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Author Topic: "Supertruck" more than doubles mpg  (Read 4633 times)

Gary RV_Wizard

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"Supertruck" more than doubles mpg
« on: March 28, 2015, 08:58:12 AM »
Freightliner has developed a concept "SuperTruck" that more than doubles the typical mpg of an Over-The-Road (OTR) tractor trailer. It uses a lot of electric power, generated as it moves down the highway, but not in the same way that hybrid cars do.  Let's hope many of these improvements find their way into a motorhome chassis before too long!

http://www.foxnews.com/leisure/2015/03/26/freightliner-supertruck-hauls-goods-sips-fuel/?intcmp=features#
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

blw2

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Re: "Supertruck" more than doubles mpg
« Reply #1 on: March 30, 2015, 08:35:14 AM »
The integral solar panels would be an easy 1st step
followed by the improved aerodynamic design features....

I can see it now.... a honda PriusRV, complete with political bumper stickers on the back.... 8)
Brad (DW + 3 kids)
13 Thor Chateau 31L Class C on Ford E-450
'06 Silverado
'05 Rockwood Freedom 1910 (5-1/2 years)
former tent campers

mistere

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Re: "Supertruck" more than doubles mpg
« Reply #2 on: March 30, 2015, 09:13:05 AM »
I think at this point, and well into the future, the cost of the unit would make it unfeasible for
any vehicle driven less than 200,000 miles a year. 
Ed
Lifetime Sahara tent trailer
2013 Toyota 4Runner

Lowell

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Re: "Supertruck" more than doubles mpg
« Reply #3 on: March 30, 2015, 10:20:52 AM »
Very interesting article, thanks for sharing.
Lowell

2005 Cherokee28A TT
pulled by 2009 Dodge 1500 Crew Cab 4X4
KF7YET

Tempe, Arizona

SargeW

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Re: "Supertruck" more than doubles mpg
« Reply #4 on: March 30, 2015, 11:21:46 AM »
That is interesting. I have wondered if it would be possible to power an electric "helper" motor with Solar Panels on the roof of the RV. Of course working out how the motor would add in the extra power is out of my wheel house.
Marty--
2017 Tiffin Allegro Bus 40SP
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8Muddypaws

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Re: "Supertruck" more than doubles mpg
« Reply #5 on: March 30, 2015, 11:39:16 AM »
There have been hybrid busses all over the country for years.  I've even seen a few hydrogen powered ones in Silicon Valley.

But, if the battery pack in a Prius costs 5K, and it weighs around 2500 pounds, what would the battery pack for a 20 ton chassis cost?  Yow!
Retired computer professional
Musician, songwriter and music director
2006 Bounder 34H, 2008 CR-V Toad

Lou Schneider

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Re: "Supertruck" more than doubles mpg
« Reply #6 on: March 30, 2015, 02:20:43 PM »
I'll go with the aerodynamic improvements right now.   The average motorhome has terrible aerodynamics, with rooftop air conditioning pods, awnings, door handles and other attachments on the sides and lack of a belly pan that breaks up the smooth airflow over and around the rig.

Just having the sloping nose on my little Chaparral motorhome versus a slab front end makes a big difference in both MPG and "feel" going down the road.

I'm not sure how much good the rest of the improvements really make, at least as applied to a motorhome.  320 square feet of solar panels just to run the cab air conditioning?   Regenerative braking only helps when you decelerate or go downhill.  It's useful for a vehicle that does a lot of stop and go driving like a city bus but on a vehicle that rarely brakes you have to offset the power gained versus the power needed to haul the weight of the batteries and the electric motor the rest of the time.

All of this equipment adds weight to the vehicle so it decreases the available payload a like amount.   If the payload is reduced by 10%, the equivalent MPG per ton of cargo carried must also be reduced proportionately.
« Last Edit: March 30, 2015, 02:42:46 PM by Lou Schneider »

Tinmania

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Re: "Supertruck" more than doubles mpg
« Reply #7 on: March 30, 2015, 02:35:46 PM »
I think the solar panels on the trailer is a waste at this point in time. There are many more trailers out there than the tractors that pull them. So outfitting something like that is just not practical. What is practical are the trailer skirts, and I see more and more of them out on the road.

But the aerodynamic properties are a plus, as well as the intelligent tranny--both already in, or going into, production. Recycling the engine exhaust heat is a plus too, along with the usual regenerative braking--which would be significant on such a rig, especially with the intelligent tranny. Of course the intelligent tranny would only work at its best with no other traffic. Another truck or two, or cars, in the way and its effectiveness is diminished.

