aero plus wind deflectors

[Thelma65]

does anyone have one - are they any good?

where can i gte a decent 2nd hand one from?

so many questions and so little answers! lol

anyone have experience of these?

carl

 

[Lutz]

The chances of achieving any improvement with a wind deflector by simply fitting one as you think best, is about as remote as a lottery win. Because aerodynamics are so complex, you only need to be a few inches off the proper position for your particular outfit configuration and it'll do absolutely nothing. You could try jiggling around a bit backwards and forwards to try to find an optimum, but count yourself lucky if you get a measurable improvement.

 

[George_374396015]

On three tow vehicles I have found a top box stops the front window of the caravan visually being seen to deflect. maybe a better solution, but that is only a subjective comment.

geo

 

[Heethers]

l agree with Lutz, back in the eighties they were all the rage until they did the test which proved no increase in MPH but a significant decrease, to top it all you used to see the idiots them driving around with it still attached after they had pitched.

Think l will stick with the smooth driving approach and keep the speed to the optimum, which will be to the relevant speed limits.

NigelH

 

[Steve L]

Hi Carl.

I have used a wind jammer aerofoil for about 10 years and can honestly say there are benefit's to be had.

True enough they were first on the market back in the 70's & 80's. I don't know what or who conducted the investigations that concluded there was no benefit.

Being a toolmaker & experimenmtal engineer by trade and having 10 years of motor industry product developement behind me, I think I can offer credable advice on this product. Oh also, I've been caravanning for 28 years.

The most obvious thing is mounting position on the tow car. If you have an estate type car, you have a long roof profile to enable optimal positioning of the tool. On hatchback's or saloons the roof profile does limit fitting but as a guide somewhere above the rear passenger to rear axle position is a good start point.

As for position, look up along the aerofoile and imagine a flow line of air flowing at the angle of the foil and passing over the van roof. Now move the foil forward so that the same flow is now about a metre in front of the van. This is a basic compensation for vehicle speed affecting the aerodynamic flow change.

I find that my Laguna 2 litre estate gained 5mpg fuel consumption and was able to tow 7Mph faster than without the foil fitting.

That might not seem a lot of saving, but if you do an average 120 mile drive to and from your chosen site, you would save around

 

[CheapnCheerful]

I can only echo what was said above. With all the differences of opinions, and especially taking account of what Lutz was saying, I did not want to spend any money only to find out the damn thing did not make the slightest difference. So I made my own out of materials I had spare in my garage, to approximately the same dimensions and angle of the aero plus. I fitted it to the vehicle as far back as possible.

I then took it on a trip where all aspects of the run were identical, wind, weather, loading, driving style, time of day - even the same day of the year! In other words the only significant difference was the wind deflector.

I did not use any expertise in fitting it that I would not expect from the average caravaner, but I did take care to record the mpg as accurately as possible. Consumption improved from 22mpg to 26mpg - or about 18%. This would suggest that in reality the chances of saving fuel are considerably better than winning the lottery, and that the aeroplus claim of 15% is not unrealistic. However, I do suspect in my case that as the caravan is an old one and probably much less aerodynamic, that on a modern van the savings might not be so great - most with the same towcar but a modern van get 26mpg+ without a deflector to begin with, so it is unlikely they would save as much as 18%.

 

[Steve L]

I do agree that certain caravans that have a distinct slope to the front panel might not show significant improvement in economy.

However if you look at Bailey caravans for instance and swift for that matter, the craving by the customer for more space inside has produced a van that has a more or less upright front panel.

I do tend to agree that nearly

 

[Lutz]

A possible alternative if you don't want to be seen driving around all the time with a cheap d-i-y setup would be to cobble up some sort of temporary wind deflector to try out and optimise regarding position, angle, etc. and then, when you've achieved the best results, replace it with a proper one.

 

[Noddy2]

I have just bought one of these on E-Bay

 

[Thelma65]

I have just bought one of these on E-Bay

 

[TopCat1]

The benefits of fitting of a spoiler to the car must be considered both on a cost of purchase and cost saving benefit. In my experience these items cannot be guaranteed to save you money. For example if you pay

 

[Philspadders]

Unless these items have been wind tunnel tested i would not believe any of the blurb.

