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Boom supersonic jet readies for rollout

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271–280 of 283 posts

Re: Boom supersonic jet readies for rollout

#271
post #101

Earlier quoted context omitted.

Yeah, much more excited if there were talk of high-speed rail criss-crossing the U.S.

High-speed rail isn't high speed enough. Even with way faster than current tech and NO stops you'd still be looking at taking 12+ hours for what a plane can do in 5. That's ignoring the trillions it would cost. The US does not have the population density to make HSR viable.

Would trying to build hsr at scale make the costs come down?

Re: Boom supersonic jet readies for rollout

#272

Earlier quoted context omitted.

Building an entire airline around it is stupid. Building certain premium flights around it, not necessarily; Singapore Airlines operates a 67-seat business class on a plane from Newark to Singapore that only has business and premium economy. BA operates a 32-seat business-only flight from London City to New York via Shannon. And these are just the subsonic flights. JAL is one of the bigger investors in this project,…

They’re almost always money-losing ego flights. BA1 rarely flies full. The ego is right there in the number. It’s a novelty. SQ hasn’t operated business class only since like 2011. It has 67 business seats and 94 premium economy seats. And still probably loses money. The one you didn’t mention was Stavenger to Houston which... only flies when oil is flying high. Because it’s not profitable otherwise.

Even so, the main point of my comment was that the maximum capacity of a Boom supersonic plane is a lot smaller than that of the Concorde (and presumably a more comfortable layout rather than the Concorde's narrow cabin.) So at least the battle it's fighting is a lot less severe.

Theoretically speaking, if the seat cost per mile is as low as advertised some airline might want to take some business class seats out and put some premium economy in. What a plane does with seating layouts is its own concern.

Re: Boom supersonic jet readies for rollout

#273

Earlier quoted context omitted.

It also ran on only two routes for most of that time, with all others shut down because airlines lost money operating Concorde on them even without having to pay off the capital costs.

The Concorde was also blocked from flying a lot of profitable routes because of sonic boom concerns, some justified, others less so. In particular, you can't legally fly over any part of the US at Mach 1 or faster unless you're military.

The problem is that there's no realistic way to fly across the US, supersonically, without massively impacting a substantial fraction of the electorate (who will enthusiastically vote for anyone who will stop the noise).

You can read about the supersonic experiments over Oaklahoma City in the 1960's to learn about the effects of sonic booms, and why people don't like them.

For reference, the Space Shuttle generated annoying sonic booms over west Los Angeles when landing at Edwards Airforce Base. The approach path to Edwards is more than 30 miles from west LA. So, for any supersonic airway, you'd need to set aside a roughly 60-70 mile wide swath of land. That's a lot of people voting to shut down your SST operation (or suing you).

Re: Boom supersonic jet readies for rollout

#274
post #163

Earlier quoted context omitted.

> The reason for that is that the concorde used afterburners (basically, pump fuel into the high speed exhaust for extra thrust) which are incredibly inefficient. To put things in perspective, Concorde was using two Olympus engines designed originally in the 50s. It was already a marvel that they can run for such a range at Mach 2.0 when designed 70 years ago. A lot of things improved since. Most fighter jets can sup…

Concorde used four engines. Two engine ETOPS over water wasn't a thing back then, first real relaxation of that rule was in '76. see: https://en.wikipedia.org/wiki/ETOPS

Of course four. My apologies, too quick to type.

Re: Boom supersonic jet readies for rollout

#275
post #151

From my understanding a big problem with Concorde was the sonic boom which happened near takeoff and bothered urban residents. I've always wondered why they can't fly at normal airline speeds until over a rural area or an ocean before accelerating to sound barrier speeds.

> I've always wondered why they can't fly at normal airline speeds until over a rural area or an ocean before accelerating to sound barrier speeds. Because geometry and engines which are efficient at very high speed are extremely inefficient at low speeds, so you want to avoid subsonic flight as much as possible. Variable geometry (mostly variable-sweep wings) bridge that issue, but they're weak points, and significa…

Thanks, that makes sense.

