I’m always for energy saving ideas when they payback the effort. Here’s one that would be an advantage for our long haul American Interstate trucking companies. This semi has both side wings and a boat tail to decrease wind drag.
It is pretty simple really:
‘Boat tail’ decreases fuel consumption for trucks by 7.5 percent
From a Delft Technical University press release
A boat tail, a tapering protrusion mounted on the rear of a truck, leads to fuel savings of 7.5 percent. This is due to dramatically-improved aerodynamics, as shown by road tests conducted by the PART (Platform for Aerodynamic Road Transport) public-private partnership platform.
Here are the other places wind resistance on a semi-truck can be addressed for fuel savings:
Public highways
A boat tail is a tapering protrusion about two metres in length mounted on the rear of a truck. The boat tail had already proved itself during wind tunnel experiments and computer simulations, both conducted at TU Delft, in theory and using small-scale models. Now an articulated lorry fitted with a boat tail has also undergone extensive testing on public highways.
Emissions
An articulated lorry was driven for a period of one year with a boat tail (of varying length) and one year without a boat tail. The improved aerodynamics, depending on the length of the boat tail, resulted in reduced fuel consumption (and emissions!) of up to 7.5 percent. The optimum boat tail length proved to be two metres.
PART
The tests were conducted by PART. This is a platform in which academics, road transport manufacturers, transport companies and shippers work together. The platform aims to reduce fuel consumption in the road transport industry by improving aerodynamics. PARTs ambition is to achieve a 20 percent reduction in fuel consumption and CO2 emissions in the road transport industry by 2020. TU Delft acts as secretary of PART. PART has previously conducted road tests on a new generation of aerodynamic sideskirts, which are to make their commercial debut later this year.
More information
More on PART: www.part20.eu
More about the side wings: www.ephicas.eu
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Here in Australia we have the worlds most efficient road transport.
http://www.volvoadventures.com/164AusRoadTrain.jpg
When I used to cart ammonium nitrate to Telfer years ago with 4 unit road trains I found the wind direction made a huge difference to speed & fuel consumption.
If you were going directly into the wind the trailers would slipstream each other.
However if you got a strong north easterly of the desert is would hit every trailer and drag you right back sometimes where you spent hours doing 40-50km / hr.It took 6 1/2 hours to do 255km one night.
A bit like a surf cat going fastest across the wind in reverse.
Of course they are spoilt now with a couple of hundred horsepower more than We used to have.
Ray (21:05:29) : “If they would use the railways more efficiently . . . ”
Warren Buffett’s Berkshire Hathaway Corp. just bet big time on your very statement. $26.3 billion. See:
http://online.wsj.com/article/SB10001424052748703740004574513191915147218.html
I don’t know what that trucking-boattail costs but a 7.5 % fuel savings ought to be recovered in a short while. That will be a big savings in dollars and diesel fuel over a year’s time.
Good work, I say. But they need to add a screen over it or folks will be jumping in for a free ride – then falling out and suing someone.
The company I work for is in the process of switching to these:
http://www.donbur.co.uk/gb/products/aerodynamic_teardrop_trailer.shtml
as it performs the same function without the extension. You just have to watch out for those low bridges and canopies. The reduction in drag is so great I wonder why it has taken so long to get around to doing this.
Eddie Murphy (22:40:56) :
I don’t get this slow bit.
Trains should be able to move freight faster than road transport, much faster! A train should be capable of 80mph+ on a long run.
DaveE.
British bus companies used to (Don’t know if they do still) mix water with diesel to reduce fuel consumption. I believe it worked quite well, but I don’t have any information about it.
Also, another factoid, is that round cornered roofs on trailers like this reduce drag and improve stability in high wind situations.
AndrewWH (22:55:45) :
Can’t see them being any higher than those John Lewis Partnership triple decks.
DaveE.
“These are also impractical and add weight to the vehicle. The truck driver must stop, remove the boat tail, then back into the loading dock. After leaving the loading dock, the boat tail must then be re-installed. Each operation requires time, and time is money to a trucking company.”
Good point – but one wonders if it couldn’t somehow be hinged so that the sides flip forward along the side of the trailer and the top up, laying on top of the trailer. Not sure about the bottom.
General Aviation and Gliding spend bucket loads on drag reduction from surfaces. Dennis Conner in the Americas Cup (about the last time it was Americas!) used a drag reducing surface on the cup winning boat.. There are a lot of these airflow controls used in these areas that would be much lower impact to control turbulent airflow if an engineer thought outside the box!
DaveE (22:57:37) : Eddie Murphy (22:40:56) : I don’t get this slow bit. Trains should be able to move freight faster than road transport, much faster! A train should be capable of 80mph+ on a long run. DaveE.
In just a few areas, they can. But trains often have to wait for tracks to clear and also wait to get into a rail yard to load/unload.
