Wind Deflectors

Whenarewethere · Guru

RE: Wind Deflectors

iana · Guru

Whenarewethere wrote:
Any wind at an angle will probably make a mess of a headwind only.

What do you mean ?

Long Weekend · Guru

I was interested in the ascertion in the video that turbulence gets UNDER the van, causing instability. First I have ever seen that theory.

Next an enterprising business will be offering a skirt to fit at the front of vans to prevent wind from passing under vans.

Murray

Whenarewethere · Guru

If you only have a headwind you only have one problem.

If the environmental wind is coming from a different direction the combined wind will now be at an angle.

Whenarewethere · Guru

Long Weekend wrote:
I was interested in the ascertion in the video that turbulence gets UNDER the van, causing instability. First I have ever seen that theory.

Next an enterprising business will be offering a skirt to fit at the front of vans to prevent wind from passing under vans.

Murray

Better to do what Land Rover does. Lower the caravan on the highway & raise it for off-road.

iana · Guru

Sounds reasonable, that's why aircraft have variable pitch propellers.

-- Edited by iana on Monday 11th of October 2021 08:37:46 PM

yobarr · Guru

Long Weekend wrote:
I was interested in the ascertion in the video that turbulence gets UNDER the van, causing instability. First I have ever seen that theory.

Next an enterprising business will be offering a skirt to fit at the front of vans to prevent wind from passing under vans.

Murray

Hmmmm.Seems my full width mudflap,designed to prevent too many stones bouncing under caravan,may have another use? Cheers

Cisco kid · Veteran Member

My experience is that you get a small fuel consumption reduction but more importantly less turbulence between the back of your car and front of your caravan , so better stability

KevinJ · Senior Member

iana wrote:
Sounds reasonable, that's why aircraft have variable pitch propellers.

-- Edited by iana on Monday 11th of October 2021 08:37:46 PM

I thought variable pitch propellers were a bit like the gears in a manual car. When set to "Full fine", for either take off or landing, you were in a low gear and had the power to take off or whilst landing, had the power available in the event of a "go around" and whilst at altitude in cruise mode, it was set to a coarser pitch, a bit like a higher gear in a car.

iana · Guru

Its more about maintaining the correct angle of attack of the prop blade to the relative airflow. When the aircraft is stationary, the relative airflow is at 90 degrees to the axis of the aircraft. As the aircraft begins to move, the relative airflow alters and is a result of the combined forward on coming airflow and the airflow to the rotating prop.
So on take off the prop would be set at fine, and would would have a theoretical angle of attack of 14 degrees, but at 400 mph the prop would be near full coarse, but still have an angle of attach of 14 degrees, to the relative airflow.

Long Weekend · Guru

More simply, the use of fine pitch and course pitch on aircraft propellers is because of air density. At ground level the air is denser, fine pitch is used. At height where the air is thinner course pitch is used.

Murray

Peter_n_Margaret · Guru

yobarr wrote:
Hmmmm.Seems my full width mudflap,designed to prevent too many stones bouncing under caravan,may have another use? Cheers

Should be banned, IMHO, for the rocks they throw at other vehicles and the damage they do to unsurfaced roads.

This is a bitumen road. Imagine the effect on a gravel road.

Besides, from an aerodynamic perspective, the air dam needs to be at the front, not the rear. Having it 2m in front of the van body would be worse than useless.

Cheers,

Peter

-- Edited by Peter_n_Margaret on Tuesday 12th of October 2021 04:12:34 PM

diggerop · Senior Member

Full length mud flaps also disrupt the cooling airflow to the transmisson and diff, more so the diff.

yobarr · Guru

diggerop wrote:
Full length mud flaps also disrupt the cooling airflow to the transmisson and diff, more so the diff.

Bit of confusion evident here? My post followed Murray's comment about "offering a skirt to fit at the front of vans ,which is where mine is. I am well aware of the issues with overheating the diff,and I agree with Peter's assertion that full width should be banned from the rear of vehicles,and that having one fitted two metres in front of the van would be worse than useless.On a recent 200km on a very corrugated dirt road,I managed to break many water pipe fittings and taps under the van,but since getting the full width mudflap fitted to the front of the van I have covered another 1000km on similar roads,with no problems,so I think it now is sorted! Cheers

Peter_n_Margaret · Guru

Wherever a full width flap is fitted is bad news for other drivers and bad news for gravel roads.
Cheers,
Peter

iana · Guru

I'm puzzled, why do full length mud flaps toss up stones, when mud flaps must be fitted to wheels just to prevent that ?

Seaeagle63 · Member

Wow. This has gone from wind deflectors to aircraft aerodynamics. Im not towing a van at 35000ft, at most 200m above sea level. . Anyway thanks to everyones thoughts both negative & positive. I do have a tonneau cover but no canopy. Would a canopy make much difference to the aerodynamics? Or would it be better to get a better tug vehicle. Tossing up between Mazda BT50 & Isuzu D-Max. I have been told they have exactly the same drivetrain.

Cheers for all the help.

Possum3 · Guru

iana wrote:
I'm puzzled, why do full length mud flaps toss up stones, when mud flaps must be fitted to wheels just to prevent that ?

It could be that the centre of the wide flap bumps and drags along centre of road (wheel ruts allowing build up of gravel in centre). Other problems are heating up of diff and creation of dust.

Peter_n_Margaret · Guru

iana wrote:
I'm puzzled, why do full length mud flaps toss up stones, when mud flaps must be fitted to wheels just to prevent that ?

They throw dust and stones by virtue of the high air turbulence they create at ground level.

Check the photo I posted.

Mud flaps deflect stones thrown by the tyre tread. They will also throw dust and stones if too close to the ground. Full width ones even more.

Cheers,

Peter

-- Edited by Peter_n_Margaret on Thursday 11th of November 2021 02:33:21 PM

Aussie1 · Guru

Bloody hell, ban full width mud flaps, ban generators. Lets keep the list going on things to be banned. If we keep going that way, we will at least solve everyone's over loaded issues.
:):)

SoloMC · Senior Member

If you have the time to wait out the wind, hang back for a few days and the wind will change direction and you will get a push. I think anyone who is concerned about rocks from oncoming vehicles should probably reconsider their need for travel on dirt roads. I have a specialised wind deflector on my roof. It's a boat. There would be some research done on those deflectors done by some university somewhere but I would suggest that the benefit would be minor. Many semi trailers have specialised deflectors fitted to the cab so I assume they work I think the benefits from a small aftermarket one would be minimal

Aus-Kiwi · Guru

Full length mud flaps create a vacuum, pulling stones off the road . Mind you a long trailer can do that anyway ?
. Most full width are two or three piece these days .. Not an issue on van . Keep in mind no matter the wind direction . Your STILL traveling at considerable pace . Yes in Europe they have side skirts for two reasons . Airo and to prevent cyclists etc getting caught between wheels ! Another good part I found helpful was air deflectors help ward off low tree branches from fitting items on roof . Awning, sat , AC etc . Guides over . Hopefully !