DodgeTrucks.Org

[HankL]

a short sweet introduction:
http://aerodyn.org/Annexes/Roadv/roadv.html

and a follow-up on a few tricks to reduce drag in 'bluff bodies' like pickups:
http://aerodyn.org/Drag/vxdrag.html

It is interesting to note some of these tricks applied to the rear roof surfaces of the newer Ford F150, tailgate of Silverado, rear wing of the SRT-10, etc

Perhaps some Dodgetrucks experimenters could come up with mods to the 1994-2000 Rams that work?

A relatively easy way to see if you have improved the aerodynamics of your truck is to coast down the same hill in neutral - if you start at exactly the same speed, wind, and air temperature an increase in speed indicates improvement.

It is easy to test this out on a long hill by opening all the windows on the second run.

If you coast down with the truck empty of payload, then coast a second time with near maximum load (1900 to 2500 lbs) in the bed, you can even solve two equations in two unknowns to find both the Cd and the rolling resistance of your particular tires.

[RamThis]

Thats some cool stuff, thanks!!
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View My Gallery

[skyjockey]

Ummm OK
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1997 RAM1500 4x4 Sport, auto 5.2L gas hog (~11MPG)
1994 Corvette LT1 300HP, auto, economy car (~18MPG)

[HankL]

More thought provoking aero articles:

http://www.autospeed.com/cms/article.html?&A=1071&P=1

http://msuinfo.ur.msstate.edu/alumni/connection/98_spring/golf2.htm

http://www.dimpletape.com/

http://www.airtab.com/

http://www.hayes-lemmerz.com/html/pngv_program.html

http://www.clarkson.edu/~visser/research/drag/truck/

[04HadaRam]

good posting Thanks

[HankL]

This webpage about some undergraduate engineerings students SAE award winning project on the aerodynamics of a 2nd Gen 1997 Ram standard cab long bed pickup was taken down a year ago, but the 'Wayback Machine' at the web.archive.org had this stored page in their files:

http://web.archive.org/web/20030414190338/http://mars.acnet.wnec.edu/~ehaffner/did.htm

Note that the blue links no longer work, because they point to the old taken-down web address.

You can go to these old pages by copying the old link location, then entering it into the web.archive.org form, but the pictures don't show up unless you do the same with their web address too. Here, for example are the links to the Tonneau page, and below it the link to the Tonneau page picture:

http://web.archive.org/web/20030414234348/mars.acnet.wnec.edu/~ehaffner/Tonneau.htm




Notice that they tested without windows on the Ram pickup, so real world results would be a little higher.

notice the 11% reduction in drag the tonneau gave. At 75 mph this much reduction would be a MPG increase of about 1.

The 'rule of thumb' is that a 10% reduction in aerodynamic drag gives about a 5% improvement in MPG.

[Steve00Ram360]

Hank, you have way too much time on your hands...
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2005 Ram 2500 QC 4x4 5.9 SB
edge w/attitude, 30" magnaflow muffler, AFE Stage 2 pro-guard filter

[Zaurusman]

[The_Trooper]

Hank's posts are as good (if not better) than the dodge techs themselves. I love when he posts because I actually learn something about my truck. But then again he just reminds me how little I actually know .
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'97 Ram CC 4x2 360
Flowmaster catback system, High flow cat, Mopar PCM, Hedman Headders shorties, F&B 52mm TB, Mopar 14 x 3, M1 4bbl intake , 180 T-stat, 21# FMS Injectors, MSD box and blaster coil for later model Mopars.
'73 Charger SE with a 446ci, 750 Vacuum Secondary Holley, TCI 727 Transmission, Edlebrock Aluminum 94cc heads, Speed Pro pistons, Mopar purple cam, Crane roller rockers, aluminum water pump... and much more.
Coming soon: eddy intake.
2006 Infiniti G35x Bone stock daily driver.

[HankL]

this webpage has a collection of aero links,
ranging from teaching the basics of aerodynamics to grade school students, to advanced vehicle and airplane topics like aerodynamics of fan blades, helicopters, etc

http://www.aerospace-techlinks.com/Top_Science_Technology_Aerospace_Aeronautics_Aerodynamics.html

[skyjockey]

Glad I got me the Tonneau cover when I bought the truck. Must have paid for itself by now
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1997 RAM1500 4x4 Sport, auto 5.2L gas hog (~11MPG)
1994 Corvette LT1 300HP, auto, economy car (~18MPG)

[HankL]

For the first time I have seen a Cd for the body modifications used on the SRT10 Ram. This webpage:

http://trucks.about.com/od/2005pickuptrucks/a/ramsrt10_quad_2.htm

reports that the Cd = 0.45 and the frontal area = 34.6 square feet

Since the SRT has:

factory tonneau,
rear wing {both lift and drag reducing according to an earlier press release}
lowered suspension
different mirrors
'poseur' hood scoop

It looks like these mods drop the Cd of the SRT10 from the 2500 3rd gen Ram's figure of 0.50, which is a not so bad 10% drop. That kind of drop would increase the MPG by about 1 at 70 mph.