Running a railroad is not quite as easy as one may think. Back in the “old days” the Naugatuck Valley was an industrial power house and all the factories had spurs and sidings for rail delivery, but it was a single track main…. scheduling and timing were everything. We could deliver reliably, but it was our schedule, not yours. A through train might drop off fifty cars in our yard and pick up 45 to take up the line, but we then had to sequence those cars for each of our deliveries, wait for the main to be clear so we could move them up to the sidings…. and then move them. On the Naugy line we had a lot of grade-level road crossings, and many of the spurs and sidings were actually along streets. One of my best memories was on the Derby Switcher moving a drag into position at a rubber factory in Shelton. Some trucker started beeping at us to get out of his way. Our engineer nuttered… “mine is bigger than yours…” and gave him a blast of the air horn that damn near blew the semi off the road.
rbateman (22:44:36) & J Hulquist,
Soros and Buffet didn’t “bet” on rail vs trucks as suddenly being more efficient; the economics of that equation have been relatively static for some time. Any “recent” bets reflect their opinion that the economics are about to change. Think “cap and tax”, and get ready to be poorer as governments mandate that everyone tithes to Gaia, with themselves as middleman.
If those boat tails are not well maintained I think there will be problems. Bad enough driving past a flapping curtain. I would hate to be anywhere near a flapping boat tail.
Have a look at this Mercedes Truck from Colani, also look at the tail end of the truck
We know how to apply aerodynamics but regulations and efficiency requirements reduce the possibilities. Take a standard 20″ foot container and you have ample lenth available to put a flat nosed truck in front of it.
Not much room for thinking out of the box if you are in the business of container transport.
http://lh3.ggpht.com/_hVOW2U7K4-M/ShTyXMU-sGI/AAAAAAABBnE/YKvo9ToXhv0/s640/335919501_644b924dc3_o.jpg
Google Colani for other breathtaking designs
DaveE (22:57:37) :
Move faster? Yes and no. Freights are usually hauled by diesel, slow to spool up but they have the torque to move huge loads. They need a good, level straight-away to move. Curves, like we have in New England, or grades like they have in the West, significantly reduce speed. (even the Acela, an electric high-speed passenger train running from DC to Boston, still runs at about 50 mph once it gets into New England. Too many curves.) Freight trains are more economical the more cars you can attach…. but a mile-long train will take more than a mile if it needs to stop. Even in the computer age, rail lines are regulated with a “block system”, a train usually may enter a block if it is empty. If it is not empty, i.e. there is another train believed to be ahead at an inknown distance, the train must proceed at a significantly reduced speed, prepared to stop if there is a chance of collision.
Me, I’m a computer geek who really doesn’t trust computerized rail traffic control systems.
Just what we need to make our highways safer. These, and those new-fangled electric maiming and death can’t-see-the-damned-things traps.
My entire career mostly as a highway engineer is about to be wasted entirely. I do have to wonder exactly why we, the taxpayers, paid so much to make our highways safer to drive on. It obviously was money wasted entirely.
And that duck-tail…. if it reduces the drafting effect, what does it do to turbulence? Trying to pass a truck gets a bit hairy once you pull even with the cab…
DAF not good enough, eh? Had be a Scania.
Here is another aerodynamic application featuring the overhaul of a standard Honda Civic. I admire the initiative and I see the driver clocking high way miles with a smile on his face, until has to park it.
http://www.aerocivic.com/
I saw, on the Drudge Report the other night (it was only there for about a half hour before it was removed) a report from one of our very own federal government departments, which said that the United States has, as a nation, more energy reserves than any other nation on the planet. About 1.3 TRILLION equivalent barrels of oil, in crude oil, natural gas and coal. Known and obtainable reserves. Russia came in second with about 1 trillion equivalent barrels of oil.
We are quickly being destroyed by humankind’s oldest enemy . . . simple greed.
Doug (22:10:11) :
“Imagine that rig in snow, ice, side winds, or getting max cargo under the length regulations. I’ve got a half million miles long haul driving and I can tell you that rig is a looser.”
7.5% savings would seem significant, and of great interest to truck companies. But there would be costs associated with this tail, and I doubt that the numbers would add up to any savings overall. But the intent here appears not to be for economic benefit, but: “to achieve a 20 percent reduction in fuel consumption and CO2 emissions in the road transport industry by 2020.”
Regulations can be changed (and some will) and companies will pass on costs to consumers and keep government “incentives” (unless the government gets into the business of price/profit fixing). Arguments could and may be made that make it appear that the obstacles you mention could be minimized or eliminated by either design or practice. But the one I doubt could be overcome is putting a tail rudder on an 80 foot long haul rig. The website says that drivers would have be “educated” and “will need [to pay] attention” to wind effects. Holy cow. A big handwave there IMO. Perhaps trucks could be fitted with articulated wheels, so they could crab in the wind like airplanes. Seriously, improving road surfaces and conditions, better tires and other measures would likely improve fuel consumption more than a nickel a mile.
This is killing a fly with a machine gun. Take a look here: http://www.meridian-int-res.com/Aeronautics/Coanda.htm – and scroll down until you come to a simple solution by Robert Englar exploiting the Coanda effect. I imagine Pamela would still be able to slipstream and Roger Sowell would still be able to back into his loading dock and get at the rear doors.
What Ripper describes happens with fully streamlined trains too, the problem is with side winds.
Yes. With the bottom part installed robbing them would be much simpler.
I trust you but it’s surprising to me: the boat tail looks like the ultimate birthplace of turbulence and whirlpools to me. 😉
You want to see a real boat tail vehicle? http://www.ultimatecarpage.com/pic.php?imagenum=3&carnum=2360
Ray (22:14:16) : “Look at this 29-trailer road train!!!”
Try that link again for us, Ray?