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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Alright, longer trucks, strange constructions protruding from the rear, just what we need on the already crowded highways in the “Randstad” (the for largest cities in the Netherlands).
And longer trucks, wait until they get off the highways and have to navigate roundabouts, speed limiting obstacles like speedbumps and chicanes and other devious devices that civil servants and city councils can think of.
Try driving through English Villages with that extra length. Particularly if you have to back up.
Roger Sowell (21:13:20) :
……………….
“There are also overall length limitations in the U.S. – the aerodynamic improvement device cannot extend more than 5 feet beyond the trailer. (23 CFR 658.16(b)(6)) Those that are 2 meters are just a bit too long.”
All European long haul trucks are cab-over, making them shorter then the common American trucks to begin with.
An expanding-contracting rear of the trailer is not a big design problem.
I say, just go for it!
Thanks to AndrewWH. There are a few points I would like to make, coming from the same manufacturer that makes the Teardrop trailers.
http://www.donbur.co.uk/gb/products/aerodynamic_teardrop_trailer.shtml
Firstly, boat-tail fins have been proven to work well, and further research from DERA (UK Gov Research) or “QinetiQ” as it is now known, has shown similar improvements to fuel economy.
As pointed out in many posts here, the rear of any trailer is subject to heavy stresses and any protruding object is likely to get ripped off in the first couple of months of service. As standard, we like to manufacture clutter-free rear frames.
Unfortunately, any aearodynamic aid that is added to a trailer is vunerable to damage and maintenance costs can far exceed any aerodynamic savings you may make thus making the whole concept unviable.
There are a number of additions we are considering, including the elimination of the tractor-trailer gap and skirting improvements, but all have to be durable, cost-effective and, more importantly, they have to provide a payback period of less than max 3 years.
Just to give you some idea how much CO2 trucks/trailers emit, try out our CO2 calculator @ur momisugly http://www.donbur.co.uk/gb/carbon_emission_calculator.shtml
considering one trailer might do say 60,000 miles per year at maybe 8 mpg, the fuel cost and CO2 output is frightening.
Yes, we are the Saudi Arabia of natural gas and there have been enough new oil finds, with improved drilling techniques, that gas should never go above $2 a gallon. But it is… Greed?
Ray (21:05:29) : ….also make the highways safer. The big rigs are a real mortal danger to us little car drivers.
A: Actually truck involved accidents continue come down with the new 10 hour break in the hours of service rule.
B: I’d say 80% of the time the reason trucks push so scary hard has more to do with the infrastructure and greed supporting the driver than the actual driver. Load planners who book too many loads and wait until the last minute to broker the load out to a company that can haul it when they see they cannot cover it.
Shippers/manufacturers who have an order to be delivered on a scheduled date dilly dally around and it gets shipped at the last moment. Dispatchers who don’t get the freight moving, forgot about the load. Receivers who won’t take responsibility to unload their freight in a timely manner, leading to late pickup of the next load. Driver unloads instead of hiring the expensive in-house lumper service and therefore gets penalized, maybe has to come back the next day. Drivers know that if the load is late the receiver will likely penalize them and make them unload at a later date. Take good ‘ol neighbor Wal~Mart for example, if you are 1/2 hour or up to 1 hour late the load has to reschedule for the next day or so. On and on it goes, I could write a book.
C. The little car drivers are a hazard period with so much inattention.
D. Bad railroad crossings kill good skilled drivers.
It’s a lift and swing issue, from a practical point of view for the load and unload, length is a legal issue.
In Australia we have road trains in the centre, that measure 3 times that beastie in length.
http://www.volvoadventures.com/164Road_Train.jpg
http://www.volvoadventures.com/164AusRoadTrain.jpg
http://www.ozprodrivers.com.au/e107_images/newspost_images/ozprodrivers_image_road%20train%20fuel%20tanker%203%20trailer.jpg
The back fairing does not have to be heavy just aero dynamic/.
I used to drive a Toyota aI needed 5 kilometres to get to speed for the overtake.
Remember those ‘spoilers’ that popped up on the wing surface of the 707’s as they came in to land? An Australian firm marketed a similar set of small angled wings that fitted to the rear sides and top of trucks and autos. and claimed up to 10% fuel reduction, by ‘laminar flow improvement’.
I made up a set and fitted them to the 92 Subaru Wagon and at least it keeps the rear window clean, does improve the mileage, and makes it a breeze to find it in a car park!
Hey, this isn’t all bad!
How many hobos can you get in there?
One last thing I used to be involved with heavy transport. And yeah I know a bit about Australian truckers. If that ugly fuggin thing can get 5% fuel economy. It will work for them. I have never met long hours in small business like they do.
One truck and a contract, and fuel is their demon nightmare. Maintenance their second, and the third one is plant legacy.
LarryOldtimer (23:44:10) : … 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.
