Truckers
 

I don't know if its legit or not, being so close to april fools, but it does seem plausible. Supposedly independent truckers are striking to object to high fuel costs.

Semi's move the entire country along, so we can't go without them, but at the same time. Why not mock up some aero improvements that truckers might try? 6-12 MPG seems to be average semi mpg, which is actually pretty good considering its hauling enough weight to carry most of our cars.. :thumbup: With a 0.6 or more Cd, some aero improvements could go a LONG way...

Anyways, heres a quick sketch I made up, I dont know how practical it would be, but its just to get ideas rolling.

http://lesbaru.com/stuff/18wheeleraero.jpg

Obviously still a LOT of improvements to be made. Some design issues like the rear wheel skirts (attached to the front of the trailer) need to give way a LOT. As well has some sort of system to connect the cab/trailer aeroly while still giving play to allow for maneuvering and suspension work. Something like how train cars connected, except smooth would work. The rear boat tail would have to be inflatable or removable quickly, since the door is back there. Theres already air systems on trucks for the brakes, so I was thinking air might be a better idea anyway.

Looks familiar: ;) :eek:

http://www.autobloggreen.com/2008/03...irst-human-po/

But seriously, those mods you made look like they would really improve efficiency. Did you ever see the semi trucks on the Future Car series? I think yours would work better.

Check this out (scroll down). This is the work of Luigi Calani, the guy I was speaking about.

http://www.darkroastedblend.com/2006...gi-colani.html

With all due respect to Luigi, his design sucks. Way too busy, aerodynamically.

What's needed is a mold made off the nose and forward fuselage of a large modern jet transport aircraft of similar dimensions to the tractor of one of these trucks, say a C-141, a C-17, a Boeing 757, etc.. After all, the truck cab/cabin is typically a tilt-up rig that is often made of fiberglass. What we have now approximates the fluid mechanics of bricks stacked on bricks. Ungood.

Wheel pants/fairings, an articulated fairing between cab and trailer box, flow fences, Coanda devices, Sinha deturbulators (if they work) and/or vortex generators have all been shown to be major drag reducers for these big rigs.

As bad as even the best common rigs are aerodynamically, just a few of the simple mods would make major improvements in fuel economy. Pick off the low hanging fruit.

There is a fortune to be made in such simple aftermarket devices.

IF we could redesign the containers too, we could make major improvements, and just make it look like the fueselage of a plane. But I dont see that happening with the billions already made to a certain standard. But with some bolt on stuff, there could still be a major loss in drag.

Yeah, lightweight fiberglass foils at the leading edges, flow fences, wheel pants, etc. could be done for peanuts. Removable and recyclable, they could be made for easy on-off application to any intermodal shipping box, for cheap. A few days at the aircraft boneyard in Tuscon could get you a decent set of fiberglass molds for the cab fairing.

The cargo tends to be box-shaped.

True that.


With all this talk of making 18 wheelers more efficient it makes me appreciate what we (as a society) will do to keep the hold on our normative ways of doing things.

To me, it's only a matter of time before we re-invest in rail infrastructure. Rail is SO much more efficient than individual trucks, it just takes that initial investment to get our rail system up to above 3rd world standards...

Truckers
 

Well, Truckers tend to add-on things that reduce Cd:

Chrome air cleaners, 4" stacks, lighting accessories. Older, less aerodynamic designs like the Peterbilt classics are popular, but the "hanging fruit" is excessive "but manly :thumbup:"

http://www.bigtruckdrivingjobs.com/t..._model379x.jpg

Super-aero looking designs won't nearly be accepted by the trucking community let alone the car-driving public.

But the new Kenworth T660 looks promising:

http://www.kenworth.com/newspics/T660.3.jpg

Product Brochure. I think the aero mods look pretty cool.

