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NASA - Dryden Flight Research Center Truck Aerodynamic study.

Just thought I'd post up this link, pdf file 170 pages, most have probably already been there, but for those that haven't:
http://ntrs.nasa.gov/archive/nasa/ca...2011024974.pdf
Just a quick summary on the van study, the numbers clearly outline the benefits of rounded edges all around:

Quote:

.....a standard passenger van modified at the Dryden Flight Research Center to investigate the aerodynamics of trucks. The resulting vehicle--re-fashioned with sheet metal--resembled a motor home, with rounded vertical corners on the vehicle's front and rear sections. For subsequent tests, researchers installed a "boat tail" structure, shown in the photograph. During a decade spanning the 1970s and 1980s, Dryden researchers conducted tests to determine the extent to which adjustments in the shape of trucks reduced aerodynamic drag and improved efficiency. During the tests, the vehicle's sides were fitted with tufts, or strings, that showed air flow. The investigators concluded that rounding the vertical corners front and rear reduced drag by 40 percent, yet decreased the vehicle's internal volume by only 1.3 percent. Rounding both the vertical and horizontal corners cut drag by 54 percent, resulting in a three percent loss of internal volume. A second group of tests added a faired underbody and a boat tail, the latter feature resulting in drag reduction of about 15 percent.

Thanks. Haven't seen the full report. More reading...

Of course it doesn't want to load cleanly right now. Reading for later.

Quote:

Originally Posted by ennored (Post 353181)

Thanks. Haven't seen the full report. More reading...

Of course it doesn't want to load cleanly right now. Reading for later.

Yeah, I had a bit of trouble,
I have found with some of these bigger pdf files it's best to just open it and leave it alone for 10min before you start scrolling, scrolling straight away seems to lock into some foreign code/script.

Here's another NASA paper, not results, more so proposals,
But there is some good explanations how things work, particular detail in boattail section:
http://wire.epfl.ch/files/content/si...A%202007-6.pdf

Ahhh, patience does the trick. All downloaded. Chock full of info. Gotta read it now, only skimmed it so far. The appendix of patents is cool. Lots of stuff that is pretty clearly less than optimum.

Thanks.

I bet this is the basis for the NASA Ames newsletter ("Astrogram") article that I read back in the late 80s or early 90s. Ames used to manage all of Dryden's NASA activities; I'm not sure if they still do or not.

-soD

FYI: if some of those old links do not work anymore, here is why.................

The latest practical consequence of the unhappy times we live in (NASA NTRS offline)
The latest practical consequence of the unhappy times we live in (NASA NTRS offline) - Boat Design Forums

Quote:

Originally Posted by daiquiri (Post 621742)

Today's bitter surprise.

From http://ntrs.nasa.gov/

"The NASA technical reports server will be unavailable for public access while the agency conducts a review of the site's content to ensure that it does not contain technical information that is subject to U.S. export control laws and regulations and that the appropriate reviews were performed. The site will return to service when the review is complete.
We apologize for any inconvenience this may cause."

:(