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Boom supersonic jet readies for rollout

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Re: Boom supersonic jet readies for rollout

#231

Post by imtringued »

philjohn wrote: post #184
masklinn wrote: post #165

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. Concorde didn't use afterburners "at speed". The afterburners were used for takeoff, and to go through the mach wall. Concorde burned insane amounts of fuel on the ground because turbojets are very inefficient at low-speed. Not unlike the SR-71's really (th…

Didn't SR-71's also leak fuel when on the ground?

That's only because they decided to not use tanks inside the wings. The wings themselves contained the fuel. You can certainly build a non leaking SR-71 if a higher weight is acceptable.

Re: Boom supersonic jet readies for rollout

#232

Post by dzhiurgis »

robin_reala wrote: post #155
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…

Expected fuel burn per passenger is minimum 3x a ‘normal’ business class seat on a modern plane: https://theicct.org/news/reviving-supersonic-flight-signific... Either way, it’s fairly obscene.

While fuel cost is minor part of total flight cost (most is staff + depreciation), I wonder how much will be saved by a good satellite network. Being able to work on a plane at some point starts to pay itself off.

Re: Boom supersonic jet readies for rollout

#233

Post by imtringued »

TylerE wrote: post #106
axaxs wrote: post #105

Earlier quoted context omitted.

I'm still hoping for rail. It's much more carbon friendly, and has the opportunity to be way less stressful. I'd do 18 hours on a NY to LA if I could walk around, eat, talk, sleep, etc over a 5 hour misery ride in an airplane any day.

A single NY-LA route alone would cost over $500 billion. High speed rail is well $100m/mile, just for the track.

At those prices you can build the railway with maglev technology. I don't think these costs are realistic.

Re: Boom supersonic jet readies for rollout

#234

Post by Already__Taken »

notahacker wrote: post #194
9nGQluzmnq3M wrote: post #192

Earlier quoted context omitted.

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.

if they revive the noise implications they might well manage to change it. IMO those restrictions are also because it wasn't an American jet so it kept the competition out.

Re: Boom supersonic jet readies for rollout

#235

Post by objektif »

nickik wrote: post #224
JKCalhoun wrote: post #68

Earlier quoted context omitted.

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

Electric Planes would make that obsolete long before its finished.

Would it make the comfort of a train absolute as well?

Re: Boom supersonic jet readies for rollout

#236

Post by masklinn »

imtringued wrote: post #231
philjohn wrote: post #184

Earlier quoted context omitted.

Didn't SR-71's also leak fuel when on the ground?

That's only because they decided to not use tanks inside the wings. The wings themselves contained the fuel. You can certainly build a non leaking SR-71 if a higher weight is acceptable.

> That's only because they decided to not use tanks inside the wings.

It's not only that. It's because they didn't have alloys which would handle the thermal constraints without significant expansion, so they had to design for that expansion. And in the same way rail tracks handle expansion by leaving gaps, that's what they did.

Furthermore, due to limited room and systems able to handle the temperature gradients, the fuel acted not just as fuel but also coolant, heat sink and even hydraulic fluid for some propulsion components (e.g. the afterburner nozzles and inlet guide vanes used JP7 as hydraulic fluid).

Re: Boom supersonic jet readies for rollout

#237

Post by nopzor »

rvense wrote: post #142
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.

Propeller planes used about half as much fuel per mile as early jets. Jets have caught up, but it took half a century to get back to earlier levels of fuel efficiency. Slowing down in general is an easy way to bring down energy usage, but it's often a hard sell.

basically true, but speed isn't the only reason why jets have dominated; being able to fly above the weather, noise, and (perceived) safety are factors too.

Re: Boom supersonic jet readies for rollout

#238

Post by nopzor »

phire wrote: post #139
flyGuyOnTheSly wrote: post #115

Earlier quoted context omitted.

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

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/

if it weren't for the concorde, airbus wouldn't really exist and be able to compete with boeing. so while your point isn't untrue, it's also fair to say that it ended up paying huge dividends and was worth it.

Re: Boom supersonic jet readies for rollout

#239

Post by tim333 »

C1sc0cat wrote: post #222
kolinko wrote: post #183

Earlier quoted context omitted.

12 hours is a lot, but for shorter distances most people would prefer a good train to a plane. Living in Europe, I will take 4-5 hour train ride compared to a 1h flight, most of my friends as well. Many people will also prefer 5-8 hour 100mph train ride to 1h plane ride due to comfort, price and carbon footprint.

Not if your doing it more than once a year and certainly business travellers wont want to. I recall one of the senior marketing guys where I worked did London to Edinburgh on the overnight sleeper didn't get much sleep and was uncomfortable.

The day train is better for that one (4hrs20). Though I've flown the last few times. It's often cheaper.
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