I've seen those big skirts for the trailers become more common over the past few years, but today driving down the freeway I saw this:
Pretty interesting, I wonder how much all of these measures improve fuel economy.
I've seen those big skirts for the trailers become more common over the past few years, but today driving down the freeway I saw this:
Pretty interesting, I wonder how much all of these measures improve fuel economy.
I would venture to guess a lot, there is a guy over on ecomodder forum who drives a bigrig, fully loaded he was doing something like 6.5 MPG after he did some aero work he was doing 14.4 MPG...
I would imagine that even a 1% improvement would pay for itself pretty quickly.
http://cleantechnica.com/2014/01/09/aerodynamic-trailer-design-doubles-fuel-economy/
http://www.cnet.com/news/trailertail-reduces-drag-saves-fuel-looks-funny/
Teh above article says that the trailer tail is a 6% improvement. which is GIANT.
The skirts and tapered tails address two of the worst drag areas on the trailers. The gains are real and are absolutely measured in the pocketbook of independent and corporate truck drivers, especially long haul. As mentioned, if the saving is only 1% then the cost and extra effort is quickly repaid.
I'm surprised the tail isn't longer and more tapered.
I saw one of these the other day...
bgkast wrote: I'm surprised the tail isn't longer and more tapered.
There is likely some overall length for a single trailer limitation, otherwise the trailers themselves would be longer...
In Kamm-back cars there is a limit to how long and how fine a point you try to make. The length can be cut short in a truncated form and you get 99% of the drag benefit. I suspect the tapered trailer extensions are following the same process. If the get longer they have to be stowable for load/unload and they ad weight which starts to limit the structure to hold them up in service.
Is aero behind the increasing number of semis running big single tires instead of duallies lately?
Drag matters less how you open the air, but how you close it.
Like others have said for the mileage these guys rack up, incremental increase add up to a lot of $$$.
Duke wrote: Is aero behind the increasing number of semis running big single tires instead of duallies lately?
That is possible. The tires/wheels are another big drag item for the trucks and the trailers. I suspect the load limit for single tires is lower than two narrow tires however. Not to mention there is less factor of safety in single tire applications.
'Erectile Aero'
My idea (about 12 years ago now) was a pair of inflatable cone halves, one on each rear door.
Internal bungees to snug it all up and out of the way when 'flaccid'.
Inflated by small compressors for highway work, flaccid for in-town.
Guess I coulda made some $$, too late now ...
The single tires are less rotating weight, less drag on the pavement, and probably a small aero improvement. Now that flats aren't as common as they were there is less danger to running a single tire.
but less load carrying capacity.. to get a single wide tyre to hold the same weight as two thinner tyres requires a significantly stiffer sidewall.. and then you also get into the problems of odd wear patterns. You also start to have to worry about brake cooling as well.
personally, while the big rigs are the big fuel suckers.. there are significantly more small box trucks about. Most of them get close to single digit fuel economy as well.. wonder what they could do to aero those more?
tjbell wrote: I would venture to guess a lot, there is a guy over on ecomodder forum who drives a bigrig, fully loaded he was doing something like 6.5 MPG after he did some aero work he was doing 14.4 MPG...
That deserves a HOLY E36 M3!
Most small trucks see shorter trips and lower speeds so the returns aren't as dramatic.
tjbell wrote: I would venture to guess a lot, there is a guy over on ecomodder forum who drives a bigrig, fully loaded he was doing something like 6.5 MPG after he did some aero work he was doing 14.4 MPG...
Starting out at 6.5 mpg seems about right. More than doubling the fuel economy with just aero mods seems a bit optimistic on an 80,000 lb vehicle.
That puts him when fully loaded getting close or better mileage than a 2500 or 3500 gas pickup with a lot less mass and frontal area.
Most big rigs won't get close to double digit economy even empty.
stafford1500 wrote:Duke wrote: Is aero behind the increasing number of semis running big single tires instead of duallies lately?That is possible. The tires/wheels are another big drag item for the trucks and the trailers. I suspect the load limit for single tires is lower than two narrow tires however. Not to mention there is less factor of safety in single tire applications.
I've also been seeing a lot of wheel covers lately.
tjbell wrote: I would venture to guess a lot, there is a guy over on ecomodder forum who drives a bigrig, fully loaded he was doing something like 6.5 MPG after he did some aero work he was doing 14.4 MPG...
Sorry. I'm throwing out the BS flag.
I spent 2 years working on fuel efficiency studies and improvements for big rigs in a company I used to work for. We had data from over 1000 trucks covering over 100,000,000 miles from fleet managers in 3 different countries.
These trucks were carefully monitored, including onboard systems that collected real time data and uploaded it continuously.
We tried hundreds of different methods to improve.
10% improvement was considered great. 15% was incredible.
We never saw a 150% increase in a simple aero mod. Not even close.
80,0000 lb vehicle punching a 100 SF hole through a wall of air at 70 mph getting 14.4 mpg? Physics says it didn't happen.
There are 45 billion gallons of on-highway diesel fuel sold per year in the US annually.
If that guy could increase the fuel economy by that much, his idea would be a $100 BILLION dollar per year industry fuel savings. That's 100,000 piles of $1 million.
I think he could do pretty well for himself. Instead, he's spending all his time posting on Ecomodder.
Nope.
My dads golfing buddies with a local fleet manager . They run around 500 trucks. I think he said if he could improve mileage by 1% it saved them $250,000 a month
arnt the side skirts so no one tries the stupid F&F
tjbell wrote: I would venture to guess a lot, there is a guy over on ecomodder forum who drives a bigrig, fully loaded he was doing something like 6.5 MPG after he did some aero work he was doing 14.4 MPG...
If it's the same truck that was all over teh interwebs a couple of years ago, he did more than just aero stuff.. he dug into the engine, trans, and axles and even things like the shape of the cooling fan.. I remember something about them working with factory engineers on the engine calibrations and cab design..
In reply to novaderrik:
I think that is the one, I wasnt sure of the other mods, i just looked over the thread quickly. either way, double digits hauling 80,000lbs is crazy
You'll need to log in to post.