But note that even with these improvements the SRT 's aero drag is worse than that of a plain, non tonneau equipped 1994 model year 1500 Ram's Cd=0.44 and frontal area = 34.5

[salarguy]

Where could we use AirTabs that would work, and be out of sight?
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Salarguy'97 Ram 5.9l 4X4, Where are the Dodge Brothers when you really need them????????

[HankL]

I have not tried the airtabs, which are molded out of plastic and cost $4 each, just the previous metal version from the same inventor called 'Streamliners' .

Have a look at this pic first:



I did a test and found that mounting 7 streamliners on a magnetic strip on the rear of the roof of a 1995 Ram Clubcab did not improve the MPG at a steady 70 mph. In fact it seem to hurt.

But the idea of using a 'Wheeler Vortex Generator' to improve aerodynamics is so well established on airplanes I still felt that putting them in a spot where they would 'kill' the vacuum of 'form drag' somewhere on the truck.

Since that test, I have cut the original Streamliners strip of 7 into individual units and tried mounting them on the sides of the truck just in front of the brake lights, and on the vent windows. My idea here is to try killing form drag from the sides, not from the roof. Looking at the red Ram in the smoke stream pic:



the idea is to try to kill the vacuum behind the rear window, and the vacuum behind the tailgate, by placing a few vortex generators on the sides. I have also put one Streamliner on the center of the roof.

I have not done a full MPG test, but I have tried coasting down a hill with them on/off. I could not tell if they improved things.

One interesting thing I did find: with a Streamliner mounted in the vent window the wind noise is less.

My guess would be mounting 3 airtabs on the vent windows, and two airtabs just in front of the rear brake lights on the sides might work - but only testing would tell. But I am not sure spending 10 times $4 = $40 plus shipping cost would be worth it. The molded plastic Airtabs are 'slicker' looking and may generate the vortices without creating as much unwanted drag. If this is true they may be worth the extra money.

It is not hard making a Streamliner out of any piece of metal that you can cut into a circle.




Those metal pieces in the pic above are actually 4.5 inch diameter stainless steel circles with those two 'fins' bent up on each side. Very simple to make.

Common large food can lids will work. Aluminum 'Flashing' for roofs will work and is easy to cut with tin snips.

A 4.5 inch circle is 14.1 inches around the edge. To make a Streamliner cut out a 4.5 inch circle and then mark a 7/8ths inch long arc on one side and directly across from it a 3 and 7/8ths inch arc. Draw lines connecting the ends of the two arcs and bend these fins upward to a little less than straight up - say about a 80 degree angle.

If you want to make a Streamliner out of a piece of metal different than a 4.5 inch circle, measure out a 22 degree arc on one side and a 99 degree arc opposite it, then bend up the two fins. I believe you could make one out of any size circle of metal from 3 inches to 6 inches.

You can mount your home-made streamliner vortex generators by either gluing them to 'kitchen magnet strips' like in the picture above, or using the strong 3M 'auto trim' double sided tape available at Target stores, or use rubber cement.

Mount the wide end toward the wind and the narrow end downstream. Each 'fin' will generate a minature 'tornado' horizontally.

I have also wondered if putting a streamliner behind the front tire would create an artificial 'side skirt' that might reduce drag.

[HankL]

Freightliner unveils wind tunnel

Freightliner last month opened a 12,000-square-foot wind tunnel at its Portland, Ore., base, allowing the truck maker more flexibility in researching and testing the aerodynamics of medium- and heavy-duty trucks. Until now, Freightliner has had to use other wind tunnel facilities in other cities at a high per-use charge. More important, company officials say, the new Portland facility was designed specifically to accommodate a heavy-duty truck.

?The new wind tunnel facility is an example of Freightliner?s continuing focus on technological leadership in the truck manufacturing industry,? said Freightliner President and CEO Rainer Schmueckle. ?The wind tunnel will help us make further gains in aerodynamics and fuel efficiency, which will ultimately lower operating costs for our customers.?

Long-term, the company has set a goal of a 15 percent reduction in drag, which would translate into an estimated 5 percent improvement in fuel efficiency. Company engineers say they will reach this milestone not by a revolutionary revamping of truck design but through dozens of small, almost imperceptible, changes in design. That?s why Freightliner believes having a dedicated on-site wind tunnel will give it an edge.

Wind tunnels are typically very expensive facilities, but Freightliner built its Portland wind tunnel at a fraction of the cost of similar facilities. To save on space, the tunnel is designed to accommodate a heavy-duty tractor and only the front end of a trailer. Because Freightliner only controls design of the power unit, it decided it only needed a small portion of the trailer just to determine the aerodynamics at the point of mating. Also, the company used largely off-the-shelf commercial ventilation fans rather than customized fans typically used in such facilities.

{Freightliner is owned by DaimlerChrysler, and was the US 'training ground' for both Chairman J. Shremp and current Chrysler Pres D. Zetsche}