1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136 
Cutting the drag
Page 24
Page 25
If you've noticed an error in this article please click here to report it so we can fix it.
by the Technical Edi
A NEW device for reducing wind drag on tractor/trailer combinations has been announced by Airshield. Known as the Roof Fairing it is similar In basic design to the company's already well known wind deflector and both are designed for mounting on the cab roof.
The Roof Fairing, manufactured from glass fibrereinforced polyester resin, is mounted on the roof at four points. The theory behind it is for the oncoming flow of air to be directed in such a way that the drag producing turbulence is reduced along the top and sides of a typical box trailer.
It was developed under a US National Science Foundation research grant awarded to Professor Frank T. Buckley of the University of Maryland.
Airshield has also announced the Gap-Seal, a vertical flexible fin which is mounted on the rear wall of the cab.
To be used, preferably, in conjunction with the Roof Fairing, the Gap-Seal is intended to reduce the effect of the high drag-producing cross winds by limiting the flow of air through the gap between the tractive unit and the trailer. It is made from high, density polyethylene with a steel•support.
The Gap-Seal answers the criticisms made of its forerunner, the Vortex Stabiliser, which was intended to have basically the same function.
Where the Gap-Seal gains is by being mounted on the tractive unit rather than on the front of the van and by being flexible.
Thus only one Gap-Seal is necessary however many trailers are likely to be used and the flexibility of the device gets over the problem of swing clearance. According to Airshield, the Gap-Seal increases the efficiency of the Roof Fairing and the original Wind Deflector by around 50 per cent.
As far as prices are concerned, no figure is available as yet for the Gap-Seal but the Roof Fairing is expected to cost around 35 per cent more than the Wind Deflector.
Airshield International and its European Distributor Groeneveld Transport Efficiency BV of Holland are conducting a detailed fue consumption trial of their owi products and of two competi tors.
It had been hoped to hay, the full results of these test available at a press confereno held in Holland to announo the Roof Fairing but gale fore. winds delayed the work. Th. provisional results to date ar shown in the accompanyin, panel.
The programme include the testing of the Roof Fairin and the Gap-Seal, the Wind Deflector and the Gap-Seal and two competitive devices, the Mercedes-Benz wind deflector and the Top Spoiler from Spier.
The testing is being supervised by an independent body, the Dutch Research Institute for Road Vehicles (T.N.0.).
The test programme involves running two vehicles at the same time, one with an aerodynamic device and one without. As the presence of wind in any direction other than straight ahead creates a wind yaw angle (the direction of the wind relative to a moving body) this is being monitored throughout the programme.
A computerised mobile 'weather station' has been built around a Monteverdi Safari which can monitor accurately road speed and distance, wind speed and direction, The Roof Fairing as tested in iolland was a modified ver3ion of the US type. The nodification was necessary as he American device is de3igned for a 2.3m (7ft 61/2in) width limit while Europe is at 2.5m (8ft 21/2in). This has entailed letting in a wooden centre section to increase the width. Production versions will be all in one piece.
In some ways Airshield is in a cleft stick over marketing the new Roof Fairing in parallel with the Wind Deflector as most of the advantages claimed for the Fairing are designed to eliminate disadvantages inherent in the earlier design.
Chet Wiley of the RudkinWiley Corporation (makers of the Airshield) said that his company was moving towards fairings rather than deflectors to make the device less sensitive to yaw angle.
It is about time that someone carried out a fullscale comparison between the aerodynamic devices available which are now many and various. (In 1973, RudkinWiley claimed that it was the only manufacturer of such equipment in the world. At the last count there were 40 competitors in the US alone.) However, it would have been a lot more representative, I feel, if Airshield had tested more of its competitors'.