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I'm having a hard time understanding this snippet: The intermediary stop in Anchorage, as opposed to flying from Shanghai to Oakland, CA, actually increases to

I'm having a hard time understanding this snippet: The intermediary stop in Anchorage, as opposed to flying from Shanghai to Oakland, CA, actually increases total flight distance by around 144 miles but allows the aircraft to carry an additional 45,000kg of cargo (instead of extra fuel) increasing revenue for the trip by around $90,000. Why would traveling an extra 144 miles allow the aircraft to carry 45,000kg of cargo instead of fuel? I feel like I'm misreading it.

jcims 5y ago
Because they can fill their tanks halfway and not fall into the ocean. https://en.wikipedia.org/wiki/Boeing_747#Specifications https://en.wikipedia.org/wiki/Boeing_747#Specifications
NikolaNovak 5y ago
It may be jet stream positioning
dgoldstein0 5y ago
educated guess, they get to stop on the ground to refuel. So while they need to travel further, they need to carry less fuel per each hop. There's probably a little bit of effect like the rocket equation going on - the further you are going, the more fuel you need to get there, and the more fuel you need to carry the additional fuel. Stated a different way, fuel requirements vs distance is worse than linear, since fuel itself has weight.
dklsf 5y ago
You stop to refuel in the middle of the trip, rather than making it nonstop.
grawp 5y ago
To carry fuel you need more fuel.
hodgesrm 5y ago
Every extra kilo of fuel means one kilo less of cargo. I would guess that the shorter hops require 45K kilos less fuel so you can load more cargo instead, thereby increasing efficiency.
koolba 5y ago
The last mile of flight time is the most expensive because the jet fuel has to be carried all the way from the starting point. By breaking a trip into intermediate hops, you get to trade “expensive” last miles for cheaper ones. For it to make economic sense it just needs to exceed the extra cost of time spent at the intermediate port. And even that can offset by adding cargo for that intermediate destination to replace the weight savings of not carrying that “last mile” jet fuel.
- jhgb 5y ago
  This is probably best illustrated by a picture: https://www.researchgate.net/figure/Relative-fuel-consumption-in-kg-km-for-an-example-longrange-aircraft-depending-on-the_fig1_228810749 https://www.researchgate.net/figure/Relative-fuel-consumptio...
eloisius 5y ago
A full tank of gas is a heavier load. The first half of the trip, you’re flying a full tank of gas just so that half of it can be used for the second half of the trip. If you stop over in the middle, you can fly two half-trips with a half tank of gas each time.
- perl4ever 5y ago
  I've thought for a while that people don't seem to be nearly excited enough about the prospect of refueling spacecraft in orbit as SpaceX hopes to.
  - dylan604 5y ago
    I'll be more excited about that when the fuel is created in space so that you're not just launching fuel for another launch to take advantage.
    - inglor_cz 5y ago
      Well, depends on what you mean by "space". The orbit around the Earth is the closest and travel there is the cheapest, but manufacturing fuel out of nothing (vacuum) is pretty much impossible. Technically, what you have on lower Earth orbits isn't vacuum, but a very, very thin gas. It is still probably too thin to be used as a source of stuff for industrial processes. The closest solid body we have as of now is the Moon. A nice source of minerals, where fuel will be almost certainly produced in situ in the future, but then you still need to fly from Earth to Moon orbit and get the produced fuel to the Moon orbit to tank the ship. (Possibly using a space elevator.) Still quite a lot of delta v. The best solution could be to intercept a comet full of volatile materials and drag it somehow to the Earth orbit, say, 1000 km above the planet. Of course, if you mess up and hit the Earth instead, you will cause a nice extinction event down there...
      - jhgb 5y ago
        > but then you still need to fly from Earth to Moon orbit and get the produced fuel to the Moon orbit to tank the ship. (Possibly using a space elevator. You mean a space elevator from the Moon (since on Earth it seems to be infeasible)? It's probably doable but I suspect that an electromagnetic accelerator would be far more affordable and technologically less demanding.
Hemospectrum 5y ago
The “total flight distance” refers to the entire trip, eg. from Shenzhen to Albuquerque, but that involves multiple flights aboard multiple planes. Using Anchorage as a hub allows them to reduce the length of the longest flight.
nkurz 5y ago
Shanghai to Oakland is about 10,000 km: https://www.greatcirclemap.com/?routes=PVG-OAK https://www.greatcirclemap.com/?routes=PVG-OAK Adding a stop in Anchorage adds about 200 km: https://www.greatcirclemap.com/?routes=PVG-ANC-OAK https://www.greatcirclemap.com/?routes=PVG-ANC-OAK The plane is probably limited by takeoff weight: body plus fuel plus cargo. By adding a stop in the middle, the plane can take off with less fuel from Shanghai. Since it has 45000 kg less fuel, it can instead carry 45000 kg more cargo. Total fuel consumption for the trip ends up slightly higher, but fuel per kg of useful cargo is much less.
- sdenton4 5y ago
  Quick, let's build an international air cargo hub on Atka Island! https://www.google.com/maps/@52.2044509,-174.2639372,10.04z https://www.google.com/maps/@52.2044509,-174.2639372,10.04z [edit]: The town of Atka apparently has a population of 53, spread over 32 households. There's an airport, but some expansion would probably be needed to handle Shanghai<->Oakland shipping traffic... https://en.wikipedia.org/wiki/Atka,_Alaska https://en.wikipedia.org/wiki/Atka,_Alaska https://en.wikipedia.org/wiki/Atka,_Alaska#/media/File:Atka.JPG https://en.wikipedia.org/wiki/Atka,_Alaska#/media/File:Atka.... https://en.wikipedia.org/wiki/Atka_Airport https://en.wikipedia.org/wiki/Atka_Airport
  - aaron695 5y ago
    I think that's a brilliant idea. It's only 200km shorter but it takes the longest leg from 7000km -> 5500km https://www.greatcirclemap.com/?routes=PVG-ADK-OAK https://www.greatcirclemap.com/?routes=PVG-ADK-OAK I wonder why it has not been done? Maybe because of this - "In 1996, the U.S. Department of Transportation exempted Alaska's Anchorage International Airport and Fairbanks International Airport from the Jones Act, which prohibits foreign airlines from transporting cargo between U.S. cities. Now, foreign carriers are allowed to refuel their planes in Alaska before continuing on to an American airport or returning home. Because of this, Ted Stevens Anchorage International Airport now handles approximately 80% of all air cargo traffic between Asia and North America." Maybe you need to find a non American location. A floating refuel location? It'd be interesting to run the numbers.
anovikov 5y ago
Because these are 2 segments so plane is fuelled twice. It means it takes max cargo with almost min fuel (to make up MTOW), then again min fuel in Anchorage.

