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The Race to Build the First Sustainable Supersonic Jet

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Re: The Race to Build the First Sustainable Supersonic Jet

#61

Post by jpeanuts »

revax wrote: post #55
melling wrote: post #26

Earlier quoted context omitted.

Nope, air transportation is not a major contributor to CO2. There are over 100,000 flights daily. They account for about 2.5% of CO2 emissions yearly. You know what is? Coal power plants that generate electricity. Maybe we should focus on electricity generation from coal. I’m a little surprised that more hasn’t been done. https://www.carbonbrief.org/mapped-worlds-coal-power-plants 13 years ago Google attempted their…

Almost the entirety of emissions are made up of 5% when you decompose by sector. There is no silver bullet for reducing your carbon footprint. You should lower emissions for all industries at the same time.

This is a very important idea. On a global scale this idea has been codified as "climate stabilzation wedges": https://johncarlosbaez.wordpress.com/2010/11/16/stabilizatio...

Each "wedge" is one method of reducing net CO2 output by 1 gigaton/year by 2054. Each wedge is a major economic and technological undertaking. Current estimates are that 13 wedges would be needed to limit CO2 to below 500 ppm. We have currently implemented 0 wedges.

Re: The Race to Build the First Sustainable Supersonic Jet

#62

Post by jabl »

grizzles wrote: post #32

I flown many long haul flights. The first time I heard Musk propose using rockets for international travel I thought it was insane. I still do. But if they are accident free for the next 10 years; would I then? Probably - if they could manage to keep my trip under ~3Gs.

Yeah, I wonder, would a suborbital ballistic trajectory save fuel compared to chugging along in the atmosphere?

If this were to become common, would need some thinking how to distinguish this from a ballistic missile attack, though.

Re: The Race to Build the First Sustainable Supersonic Jet

#63

Post by usrusr »

choeger wrote: post #56
mrpopo wrote: post #51

Earlier quoted context omitted.

This comment makes no sense because it doesn't state how many people get electricity and how many people fly. The carbon footprint of one transatlantic flight is on the same order of magnitude as one person's yearly electricity consumption. People who fly every year can substantially reduce their carbon footprint by not flying, people who already don't fly every year (the majority of the population) can't.

The climate does not care how many people caused the co2 emissions.

People care. And even if you somehow think they should not you are in no position to decide what they care about.

Re: The Race to Build the First Sustainable Supersonic Jet

#64

Post by tda »

pengaru wrote: post #54
melling wrote: post #26

Earlier quoted context omitted.

Nope, air transportation is not a major contributor to CO2. There are over 100,000 flights daily. They account for about 2.5% of CO2 emissions yearly. You know what is? Coal power plants that generate electricity. Maybe we should focus on electricity generation from coal. I’m a little surprised that more hasn’t been done. https://www.carbonbrief.org/mapped-worlds-coal-power-plants 13 years ago Google attempted their…

> There are over 100,000 flights daily. They account for about 2.5% of CO2 emissions yearly. The generally accepted emissions weighting factor for aviation co2 emissions is ~2.6. So it's more like 6.5%, and growing fast.

Just to clarify: in the cases of high-altitude airliners which frequently fly near or in the stratosphere, non-CO2 altitude-sensitive effects may increase the total impact on anthropogenic (human-made) climate change significantly

https://en.wikipedia.org/wiki/Environmental_impact_of_aviati...

Re: The Race to Build the First Sustainable Supersonic Jet

#65

Post by jabl »

KoftaBob wrote: post #33
jpeanuts wrote: post #24

In my opinion it is disingenuous to call any supersonic aircraft sustainable. Independently of any clever aerodynamic design to moderate the drag coefficient, aerodynamic drag always increases like the velocity squared. Doubling the speed will mean applying 4x the force for 1/2 the time, so all propulsive efficiencies being equal, you will expend twice the fuel to go the same distance - at an absolute minimum. In rea…

Air transportation only makes up 10% of emissions caused by the transportation industry, and that industry as a whole makes up 26% of total global emissions. In other words, air transportation makes up 2.6% of global emissions, which is not even remotely close to being a "major contributor to CO2 emissions". As for your last sentence, if we can find ways to travel the world faster, why the hell not? Once we start hav…

As another poster pointed out, the climate forcing due to high altitude emissions is about a factor of 2.6 worse than the CO2 alone. So 2.6 becomes about 6.8%, and rising fast. And to make it even worse, we basically know how to decarbonize other forms of transportation and electricity production, heating, some major industrial processes etc., meaning that when those solutions start rolling out at scale, air travel will rise even faster as the proportion of the total.

By all means, let's continue developing aerospace technology, but I think it's a fantasy that we'd be able to have anywhere close to the same volume of flights as today in a decarbonized world.

Re: The Race to Build the First Sustainable Supersonic Jet

#66

Post by ryanlol »

smachiz wrote: post #44
FDSGSG wrote: post #36

Earlier quoted context omitted.

Most Emirates long haul flights departing from AMS,BCN or MXP seem to be that cheap, I'm sure there are other cheap airports but I'm too lazy to look. This is probably the case with all the euro airports that don't charge super high fees and lack large quantities of F pax. I'm seeing MXP-HKG at 4000eur for a round trip, MXP-BKK for 3800eur. There are probably even better deals available if departing from some third w…

I think you’re seeing corona virus at work. Those F tix are usually more from what I’ve seen.

I was paying those prices last year. Only the LHR rates there seem highly unusual.