Lightweight materials are helpful but it is not very significant unless applied to the materials in the load itself. And on the trailer-side you have way too many already out there for it to be meaningful for quite a few years to come.




Mike

carson

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Re: "Supertruck" more than doubles mpg
« Reply #8 on: March 30, 2015, 04:16:58 PM »
Interesting subject.  My take: No matter what you due to streamlining etc. still does not change the fact that a big trailer has to punch a hole in the air to move forward.
  For example, a 53' trailer needs a 4000 cubit foot space to exist.
  Streamlining only has a small effect on the whole picture.

What do I know--- I am not a Trucker.
  see size of trailers here  >>>  http://yrc.com/trailer-dimensions/

Carson, 
 West Central Florida
Ex RV'er. (1995 Winnebago Adventurer)
2007 Buick Rendezvous, SUV / CROSSOVER

...Logic works like a charm...

blw2

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Re: "Supertruck" more than doubles mpg
« Reply #9 on: March 31, 2015, 08:37:47 AM »
Interesting subject.  My take: No matter what you due to streamlining etc. still does not change the fact that a big trailer has to punch a hole in the air to move forward.
  For example, a 53' trailer needs a 4000 cubit foot space to exist.
  Streamlining only has a small effect on the whole picture.

What do I know--- I am not a Trucker.
  see size of trailers here  >>>  http://yrc.com/trailer-dimensions/

You are correct that frontal area is a big variable
If you look at the equation to calculate drag force..... it considers things such as fluid density, the measure of turbulence, and lots of other things
.... but simplifying
if you boil all that down into a " preliminary number"....
then you multiply that by the area (which is your point, is a direct 1:1 affect).
and then you multiply it by the velocity squared (which basically means multiply it by the velocity then multiply it by the velocity again)
     which incidentally is why speed has such a huge affect
then you take the result and multiply it by the drag coefficient.... which is the consideration of the streamlining.  It's affect can be huge.

Click here to see the drag coefficients for some basic shapes
http://en.wikipedia.org/wiki/Drag_coefficient
a cube is 1.05... which adds 5%
but a half streamlined body.... such as a perfect race car.... is 0.09..... which takes away 91%!!!
Brad (DW + 3 kids)
13 Thor Chateau 31L Class C on Ford E-450
'06 Silverado
'05 Rockwood Freedom 1910 (5-1/2 years)
former tent campers

Ernie n Tara

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Re: "Supertruck" more than doubles mpg
« Reply #10 on: March 31, 2015, 09:19:17 AM »
What Brad said!! Drag is easily the biggest consumer of horsepower in a truck or motor home. I would estimate the coefficient of drag to be around 0.8 for the typical class A, while, for example, cars are commonly around 0.3. The difference is easily 25% of the energy consumed in moving the vehicle at highway speeds!

Ernie

Incidentally the formula for drag is    d = 1/2 * p * v^2 * Cd *  area.

drag is in lbs.

 d = density of the fluid (air in this case 0.0023 lb / cubic ft)
 v = velocity in ft per second
Cd = coefficient of drag
Area is in square feet
« Last Edit: March 31, 2015, 09:23:02 AM by Ernie n Tara »
Ernie 'n Tara

2011 Winn Journey 34y
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Tinmania

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Re: "Supertruck" more than doubles mpg
« Reply #11 on: March 31, 2015, 10:17:09 AM »
Reducing drag is of course a good thing. And in a perfect world it is a great thing.

But often a headwind is not 0 degrees to the vehicle. Change that to 20 degrees and the frontal area of a tractor trailer is very different as far as the wind is concerned. The effect of crosswinds is somewhat debatable but unless you are wind surfing it is generally not a good thing. A long flat side, such as on a trailer is just hard to overcome. Now if trailers had boat tail designs they might fare better. But the reduced cargo area could offset that.



Mike

SargeW

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Re: "Supertruck" more than doubles mpg
« Reply #12 on: March 31, 2015, 10:55:36 AM »
Reducing drag is of course a good thing. And in a perfect world it is a great thing.

See, I always knew that waxing my rig got me better fuel mileage! ;D
Marty--
2017 Tiffin Allegro Bus 40SP
Cummins ISL 450 HP/Powerglide chassis
Visit our new travel blog! http://www.mytripjournal.com/rvnchickTNG
Support your local Police Officer, Fire Fighter and Military!

8Muddypaws

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Re: "Supertruck" more than doubles mpg
« Reply #13 on: March 31, 2015, 11:45:52 AM »
See, I always knew that waxing my rig got me better fuel mileage! ;D

I've heard that's kinda painful.   ;D
Retired computer professional
Musician, songwriter and music director
2006 Bounder 34H, 2008 CR-V Toad

Lou Schneider

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Re: "Supertruck" more than doubles mpg
« Reply #14 on: March 31, 2015, 12:27:59 PM »
Reducing drag is of course a good thing. And in a perfect world it is a great thing.

