Reçu ce matin un mail de Ray Battersby, spécialiste ès-Suzuki incontesté, qui m'avoue que, même s'il est en ce moment absorbé par l'écriture d'un livre concernant les productions de l'ex RDA (pour lequel il m'indique qu'il collabore étroitement avec un jeune pit-laineux qui se dénoncera lui-même si ça lui chante ....) , il ne néglige pas pour autant totalement pit-lane et prend plaisir semble-t'il à lire nos élucubrations sur des thèmes au sujet desquels il ne devrait pourtant plus avoir grand'chose à apprendre ......
Il m'indique ainsi avoir lu récemment sur le topic RG 500 les questionnements de notre ami italien gigi400 au sujet des variantes de selles et carénages des XR14 d'usine au cours de la saison 1977.
- gigi400 a écrit:
and now a little question about the RG500 XR14 1977 of Barry.
I have pictures of at least 3 types of fairing in 1977.
I think the upper one is the first, due to back springs and rear swing arm without lower support.
And after we have 2 pictures with some improvements.
But these are only my suppositions...
Do anyone know the story about this?
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....et je rajoute pour faire bonne mesure une autre photo de Pat Hennen sur la machine avec laquelle il a chuté au Grand prix d'Italie, carénage semble-t'il du même modèle que celui de la photo du bas de Barry Sheene ci-dessus . [Vous devez être inscrit et connecté pour voir cette image]
Pour tenter de clarifier les choses, Ray nous offre un extrait d'un article sur les essais aérodynamiques en compétition moto au fil des années, qu'il avait écrit (sous un pseudo fantaisiste) pour la revue anglaise Motor Cycle Sport en mai 1979 :
CHEATING THE WIND (Extract)
By A. D. Tankstraddler (AKA Ray Battersby)
Motorcycle Sport, February 1979 Pages 98, 99 and 111
Another important facet is that concerning high speed and cornering stability, and cunning changes to the factory Suzuki RGs were intended to improve these points. During the 1977 season two of the factory riders, Sheene and Hennen, quietly tested five different designs of front fairings and two designs of tail units.
The 1977 over-the-counter RG500s were produced with a normal two piece fairing incorporating small longitudinal ledges at the joint and with a tail unit similar to the 1976 version except that the aluminium muffler guards were replaced by small ‘ears’ moulded into the seat units. The first special design was very similar except that it had an additional wing moulded around the bottom leading edge of the fairing. Nicknamed ‘Donald Duck’ by the factory mechanics, this additional stabilizer was designed to keep the front wheel down when exiting from fast sweeping bends, a problem suffered by the exceptionally torquey motors of the works machines, especially the 652 cc fours. In addition, a modified seat unit with a larger stabilizing fin along each side and across the back and much larger side ‘ears’ was specified.
This combination was used by Sheene, Hennen and Steve Parrish for the early-season events but just prior to the Austrian GP a series of crates arrived at Heron Suzuki GB's HQ at Croydon. They were found to contain no fewer than eight new fairings: two each of four new designs, and with a couple of new tail units, to boot.
These fairings were completely new in that the radiused lower leading edge of the old fairings had given way to a razor-edge design. The old radiused bellypan was superseded by a dead flat equivalent and the new tail units were all-enveloping and similar in concept to those of the works Yamahas. Strict instructions said that under no circumstances were the old tail units to be used with the new fairings. These new units had been developed in Japan by the Suzuki engineers who, lacking their own wind tunnel, trundle over to a friendly aircraft company, an hour’s drive distant, for the use of a tunnel. The test results showed that these new units would add 13 kph to the RG’s top speed.
Only Sheene and Hennen were to use these new units, and there were four options open to each rider; for starters, there was a choice of radiator width - 26 or 28cm. depending on the ambient of the GP course on race day. Additionally, there was a choice of either a pointed nose (lower front) or blunt nose. Sheene and Hennen hot footed it over to Cadwell Park for a test session, and these new units were found to be a big improvement over the ‘Donald Duck’ design. Even though the lower fairing stabilizer had disappeared, cornering stability was improved no end.
During the 1977 GP season Hennen and Sheene swapped and changed their fairing specs in an attempt to find the optimum for each circuit. To simplify this, the upper fairings were identical, and to change the lower units was a job taking only a few seconds. The consensus fell on the blunt nose design, both riders commenting that they could feel the difference between the two nose designs.
First used at the Austrian GP, at which both riders were involved in the walkout over riders’ safety, these fairings were also campaigned at Hockenheim, Imola and Paul Ricard with great success. After all, Barry Sheene did retain his 500 cc world title. For 1978, the factory Suzuki fairings, similar to the 1977 cowls, had sprouted a pair of small riveted on fibre glass stabilizing fins. Sheene claims a small speed increase although the aim is to improve cornering stability and help to keep the front wheel down during acceleration.[Vous devez être inscrit et connecté pour voir cette image]