Quote:
Originally Posted by Gen Disarray
Has anyone else noticed that they get worse push from the box type trucks such as the moving vans?
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Yup, short, sharp and
hard.
Straight trucks (so-called as their is no trailer) are often maxed out as to height/width. And sometimes, not even rounded corners.
I've read today, elsewhere, that the old COE combinations hit the hardest (Cab-Over-Engine; flat front); that they could force aside 18-tons of air at 60 mph. (See link below).
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In the reading around I had the leisure for today, I came across the product called AIRTABS (with which some of you are familiar). They may not save much in the way of fuel (small measurement best applied across a fleet), yet it is remarkable how often, how consistently, other RV'ers are reporting them to be good for mitigating wind-induced sway. Granted, the rolling boxes benefit most:
Air Tabs (vortex generators)
NASA & Vehicle Aerodynamics: Spinoff Technology
Aerodynamics Research Revolutionizes Truck Design
RV Applications: Airtab
Motorhome Test, 2009
http://www.airtab.com/vm/newvisual/a...r2009page2.pdf
Car Hauler Test (rv.net)
I towed down to Watkins Glen and back to Hamilton, [Ontario] on the weekend, first test for the Airtabs. I found that the gas mileage was probably better, but not by enough to really test without some greater mileage, probably on the order of 5% better. The truck pulled fifth gear easier and we ran along easily at 120 Km/hr (75 mph)for a significant part of the trip.
The gain in handling was more pronounced - almost no tractor-trailer induced sway, down from fairly bad sway, and the trailer was more stable in cross-winds as well. Even a bus blowing by at 15 mph faster than I was doing didn't cause a minor heart attack the way it did before. I would say the claims are proven, but with the number of miles I do a half MPG will take a long time to pay back. The improvement in sway control is impressive and worth the money to me.
RV.Net Open Roads Forum: Towing: Airtab test results
One year with Airtabs on motorhome
Coast Resorts - Cookies
Airtabs for [3] years (Airstreamer67)
7.3 PowerStroke in a 1996 F250 towing a 6000 pound JayFeather 25F between 55 and 60 mph when on the highway.
The idea is to prevent as much of the suction effect on the rear as possible. Honestly, I don't think the AirTabs increase the economy significantly, but they surely increase stability in windy conditions and when 18-wheelers zoom by.
RV.Net Open Roads Forum: Towing: how make my Ram increase more MPG towing?
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Finally, a bit of nostalgia. I remember reading this article ca. 1973:
How You Look to a Truck Driver
Popular Mechanics, May 1969
Popular Mechanics - Google Books
There is hope that fuel economy concerns will finally allow us to see more aerodynamic commercial traffic. Hopefully, these "green" tractor-trailers will manage airflow to our mutual benefit in re the topic.
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