Dont get me started on British leyland,not surprising the build quality was crap the amount of stikes they had.That Austin rover forum is quite interesting for anyone whos as sad as me.ha ha
ok Sir Baldrick, so pray tell us why all tractor units have deflectors fitted if they are a waste of time and do no good, of course reducing speed can save fuel because the engine revs are lower, but then theres the side effect isn't there, if the wind brake factor means the towing vehicle cannot maintain the lower revs at a constant speed you have to change down to a lower gear and as soon as you do that the revs go up and so does the fuel consumption,Gafferbill said:.....it is a well known fact among HGV owners that the best way to save fuel with a vehicle that is obviously not aerodynamic is to slow down.
I could get a 14% decrease in fuel consumption from my fully air kitted 38ton Volvo artic by running at 50mph rather than 56mph.
I disciplined myself to do this as it did not affect journey times by that much and it increased my profit by £6000.00/year for no cost input. (over 80,000miles/year)
Trying to streamline a car/caravan outfit is a waste of time mainly due to the low annual mileages involved making any savings minimal.
If you want fuel savings just slow down
I well remember towing with the 1.6 petrol mondeo when I first went back to a tourer the buffeting and wind brake effect was awful it was almost impossible to maintain any sort of speed in top gear on every incline I had to change down sometimes into second, the fuel economy towing was non existant about 26 mpg but would happly give 50+ solo. I would have been very happy to have a tow from the hole created by a HGV but the trouble was I could not catch up to one,
I did want to try a windslammer but could not find one at the time and posted on forum to ask, one member offered me one he had in his garage but was too far to go to collect it, wish I had now as I am sure it would have improved things somewhat.
Aren't artics more closely coupled to the trailer in relation to their overall size than is the normal car- caravan combination and getting the air deflector position and angle correct on an artic is probably easier than for a caravan outfit which is probably not backed up by any real trials. Given the mileage HGVs do any results would be quickly apparent and the effect of wind speed, wind direction etc would be quickly ironed out into an overall result as HGVs have to travel 24/7.
Prof Al Google...........I found the lights on the Montego to be very poor so I added extra lights as shown.
The two central lights were spots that only came on with main beam.
The two outside lights were wide angles set very wide and low and were operated by a separate switch.
Gybe......... bad luck with your petrol Monty.
I bought my diesel version new in 1989 and kept it till 2003 when it was T boned by a van driver pulling out of a side road!
It had done 138000 miles never giving any trouble. It never had any rust........repairs were new clutch, front wheel bearing, alternator and head gasket and normal were and tear items.
The fact that it was 81bhp made it hard work as a tow car but very frugal.
colin-yorkshire.......... please read my post again especially this bit..............
"I could get a 14% decrease in fuel consumption from my fully air kitted 38ton Volvo artic by running at 50mph rather than 56mph".
I did not say taking steps to make a vehicle more aerodynamic was "a waste of time and do no good"
I said trying to do this for a car and caravan outfit was economically pointless and much better economic results could be achieved by reducing speed.......especially over the average outfit towing mileage
Others have reported that fitting an aerofoil made their outfits more stable and I see no problem with this.
The two central lights were spots that only came on with main beam.
The two outside lights were wide angles set very wide and low and were operated by a separate switch.
Gybe......... bad luck with your petrol Monty.
I bought my diesel version new in 1989 and kept it till 2003 when it was T boned by a van driver pulling out of a side road!
It had done 138000 miles never giving any trouble. It never had any rust........repairs were new clutch, front wheel bearing, alternator and head gasket and normal were and tear items.
The fact that it was 81bhp made it hard work as a tow car but very frugal.
colin-yorkshire.......... please read my post again especially this bit..............
"I could get a 14% decrease in fuel consumption from my fully air kitted 38ton Volvo artic by running at 50mph rather than 56mph".
I did not say taking steps to make a vehicle more aerodynamic was "a waste of time and do no good"
I said trying to do this for a car and caravan outfit was economically pointless and much better economic results could be achieved by reducing speed.......especially over the average outfit towing mileage
Others have reported that fitting an aerofoil made their outfits more stable and I see no problem with this.
With the cost of fuel today any slight increase in fuel consumption has to be good. Our Windslammer is about 30 years old and was a free gift. We've always done long distances with our caravans and anything that can smooth the running or aid fuel consumption is fine by me. We've used the windslammer on numerous cars and its given small MPG increases, cut gear changing and cut movement of the caravan as buffeting of the caravan has been reduced.
