Re: Who recycles/conserves ?

In article <4jqavaF94rq4U1@xxxxxxxxxxxxxx>,
"Charles R. Kaiser" <ckaiserca@xxxxxxxxxxxxxx> wrote:

Several web sites also seem to confirm this with the following offering
a good description of why: Heller Auto Group Web site,
http://www.hellerauto.com/faqs.htm.

"[...]they actually performed drag tests on pickups with the tailgate
both up and down and found that drag was actually lower with the
tailgate closed! This ran counter to their intuition....
The reason is that a closed tailgate sets up a large "bubble" of
stagnant air that slowly circulates around the bed of the truck (we aero
types call this a "separated bubble").

When air approaches the truck, it "sees" the bubble as part of the
truck. So to the air, the truck looks like it has a nice, flat covering
over the bed, and the air doesn't "slam" into the vertical tailgate.
If the tailgate is open, or replaced by one of those "air gate" nets,
however, that nice, separate bubble in the truck does not form (it
"bursts"). Then the air approaching the truck "sees" a truck with a flat
bed on the back of a tall cab. This is a very non-aerodynamic shape with
a very large drag."

.... Which is great, if your truck is headed directly into the wind, as
in a wind-tunnel. More than likely, though, you're driving with some
component of cross-wind (us aero types call this "some component of
cross-wind" ;), which disrupts, flattens and disperses said "bubble",
leaving you with the former intuitive "hole".

This is why people who don't drive in wind-tunnels but, instead, on the
freeway (like Hutch & Lee) see a marked improvement in mileage with the
gate down.

Covers help, too.

--
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Relevant Pages

  • Re: Who recycles/conserves ?
    ... "they actually performed drag tests on pickups with the tailgate ... When air approaches the truck, it "sees" the bubble as part of the ...
    (alt.smokers.cigars)
  • Re: Aerodynamics acording to Myth Busters!
    ... and caused it to consume fuel faster than the identical truck driven ... It was later revealed that the closed tailgate ... creates a locked vortex flow that created a smoother flow of air over ... wind tunnel and the drag change was noticeable also. ...
    (rec.aviation.homebuilt)
  • Re: Aerodynamics acording to Myth Busters!
    ... Driving with the tailgate down actually increased drag on the pick-up ... and caused it to consume fuel faster than the identical truck driven ...
    (rec.aviation.homebuilt)
  • Re: Aerodynamics acording to Myth Busters!
    ... Driving with the tailgate down actually increased drag on the pick-up and caused it to consume fuel faster than the identical truck driven with the tailgate up. ...
    (rec.aviation.homebuilt)
  • Re: Aerodynamics acording to Myth Busters!
    ... It is more fuel efficient to drive a pick-up truck with its tailgate ... Driving with the tailgate down actually increased drag on the pick-up ...
    (rec.aviation.homebuilt)
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