U Mich Study: Bed Cover reduces drag by 22%

[jbplock]

Interesting Study ...

Aerodynamic Characteristics of General Motors Truck (http://sitemaker.umich.edu/um.gm.truck)

"four configurations tested affected the drag as follows:

Sloped Cab Extension: + 5.66 %
Tailgate Off: + 3.92 %
Spoiler: - 6.98 %
Bed Cover: - 22.03 % :eek:

Where a plus sign (+) indicates an increase in drag and a minus sign (-) indicates a decrease."

smile.gif

[Seth McKinney]

Nice -- a bed cover it is then...

[Seth McKinney]

Wait a second -- how in the world would taking the tailgate off increase drag???

[madmatt]

I've read that before also(the tailgate thing). It has something to do w/ the tailgate creating a pocket of turbulent air behind the cab that allows for cleaner airflow over the cab and bed by not allowing the "clean" air to suck in behind the cab therefore creating sort of a "vaccum" effect. Thats just how I remember reading it.

[mjammer]

I wish they would have measured a full height truck cap too.

[More Power]

One of GM's prototype Duramax trucks Chevrolet brought to Montana in 1999 had a soft tonneau. It was thought that they used this truck for fuel economy tests.

Didn't Banks' diesel land speed truck have a tonneau? Craftsman's series trucks? smile.gif

MP

[madmatt]

the Banks truck used a partial cover that covered about 2/3 of the bed forward of the tailgate then sloped down to the bed floor near the cab.

[HammerWerf]

I think the idea of a "bubble" forming in the bed is true. I have noticed while driving my 83 CC(no cover or cap) at about 40mph, if I had a paper wipe into the bed it would "jump up and down" to about the roofline. Kinda entertaining for me, but I wonder what the chaps following me thought.

HammerWerf

[Turbo Al]

It's all slaps and giggles then when we see someone without there tailgate saving money on fuel tongue.gif

I hate to say it BUT before I got any brains at all I drove FORDS--there I said it--More Power PLEASE don't ban me!

Anyway the 1989 gas pot I had got 1 mpg+ better after I installed the fiberglass bed cover which weighed about 200 lbs.

[Craig M]

They ran 5 different wind speeds in the wind tunnel They should have 5 different sets of results. Are their results the average of the 5? the highest velocity? or? Testing is a great idea, but precision of the results is required, not just a simple number. The next question is how does drag relate to fuel consumption.

[Craig M]

70 meters per second is equal to 157 miles per hour.

[Jim Brzozowski]

The lower the drag coefficient the lower power required to push the vehicle thru the air. Obvoiusly less fuel to do so.

[Craig M]

E-mailed the name at the bottom of one of the pages for the study. The testing was done a few years ago so not sure if she is still at the University. Trying to get a few answers on the testing and data.

[Craig M]

Got no response from the email noted at the bottom of the study. Must have graduated and gone on. Would like to get sdome answers and raw data.