Re: The Race to Build the First Sustainable Supersonic Jet

#67

Post by usrusr »

taneq wrote: post #39
jpeanuts wrote: post #24

In my opinion it is disingenuous to call any supersonic aircraft sustainable. Independently of any clever aerodynamic design to moderate the drag coefficient, aerodynamic drag always increases like the velocity squared. Doubling the speed will mean applying 4x the force for 1/2 the time, so all propulsive efficiencies being equal, you will expend twice the fuel to go the same distance - at an absolute minimum. In rea…

"Sustainable" doesn't mean "optimized for minimal energy usage", it means "we can keep doing it without running out of anything." If we can make jet fuel out of atmospheric CO2 using solar power without crippling the rest of our industry, it's 'sustainable' even if we just use that jet fuel for Nitro Circus antics. Also, 'efficient' doesn't mean anything without saying what you're optimizing for. Slow, lightly loaded…

We didn't stop because we ran out of Concordes either and nobody would call them sustainable.

The article is truly disingenuous in this part because it starts with the sustainable claim, then goes on listing pollution as the biggest problem of the Concorde alongside two noise issues, as if building up to take them down one by one. Then it's taking down only the noise issues and calls it a day. In fact it even has to admit that the new plane will be just as range-limited as the Concorde was. This hints at the fuel issue definitely not being solved, given the 60 years (!) of engine advancements between them. (it isn't a sized issue, even business jets can reach quite impressive ranges)

Re: The Race to Build the First Sustainable Supersonic Jet

#68

Post by usrusr »

mshook wrote: post #7
chrisseaton wrote: post #3

Earlier quoted context omitted.

> they don't impact productive time Even flying in first class I’m sure I’d get there much more refreshed for a short four hour flight than an eight hour one, improving my productivity when I get there. And why are you only considering overnight flights?

Regarding Concorde and from a customer's business perspective, going west (from Paris or London to NYC) made sense as you'd pretty much land before you took off (in local time). So you'd gain time. For instance you'd leave Paris at 10:30am and you'd land at JFK at 8:25am or so. But on the way back, you'd take-off from JFK at 8am to land at 5:45pm... To/From London would be 10:30am/09:25am and 8:30am/17:25pm. Bottom l…

> That's why Concorde was often carrying more passengers on the way west than on the way back: people would choose to get a first class overnight flight...

So in a fully realized 1960ies space age utopia you'd have a fleet of supersonics circling the planet hub to hub slightly ahead of the dawn line and a fleet of saloon cruisers going the opposite direction. Instead we got mobile internet.

Re: The Race to Build the First Sustainable Supersonic Jet

#69

Post by mrpopo »

choeger wrote: post #56
mrpopo wrote: post #51

Earlier quoted context omitted.

This comment makes no sense because it doesn't state how many people get electricity and how many people fly. The carbon footprint of one transatlantic flight is on the same order of magnitude as one person's yearly electricity consumption. People who fly every year can substantially reduce their carbon footprint by not flying, people who already don't fly every year (the majority of the population) can't.

The climate does not care how many people caused the co2 emissions.

The climate system itself doesn't, but the total carbon budget has to be allocated to and split between 7 billion people one way or another.

What is a fair split?

Of course, if you want to keep flying at 800 km/h around the globe AND get power for your home's computers and 4k TV, you will have to advocate for cutting electricity AND blocking air transport of some other people until their coal plants are powered with solar panels. It's your right to decide so, but you have to admit it that it's unethical.

Re: The Race to Build the First Sustainable Supersonic Jet

#70

Post by jillesvangurp »

ncmncm wrote: post #42

The only way this thing could be honestly sustainable would be if it were hydrogen-powered. That might also be a prerequisite for profitability. But the airframe would need to be quite different from current designs because hydrogen tankage needs a lot more room than kerosene fuel would. Extra space on an aircraft is fairly cheap to provide. What is difficult is more weight, including extra fuel needed to get enough…

Methane is a more than viable alternative and there are a few others. Of course for both we'd need infrastructure to generate it from renewable energy (as opposed to extracting using or extracting hydrogen from natural gas). In terms of energy density, methane is good enough for space flight. E.g. the spaceX raptor engines burn methane. The long term plan for SpaceX is to use renewable energy to generate methane; which as solar & wind cost drops, might actually become cheaper than using natural gas. On Mars this will actually be the only way to generate methane as there is no natural gas there.

Even just switching to natural gas would already be more sustainable as it burns a lot cleaner and there's less need for energy intensive processing of crude oil to produce kerosine (not to mention shipping oil around the globe using oil tankers & trucks powered by bunker & diesel fuel). Kerosine is nasty stuff in terms of sustainability.

So, there's a path to 0 carbon for jets (supersonic and otherwise). Even compressed natural/synthesized methane gas is viable for GA and there have been some prototype planes for that. For jets, you'd want the cryogenically cooled liquid variety because it's easier to store (lighter tanks).

Of course this would require the usual suspects to get off their ass and start innovating. E.g. Boeing had some plans for this https://www.wired.com/2012/03/boeing-freezes-design-with-liq... but not much seems to be happening. In light of Boeing's recent trouble with the 737 Max, this might be worth revisiting for them. Also the blended wing concept that Airbus demoed recently would apparently be quite good for holding liquid methane tanks. Also a 60% reduction in fuel cost sounds like it should be a nice incentive.

I wouldn't be surprised to see SpaceX pivot to producing jet engines at some point as it's an obvious thing to do and they seem to have a lot of competence around the logistics and technology involved with generating, handling, storing, and burning methane.

In any case, SpaceX is already doing supersonic flights powered by methane every time they launch a Falcon 9 and they have some wacky notion of actually using their spaceship to enable 90 minute hops to the other side of the planet.

Guilt free sustainable supersonic travel is possible but it requires people to start thinking out of the box. IMHO the first aviation company that nails this is going to do extremely well.

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