Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Will we ever fly supersonically over land?

newyorker.com

Post reply on HN
Print view View original

141–150 of 220 posts

Re: Will we ever fly supersonically over land?

#141

Post by FridayoLeary »

wpearse wrote: post #91
the__alchemist wrote: post #82

Earlier quoted context omitted.

It happens in the Lake District and Wales reasonably often. Often the pilot/crew will go out and apologize to a farmer. Sometimes livestock allegedly die, although I'm not sure what the mechanism is.

Best childhood memories are from doing walks in the Lakes and having jets zip past in the valleys below. Insanely close, too — I distinctly remember seeing the pilot’s visor and making out white text on the side of the aircraft.

I've had similar in Wales. I once got the shock of my life when a jet roared probably not more then 100 foot over my head.

Re: Will we ever fly supersonically over land?

#142

Post by beerandt »

ClumsyPilot wrote: post #119
beerandt wrote: post #102

Earlier quoted context omitted.

It was covered in a sustainable engineering class I took. There's not much generic into about it because every rail route proposal is different, even between the same destinations. Depends a lot on geography and what's already there. You basically need to do a full Life Cycle Analysis (LCA) for each route. Sometimes they're included in the EIS for a proposed project. That's prob the best place to start. But there's a…

China has more high-speed than the rest of the world combined, with even remote parts of China hooked up to the rail network. And when you compare energy, you have to take into account that Rail is already electric, powered directly by grid without batteries or any other efficiency loss in between. Airplanes use fuel that takes a lot of energy to refine and deliver, and will at best use hydrogen in 15 years which is…

I'm not against it. But it's usually not more energy efficient. Life Cycle Analysis takes all the inefficiencies you mention into account, down to the zip code, and includes thing like present and future mix of electrical generation.

Doing it because China is, isn't really a reason.

You can take into account electrifying rail, but it doesn't really change much. This all gets taken into account.

>other efficiency loss in between.

The grid has plenty of inefficiencies, especially if we have to start designing beyond capacity to account for intermittent sources. But electricity's main inefficiency is in its creation.

LCAs take all of this into account. It's the whole purpose of doing one. Embedded energy involved in manufacture, refining, transport, everything, is all added up based on things like location and present and/or future inputs.

Re: Will we ever fly supersonically over land?

#143

Post by nradov »

katbyte wrote: post #110
flatiron wrote: post #103

Earlier quoted context omitted.

That mechanism is trying to get compensated for dead live stock and pulling straws. Thunder is a sonic boom. It’s like saying thunder killed a cow.

very loud sounds can panic/shock animals and if it's too much for them, they die.

Is there documented proof of this actually happening?

Re: Will we ever fly supersonically over land?

#144

Post by tshaddox »

bluGill wrote: post #94
perl4ever wrote: post #80

Earlier quoted context omitted.

>that's not taking into account the cost of the road networks we build and maintain Well, why would you? Then you'd have to take into account the airports and the transportation networks to get to them...

Please do so. Airports are nothing compares to just I80 across the US. There are a lot of other roads as well that we could downgrade if more people flew.

The interstates tend to go to the airports though.

Re: Will we ever fly supersonically over land?

#145

Post by nradov »

yurishimo wrote: post #111
bluGill wrote: post #94

Earlier quoted context omitted.

Please do so. Airports are nothing compares to just I80 across the US. There are a lot of other roads as well that we could downgrade if more people flew.

I think autonomous vehicles will help here eventually too. A lot of road maintenance is due to large semi-trucks. If those vehicles are operated autonomously, they can be programmed to drive more efficiently in regards to wear on the roads. Slower braking, slower speeds (since you don’t need stops for drivers to sleep to reach your destination in the same amount of time). We’d also see a closure of many roadside stop…

Road wear is caused by weight. Driving and braking slower won't make a significant difference.

Re: Will we ever fly supersonically over land?

#146

Post by istillwritecode »

Zababa wrote: post #133
nostromo wrote: post #76

Earlier quoted context omitted.

Flying on a full or almost-full plane is more carbon efficient than driving solo. And that's not taking into account the cost of the road networks we build and maintain to allow high volumes of vehicular traffic. https://yaleclimateconnections.org/2015/09/evolving-climate-...

> Flying on a full or almost-full plane is more carbon efficient than driving solo. But how do they fare against trains, especially since trains can run on electricity? The mpg quoted in your article (21.6) also seems really low.

Oddly light rail in silicon valley uses more BTUs per passenger-mile than cars do. Of course that is caused by the fact that light rail has so few passengers (and the number has been falling even pre-covid).

Re: Will we ever fly supersonically over land?

#148

Post by LinuxBender »

hollerith wrote: post #55
avereveard wrote: post #29

Earlier quoted context omitted.

not really the same, fighters are quite smaller than airliners.

They might be smaller, but the boom is quite startling; I certainly wouldn't want to endure them regularly. I know because booms from fighters were common during my trip to West Germany in 1970. (I'm relying on what locals told my parents as to the source of the booms: I never saw a plane.) I've never heard a sonic boom in my 60 years of living in the US.

I heard them all the time near Vandenburg AFB in the 70's and early 80's. I don't remember when exactly I stopped hearing them.

Re: Will we ever fly supersonically over land?

#149

Post by aaron695 »

OT but I think better than another boring air travel bad spiel -

Dyson did some cool computer modelling around Helmholtz acoustic cavities to create quieter fans. I think there's a lot of interesting stuff we can re-visit today because of improved computer power around noise pollution -

“At Dyson we make hundreds of incremental changes rather than one leap forward at a time,” said Schneider. “That means we produce and test hundreds of prototypes for each project. 640 prototypes from handmade models to 3D printed designs were made during the development of the Cool fan.”

https://www.theguardian.com/technology/2014/mar/06/dyson-sil...

Re: Will we ever fly supersonically over land?

#150

Post by dreamcompiler »

hollerith wrote: post #55
avereveard wrote: post #29

Earlier quoted context omitted.

not really the same, fighters are quite smaller than airliners.

They might be smaller, but the boom is quite startling; I certainly wouldn't want to endure them regularly. I know because booms from fighters were common during my trip to West Germany in 1970. (I'm relying on what locals told my parents as to the source of the booms: I never saw a plane.) I've never heard a sonic boom in my 60 years of living in the US.

I used to hear them all the time in Texas when I was a kid in the 70s. We were fairly close to an air force base and we'd be out in the yard on a bright sunny day when we'd hear a thunderclap, as if lightning had struck less than a mile away. We'd look up, see a contrail, and say "Oh." It never caused any damage; it was just surprising.
Post reply on HN