Trailers -- well, first -- a fairing is a good first step: something adjustable, since the rear axle set often requires fore-aft movement for proper load distribution:

http://pic16.picturetrail.com/VOL698.../145994169.jpg

Next, the whole rig can save rolling resistance with single instead of dual wheelsets:

http://www.greencarcongress.com/images/widebase.png

Green Car Congress Says...
A lot can be done -- but money is super-tight with the independents right now. Large firms may be able to pull it off if they commit to it. Wal-Mart (shiver) is at the forefront of their fleet saving diesel -- bottom line stuff, IMO.

RH77

EDIT: I agree Andrew, rail is by far the most efficient. My Pops is a retired Railroad Engineer, so that has pretty much been a standing fact in the family forever. But, the rail companies focus on monopolizing markets, and being late in the game to emissions reduction. Intermodal is a growing trend -- seems efficient and engages all forms of transport.

AndrewJ -

Funny you should say that :

Warren Buffett's New Train Set - 09.11.2007
http://www.treehugger.com/files/2007...n_buffetts.php
Why Warren Buffett is buying railroads - March 20, 2008
http://money.cnn.com/2008/03/07/pf/sivy_apr.moneymag/

CarloSW2

A couple of months ago, I was on my way to work at approximately 3:15 -3:340 A.M.
My route takes me through an industrial part of town ( Austin, Texas ).
In the lane beside me I saw a semi that had a trailer with a full Kamm back, as well as wheel covers.
( This design actually had the trailer with a sloping roofline, unlike some designs that have what looks like a rounded 'hottub' strapped to the back of the trailer. )
Of coarse I did not have a camera with me, and I was running late for work.
I have to wonder if they were testing some new prototype. I truly hope so.
My jaw dropped when I saw it and I almost ran off the road.
I work in shipping unloading trucks, and so I know how that some ideas will not work because they would not be practical.
I wonder how that the Kamm back design that i saw works in real life, since you must drive a forklift in the trailer.
I see a lot of semis that are driving back to their RDC center without a trailer, and I have to wonder how hard that it would be to rig up some sort of accordian type of Kamm back that could be pulled out from the back of the cab.
Once the rig had to dock with the trailer, all the trucker would have to do would be to pull back the thing ( or if he's feeling lazy just back into the trailer and the thing would fold itself up.
Not only could it be inexpensive and easy to set up, but it would pay for itself many times over , not to mention the fact that it would not obstruct the truckers vision or add practically any weight.
Also the Kamm back could extendd back to the trailer and fill in the gap between the cab and the trailer. In a corner, the assembly would flex since it would be like an accordian.
The city of Dallas already has stretch busses with this feature. ( The bus has an accordian like structure in the center portion of the bus which flexes when the bus goes into a corner.

Cd, I must have seen the same kind of truck, last year. The one I saw had no name or labels on it. My impression was that it was some kind of specialty truck. I once saw a similar truck at the EAA, carrying - of course - a plane with folded wings.

You've definatly never driven truck before..

duals have less tire on the road, so youd be adding MORE tire to the road with a large wide setup..

with a large wide single the back end of the truck feels too loose and gummy,
its a looks thing and you wont see it too oftin because its dangerious when hauling.

I had to drive one and it was not a pleasent feeling..

one of my 2 favorites are the Volvo (monster engines) and the Freightliner Conventional S/T's safest around IMHO..

Both very aero..

18-wheelers
 

In the 1980s,Fruehauf teamed up with Peterbilt,and came up with a concept that got 10-mpg.It had all the goodies,including a boattailed trailer.Its never been produced.Truckers I know really consider weight an issue,as it cuts into payload potential.Aero mods will have to be very light with respect to size and effectiveness.Two points mentioned by members want to touch on.The single "floatation" wheel/tire combos offer 20% less rolling resistance than duals,in spite of increased frontal area.Blowouts suck though.Secondly,BMW and The Waggoner's Trucking Co.,of I believe S.Dakota,both run a fiberglass boattail on their trailers.The Waggoners get to run additional length,drivers don't know anything about any economy gains,perhaps the headquarters could respond to that.I've always been to busy to follow up on it.Left to me,I would completely re-design tractor-trailers,and I'm sure all the current builders would hate it completely.

