I don't have a good intuitive feel for that.

At 25km altitude, with 1% of normal atmosphere, maybe you're close enough to vacuum that it can get really quiet?

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