Full story (or another version) here, Larry: …converted to a barrels of oil equivalent (BOE), the U.S. has the largest reserves in the world.
And then there is the Volvo hybrid truck:
http://www.hybrid.com/hybrid-car-news/item/161-volvo-trucks-the-hybrid-truck-future-is-here
My brother has a Kenworth Conventional, mounted under the front of the truck is a wind deflector that is mounted on a hydraulic piston which has a reach of 3 feet, which he can extend at will, he says that it gives him ( on the open road) an extra 2.5 to 3 miles a gallon. He also has an ex military aircraft oil cooler mounted before the turbo and an air cooler ( from the same aircraft ) after the turbo which maybe one of the many reasons that his 600hp gives him a compact car economy,
Michael J. Bentley:
[i]”I want to die in bed – or anywhere else besides on the highway.[/i]
Amen to that!
I want to die like my Grandfather, in his sleep. Not screaming and swearing like his passengers…….
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.
—
Another significant delay with railroads is not “getting to the other side of the state (or country even)” but “stopping and backing and breaking up the train cars to get the specific one or two cars needs for each different customer moved off the main line, stepped in front of the right door at the warehouse, and re-connecting the train to go to the next warehouse and doing it all over again.
If it takes 30 minutes to drop of two cars and get moving again, you can only make 8 stops (drop offs or pickups) in an entire morning. And the last customer gets his rail car at 12:00 – when eh may or may not want it, and the first customer gets his at 8:00 – when HE may or may not want it.
In the meantime, the rest of these 8 warehouses are getting 120 or 200 trucks in AND OUT at exactly the right time they want their specific cargo loaded or offloaded. Need space? Park the trailer in he parking lot for a few hours (or days.) Need only a little bit unloaded – do it. You don’t need to call the entire train back to get three boxes send early.
Best economy is free market: let the customers decide what THEY need for the best price.
I would also like to point out that there is ~ 8% difference between the best & worst on a modern diesel’s BSFC (brake specific fuel consumption ) curve which is measured in lb’s per BHP per hour.
So if you drive and keep the revs as close as practicable to the optimum BSCF point you can make real fuel savings for minimal loss in travel time.
Back in the 1950 they experimented with an inflatable boat tail, it worked well, but was difficult to inflate after every stop.
Silver I never said it worked, I said if it worked.
Troll.
My father was a truck driver as well as a private pilot. I remember discussions with him on this same subject 25 yeas ago and his comment that a bullet would be more efficient if it flew backwards.
It would have the basically the same surface area facing forward and wouldn’t have the drag due to turbulance behind it.
Note that it might be just a bit less stable, though 😉
Kind of reminds me of what they did with the Space Shuttle to reduce lag on it’s ferry flights. http://www.flickr.com/photos/oregonhiker/142562713/
Greetings, I’ve followed this site for quite a while, and finally a subject I have some personal experience with. I work in the service department of a small trucking company in northern Wisconsin.
Improving fuel efficiency is one of our constant challenges. We constantly monitor and try to improve the way the trucks are operated to attain our best fleet average. The things that helped the most are limiting idle time, and lowering the governed highway speeds. Slower speeds = fuel saved! You will notice many trucks in North America that travel slower than the cars one the highway and this is one reason why.
Many products come with a claim of a certain percentage of improvement, but they just do not work out in real life situations. Sometimes it is just because the actual time spent at highway speeds is less than the time spent in town, at slower speeds, making deliveries, dealing with traffic congestion, bad weather or any of the other daily problems of the trucker. If the truck is traveling at less than 30 mph, what will the boat tail do for fuel efficiency?
I’m sure some of these ideas will help in the design of new equipment, but they must pass the test of practicality in the real world.
Alvin (22:03:08) :
Why is this a good idea? Because it saves money.
In business, that should be the one and only motivation. But in Warmland, the motivation instead becomes “saving energy”, and, ultimately, “cutting carbon”. The actual costs are never mentioned. Why? Because again, in Warmland, those aren’t the motivation. Think about it. If trucking companies wanted to save money, don’t you think they would already be doing these sorts of things?
I tested a similar model in our wind tunnel some years ago. Drag was significantly reduced. One of the problems that the student pointed out in his report was that braking efficiency was also reduced.
Rather than the tacked on boat tail, couldn’t you just have the rear doors shaped like \/ rather than — ?
Boat tails on semis are nice, amen! They’ve been tickling my brain for twenty years… But consider this: how much longer of pavement will get occupied on bumper to bumper urban highway in the city? Anything that takes more pavement lenght decreases traffic swiftness as soon as the traffic significantly slows down, e.g. when there is less than around two-three seconds of distance between cars. If you like your present traffic jams, wait till you try to save 5% of fuel on a few semis… You will have thousand more automibiles and trucks idling along in urban traffic jams, each costing opportunity time, and fuel. Opportunity time might be the biggest cost of all, decreasing quality of life.