No, nothing with a tandem-axle setup -- the largest were straight-chassis 6-wheelers. Largest stuff was Fire Apparatus: 1800 gallon tanker, pumpers, ladders, rescue, Medium-Duty ambulance box (Freightliner) -- mostly an easy driving E-350 Ambulance conversion.

Multiple studies (including those of the EPA), prove otherwise. The Green Car Congress thread has a link in the story to the study mentioned and likely other studies for more info.

Good info to know. I do see them more on trailers, which makes sense from the stability standpoint. I can appreciate the gummy feeling -- the company once ordered new tires for the E-350's, with too weak of a sidewall. The back-end was really yawing in level driving -- had to take them back. Not good on high-performance/response cornering either.

RH77

I was just at the Mid-American Truck Show[MATS] last weekend, and running a "super single" as they are called does improve rolling resistance, and does help with weight. Most truckers from the show said they would rather run those after driving on a set, but the cost is too much for most to make the switch. There was a few vendors with full side skirts the the trailers. They had hinges on them so they are less likely to break off, instead they fold under the trailer. A few manufacturers had new rigs set out for aerodynamics to increase gas mileage. Using lighter materials to build the cabs, and a few design changes in the front end to help with CD.

one thing the duals have over the "super single" couldnt remember the term, thanks..

When one of the duals turns alligator,
you still have something to rely on to get you off the road safely..

with a super single, your done..
pull it over and change your log because your no longer making money.

This mod is to Rigs as spinner wheels are to SUV's/trucks.. uesless showoff crap..

actually i think they run intertubes, like in NASCAR, so if they do have a blow out, they will still have a few inches of rubber, so they can safely change in. Even with duals, if you have one go out, then you still have to pull over to change it because then the weight bearing tire on that axle may not be able to handle the added stress.
i don't really remember it all, i was exhausted when we even got to the show, so i'll have to call my more alert buddies on what they remembered about them.

if your a self employed trucker... a new rig ain't gonna be cheap. It's like buying a new prius, or stick with the old beater. how long will the gas save you to make up for the 20grand you spent on the prius?

I think that modding the back is a bad idea. if you boat-tail, people in miata's and small things will get in there and tailgate... that' ain't gonna be pretty. The best bet is to smooth out the front and get rid of Cd there. as well as some frontal area drag.

At these speeds - the trailing edge will show much more significant gains. But, given the longness - I'm fairly certain flow has gone turbulent by the time you reach the end of the trailer....


In any case - you're right about the cost of things.... The cost per ton for a semitruck, as it is now, is pretty cheap. Not comparable to rail, but much cheaper than any of our cars or trucks. I really need to find that fuel and efficiency breakdown by industry chart....

Rolling resistance is usually a bigger issue than aerodynamics for semis. Rolling resistance is at their lowest when tires break in...dropping by significant margins as far as I remember. I wonder if LRR tires are being developed (exist?) for the industry...

I do agree that rail is more efficient than trucking, but isn't (large-scale) shipping even more efficient than rail? How about the marriage of the speed of air shipping, capacity of the trucking industry, low congestion of shipping, and some of the efficiency of rail...the ekranoplan. :p

Ekranoplan
http://www.youtube.com/watch?v=RwKi5...eature=related

Just a little off topic...:)

- LostCause

I dont plan on designing a new truck, I'm not working for peterbilt.

I was just thinking some simple stuff that anyone can do at home to to THEIR truck help ease the pain of the costs of diesel.

I was reading the papers today about how truckers actually are protesting. 80 truckers drove a couple hundred miles to protest at the state capitol.... I wonder sometimes what they think burning up extra gas, not doing any actual work, and demanding special treatment about something that isn't under the capitols control is going to do.

But oh well, its America. That **** flies all the time.

I don't agree that rolling resistance is a bigger issue, though it's pretty obvious that with 18 wheels, there's a heck of a lot more rolling resistance on a truck than a car. Add a full load and it gets worse.

