Jerry, it's well known that glass fiber composites don't give the strength-to-weight advantages of CF composites, in either commercial aerospace or high-volume automotive manufacturing. If they did the job, there wouldn't be much reason to investigate CF for these purposes. BTW, UPS is already using EV trucks: http://pressroom.ups.com/Press+Releases/Archive/2011/Q3/UPS+Purchasing+100+All-Electric+Vehicles+for+California+Deployment
Sometimes people blame marketing departments as fudging numbers when the data don't seem to add up, but having worked in those departments for technical companies long ago, I tend to disagree with that assumption. Due to the reporting requirements of public companies like UPS, they generally don't make such claims unless they can back them up, since there are legal consequences. We don't have all the facts and for whatever reasons, UPS decided not to share them.
Thanks for doing the math Dave. It looks like only UPS (or Utilimaster) knows how they're boosting fuel efficiency by 40%. I suspect your hypothetical changes in the engine are key. The two things UPS mentions are weight reduction (of an empty vehicle) and powertrain improvements. Those are the same two factors I'm hearing while researching an upcoming feature on the use of carbon fiber-based components in cars.
That link, Ann, spells out a lot more of the story. I think the commenters were savvy to catch the incongruity of the weight savings versus energy savings. But the links shows there is more to the story.
@Ann: Can you explain why a 10% reduction in empty weight results in more than a 10% reduction in gross (loaded) weight? I'm not sure I follow you.
It seems to me that it would be the opposite; 900 pounds is a smaller fraction of the gross weight than it is of the empty weight. Assuming an 80% payload capacity, the gross weight should about be 9000 x 1.8 = 16,200 pounds. 900 pounds is about 6% of this.
On the other hand, the article mentions that there is also a 10% reduction in cargo capacity. Obviously, this would reduce the loaded weight somewhat. Again, assuming an 80% loading capacity, a 10% reduction in cargo capacity should mean a reduction of 0.1 x 0.8 x 9000 = 720 pounds, or about 4%.
900 pounds (6%) due to the reduction in the empty weight plus 720 pounds (4%) due to the reduction in cargo capacity adds up to 1620 pounds, or 10% of gross weight.
Still, if you take a 10% decrease in gross weight, along with a 30% reduction in horsepower (from 215 HP to 150 HP) and a 60% reduction in displacement (from 6.7L to 2.5L), plus some miscellaneous improvements in aerodynamics, a 40% reduction in fuel consumption is at least borderline believable.
I think you're saying the 40% fuel savings is a faulty claim, based on the data provided. I think you're right. Likely a number that was born in the Marketing department vs. the Engineering department.
The 900-lb weight savings is of the empty truck. As several commenters have rightly pointed out, a 10% savings in weight is nowhere near enough to produce a 40% fuel savings. Since fuel savings occur when the truck is out doing deliveries, i.e., loaded with packages, that's where added weight comes in to the formula, so the total loaded weight savings is obviously a lot more than 10%. There were some additional fuel savings because of powertrain improvements. The use of composites let Ultimaster re-design truck body components, and composite body panels are now easier to remove and repair/replace than components made of metal: http://pressroom.ups.com/pressroom/staticfiles/media/image/UPS_composite_vehicle.jpg
That's the hardest thing about changing soooo many "set-in-stone" ideas and paradigms. One tired phrase I ALWAYS wince at, is: "That's the way its always been done". Kudus to both UPS and Utilimaster for getting out of that box.
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This is part one of an article discussing the University of Washington’s nationally ranked FSAE electric car (eCar) and combustible car (cCar). Stay tuned for part two, tomorrow, which will discuss the four unique PCBs used in both the eCar and cCars.
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