Re: Boom supersonic jet readies for rollout

#276
post #102

Earlier quoted context omitted.

I think the real problem is that the Concorde wasn't fast enough to justify the cost. Whether you can fly JFK-CDG in 8 hours or 4 hours, when you factor in how irritating airports are, parking, security line ups, waiting for baggage, etc, it still takes all day to make the trip. Might as well save several thousand dollars and take a longer flight. I believe they would have to cut the flight time down to about an hour…

The concorde didn't fail because it was expensive. It ran profitably for 27 years. [0] It failed because it crashed and killed 109 people 3 years before they threw in the towel. [1] [0] https://en.wikipedia.org/wiki/Concorde#Operating_economics [1] https://en.wikipedia.org/wiki/Air_France_Flight_4590

These are true but with Air France what made it profitable were all the special and charter flights...

And realistically it also failed because while flying west makes sense as you could land "before" you took off, going east didn't work like that. Sure you're losing less time either way compared to a regular flight but flying east, you might as well take a slow flight to get some shuteye.

This problem still hasn't been solved.

Re: Boom supersonic jet readies for rollout

#277
post #151

From my understanding a big problem with Concorde was the sonic boom which happened near takeoff and bothered urban residents. I've always wondered why they can't fly at normal airline speeds until over a rural area or an ocean before accelerating to sound barrier speeds.

It never really flew supersonic over land. Sure some people would get to hear the sonic boom based on weather or poor planning but all the routes were designed so she'd go supersonic over water.

There were few countries were you could go supersonic over land: Russia and Saudi Arabia comes to mind.

And when BA last flew one of its Concorde from NYC to Seattle, it flew supersonic over Canada.

https://en.wikipedia.org/wiki/Concorde#British_Airways

The final flight of a Concorde in the US occurred on 5 November 2003 when G-BOAG flew from New York's JFK Airport to Seattle's Boeing Field to join the Museum of Flight's permanent collection. The plane was piloted by Mike Bannister and Les Broadie, who claimed a flight time of three hours, 55 minutes and 12 seconds, a record between the two cities.

Re: Boom supersonic jet readies for rollout

#278
post #275

Earlier quoted context omitted.

> I've always wondered why they can't fly at normal airline speeds until over a rural area or an ocean before accelerating to sound barrier speeds. Because geometry and engines which are efficient at very high speed are extremely inefficient at low speeds, so you want to avoid subsonic flight as much as possible. Variable geometry (mostly variable-sweep wings) bridge that issue, but they're weak points, and significa…

Thanks, that makes sense.

To put that in perspective: the hourly fuel consumption of Concorde at Mach 2 or at Mach 0.9 are pretty similar... So you want to fly supersonic if you want to go far...

Re: Boom supersonic jet readies for rollout

#279
post #81

Earlier quoted context omitted.

The new 787 has made her lag a lot better with better air quality, timed, dimming cabin lights and a few other comfort trucks, it definitely takes the edge off.

One of the biggest factors is cabin altitude. Both the Boeing 787 and the Airbus A350 XWB have a lower (than previous airliners) cabin altitude of 1,800 m. Note that some private jets do quite a bit better again: the Gulfstream G650 has ~1480 meters.

Concorde cabine altitude was set to 1,700 metres or 5,500ft...

Re: Boom supersonic jet readies for rollout

#280

Earlier quoted context omitted.

Fast electric trains are also, well, electric already. Powering planes in a sustainable marrer is not a solved problem.

So I think that’s not really true. Even existing battery chemistry could do 1000km per stop (although it still needs certification for aircraft) and at comparable speed as HSR. That’s much longer than the California HSR project that was canceled, plus you just need a recharge (or swap) to continue on your way. With further efficiency improvements and battery chemistries in development right now like Li-S, we could po…

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