With those big gaps, the enormous open belly with girders and spares and tanks hanging in the breeze, and the bluff nose and tail, the aero of a truck is accurately described as "brick-like," if the brick had a few extra cracks added to it.

My understanding is that rolling resistance increases as a linear progression, but aero is a exponential progression. So the rolling load increases, but not as fast as aero drag does.

Trucks are just about the most inefficient way to get bulk goods from here to there. For distribution inside a city they make great sense, but for anything longer than 200 miles I'd say load it on a train.

At some point, someone posted a great link to an informative article published by one of the Diesel engine manufacturers (Cummins, CAT, Detroit Diesel). My other laptop fried with the file :o

It's posted here somewheres...

Not only does rolling resistance play a part, put you'll see tire alignment, wear, etc.

I like this Wiki page -- efficiency of each mode of travel and transport.

RH77

I forgot where I read the rolling resistance information, but it depends heavily on speed. Any trucker doing the legal limit (55mph) and not fighting a headwind/crosswind, will see most of his fuel being spent on rolling resistance...especially when brand new tires are fitted. Above 55mph, drag starts shooting up immensely dur to air drags exponential rise (as you've noted).

Again, I've forgotten the exact penalty truckers pay for speeding slightly (~5mph), but I remember it being fairly immense (~25% FE hit, I believe). At 55mph, air drag is a major source of drag...but I am pretty sure it is not the overwhelming source. Ofcourse, lowering it will still help immensely...but the point is that rolling resistance is a big deal in the trucking industry.

- LostCause

Cultural Learnings of America for Make... Er, I mean, Cummins Reveals Secrets to Great MPG. Page six has a nice graph, and according to it, if trucks dropped from ~75mph to ~60mph, they'd see a good ~30+% increase in efficiency. In other words, if they slow down to ~55-60mph across the board instead of the ~70-75mph I've seen, they would see the equivalent of $3/gallon diesel even with prices at $4/gallon due to the increase in mileage. That being said, given the horrible drag coefficient of most rigs, aeromods could probably do the same as slowing down a normal rig.

Yes!
 

Yes, that's it! This should be essential reading for any hypermiler -- the truck techniques transfer to any vehicle quite easily (in most cases).

(It's now saved on the backup computer) :thumbup:

RH77

Maybe if they did a partial kammback or something... oh, and remember there's bars in the back, so no boat-tailing from the bottom. If they did the sides, there's still a visibility issue with vehicles hiding inside of the 3/4 boat-tail. So I think a Kammback would be the best bet for the rear.

Arg... I really hate statements like this...
It makes it sound like aero shouldn't be considered at all below 50...

According to that chart - aero costs ~140hp @50mph, a tad below 100hp @40mph, ~50hp at 30mph....

Seriously, 50hp is half of my engine's output... And that said - according to that chart - aero beats tires around 20mph.. what gives? I may be reading that chart wrong (whenever I use a chart like that - the x axis is zero for everything)...

Trains are indeed more fuel efficient than trucks. Look at one from the air...it approximates the shape of a spear. Add to that the rolling resistance is the same as a rubber tire on polished glare ice. Railroads are generally laid out along water grade. There is still a bit of track at over 2% grade but there ain't much. Even the UP's Sherman Hill grade and CSX' Cheviot Hill got bypassed.

A train will generally reach what railroaders call the "ruling grade" (a combination of steepness and length) and when the train tops that grade, the engineer can coast the rest of the way to the next stop. Quite often they will top the ruling grade and have to immediately go into dynamic braking.

Another advantage of railroads is that the amount of mainline track (where most of the energy is used) is down to about 10,000 miles. We are reaching the point where mainlines could be electrified. Electrification is well-proven old tech. Electrification allows railroads to free themselves (for mainline use at least) of oi and they could use electricity which in the US is mostly generated by coal or nuclear power. Speaking of dynamic braking, an electrified line can recycle about 85% of the energy needed to climb a hill. When a trian reaches the top of the hill, a dispatcher holds the train until another train starts up the hill. The train at the top of the hill is released and goes into dynamic braking and feeding the electricity back into the catenary, where the climbing train can use it. Very efficient.

