# Bernoulli wore tights and a funny hat…… I’m putting my money on Coanda. Geoffrey Hatcher MEI,CFII, IGI, AGI 1915 Biscayne Little Rock, AR 72227 (501) 680-7283.

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Bernoulli wore tights and a funny hat…… I’m putting my money on Coanda. Geoffrey Hatcher MEI,CFII, IGI, AGI 1915 Biscayne Little Rock, AR 72227 (501) 680-7283 www.geoffhatcher.comwww.geoffhatcher.com geoff@geoffhatcher.com

Romanian aerodynamicist Henri-Marie Coanda (1885- 1972) Discovered and named this phenomena. You probably discovered it when you washed your hands and the water flowed down your arm dripping off your elbow and onto your pants. Kind of embarrassing huh? That’s not the point though. You can see this effect in action by placing a glass horizontally under a stream of water. Surface tension and viscosity redirect the water.. This is how a wings upper surface produces its lift irregardless if it's a symmetrical, a non- symmetrical or even an upside down wing.

Coandas Effect: Due to its viscosity, surface tension, and adhesion properties: a fluid will stick to a curved shape as it flows along its surface in the manner illustrated. To a certain extent this adhesive force will resist other forces such as gravity or inertia and will accelerate the fluid by changing it direction. Its limitation is Angle of Attack. As you will see, Coandas’ effect is the primary phenomena associated with lift.

Every thing flows smoothly until too much is expected of the dynamic surface tension. As the angle of attack becomes to great; gravity eventually overcomes the surface tension of the fluid and it goes its separate way.

Acceleration=Change in direction or velocity Mass x Acceleration = Force Lets first look at a highly cambered airfoil used in slow high lift configurations. (Cessna wing with flaps extended.)

Coandas’ effect works with symmetrical airfoils as well as inverted ones. Mass x Acceleration = Force

Coandas’ effect works with inverted airfoils too. Mass x Acceleration = Force

Lift = reaction to force applied Original relative direction Final relative direction Force Applied Vector Math

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