Unless the deflector (its not an aerofoil- an aerofoil,depending on the section will generate lift,pressure,increases in flow,changes in drag and are very complex) is in exactly the correct position and at exactly the correct angle ,the deflector could have a very negative effect.Firstly if its at too shallow an angle the induced drag and turbulance caused by the air flow breaking away from the trailing edge of the deflector could slow you down.

If the deflector is too steep it will simply act as air brake.

If the deflector is too far forward or back the airflow may not do what you think it is. If its too far forward the pressure drop at the trailing edge could cause the airflow to fall from the rear of the deflector and increase the forward air flow / pressure at the front of the caravan.

If its too far back and at high speed the loads on the deflector could adversely affect the handling of the towing vehicle.

As the previous poster said "aerodynamics is a very complex subject".

 

[CheapnCheerful]

Thats exactly what I thought. So rather than waste money on something that did not work, I made one myself out of a scrap piece of plywood for the sole purpose of doing an accurate test to finally prove it one way or another, with no financial outlay.

On two identical runs, the ONLY difference being the fitment of a crude home made deflector, without wind deflector I got 22mpg, with deflector I got 26mpg. Thats an 18% improvment. Or about

 

[Philspadders]

what were the recorded wind conditions on the days of the run...direction and speed etc as this would have an effect.

the only way to measure the effects of a deflector are to place it in a wind tunnel where conditions are controlled and repeatable.

 

[CheapnCheerful]

The wind speed on both runs was so low it was not noticable. In fact I had a go at trying to find historic data for the two days in question - Saturday 16th May 2009 and Saturday 17th May 2010, Midlands towards London at about 07:30 am. Not as easy as I thought despite the internet. Suffice to say there was no noticable wind on either day, and that therefore there was no way that that the theory of wind, or indeed any other weather could possibly have effected the results significantly - let alone as much as 18%!!

In fact it could be argued that my results are more realistic than a wind tunnel, because my results were recorded in a real situation rather than an artificially created one, and therefore more representative of the savings that can actually be achieved on the road in real life, which is what really counts, rather than a theoretical saving demonstrated in a laboratory.

I specifically wanted to prove this one way or the other - I had an open mind - not even having being tainted by buying a deflector and trying to justify it, I have no agenda. - it cost me

 

[wattie]

In the transport industry (hgv`s etc) every pound is a prisoner

and you do not see many modern large trucks without them.

I admit they do large mileages though.

 

[Steve L]

Walt is quite right to indicate that the transport industry have embraced deflectors, after all while they do on average 400 miles per day per artic on trunk work, they have to watch every penny.

I used to have a Lt35 curtain side truck which without a deflector could not get above 50Mph due to there being a flat front panel of body work some 6ft high and 7ft wide above the cab. After fitting the deflector, I could get 70Mp if needed and about 10% better fuel.

As for using one on a car towing a caravan I do that too and get 5mpg better fuel consumption which is about 18% improvement, and also can get 7mph faster top speed if required. Also as david has noticed, the front panel of the caravan does become virtually bug free which is a clear (natural wind tunnel test) indication that the main air flow has been redirected to clear the caravan front panel, thus improving air resistance to being towed, hence a noteable fuel consumption reduction and consequently more pounds left in the wallet.

One can argue the technicalities all day long, but if you see a financial pay back by way of fuel saving, then there will be a point in time where the deflector ends up paying for it's self and from the point on you are saving money.

You don't need a wind tunnel test to get the right position on the roof of the tow car, the bug count on the roof panel above the front windows will tell you when you've found the right spot. Also your Mpg will also reach a peak point of improvement, again confirming the position is optimal.

Apart from upsetting a park warden because I had twenty or so holiday stickers on my deflector which was "too much of a carnival" according to him, which led to me turning the deflector round while it was stored at the back of the caravan. I'm quite happy with the posative benefits and considering I can now fit it in about 5 minuits, it's easy money saved.

