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Detroit, 3:55 PM
Thu Nov 26
12 posts in the last 24 hours
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11/10/09
Keep in mind that this is likely only indended for highway use, on surface roads at normal traffic speeds this could not possibly improve consumption by 7.5%, so the concerns regarding navigating intersections are very likely completely moot as this would not be deployed on surface roads anyway...
:P #trucks
11/10/09
Imagine this guy in the left-turn lane at a regular 5-lane (U.S.) intersection, so that if you're going straight ahead, you'd see a view like this pic. He gets the left-turn arrow and goes straight part-way into the intersection, and then whips his left as late as possible so he doesn't drag the trailer over the hoods of the cars waiting to turn left off the street he's turning on to. As the nose of the trailer goes left, all the junk in the trunk behind that center trailer-axle goes right and shoves the cars waiting to go straight in the "fast" lane sideways into the cars in the "slow" lane. All this happens completely in the drivers blind-spot, so he just keeps on driving. It's even worse if he's making a right-turn. Folding this thing up so you can drive in traffic would eliminate any savings at all, because no driver would just deploy it only when "not in traffic", because that would be never.
Great idea, but as someone who's spent his whole life in the trucking industry, if they could save 1/100th of a penny, they would, and would have for a while, because it's all about economies of scale. If you can save 10 pennies per day/per truck, and you've got 10,000 trucks, that's a thousand dollars a day, for a dime! Cheap-ass fuckers..... I'll explain speed-limits and hours-of-service later... #trucks
11/10/09
In the US and Australia (and others too, I'm sure), semis spend a lot of time on highways (most of their time?). That is where this would offer the greatest fuel savings and where it would offer the least potential for the issue you describe. #trucks
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Strangely enough, owner-operators, the one set of drivers who could be depended on driving something like this responsibly and deploying it effectively have historically been the most resistant to change when it comes to aerodynamics. Trucks look the way they do because that's what Daddy's Truck looked like. When the bean-counters got Kenworth to design and build the T-600 (Ant-Eater) in the mid-80's, the first real re-design of the Truck and the first to even contemplate aerodynamics in the history of ever, it met such horrendous backlash, led mainly by the owner-operators who had the most to gain, that Kenworth considered scrapping it entirely. You literally had to pay someone to drive one, and they kept their radio off.
The classic struggle between the cheap-f*ckers and the dumb-asses, and I'm proud to have played on both teams with equal enthusiasm no matter where I was. #trucks
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Just ask Volvo. #trucks
11/09/09
Because of euro length regulations, the trucks are all cabovers, so the critical frontal profile is pretty bricklike. That's likely where the most improvement would lie. #trucks
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11/09/09
I considered, for a good while, putting them on the diesel-pusher motorhome we have, 'cause when your lifetime, 117K mile average is 9.9 MPG, well, 7.5% is huge.
Over 0.5 MPG on a 90 gallon tank, which I've put 88 gallons in, means even more cushion when in an area where fuel prices are just stoopid. There are times when, if you go 100 miles, the price difference is more than 10%. If refueling costs well into the triple-digits, you pay attention to subtleties many gloss over.
I mean, that's 4 gallons per tank...assuming an 80 gallon refill point, which was my tank-to-tank goal. $10/tank...yeah, it may have been worth it at the beginning of our travels, 80K miles ago, but I couldn't believe they weren't overpriced. Something like 300 clams for enough to do the perimeter of a 8'x12' rectangle.
I've since spoken with someone who has 'em on a similarly barn-door-like aerodynamic dynamo, and he claimed he saw about a .5 MPG improvement.
Of course, most people could see this by, in a huge machine like I'm referring to, slowing from 65 MPH to 58, or so. Still not an obstacle, most places, and 7 MPH isn't going to make you miss anything. You save some in refuel time, anyway.
Oh, and just so you don't think I'm one of those bastards in the left lane clogging up traffic, I know the redline-limited top speed of this 40' motorhome is 86.5 MPH, as verified by GPS on flat, straight ground. Lemme tell ya', over 80 it's weird feeling...being behind a very, very large slab of glass. #trucks
11/09/09
Also, when are you Yanks going to measure mileage properly, as in Gal/Mile?
:) #trucks
11/09/09
Hey...HEY! Don't screw with my distance per volumetric unit!
Metric-loving freakazoids...
/wishes the entire NA continent embraced a base-10 system.
I know, usually, how far I need to go, but the amount in the tank, unless I'm in the motorcoach, is not known to any great degree of accuracy. Both the RX300 and the E320, as accurate as the gauges are, require interpretation based on orientation and just where the needles is pointing.
OTOH, the VMSpc connected to the Cummins ISB, I took the time to calibrate to within 8 ounces over a 90 gallon tank. It reads both fuel rate consumption, total used, amount left, and a ton of other info which makes the info-geek in me tingle with delight. I think the 8 ounce discrepancy is because with a 40' long machine, even with leveling jacks, it's a bitch to get it perfectly level in diffferent locations.
And yes, I'll dump the suspension air and level with the jacks when getting fuel, if the pump is on a noticeable incline. Takes an extra 30 seconds...if that.
/loves having 5 trip odometers #trucks
11/09/09
@that ain't the way to have fun, son: I don't get why they don't just invert the number for you guys. It basically takes the non-sense number you have now and allows you to cross shop vehicles, but they just don't seem to want to do it.
And I admire your dedication! I guess what I'm trying to say is to track marginal changes in consumption is tough. It's going to be difficult to find any moderate gains outside the margin of error. Traffic, speed, wind speed and direction, route, driving style, etc will affect your mileage by enough percentage points that it would be hard to find gains, even though your actual measurement is pretty good. There is also the common problem of psychology - when you are watching for gains, you'll drive a bit more economically and carefully. I've got a vehicle telematics contractor working on the measuring problem, and they can get within about 1-2% reading the ECU and float level, but it's tough.
If you're looking for 0.5 mpg like your buddy, you also have to consider that when tracking consumption, you need to have the BEFORE and AFTER numbers on his mpg to give meaning to that. If you look at this nice Wikipedia curve, you guys fall into that nice meaty section where the consumed fuel starts to skyrocket with small deviations in mpg.
Generally, when trying to save fuel, aero is one of the last places I would look. It's free from the factory but trying to get more slip after the fact is tough. #trucks
11/09/09
I'd be curious how this would work on a typical trailer here, with it's wheels and other chassis bits exposed to the airflow. #trucks
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That said, if I was an owner/operator, I'd be finding ways to squeeze every bit of efficiency out of my truck possible. #trucks
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