Boom supersonic jet readies for rollout • Hacker News Board

Re: Boom supersonic jet readies for rollout

#191

Post by notahacker » Fri, Jul 10, 2020, 9:18 AM UTC

pedalpete wrote: post #51

galacticaactual wrote: post #23

As a (pre-Covid) extreme frequent flyer, supersonic and other rapid point to point initiatives are thoroughly unenticing. Part of the reason I loved long flights was the ability to put away the laptop and zone out to a book or movie with some wine before landing, dealing with immigration, hotels, Ubers, and days of frenetic, high stress meetings afterward. The prospect of trying to optimize how fast we can jump from…

You're not doing Sydney->Los Angeles, Santiago->Tokyo type long-haul, are you. When you're continent jumping (excluding Eastern US to Europe) 7hrs at supersonic is long enough to get a movie and relax a bit. When you're getting 16 hour flights on a regular basis, you get used to it, but when you've seen all the movies, you realize how much time you've wasted on a plane.

The trouble is, supersonic flight is optimised for flights which take 7hrs in regular aircraft, not longer flights Boom isn't claiming it might have the range for in one hop.

Even where fuel stops somewhere like Hawaii are practical, the disadvantage of the supersonic flight is that its still long enough for you to notice they're a lot less comfortable than the first class seat you could have slept and got a morning's worth of work done in...

Re: Boom supersonic jet readies for rollout

#192

Post by 9nGQluzmnq3M » Fri, Jul 10, 2020, 9:23 AM UTC

notahacker wrote: post #185

phire wrote: post #139

Earlier quoted context omitted.

The main reason the airlines managed to run Concorde at a profit is because they bought the planes for quite cheap. At one point the British government even sold two planes to British airways for £1 each. [0] The airlines might have profited, but the R&D and manufacturing programs were a more or less write offs. [1] https://simpleflying.com/british-airways-1-pound-concorde/

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.

Re: Boom supersonic jet readies for rollout

#193

Post by notahacker » Fri, Jul 10, 2020, 9:30 AM UTC

bobthepanda wrote: post #93

smachiz wrote: post #78

Earlier quoted context omitted.

Umm... ask every 'business class only' airline that has come (and gone...) about that.

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,…

You don't need 'certain' premium flights to make an airframe programme commercially viable though, you need 100+ which airlines are sufficiently confident of to make downpayments on aircraft, and it's not like such routes haven't been unsuccessfully experimented with before.

Re: Boom supersonic jet readies for rollout

#194

Post by notahacker » Fri, Jul 10, 2020, 9:41 AM UTC

9nGQluzmnq3M wrote: post #192

notahacker wrote: post #185

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.

Sure, but I don't see a startup called Boom changing the political landscape around sonic boom concerns, particularly not in an era where there's also a lot of environmental lobbying.

Re: Boom supersonic jet readies for rollout

#195

Post by grkvlt » Fri, Jul 10, 2020, 9:47 AM UTC

bogomipz wrote: post #124

na85 wrote: 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…

Well for all but the last two years of the Corcorde's existence there was no TSA or security lines. Also I know at JFK at least the Concorde had it's own private departure lounge called the The Concorde Room(it's actually still there) and it also had its' own private jetway as well. So it was definitely a premium experience all the way around.

that's true of LHR as well, there is a Concorde Room just after the priority security scan lane, and first class or top tier BA pax get invited. the place is insane in terms of 'premium-ness' with the experience being s whole level above the usual BA first class lounges - you'll find the full details on the ba.com site. sadly i only managed to use it once or twice, when my boss guested me in ;(

Re: Boom supersonic jet readies for rollout

#196

Post by gsnedders » Fri, Jul 10, 2020, 9:53 AM UTC

paulmd wrote: post #154

alfalfasprout wrote: post #118

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. Great for a fighter jet where you need a sudden burst of extreme thrust, but not something you want a long-haul airliner to use. Boom uses turbofan engines to reach supersonic speeds which are much, much more efficient. In fact, many airliners could theoretic…

Concorde itself could have been much more efficient, there were plans for a "Concorde B" with high-bypass engines that would have carried a larger payload with additional range at higher efficiency. https://www.heritageconcorde.com/concorde-b

The Mk622 engine was still a turbojet, albeit improved. Primarily its gains came from a more efficient compressor, providing more oxygen to the combustion chamber.

Re: Boom supersonic jet readies for rollout

#197

Post by grkvlt » Fri, Jul 10, 2020, 9:55 AM UTC

dmix wrote: 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.

a sonic boom is a phenomenon that occurs continuously when traveling over mach 1.0 so supersonic flight is usually limited to over water routes and forbidden over or near urban areas.

Re: Boom supersonic jet readies for rollout

#198

Post by throwaway_pdp09 » Fri, Jul 10, 2020, 9:56 AM UTC

agurk wrote: post #171

DomenicoMazza wrote: post #18

If I recall correctly the Concorde used about 2 tonnes of fuel rolling on the ground alone.. I wonder how this new aircraft fares for fuel consumption? I believe the Concorde is a marvel. You could travel faster than the rotation of the earth in it! However I don’t think we need more environmentally unsustainable travel.

Looking at the Concorde's fuel usage taxing is only part of the picture. All turbine engines are very inefficient at low power outputs due to the need to use energy to create sufficient compression for them to function. On top of this the Olympus engines generated a lot of thrust at idle, so much so that only two were used for taxing and it was still apparently tricky to control. While cruising at supersonic speeds t…

I'm a bit suspicious of the qualification 'thermal' in 'thermal efficiency' which sounds like it's hiding something. From the wiki article on thermal efficiency https://en.wikipedia.org/wiki/Thermal_efficiency, and I'm no wiser for reading it:

"For a heat engine, thermal efficiency is the fraction of the energy added by heat (primary energy) that is converted to net work output (secondary energy)."

Does thermal efficiency = actual efficiency in the case of jet engines? I find that difficult to believe.

Re: Boom supersonic jet readies for rollout

#199

Post by grkvlt » Fri, Jul 10, 2020, 10:04 AM UTC

starpilot wrote: post #48

Alupis wrote: post #35

Earlier quoted context omitted.

I trust Boom has smart people working on these things, but... model aviation doesn't scale up[1]. It's interesting they're going with a scaled-down model instead of a full-scale testbed. The article seems to incidate they're wanting to go from the scaled-down model as a PoC, then onto an actual airline that JAL want's to fly. I'd think they'd need a full-sized PoC first... > “They want to enjoy a first-mover advantag…

Quadcopters don't scale up. Flyable scale models have used extensively in other aviation research: https://www.youtube.com/watch?v=pgDRkNseNxU

quadcopter aircraft scale up fine, for example the bell x-22 [0] research vehicle.

0. https://en.wikipedia.org/wiki/Bell_X-22

Re: Boom supersonic jet readies for rollout

#200

Post by ghaff » Fri, Jul 10, 2020, 10:05 AM UTC

meddlepal wrote: post #127

na85 wrote: 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…

It made way more sense as an aircraft when: 1. Communication was not as instantaneous as today and more things required face to face meetings. 2. You could basically walk onto an air plane with minimal security interference. My dad said he flew the Concorde several times from Europe to NYC for business in the late 70s and early 80's and he said it was worth it in that context. I should ask him how comfortable it was…

The Concorde interior was pretty similar to the first class seating of the era (maybe a bit tighter), i.e. more like today's conventional domestic business/first than Polaris lie-flat seats (much less the mini-cabins airlines like Emirates have available).