But often a headwind is not 0 degrees to the vehicle. Change that to 20 degrees and the frontal area of a tractor trailer is very different as far as the wind is concerned. The effect of crosswinds is somewhat debatable but unless you are wind surfing it is generally not a good thing. A long flat side, such as on a trailer is just hard to overcome. Now if trailers had boat tail designs they might fare better. But the reduced cargo area could offset that.

Unless you're driving in a hurricane, side or head winds are only a small percentage of the velocity of air moving past the vehicle.   Since wind resistance increases with the square of the speed, they'll contribute a relatively small vector to the overall air movement.

Sam!

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Re: "Supertruck" more than doubles mpg
« Reply #15 on: March 31, 2015, 02:33:15 PM »
In a motorhome some of this can be accomplished by integrating a toad prius to the tow vehicle and it's charge system, brakes, and percentage of drive power.
thoughts?
1997 Serro Scotty 25' Diesel Cummins 4x4
2005 Dodge Ram 3500 Diesel SRW
2000 Tacoma Dezert trux
San Diegan

Lou Schneider

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Re: "Supertruck" more than doubles mpg
« Reply #16 on: March 31, 2015, 03:15:26 PM »
Toyota says the Prius can't be towed 4 down.   Even if it could, it's regenerative braking abilities and battery size are far too small to have any impact on a motorhome's fuel consumption.

A stock Prius has a 1.4 kw/h battery to store it's regenerative braking energy.  In energy terms that's equivalent to 0.04 gallons, or just over 5 ounces of gasoline.  Taking gas or diesel engine efficiency into account, regenerative braking may may add the equivalent of a cup of fuel for every full discharge/charge cycle.

That may be significant on a vehicle that's consuming 1-2 gallons of gas per hour, not so much on one that uses 5-10 gallons per hour at highway speeds  (60 MPH / 10 MPG = 6 GPH consumption).   It's contribution gets even lower if you're recharging the battery while not braking, since it adds just that much more drag.
« Last Edit: March 31, 2015, 03:31:23 PM by Lou Schneider »

RobertRyan

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Re: "Supertruck" more than doubles mpg
« Reply #17 on: March 31, 2015, 03:16:43 PM »
Freightliners owner Mercedes and Volvo are doing similar things in Europe

Tinmania

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Re: "Supertruck" more than doubles mpg
« Reply #18 on: March 31, 2015, 03:23:00 PM »
Unless you're driving in a hurricane, side or head winds are only a small percentage of the velocity of air moving past the vehicle.   Since wind resistance increases with the square of the speed, they'll contribute a relatively small vector to the overall air movement.
Quote
Crosswinds also tend to diminish the
effectiveness of aerodynamic drag-reducing
devices such as cabmounted flow deflectors.

Tailwinds are generally beneficial in
increasing fuel economy because of the
reduced airspeed for a given highway
speed. However, if the driver takes
advantage of the tailwind and increases
his highway speed, the fuel economy
gains will be reduced or lost completely

That was my point.

http://www.goodyeartrucktires.com/pdf/resources/service-manual/retread_s9_v.pdf





Mike

Sam!

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Re: "Supertruck" more than doubles mpg
« Reply #19 on: March 31, 2015, 06:24:27 PM »
yes all this being hypothetical vision of a contributing efficient Toad
 
Correct regenerative as in its own batteries and the coach and chassis only for braking or coasting.
also using its motor for driving forward motion at a given percent load (electric motor use)
last if it where a more efficient option as a generator for 110v to power the RV.

Toyota says the Prius can't be towed 4 down.   Even if it could, it's regenerative braking abilities and battery size are far too small to have any impact on a motorhome's fuel consumption.

A stock Prius has a 1.4 kw/h battery to store it's regenerative braking energy.  In energy terms that's equivalent to 0.04 gallons, or just over 5 ounces of gasoline.  Taking gas or diesel engine efficiency into account, regenerative braking may may add the equivalent of a cup of fuel for every full discharge/charge cycle.

That may be significant on a vehicle that's consuming 1-2 gallons of gas per hour, not so much on one that uses 5-10 gallons per hour at highway speeds  (60 MPH / 10 MPG = 6 GPH consumption).   It's contribution gets even lower if you're recharging the battery while not braking, since it adds just that much more drag.
1997 Serro Scotty 25' Diesel Cummins 4x4
2005 Dodge Ram 3500 Diesel SRW
2000 Tacoma Dezert trux
San Diegan

 

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