Crisp appraisal of wind deflectors
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by Graham Montgomerie
A1RSHIELD wind deflectors have been given a lengthy appraisal under normal operating conditions by Golden Wonder Ltd, and Mr Don Boote, company transport manager, has now decided to install them on his entire fleet of Ford artics.
About one year ago Commercial Motor assisted Golden Wonder in the first trials of this device at the MIRA proving ground. The encouraging results obtained during these tests persuaded Mr Boote that significant savings in fuel costs could be achieved with aerodynamic aids. So he embarked on a detailed assessment of the principle using them on his regular trunking vehicles on their daily runs.
Along with the Airshield system marketed by CT (L ondon) Ltd, 3 Hobart Place, London SW! OHW, two other devices were tried under normal operating conditions: the Rivers Windcheater and the York Air-O-Foia. After a fuel flow meter began to give some erratic results, he reverted to the full tank system.
Each driver had a separate "log book" to fill in which recorded the mileage before and after the run, the weather and traffic conditions and the quantity of fuel put in. A round number of gallons was put in every day with the tank being topped up completely only on the last day of the appraisal period. This was to eliminate any cumulative error in "rounding up" the fuel added at each fill up. The final topping-up of the tank was carried out under supervision.
A check of the daily destinations was made to ensure that comparisons with and without the various devices were valid over the same type of road. In general, most of the runs were between Corby and Barming which included some motorway use, some general A-road work and some stopstart traffic conditions on the North Circular.
The trial of the Airshield was carried out using the same Ford trailer as was used for the original tests reported in CM on February 7, 1975. The total distance over which the fuel consumption was monitored was 15,353km (9,540 miles) of which 7,695km (4,781 miles) were with the equipment fitted and 7,660km (4,759 miles) were in standard trim. The overall improvement in fuel consumption with the Airshield fitted was 6.25 per cent.
Taking the month of March 1975 to illustrate the point, the average consumption without any aerodynamic aid was 28.7 litres/100km (9.84 mpg) which improved to 26.9 litres/ 100km (10.51mpg) with the Airshield. The standard version costs £140.42.
When the preliminary MIRA trials of the Airshield equipment were made, both the cab deflector and the Vortex stabiliser were used. During the "in service" tests only the cab deflector was fitted. The vortex stabitiser was not used owing to certain dimensional difficulties inherent to Mr Boote's type of operation.
The York semi-trailer in conjunction with the Ford artic have a special configuration due to the light payload. The semi-trailer has an inside length of 12.27m (40ft 3in) to enable it to carry 21 standard 1,219 x 1,016mm (48 x 40in) pallets, and to comply with the maximum length requirements the kingpin is set at 1,092mm (43in). This has resulted in a fairly tight swing clearance on the turns which would be aggravated by the use of the vortex stabiliser.
A second and different prototype cab deflector developed by Rivers Tru stop Ltd of Carlton Road, Carlton, Barnsley, was put through the same test procedure. The Rivers Windcheater was tested over 2,950km (1,834 miles) with a corresponding distance in standard trim of 2,970km (1,846 miles) giving a total operational trial distance of 5,922km (3,680 miles). The measuring was again carried out on a full tank to full tank basis and the overall improvement in fuel consumption was 3.18 per cent.
Blister
The final device to be appraised was the Air-O-Foil from York Trailer Co Ltd, Northallerton, Yorks. This consists of a grp blister which can be mounted on the front bulkhead of vans or any other high trailer. York says that it doesn't have to be a York van for the device to fit.
The Air-O-Foil was fitted to a 12.2m (40ft) tandem-axle Freightmaster trailer coupled to a Leyland Marathon tractive unit on loan from Lex Tillot son. The test distances were 8,1801m (5,083 miles) with and 2,480km (1,541 miles) without for a total of 10,660km (6,629 miles). An improvement in fuel consumption of 5.1 per cent was achieved.
A further test of the Air-OFoil was started using the Ford 1614/York "special" combination, but this was discontinued owing to the problem of swing clearance. Results obtained before this would appear to support an improvement of about 5 per cent. This equipment costs E120.
As a result of these tests Mr Boote is to equip his fleet of Fords with the Airshield as he believes that this device is the best means of reducing air drag suitable for his type of operation.
This did not mean that the standard Airshield deflector was ideal for the Golden Wonder fleet: in fact, a major modification of the mounting system was required. Mr Boote had earlier criticised the on ginal mounting through the actual cab roof. For his requirements, he specified that a separate frame be fabricated so that the load is carried by the roof pillars rather than the roof itself.
Fold-flat assembly
To enable the Fords to clear the doors of the Golden Wonder workshops, the deflector has been designed to fold flat as and when required. Airshield is now thinking of offering the fold-flat assembly as an option. The fold away modification costs an additional 20 per cent.
Improving the aerodynamics of commercial vehicles with a consequent decrease in the amount of fuel used has been the subject of a great deal of operator interest during the past year although relatively few of them have actually done anything about it.
Mr Boote was one of the exceptions and it will be interesting to see how many follow ' his lead in equipping his fleet with aerodynamic aids. In the Golden Wonder case it is hoped to write off the cost of the Airshield against the fuel saving per truck within one year.