jcims 5y ago

Because they can fill their tanks halfway and not fall into the ocean. https://en.wikipedia.org/wiki/Boeing_747#Specifications https://en.wikipedia.org/wiki/Boeing_747#Specifications

NikolaNovak 5y ago

It may be jet stream positioning

dgoldstein0 5y ago

educated guess, they get to stop on the ground to refuel. So while they need to travel further, they need to carry less fuel per each hop. There's probably a little bit of effect like the rocket equation going on - the further you are going, the more fuel you need to get there, and the more fuel you need to carry the additional fuel. Stated a different way, fuel requirements vs distance is worse than linear, since fuel itself has weight.

dklsf 5y ago

You stop to refuel in the middle of the trip, rather than making it nonstop.

grawp 5y ago

To carry fuel you need more fuel.

hodgesrm 5y ago

Every extra kilo of fuel means one kilo less of cargo. I would guess that the shorter hops require 45K kilos less fuel so you can load more cargo instead, thereby increasing efficiency.

koolba 5y ago

The last mile of flight time is the most expensive because the jet fuel has to be carried all the way from the starting point. By breaking a trip into intermediate hops, you get to trade “expensive” last miles for cheaper ones. For it to make economic sense it just needs to exceed the extra cost of time spent at the intermediate port. And even that can offset by adding cargo for that intermediate destination to replace the weight savings of not carrying that “last mile” jet fuel.

jhgb 5y ago
This is probably best illustrated by a picture: https://www.researchgate.net/figure/Relative-fuel-consumption-in-kg-km-for-an-example-longrange-aircraft-depending-on-the_fig1_228810749 https://www.researchgate.net/figure/Relative-fuel-consumptio...

eloisius 5y ago

A full tank of gas is a heavier load. The first half of the trip, you’re flying a full tank of gas just so that half of it can be used for the second half of the trip. If you stop over in the middle, you can fly two half-trips with a half tank of gas each time.

