Purpleline Aeroplus wind deflector

[anotherDavid]

I have just returned from a 2000 mile towing trip to Spain and tried to carry out as scientific assessment as I could, comparing the fuel consumption using an Aeroplus with last years identical runs (between fillups) I did keep an eye on the cars computer mpg figures and have checked this since we got back using the actual "fill to fill" figures and these seem to confirm what I suspected, that it appeared to make little difference, just possibly slightly over 1/2 mpg and this is small enough to be down to other factors such as weather the car engine loosening up etc . It was mounted as far back as possible on an estate car and I tried all 3 angle settings.
The only thing I can be certain of is that insects are clearing the van. I got it quite cheap on ebay but before I dump it (or try to sell it) it would be interested if anybody else has had more success .

 

[ProfJohnL]

Hello David,

Your findings tend to confirm what a number of us have said on many occasions regarding wind deflectors. The aerodynamics around cars and caravans are very difficult to predict and understand, thus wind deflectors if they are to make any difference need to be tried in different positions

The positioning is critical, and if they are not in the correct place, they can easily harm fuel efficiency, However you must have found a position that neither adds or detracts – which is in itself quite an achievement.

Although the fuel situation may not have changed significantly, did you notice any changes to the handling of the outfit?. Was it perhaps less affected by passing lorries?

Although it may not have made fuel saving, if it made any improvement to the handling, then it could still be worth keeping, and perhaps trying different positions to see if you can improve the fuel consumption.

 

[Dustydog]

Hello David,
Although the fuel situation may not have changed significantly, did you notice any changes to the handling of the outfit?. Was it perhaps less affected by passing lorries?
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Although it may not have made fuel saving, if it made any improvement to the handling, then it could still be worth keeping, and perhaps trying different positions to see if you can improve the fuel consumption.

Prof John
And there's me thinking you are an advocate that modifications to the vehicle ,eg suspension aids etc . are unneccessary?

where's the tongue in cheek one??

 

[TimM]

I did a degree in automotive engineering and design 25 odd years ago. A friend on the course was the son of then sales and marketing director of Swift. One of our projects was to optimise the aerodynamics of a car caravan combination. What reduced drag best was sloping the front of the caravan back and having a sharp cut off on the roof at the back of the caravan. In fact co incidence or not, pretty much the shape that Swift group caravans became although I don't know whether they had access to our research. Completely fairing the front of the caravan to the rear of the car made a spectacular difference, but isn't very practical in reality.

Our "car" could be configured as a 3-box saloon, hatchback or estate and from memory I think the estate was slightly better than the others. We could not find any benefit with car-mounted deflectors, usually finding that the flow became completely turbulent again between the deflector and the caravan. We tried different angles and making the deflector more aerodynamic, but overall it tended to increase, not decrease the drag of the whole outfit. Of course we were working with scale models, not full size. I know MIRA have tested the deflectors and the company making them is claiming a positive result. It would be interesting to see their full report.

 

[Steve L]

For many years I have used the original wind jammer aerofoil while towing caravans.
The first outing was with a Renault 25 towing a swift danette which was as light as a feather behind the car. Then we swapped to a Link575 20ft twin axle which was 36 Kgs over the tow car capacity. with both vans I got upto 5Mpg better and especially on the latter van I got upto 7Mph faster, enabling me to get 63Mph if desired.

Those of you familiar with the 25 will know they are a large hatchback with an airflow ending in a low turbulence at the rear. This turbulence caused the front of both vans to get very dirty without the foil fitted.

Since then I changed to a Laguna estate 1998 vintage (box on wheels). I have used the foil with simlar results.

On both vehicles I ended up , after trials, fitting the foil approximately above the rear axle on both vehicles.

A lot of you may recall, I have worked in R&D with a company developing chassis for Lotus and AML and being an Engineer and prototype tester, I used my knowledge to good affect on this subject.

I have an idea of how to develope better air flow transition between tow car and caravan, but at present it's just sketches on paper. If wind tunnel test's work out, it could be quite reolutionary to all high sided trailer towing. Thats if it gets tye approval.

You may want to give it a shot David, before ditching the foil.

Atb Steve L.

 

[ProfJohnL]

Hi Dusty,
'Foiled' again! I shall let your last comment 'blow' over me

 

[Dustydog]

Hi Dusty,
'Foiled' again! I shall let your last comment 'blow' over me

Double

Prof.