[PCW] Air cushion between catamaran hulls

[Georgs Kolesnikovs]

From: "Jim Russell" <jimrussel at sympatico.ca>
To: "'East Cape Marine Ltd.'" <info at eastcapemarine.com>, "'Power
	Catamaran List'" <power-catamaran at lists.samurai.com>
Subject: RE: [PCW] Air cushion between catamaran hulls
Date: Wed, 4 Mar 2009 17:05:08 -0500

The "air cushion" effect that is referred to is really the hull's aerofoil
generating aerodynamic Lift & Drag in "close ground proximity or "ground
effect".  Physical characteristics that affect the contribution of aero Lift
of the tunnel hull's aerofoil include - tunnel height, angle of attack, wing
aspect ratio (width/chord), plan area of wing, wing thickness (upper deck to
tunnel roof), aerofoil shape (camber).  The contribution of aerodynamic Lift
(as compared to hydrodynamic lift from sponsons) can vary from 10% on
heavier hulls or slower velocities to 80% to lighter hulls and high
velocities.

Jim Russell, P.Eng.
AeroMarine Research
http://www.aeromarineresearch.com

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