perl4ever 5y ago
I've thought for a while that people don't seem to be nearly excited enough about the prospect of refueling spacecraft in orbit as SpaceX hopes to.
- dylan604 5y ago
  I'll be more excited about that when the fuel is created in space so that you're not just launching fuel for another launch to take advantage.
  - inglor_cz 5y ago
    Well, depends on what you mean by "space". The orbit around the Earth is the closest and travel there is the cheapest, but manufacturing fuel out of nothing (vacuum) is pretty much impossible. Technically, what you have on lower Earth orbits isn't vacuum, but a very, very thin gas. It is still probably too thin to be used as a source of stuff for industrial processes. The closest solid body we have as of now is the Moon. A nice source of minerals, where fuel will be almost certainly produced in situ in the future, but then you still need to fly from Earth to Moon orbit and get the produced fuel to the Moon orbit to tank the ship. (Possibly using a space elevator.) Still quite a lot of delta v. The best solution could be to intercept a comet full of volatile materials and drag it somehow to the Earth orbit, say, 1000 km above the planet. Of course, if you mess up and hit the Earth instead, you will cause a nice extinction event down there...
    - jhgb 5y ago
      > but then you still need to fly from Earth to Moon orbit and get the produced fuel to the Moon orbit to tank the ship. (Possibly using a space elevator. You mean a space elevator from the Moon (since on Earth it seems to be infeasible)? It's probably doable but I suspect that an electromagnetic accelerator would be far more affordable and technologically less demanding.

Hemospectrum 5y ago

The “total flight distance” refers to the entire trip, eg. from Shenzhen to Albuquerque, but that involves multiple flights aboard multiple planes. Using Anchorage as a hub allows them to reduce the length of the longest flight.

nkurz 5y ago

Shanghai to Oakland is about 10,000 km: https://www.greatcirclemap.com/?routes=PVG-OAK https://www.greatcirclemap.com/?routes=PVG-OAK Adding a stop in Anchorage adds about 200 km: https://www.greatcirclemap.com/?routes=PVG-ANC-OAK https://www.greatcirclemap.com/?routes=PVG-ANC-OAK The plane is probably limited by takeoff weight: body plus fuel plus cargo. By adding a stop in the middle, the plane can take off with less fuel from Shanghai. Since it has 45000 kg less fuel, it can instead carry 45000 kg more cargo. Total fuel consumption for the trip ends up slightly higher, but fuel per kg of useful cargo is much less.

sdenton4 5y ago
Quick, let's build an international air cargo hub on Atka Island! https://www.google.com/maps/@52.2044509,-174.2639372,10.04z https://www.google.com/maps/@52.2044509,-174.2639372,10.04z [edit]: The town of Atka apparently has a population of 53, spread over 32 households. There's an airport, but some expansion would probably be needed to handle Shanghai<->Oakland shipping traffic... https://en.wikipedia.org/wiki/Atka,_Alaska https://en.wikipedia.org/wiki/Atka,_Alaska https://en.wikipedia.org/wiki/Atka,_Alaska#/media/File:Atka.JPG https://en.wikipedia.org/wiki/Atka,_Alaska#/media/File:Atka.... https://en.wikipedia.org/wiki/Atka_Airport https://en.wikipedia.org/wiki/Atka_Airport
- aaron695 5y ago
  I think that's a brilliant idea. It's only 200km shorter but it takes the longest leg from 7000km -> 5500km https://www.greatcirclemap.com/?routes=PVG-ADK-OAK https://www.greatcirclemap.com/?routes=PVG-ADK-OAK I wonder why it has not been done? Maybe because of this - "In 1996, the U.S. Department of Transportation exempted Alaska's Anchorage International Airport and Fairbanks International Airport from the Jones Act, which prohibits foreign airlines from transporting cargo between U.S. cities. Now, foreign carriers are allowed to refuel their planes in Alaska before continuing on to an American airport or returning home. Because of this, Ted Stevens Anchorage International Airport now handles approximately 80% of all air cargo traffic between Asia and North America." Maybe you need to find a non American location. A floating refuel location? It'd be interesting to run the numbers.

anovikov 5y ago

Because these are 2 segments so plane is fuelled twice. It means it takes max cargo with almost min fuel (to make up MTOW), then again min fuel in Anchorage.