Seaeagle63 wrote:

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Gday All, just after some feedback from those that use wind deflectors. Are they any good and do they really work? What, in your opinions, are the best ones? 
Cheers & Beers

Pat

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 Had one for a while,but took it off and gave it to someone I dislike.Cut to the chase,below about 100km/hr they are almost ineffective.Cheers

-- Edited by yobarr on Wednesday 6th of October 2021 03:12:48 PM

yobarr wrote:

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Seaeagle63 wrote:

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Gday All, just after some feedback from those that use wind deflectors. Are they any good and do they really work? What, in your opinions, are the best ones? 
Cheers & Beers

Pat

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 Had one for a while,but took it off and gave it to someone I dislike.Cut to the chase,below about 100km/hr they are almost ineffective.Cheers

 

 

There are no simple, "one size fits all" answers when it comes to aerodynamics and anything that moves through the air ......  KB

-- Edited by yobarr on Wednesday 6th of October 2021 03:12:48 PM

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Hello Pat,

I fall into the category of a wind deflector fan. Have had one and used it for 40 odd years. 

Do they work, I think it depends a lot on how you set it up on your vehicle. I tow using a wagon, currently a Y62 and try to mount the deflector as far back on the roof as possible. I also have nothing else on my roof to reduce drag, and aid the deflector do its work. 

Evidence of some kind of effectiveness can be derived by looking at the front of your van towing with and without a wind deflector, no deflector lots of bug spatter, using the deflector no bugs behind it on the van. I use bugs to help me determine the ideal angle for the deflector, increasing the angle until there are no bugs on the top of the van. 

Here in WA with lots of long distance open road journeys, especially heading north with a north easterly or coming back across the nullarbor with a westerly, I believe it does save fuel, maybe different in other geographical and climatic conditions though.

You rarely see a long distance truck without one, the principal is the same.

Hope this helps.

Bob

 

 

 

 

 

-- Edited by bomurra on Wednesday 6th of October 2021 08:15:09 PM

Seaeagle63 wrote:

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Thanks Bob, I too am in WA. Im currently in Carnarvon and the wind is blowing up from the SE at around 40-50 Kmh. Im slowly working my way back to Perth. I tow with an MQ Triton 2.4l TD (no canopy) but have roof bars but nothing on top. The trip from Karratha to Carnarvon was very slow struggling to stay on 85kmh due to strong headwinds, hence why Im considering on getting one in Gero.

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 Don't want to spoil the party,but save your money.At the speeds you will be able to travel at in your 133kw Triton,all a deflector will do is flick a few bugs over the roof,and increase wind resistance.Because your vehicle has no canopy,the deflector will have to go on the car's roof? The distance from the deflector to the van will be too great for the deflector to have any effect at all. "Forget it" is my suggestion.Cheers

 

-- Edited by yobarr on Wednesday 6th of October 2021 10:21:18 PM

oldbloke wrote:

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yobarr wrote:

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Seaeagle63 wrote:

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Thanks Bob, I too am in WA. Im currently in Carnarvon and the wind is blowing up from the SE at around 40-50 Kmh. Im slowly working my way back to Perth. I tow with an MQ Triton 2.4l TD (no canopy) but have roof bars but nothing on top. The trip from Karratha to Carnarvon was very slow struggling to stay on 85kmh due to strong headwinds, hence why Im considering on getting one in Gero.

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 Don't want to spoil the party,but save your money.At the speeds you will be able to travel at in your 133kw Triton,all a deflector will do is flick a few bugs over the roof,and increase wind resistance.Because your vehicle has no canopy,the deflector will have to go on the car's roof? The distance from the deflector to the van will be too great for the deflector to have any effect at all. "Forget it" is my suggestion.Cheers

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 You read my mind. Positioning is important. 

 Anyway the Triton will handle it no worries. Heaps better than those Toyota bombs. 

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 In this case,Neil,you may well be correct,as it seems that Pat,the OP,is travelling downhill? At least,that's what the map shows? Also,today I spotted a chap using a Triton to tow a Retreat 210c.These vans tare at 2400kg+/-,and have ATM of 3200kg.At 21ft,it is way too big and heavy for a Triton,if safety is of ANY concern.Cheers

-- Edited by yobarr on Thursday 7th of October 2021 07:02:54 AM

I guess this supports Yobarr's argument but in the 60s when I was a trainee tech in the PMG my boss did a trial of fuel consumption between two cars we had - both were 1965 HD Holdens. One was a stn wagon, the other was a utility with a vinyl cover on the tub. While being heavier, the wagon was the most economical - the turmoil of the air behind the cab & the tub of the ute being blamed.

A few years ago there were small deflectors that could be added to the side of a caravan to "improve economy, handling." As I have not seen any on our travels, I can only assume they were a "deflector of money from your pocket to the marketers". I have seen the traditional deflectors on some cars towing vans - they must have some benefit or I guess they would be removed.

yobarr wrote:

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oldbloke wrote:

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yobarr wrote:

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Seaeagle63 wrote:

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Thanks Bob, I too am in WA. Im currently in Carnarvon and the wind is blowing up from the SE at around 40-50 Kmh. Im slowly working my way back to Perth. I tow with an MQ Triton 2.4l TD (no canopy) but have roof bars but nothing on top. The trip from Karratha to Carnarvon was very slow struggling to stay on 85kmh due to strong headwinds, hence why Im considering on getting one in Gero.

