Fairing Well,NASA truck aerodynamics
 

Here's a link to NASA's book about their truck aerodynamic research at Edwards Air Force Base,by Christian Gelzer.
All I can say is WOW!
http://history.nasa.gov/monograph46.pdf

Thanks aerohead. A ton of information and a lot of food for thought.

Wow, a good 75 pages of images and diagrams. :thumbup:

Not that there hasn't ever been any money wasted by the gov't, but every now and then you come across something where you just have to say, "as a taxpayer, I got my money's worth out of that". Thanks for the link.

Generally I found it to be a very interesting read. :thumbup:

However, as I plowed through it I noticed statements that were "red flags" to me:
pg 14: 1914 Ricotti wasn't just plans; it was built.
pg 15: Odd how the early aero heavyweights were omitted- Jaray, Porsche, etc.
pg 16: Retractable gear doesn't matter on planes going less than 250mph?? Wrong!
pg 23: Rounded rear corners on "shoebox" better than sharp? Really?
pgs 41-42: Yah, the chopped-off tail worked just as well because the full tail tapered too rapidly- that's why the separation was so bad.
pgs 50-51: Ignorant candy-arse truckers :/
pg 59: COE inherently less aero? Pointy nose better? Less frontal area? From what I've been taught, that's all B.S. Footnote had it right: better ride.
pg 66: Tire nitrogen? Air tabs? Eyebrow rising; starting to lose me...
pg 67: Generate lift, reduce trailer weight 15% = more efficiency? Uh-Oh. How much more of this article is suspicious or worse yet, garbage? :mad:
pg 78: Efficiency = effeminate; inefficiency = macho... TRUTH! SUVs and PUs...

There was more good than bad by a long shot though; to list the good would test my and anyone's A.D.D.

^^ Too right!

Speaking specifically to your point regarding page 16, about retractable gear making no difference:

My favorite airplane (in the private plane sector), the Cessna 182, is also available in a retractable gear design. That alone makes it unique, you don't often see private planes available in both styles.

The fixed gear 182 has a cruise speed of 140 knots, the retractable model - same power - has a cruise speed of 156 knots. That's over 10% more speed. The rate of climb is over 10% better as well, even though the RG plane weighs more.

I do like the 182. It's a very handsome plane, especially in flight with the gear retracted. It comes close to embodying the old "if it looks right, it is right" maxim vis-à-vis small planes.

This paper is a few years old. And some of the stuff in it is decades old. Still a great recent look at a lot of work NASA has done. I've had it saved on my computer for a while. I'm sure it's been mentioned here before, or I wouldn't have known about it.


You must be quoting page numbers in the pdf, not the actual report? (They don't match up.) Just to be clear.

^Yes.

So I looked up Bob Englar and I doubt he's naive. I think this is a garbled-up editing error and I postulate the intended statement was something like, "...and led to as much as a 15% drop in lift on the trailer, improving vehicle efficiency."

That's Englar. Active aerodyamics via pumped air. He found he could effect plus/minus drag and lift by valving the slots on the four rear sides; All on to go, sides off to stop, top off (I think) for lift and bottom off for downforce (or vice versa).

The fuel savings comes from reduced tire sidewall flex, while retaining the ability to quickly drop the load for better braking.

Appendix B is more than I wanted to know about reducing shrinkage on the way to the slaughterhouse.