As a general rule air scoops on the roof of the car are not much of an advantage unless they extent to very close to the van as air turbulence is created behind the scoop.
They do help in front of a bulky load stored on a roof rack.
Keeping down the speed to 80/85 km per hour would do more to reduce air resistance, save fuel, and reduce swaying.
Cheers, Tom
__________________
I had a thought but it got run over as it crossed my mind.
Can't imagine why caravan haulers are so hated by the rest of the road users. Seriously, if you have to become a "mobile chicane" in order to save a few dollars, you need to ask yourself if you can afford to go on holidays.
I tried the idea many years ago and it made absolutely no difference so total waste of time and of money in building it,as greyhoundtom said far more effective to drop the speed a bit but not to the level where you hold up everybody behind as this can be very dangerous.
__________________
Life was meant to be enjoyed Australia was meant to be explored
Happily doing both to the Max.
Life is like a camera, focus on what's important & you will capture it every Time
Can't imagine why caravan haulers are so hated by the rest of the road users. Seriously, if you have to become a "mobile chicane" in order to save a few dollars, you need to ask yourself if you can afford to go on holidays.
The fuel savings for traveling at 85 km per hour unless rolling down a hill instead of 100 km per hour add up to around 2,500 to 3,000 dollars per year while doing the big lap. Certainly worth my while.
Most hated? So be it, but then whenever possible I do everything I can to assist trucks and coaches to get past me safely with the absolute minimum holdup.
Cheers, Tom
__________________
I had a thought but it got run over as it crossed my mind.
A total waste of time & money as well as additional useless weight. They were trendy back in the 70's, then gradually died out. I recently took my deceased Father-in-laws one to the Tip. He had a map of Australia painted on it & places he'd visited marked on it. Back in WW2 he drove Army supply convoy trucks up the Centre & back to Darwin. In retirement he still fancied himself as a truckie even though he was towing a 12ft 6in Viscount caravan with a Holden Commodore. LOL. They're not really coming back into fashion are they? LOL.
-- Edited by Desert Dweller on Thursday 24th of September 2015 06:46:05 PM
__________________
Cheers Desert Dweller.
Our land abounds in Natures gifts. Of beauty rich and rare.
They may or maynot be of any use but the only way to tell is in a wind tunnel , I have played with aerodynamics on my race car for many years . they clean up the air flow for sure but the placement is critical . at 240 kph my rear wing deflects down 200mm without the centre stay but at 80 kph I doubt if they would have a great effect . it would probably only clean the air flow between the tug and van.
Hi aussietraveller, back in the 80's I had one on our lwb F100 fiberglass canopy for 20 years, fitted right at the back of the canopy with adjustable annex pole top struts about 300 long and the deflector about 350 high by memory, so you could adjust the angle to suit.
To set it up,we trialled a deflector setting and got up to cruise speed and released a handful of leaves over the cab roofline, to see in the mirror where the leaves hit the front of the van at cruise, and then made adjustments to get the leaves
as high up the front of the van till the deflection height started to start to come back down,and then marked that point on the strut for future reference next time. You may not get the leaves over the top,but even half the height difference up the front
of the van is a huge deflection of wind. When not towing, it folded down flat on the roof out of the way.
You just need to spend a bit of time to set the angle to optimum for it to work.The setting would be an individual thing to each vehicle and caravan combination.
Height of vehicle, distance between back of car and van front, then the height and slope of the roof line of the van.
as we read here a couple of weeks ago on this subject , it's about drag.
I have an SUV , a pop top . Both Relatively modern.2009car , 2008van.
I have a Modern approach to this "vanning thingee" , rather than >
"Let's hook up th van & p*ss off"
from my experience of driving diesel vehicles , during daytime . They Love
to sit on 90 to 95 k an hour , after "dewpoint" they want to party a bit , then ,
come th night time , they want to party all night , well seeing we are day time folk,
it seems 90 to 95
I for one could not agree more, when the sun goes down out comes the kid in me, but now after 40 plus years of driving all sorts of transport all I want to do now is to be parked by sundown and cruise along at or about 90 so I can see the country side and be an easy target to get around.
I also don't like to be on the road before 9am to allow the parent to race there little ones to school.
Dunno about a wind breaker on the top, but a wind breaker on the front seat definitely slows you down because you have to open all the windows to let it out. And that causes more drag..
__________________
Yes I am an agent of Satan, but my duties are largely ceremonial.