Air flow over a car doesn't hug the roof as the windscreen lift, the Purpleline site photo shows that fairly clearly and their deflectorst lower edge isn't to close to the roof. If we were low mileage short trip UK only caravanners I don't think I'd pay Purpleline price. As high mileage long distance motoway caravanners Windslammer will be worth a try from previous experience with a lower roofed car.
It's bad enough towing at snail like pace compared to non caravanners with their mobile road block gripes, going even slower isn't going to improve the aerodynamics, towing hundreds of miles in a day we want a smooth reasonably brisk trip without winding up other road users.
MIRA is a world leading research establisment that does automotive testing for most of the worlds car manufacturers. Would they endorse false claims? Can a modern day manufacturer really get away with making false claims?
http://www.purpleline.co.uk/products-aeroplus.php
Air flow over a car doesn't hug the roof as the windscreen lift, the Purpleline site photo shows that fairly clearly and their deflectorst lower edge isn't to close to the roof. If we were low mileage short trip UK only caravanners I don't think I'd pay Purpleline price. As high mileage long distance motoway caravanners Windslammer will be worth a try from previous experience with a lower roofed car.
It's bad enough towing at snail like pace compared to non caravanners with their mobile road block gripes, going even slower isn't going to improve the aerodynamics, towing hundreds of miles in a day we want a smooth reasonably brisk trip without winding up other road users.
MIRA is a world leading research establisment that does automotive testing for most of the worlds car manufacturers. Would they endorse false claims? Can a modern day manufacturer really get away with making false claims?
http://www.purpleline.co.uk/products-aeroplus.php
I have got one lying on the shed floor, I bought it because years ago I had the old Windslammer and did think it helped with speed and fuel consumption. The aeroplus really looks the part and I thought it could only be better than that metal sheet however my experiance has been that it was £90 to keep flies off the front of the van. I have an estate that allows the device to be fitted much further back than any saloon car and after trying out all 3 setting positions over severasl hundred miles each I found no improvement whatsoever in fuel consumption.Gybe said:
With the variety of car shapes and sloping rooves on many estates and hatches I'll hazard a guess that the purpleline offering needs many more positions.or be completely variable like the old Windslammer.
The Aussie's reckon the purpleline increases fuel on their test outfit.
The Aussie's reckon the purpleline increases fuel on their test outfit.
Hi all, many years ago I worked for a very large food company (RHM) who ran there own fleet of trucks, this was back in the late 70s,
they did a lot of reaserch in to wind deflectors including wind tunel tests, the end result being that they do improve MPG, proving that the angle of deflection is spot on, if not they found in trials that if incorrectly positioned they actually decreased MPG.
I used to use one my self,on top of a 144 Volvo, and to be quiet honest I found no benefit in using it, fuel wise or stability,
Gaferbill, the lamps fitted to the front of your Monty would only have been legal to use in severely restricted vision due to there mounting hight, auxiliary driving lamps would have to have been mounted at higher level, and as you quite rightly state wired in to the high beam circuit.
still one of my pet hates when you see drivers in perfectly clear conditions illegally using front fogs.
they did a lot of reaserch in to wind deflectors including wind tunel tests, the end result being that they do improve MPG, proving that the angle of deflection is spot on, if not they found in trials that if incorrectly positioned they actually decreased MPG.
I used to use one my self,on top of a 144 Volvo, and to be quiet honest I found no benefit in using it, fuel wise or stability,
Gaferbill, the lamps fitted to the front of your Monty would only have been legal to use in severely restricted vision due to there mounting hight, auxiliary driving lamps would have to have been mounted at higher level, and as you quite rightly state wired in to the high beam circuit.
still one of my pet hates when you see drivers in perfectly clear conditions illegally using front fogs.
Prof Al Google said:
My light fitting on my Monty fully complied with UK law which is as follows..............
When fitting a pair of fog or driving lamps you should obey the following legal requirements:
Fog and Driving Lamps should be positioned symmetrically; the same height from the road and the same
distance from the sides of the vehicle.
Fog Lamps should be fitted so that their outer edges are no more than 400mm (16”) from the outer edge of
the car.
Maximum height above ground 1200mm.
Driving Lamps can only be used with main beam and should be extinguished when headlights are dipped.
Fog lamps can be used on their own but should never be used unless visibility is seriously reduced.
There are no requirements for the positioning of driving lamps, but you should not dazzle any other road
user.