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 Don't want to spoil the party,but save your money.At the speeds you will be able to travel at in your 133kw Triton,all a deflector will do is flick a few bugs over the roof,and increase wind resistance.Because your vehicle has no canopy,the deflector will have to go on the car's roof? The distance from the deflector to the van will be too great for the deflector to have any effect at all. "Forget it" is my suggestion.Cheers

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 You read my mind. Positioning is important. 

 Anyway the Triton will handle it no worries. Heaps better than those Toyota bombs. 

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 In this case,Neil,you may well be correct,as it seems that Pat,the OP,is travelling downhill? At least,that's what the map shows? Also,today I spotted a chap using a Triton to tow a Retreat 210c.These vans tare at 2400kg+/-,and have ATM of 3200kg.At 21ft,it is way too big and heavy for a Triton,if safety is of ANY concern.Cheers

-- Edited by yobarr on Thursday 7th of October 2021 07:02:54 AM

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 My Mn Triton is towing 2.5t. To be honest that is the practical max IMO. 

 

Most manufacturers exaggerate the towing capacity for sales purposes. But it's still best tow vehicle available.

 

Hello Again Pat,

You should find the winds die off a bit once south of Carnarvon, we have done that trip quite a number of times and found it usually is the case.

I also used a wind deflector for many years on sedans, around australia, across the nullabor etc, it made a difference on them also.

Enjoy your caravanning mate.

Regards,

Bob.

If it is a high headwind day & you are not in a rush, stop for the day.

I don't tow but the difference between a headwind & tailwind is 12.5L vs 7.8L per 100km on the Nullarbor.

https://www.windy.com/?-32.108,128.819,6

 

You will probably save more money cleaning than using a deflector which won't be close enough to the trailer to be effective anyway.

 

An old 747 is a tonne heavier due to the ground in dirt, so more fuel. Spend the money on a bucket & use some elbow grease or use air/water & compressor to clean if you are too lazy.

Or get the wife to clean!

 

If your in no hurry avoiding head wind is very sensible. Have done that myself.

Ge wrote:

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The way i see it and i don't tow anymore is, when it comes to big trucks ect the wind deflector is closer to the trailer so can make an effect on fuel economy.

When it comes to small tugs ( utes, suv, LC ect) the wind deflector needs to be as far to the rear of the tow vehicle as possible and then lies a problem as the gap between the tug and van is to great.

Now when a wind deflector is used what about the gap between the vehicle roof and the bottom of the deflector where does that wind go, u got it smack bang between the gap right into your van. Tow vehicles are not as wide as your van so where does the wind down the side of your vehicle go, u got it smack bang into the front of the van. With open tray utes you are wasting your money, test have shown with open tray utes with or without sides it makes no difference to fuel economy. Last of all look at trucks the prime mover is the same width and height as the trailer thus making a smother and economical transition.

My opinion for what its worth i wouldn't bother also don't forget the pain of taking them of/on when not using.

My personal opinion may differ to yours so lets show mutual respect to each other.
Havagoodday.

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 Well explained,and simple logic,really.Waste of money for cars towing vans.Cheers

Ge wrote:

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The way i see it and i don't tow anymore is, when it comes to big trucks ect the wind deflector is closer to the trailer so can make an effect on fuel economy.

When it comes to small tugs ( utes, suv, LC ect) the wind deflector needs to be as far to the rear of the tow vehicle as possible and then lies a problem as the gap between the tug and van is to great.

Now when a wind deflector is used what about the gap between the vehicle roof and the bottom of the deflector where does that wind go, u got it smack bang between the gap right into your van. Tow vehicles are not as wide as your van so where does the wind down the side of your vehicle go, u got it smack bang into the front of the van. With open tray utes you are wasting your money, test have shown with open tray utes with or without sides it makes no difference to fuel economy. Last of all look at trucks the prime mover is the same width and height as the trailer thus making a smother and economical transition.

My opinion for what its worth i wouldn't bother also don't forget the pain of taking them of/on when not using.

My personal opinion may differ to yours so lets show mutual respect to each other.
Havagoodday.

 

-- Edited by Ge on Monday 11th of October 2021 11:07:56 AM

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 Yes, well stated. Clear and not too long winded.

Mike Harding wrote:

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Surely *someone* must have modelled this!? It's pretty straightforward fluid dynamics these days. 

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 https://openfoam.org

 

 

Bobdown wrote:

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Check this out........makes sense.

https://www.youtube.com/watch?v=QmwkrQbTgNQ

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 Have to disagree Bob,as it is simply a self-promoting advertisement aimed at the more gullible amongst us. All the negatives that were clearly explained by Ge,in an earlier post,were confirmed with this video.The caravan was twice as wide as the car,wind went under the deflector,and all we saw was a bit of water flicked over the roof.The car was a long way from the caravan,as earlier stated,so benefits are virtually nil.But some people will believe anything.However,thanks for putting it up for all to see.Cheers