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Une aile rigide "hybride" / Le concept MastFoil

Une aile rigide "hybride" / Le concept MastFoil

Messagepar Nrs » 16 Avr 2012, 10:12

Quelques vidéos du cata d'essais et de démonstration de la voile de Chris White avec et sans foc bômé


http://chriswhitedesigns.smugmug.com/Ot ... &k=spKxqLj

;)
Nrs
 
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Re: Une aile rigide "hybride" / Le concept MastFoil

Messagepar Laurent » 08 Jan 2013, 13:30

Bonjour,

sur le site de Chris White, on peut y voir l'Atlantic 47 Mastfoil mis à l'eau fin octobre 2012.
Une vue de la "mini" aile rigide à deux volets (mini par la longueur des profils), tout de carbone, permet d'en cerner un peu mieux les contours.
http://www.chriswhitedesigns.com/atlant ... 1-12.shtml

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Ce que Chris White dit au sujet de la voilure :

"The MastFoil rig is aerodynamically very clean, meaning there is very little drag. This is readily apparent sailing upwind, where the rig is extremely quiet. A conventional rig makes a fair bit of noise in apparent wind speeds over 20 knots, but the MastFoil hardly makes a sound. Less aerodynamic drag equals better performance.

Upwind tacking angles look very good on the GPS chart plots and more definitive data will be forthcoming. One pleasant surprise was how effectively the MastFoil rig sails to windward in 15 kts true wind WITHOUT SAILS! Measured course made good to the true wind direction was 65 degrees! Pretty impressive for a sailboat without any sails flying.

Close reaching in 18 kts true wind speed under MastFoils alone generated 7.5 kts boat speed. The helm was balanced well and the boat fully controllable.

Of course the intent is to use soft sails for the majority of power in light to moderate winds and unrolling the sails pumps up the performance to the typical Atlantic Cat standards. But still it is a unique feeling to be sailing at “conventional boat” speeds under nothing but the two relatively small and easy to manage MastFoils."



Puis concernant le comportement de l'aile dans la tempête :

"One area of particular concern has been the behavior of the foil in very high winds. To investigate this further, we mounted a test section of the A47 MastFoil on a trailer and pulled it down the highway at 70 mph. The foil behaved very well with no vibration or oscillations. When it was disturbed by a gust from a truck coming the opposite way, the foil shook momentarily then immediately stabilized. I don't foresee problems feathering the foil in storm conditions. The ability to feather the foil with any wind angle is a key component to the inherent safety of the MastFoil design, as is the ability to use the foils as effective and easy to handle storm sails."

Voici donc une nouvelle preuve de l''excellente tenue d'une aile rigide dans les vents forts.
Du fait d'une nette diminution de la trainée, une aile à profil épais symétrique se comporte sans les mouvements parfois violents et brutaux qu'on voit sur les grand-voiles, génois, etc…


Chris White s'étend un peu plus sur le concept MastFoil, dans cette page :
http://www.chriswhitedesigns.com/atlantic_cats/mastfoil/index.shtml



Laurent.
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