4 ms·

I've often wondered why so much of our transportation infrastructure appears to utterly discount things like aerodynamics. Planes and (some) passenger cars pay

by rosser 10y ago

I've often wondered why so much of our transportation infrastructure appears to utterly discount things like aerodynamics. Planes and (some) passenger cars pay attention, but trucks, tractor-trailers, trains, and buses are basically moving bricks, slamming into the air in front of them, and dragging a partial vacuum behind them. Awfully fuel-inefficient, that.

masklinn 10y ago
> trucks, tractor-trailers, trains, and buses are basically moving bricks, slamming into the air in front of them, and dragging a partial vacuum behind them. There are lots of aero studies for these (aerodynamic efficiency is why tractor trailer often convoy on highways, it's also why some trailers are skirted), but aerodynamic efficiency is not the only concern, and the speed at which they go means the actual effect is relatively low (just look at trains, serious locomotive profiling starts at system going twice the standard speed of a semi or more, trains going at roughly semi- or car-speed like freight trains tend to be even boxier than semi tractors)
walrus01 10y ago
Trucking companies care a great deal about fuel efficiency, actually: http://www.stemco.com/product/trailertail/ http://www.stemco.com/product/trailertail/ http://www.nytimes.com/2012/12/30/automobiles/stretching-trucks-mileage.html http://www.nytimes.com/2012/12/30/automobiles/stretching-tru... The side skirts you see hanging from 53' trailers on the freeway are a cheap example. Some of these hardware improvements will pay for themselves quite quickly if the gain is 0.5 mpg over many hundreds of thousands of km, at normal diesel prices in the US and Canada. Trucking is such a thin margin business that anything which gives a competitive edge in operational costs and $ per km will be adopted quickly.
imaginenore 10y ago
Ships, out of all modes of transportation, could use the wind to really reduce the fuel consumption. Giant kites that are fully automatic should be able to drag even the largest ships.
- qbrass 10y ago
  https://en.wikipedia.org/wiki/MS_Beluga_Skysails https://en.wikipedia.org/wiki/MS_Beluga_Skysails
- rosser 10y ago
  I actually posted another comment, previously in this story's discussion, mentioning high-altitude kite propelled container ships. You'd probably still need to burn something (or somehow otherwise) turn screws for maneuvering and propulsion in coastal waters, but that's a small fraction of the fuel burned each crossing.
  - nradov 10y ago
    No even with kite propulsion cargo ships will still need to run the main engine constantly. Wind just isn't strong enough to push a huge ship through the water a reasonable speed using a relatively small kite. See the other link in the sibling post; total fuel consumption with a kite is only 5% lower. http://www.skysails.info/english/skysails-marine/skysails-propulsion-for-cargo-ships/advantages/ http://www.skysails.info/english/skysails-marine/skysails-pr...
    - imaginenore 10y ago
      With one specific kite. Nothing stops you from adding multiple kites, and larger ones too.
      - nradov 10y ago
        There are practical limits to kite size in order to keep them controllable. And where would you put multiple kites? Deck space is at a premium and they won't sacrifice cargo capacity.
        rosser 10y ago
        Currently, yes. Currently, aeons-decomposed dinosaurs are still plentiful enough that we're profligately burning them, at our own peril, too. Both of those things will change.
lmm 10y ago
Modern trains are very much designed for aerodynamics, look at something like http://www.hitachirail-eu.com/super-express-iep_57.html http://www.hitachirail-eu.com/super-express-iep_57.html
- rosser 10y ago
  That's a bullet passenger train. I'm well aware of them. I'm talking about freight rail.
alexhawdon 10y ago
IIRC Trucks are the shape they are because of maximum length restrictions. (Making the 'nose' longer and more aerodynamic sacrifices cargo space.) I believe that, in Europe at least, these restrictions are due to be relaxed, so we'll start seeing more aerodynamic trucks in the coming years.

by rosser 10y ago

masklinn 10y ago

> trucks, tractor-trailers, trains, and buses are basically moving bricks, slamming into the air in front of them, and dragging a partial vacuum behind them. There are lots of aero studies for these (aerodynamic efficiency is why tractor trailer often convoy on highways, it's also why some trailers are skirted), but aerodynamic efficiency is not the only concern, and the speed at which they go means the actual effect is relatively low (just look at trains, serious locomotive profiling starts at system going twice the standard speed of a semi or more, trains going at roughly semi- or car-speed like freight trains tend to be even boxier than semi tractors)

walrus01 10y ago

Trucking companies care a great deal about fuel efficiency, actually: http://www.stemco.com/product/trailertail/ http://www.stemco.com/product/trailertail/ http://www.nytimes.com/2012/12/30/automobiles/stretching-trucks-mileage.html http://www.nytimes.com/2012/12/30/automobiles/stretching-tru... The side skirts you see hanging from 53' trailers on the freeway are a cheap example. Some of these hardware improvements will pay for themselves quite quickly if the gain is 0.5 mpg over many hundreds of thousands of km, at normal diesel prices in the US and Canada. Trucking is such a thin margin business that anything which gives a competitive edge in operational costs and $ per km will be adopted quickly.

imaginenore 10y ago

Ships, out of all modes of transportation, could use the wind to really reduce the fuel consumption. Giant kites that are fully automatic should be able to drag even the largest ships.

qbrass 10y ago
https://en.wikipedia.org/wiki/MS_Beluga_Skysails https://en.wikipedia.org/wiki/MS_Beluga_Skysails
rosser 10y ago
I actually posted another comment, previously in this story's discussion, mentioning high-altitude kite propelled container ships. You'd probably still need to burn something (or somehow otherwise) turn screws for maneuvering and propulsion in coastal waters, but that's a small fraction of the fuel burned each crossing.
- nradov 10y ago
  No even with kite propulsion cargo ships will still need to run the main engine constantly. Wind just isn't strong enough to push a huge ship through the water a reasonable speed using a relatively small kite. See the other link in the sibling post; total fuel consumption with a kite is only 5% lower. http://www.skysails.info/english/skysails-marine/skysails-propulsion-for-cargo-ships/advantages/ http://www.skysails.info/english/skysails-marine/skysails-pr...
  - imaginenore 10y ago
    With one specific kite. Nothing stops you from adding multiple kites, and larger ones too.
    - nradov 10y ago
      There are practical limits to kite size in order to keep them controllable. And where would you put multiple kites? Deck space is at a premium and they won't sacrifice cargo capacity.
      - rosser 10y ago
        Currently, yes. Currently, aeons-decomposed dinosaurs are still plentiful enough that we're profligately burning them, at our own peril, too. Both of those things will change.

lmm 10y ago

Modern trains are very much designed for aerodynamics, look at something like http://www.hitachirail-eu.com/super-express-iep_57.html http://www.hitachirail-eu.com/super-express-iep_57.html

rosser 10y ago
That's a bullet passenger train. I'm well aware of them. I'm talking about freight rail.

alexhawdon 10y ago

IIRC Trucks are the shape they are because of maximum length restrictions. (Making the 'nose' longer and more aerodynamic sacrifices cargo space.) I believe that, in Europe at least, these restrictions are due to be relaxed, so we'll start seeing more aerodynamic trucks in the coming years.