Atb Steve L.

 

[TimM]

Back in the mid 80's I was a student at Loughborough University studying Automotive Engineering. With me on my course was a son of either a director or senior manager at Swift, (I can't remember exactly). On one of our aerodynamics projects the two of us wind tunnel tested car caravan combinations to assess what features helped reduce drag and therefore fuel consumption. I can't remember the figures anymore but apart from some fairly impractical ideas I rememebr that the following improved drag.

On the caravan sloping the front windows back with as generous a transition as possible from front to roof. That made the biggest difference of anything we tried. A sharp cut off at the back of the roof with no radius. Blending the front in to the sides of the caravan as much as possible.

I have no idea whether our findings were fed back in to Swift but their caravans are pretty good compromise over the shape we came up with and a practical caravan.

Regarding the car, we obtained slightly better results with an estate car than traditional 3 box saloon. We also tried wind deflectors but in all the tests we did, we found they increased drag rather than reduced it. We were working with scale models and the real world is not always the same. I know one company is showing good results with a delfector tested at MIRA. MIRA are a very reputable orgainsation and I am sure their results are accurate but it would be interesting to see the full results, test conditions, speeds tested etc.

 

[TimM]

Cheap 'n' Cheerful.

Historic Met office data shows for Bedford 9 knots from the West for 8.00 Summer Time on both the days you mention.

Tim

 

[CheapnCheerful]

So there we have it. Identical wind conditions too, just as I remembered it. There is absolutely no two ways about it, the deflector definately improved mpg. You will not get a more representative or conclusive test than that.

 

[CheapnCheerful]

Cheap 'n' Cheerful.

Historic Met office data shows for Bedford 9 knots from the West for 8.00 Summer Time on both the days you mention.

Tim

Thanks very much for that. I did try the Met office web site, but could not work out how to navigate to the info I wanted. Tried the search facility with no luck etc.

 

[CheapnCheerful]

Back in the mid 80's I was a student at Loughborough University studying Automotive Engineering. With me on my course was a son of either a director or senior manager at Swift, (I can't remember exactly). On one of our aerodynamics projects the two of us wind tunnel tested car caravan combinations to assess what features helped reduce drag and therefore fuel consumption. I can't remember the figures anymore but apart from some fairly impractical ideas I rememebr that the following improved drag.

On the caravan sloping the front windows back with as generous a transition as possible from front to roof. That made the biggest difference of anything we tried. A sharp cut off at the back of the roof with no radius. Blending the front in to the sides of the caravan as much as possible.

I have no idea whether our findings were fed back in to Swift but their caravans are pretty good compromise over the shape we came up with and a practical caravan.

Regarding the car, we obtained slightly better results with an estate car than traditional 3 box saloon. We also tried wind deflectors but in all the tests we did, we found they increased drag rather than reduced it. We were working with scale models and the real world is not always the same. I know one company is showing good results with a delfector tested at MIRA. MIRA are a very reputable orgainsation and I am sure their results are accurate but it would be interesting to see the full results, test conditions, speeds tested etc.

Thank you very much for that. I am sure that one reason why I achieved such an improvement is that the aerodynamics of my van are really rather poor as they are, compared to the modern ones you describe. It is quite likely that the car/van combination I had was one that stood to benifit the most. Others may not be anywhere near as successful.

 

[Noddy2]

THANKS FOR THIS

LET ME KNOW HOW YOU GET ON WITH YOUR AEROPLUS AS THAT IS THE ONE I SAW ON EBAY!

This is a follow up to an earlier posting, I've just returned from 3 weeks caravaning. On the long motorway runs the Aeroplus made the unit so much more stable, no wobbles when white vans race past, it was a pleasure to drive, still keeps the bugs off the van. Bad news as near as i could tell mpg increased by 1mpg with the Aerofoil fitted, I stopped at services and removed or refitted it to make sure.

I will continue using it just for the stability it gives and will tinker with it to try and increase mpg, I have also written to Purple line for their comments. Hope this helps David