I allways thought driving lamps had to be covered if their centers were less than 24in from the ground
"Fog lamps can be used on their own but should never be used unless visibility is seriously reduced."
not quite correct,
You MUST use headlights when visibility is seriously reduced, generally when you cannot see for more than 100 metres (328 feet). You may also use front or rear fog lights but you MUST switch them off when visibility improves (see Rule 236). Law RVLR regs 25 & 27
I stand corrected with the aux driving lamps, at one time of day they had to be mounted above a certain hight from the ground and only used in conjunction with main beam.
not quite correct,
You MUST use headlights when visibility is seriously reduced, generally when you cannot see for more than 100 metres (328 feet). You may also use front or rear fog lights but you MUST switch them off when visibility improves (see Rule 236). Law RVLR regs 25 & 27
I stand corrected with the aux driving lamps, at one time of day they had to be mounted above a certain hight from the ground and only used in conjunction with main beam.
Prof Al Google.......sorry!
I was quoting the law on the fitting of auxillary lighting not their use.
It would have been better if I had written ...............
Fog lamps can be fitted on their own (without driving lamps) but should never be used unless visibility is seriously reduced.
(which means they need a seperate switch by law)
I was quoting the law on the fitting of auxillary lighting not their use.
It would have been better if I had written ...............
Fog lamps can be fitted on their own (without driving lamps) but should never be used unless visibility is seriously reduced.
(which means they need a seperate switch by law)
(which means they need a seperate switch by law)
Or wired via the use of a relay with the primary circuit being fed via the main beam output in the case of auxiliary driving lamps, making it impossible to use without the main beam being activated, and of course extinguished once dipped beam Is selected.
Oh how times change, I can almost remember when the dip beam switch was mounted on the floor next to the clutch pedal, and before the advent of double filament bulbs, used to extinguish the offside headlamp!
Far less dazzle and glare in those days compared to the high intensity lights of today's modern cars.
Cheers Gaffer.
Or wired via the use of a relay with the primary circuit being fed via the main beam output in the case of auxiliary driving lamps, making it impossible to use without the main beam being activated, and of course extinguished once dipped beam Is selected.
Oh how times change, I can almost remember when the dip beam switch was mounted on the floor next to the clutch pedal, and before the advent of double filament bulbs, used to extinguish the offside headlamp!
Far less dazzle and glare in those days compared to the high intensity lights of today's modern cars.
Cheers Gaffer.
The question says wind defectors a generic term while the thread quickly changed to wind slammer which is a very specfic make with history
That is, Bath Uni were asked to see if the currect crop of deflectors at the time offered any real benefit, answer to that was essentially no. Loughbrough Uni on the otherhand were surprised at the answer considering the principle to be sound, so attacking the questionp from the other direction, came up with their own and working design which was then marketed as the Wind Slammer.
Do the Wind Slammer work, Dad did around 2000 miles around Europe each year and he swore by it, this though with a 72 Avondale complete with eybrow!, he said a big advantage was the amount of air it throws to the side and down the sides of the van, this being of great benefit as the old flat sided trucks came by, Curtain sided trucks have much less affect to those old ones, especially those with sharp corners that used to blow over themselves in high winds!.
Me I only used it a few times, same van but mk2 or4 Escort Est, what I found was little or nothing until 50mph plus, then the van would lighten up as full air deflection took hold, quite dramatic at times but you knew it was working and well.
Also as Dad said about diverting air flow to the side, once in heavy spray this was very clear to see in the wing mirrors, so yes that's certainly true
Only real question now is given everythings changed, difficult to guess know how much benefit is left?
PS, Dad I'm sure said 7ft was the optimum, that being the distance from van to deflector, long time though so could be wrong?
That is, Bath Uni were asked to see if the currect crop of deflectors at the time offered any real benefit, answer to that was essentially no. Loughbrough Uni on the otherhand were surprised at the answer considering the principle to be sound, so attacking the questionp from the other direction, came up with their own and working design which was then marketed as the Wind Slammer.
Do the Wind Slammer work, Dad did around 2000 miles around Europe each year and he swore by it, this though with a 72 Avondale complete with eybrow!, he said a big advantage was the amount of air it throws to the side and down the sides of the van, this being of great benefit as the old flat sided trucks came by, Curtain sided trucks have much less affect to those old ones, especially those with sharp corners that used to blow over themselves in high winds!.
Me I only used it a few times, same van but mk2 or4 Escort Est, what I found was little or nothing until 50mph plus, then the van would lighten up as full air deflection took hold, quite dramatic at times but you knew it was working and well.
Also as Dad said about diverting air flow to the side, once in heavy spray this was very clear to see in the wing mirrors, so yes that's certainly true
Only real question now is given everythings changed, difficult to guess know how much benefit is left?
PS, Dad I'm sure said 7ft was the optimum, that being the distance from van to deflector, long time though so could be wrong?
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