Drawbacks of electrification: High capital cost. $10 million a mile on average. Railroads run at nearly right angles to high-voltage transmission lines. Lots of new high-voltage rights of way will be needed. Catenary electrification is butt ugly. The US does not have enough excess electricity to run electric mainline operations.

Yeah, that sounds to be an oversimplified statement -- probably to appeal to city-only drivers to focus mostly on tires, etc. The graph doesn't seem to equate. I used the x=0 as well (which is confirmed by the legend). Probably what their doing is stating that aero and tires are equal at 50, but is actually double, which negates the x=0 assumption of evenness -- which happens at, what ~18 mph?

The UP/BNSF Cajon Pass (~11%) and Tehachapi Loop series at 2.2% is also a tricky combination. But -- it's the main passage from LA to points East (big Intermodal traffic) so they keep rolling. Risky business.

That sounds like a great idea -- aside from the cost, the fuel saved on the ascent would pay for itself quickly.

I figured it out... Zero is at the line of the item below the one you're looking at. The zero for tires occurs at the top of "other" and the zero for aero occurs at the line for tires. When you calculate the range based on that - it matches the data written (and a graph a few pages down)...

A poor method to communicate data :p

The one right over the 50mph quote, right? It seems about right according to the graph. At 50mph aero power is about the same (It looks it be slightly less, but not by much) as rolling power, and after that aero becomes a larger component by a wide margin.

Edit-OIC! Yeah, that's a funny way to graph it but it allows people who don't have experience with graphs to see the breakdown and differences.

That being said, since IME, a lot of transport companies, such as LTLs, tend to run their trucks at less than 80,000lbs GCW, the point where aero drag is the same as rolling is probably ~30-40mph.

Oh, and the reason why I'm seeing grocery trucks doing 50-55mph consistently is because their GCW is probably less than half of the 80,000lb GCW Cummins assumed, so at 65mph the ratio of aerodynamic to rolling drag is probably about three or four to one as opposed one and a half to one, meaning that as long as they use their gearing well, dropping 15mph probably increases fuel efficiency by ~30-45%. As diesel prices increase/hold, even hedging will become harder, so I imagine carriers will start driving efficiently in greater numbers.

Look what I found: http://www.alternative-energy-news.i...hybrid-helper/

Maybe they should build them like this.

http://lh3.ggpht.com/abramsv/SAGvHA2...0/727out.0.jpg
http://www.mavromatic.com/images/wingless727.jpg
Yes, it was a 727, now it's a limousine with seating for 50, top speed of 124mph (200kph) and runs on a 6 cylinder turbo-charged diesel.

picture no worky

After all this reading I thought about this ... The gap between truck cab and trailer is quite large and no doubt impacts efficiency. What if at highway speeds the fifth wheel was able to draw the trailer closer to the cab thus eliminating or reducing the gap and improving MPG's. I guess a technology very similar to the porsche tails or the VW turbo wing, just on a larger scale.

Here's an interesting SAE paper on aeromodding big rigs: http://www.solusinc.com/pdf/2003-01-3377.pdf

And here's their website with links to their products in the lefthand column: http://www.solusinc.com/index.html

I think Cajon Pass grade is 1.1%. The theoretical max grade for steel wheels on sanded steel rail is about 6% for the locomotive only.

As a rule one uses a cog railway in excess of 5%.

Back on topic, it would astound you how far trains can coast. Quite often you pass the "ruling grade" and coast 50-70 miles or more to the division point. For instance on the old B&O (now CSX) St. Louis division the ruling grade westbound was at Loogootee Indiana. Once over this grade, the train coasted all the way to Cone Yard in East St. Louis. Yep. The train coasted all the way across Illinois and was on the brakes just outside Cone.

Trains are 4-8 times as fuel efficient as rubber-tired vehicles, but they are terrible for door-to-door service.