Hi Kazken, Welcome to the Gang, I can tell you that the wind defectors DO work, I fitted one to our Patrol for a trip around the Block,
I was ready for the wind blast from The first truck that passed, but there was nothing at all, it has since proved it's self over and over again.
Just to test it before we left on our trip, I fitted a large roof rack on top of the Patrol filled it with a spare tyre plus fuel tanks and an upright gas bottle,
I then hooked up the Caravan, turned on a high powered hose and aimed it at the windshield, the spray of water deflected right over the top of the caravan, this proved to me that the shield was doing it's job with ease.
picture taken in Tenterfield NSW around MAY 2010
If you live near Perth, I now have the Windshield for sale, dead cheap at $ 150.00 ONO
K.J.
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From Coast to Coast, We'll see it all.......One Day
To answer your first question Fringe Dweller, There was no noticeable dirt on the rear of our patrol,
Now please tell me, if as you say these wind deflectors don't do any good at all, Why has the truck in your photo got a dirty great wind deflector attached to the cab ???
As you stated, they don't help with the Drag, I suggest that with a great flat surface on the front of your rig, would be causing a heap of drag,
For the life of me I can't see what use a nose cone would be, apart from making the wind blow a few insects off the wind screen.
Anyway, everyone to their own opinion , and I do know that as far as the wind deflector on our Nissan went, it did the job and I was more than happy with the results.
K.J.
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From Coast to Coast, We'll see it all.......One Day
During the training I had as an apprentice, I had to do quite a bit on aerodynamics. What we were taught was that the front of a vehicle / aircraft was not that critical in reducing drag, as a high pressure cell or pocket formed there and the airflow went around it, sort of like natural streamlining. The worst area of drag was at the rear, and profile and induced drag not helping. The slower the vehicle, the less effect drag had on it, as drag increases at the square of the speed.
Induced drag is putting protrusions out into the airflow, e.g. roof racks, air con units etc., profile drag is the actual form of the vehicle. Personally I think any addition one adds, the improvement would be all in the mind, compared with the massive drag caused at the back of the vehicle.
Out of curiosity I just Googled "Streamlined trucks", and streamlined cars"", it seems that during the 1930's, streamlining was taken very seriously. The pictures there of trucks and cars show the blunt nose, streamlined and tapered rear end, with no protrusions into the airflow nicely. From a practical point of view, the shapes are not very economical, as trucks loose load carrying ability, and only some sports cars these days streamline like that.
Hi Desert Dweller,
As you say back in the 70s and 80s I had one fitted to the long wheel base F100 for years, on the canopy at the back with adjustable rear legs so you could change the angle to get the optimal set, and to set it I grabbed a handful of dry leaves to release over the F100 roof once you got up too cruising speed,
while watching in the mirror release the hand full of leaves and see how far up the van front they rise, then keep raising the angle till they pass over the top edge of the van roof and mark the leg and lock it at that point. [ bush engineering ] It has to be done this way too get the optimal angle set with the least amount of drag.
My deflector was 300mm high and the full width of the ute body with adjustable top annexe poles cut to size for legs. You cannot just put up a piece ply on any angle and think that will do the job. this is why some people think it is a waist of time. When you unhook the van for any period, you can lower
it down flat out of the wind. I hope this is of help to some people.
The deflectors on trucks are designed in wind tunnels to get the correct shape and angle and cost hundreds of $$$. They do work.
