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Comment by rosser | Hacker News Reader

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.

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Trucking companies care a great deal about fuel efficiency, actually:

http://www.stemco.com/product/trailertail/

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.

> 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)

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

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

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.

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

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.

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-pr...

With one specific kite. Nothing stops you from adding multiple kites, and larger ones too.

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.

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.

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.

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