It's not correct to describe the '1/2' as a factor derived through experimentation to make the numbers work. That's more accurately assigned to Cl - a non-dimensional number that accounts for Angle of Attack & aerofoil shape.
Rough guide:
Lift formula is related to classical mechanics. Force, momentum, acceleration, mass etc.
It starts with mass x velocity = momentum
Kinetic energy = momentum squared / twice the mass. Substitute mv in the formula and it becomes
Ek = m v^2 or 1/2mv^2
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2
Force = mass x acceleration. Accelerating a mass requiress a force. If a mass of air can be made to accelerate than a force must have been involved and a reaction opposite that force.
L (a result of making the air accelerate) = CL x 1/2 x rho x v^2 x s where
Rho is the air density (a way of accounting for mass) and has an equivalent part in the lift formula as Mass has for Kinetic Energy. Substitute 1/2mv^2 and you have
L=CL x Kinetic Energy x area
In other words the energy contained in a parcel of air acts over a body with an area that, due to it's shape and angle, accelerates the air to produce a force (or a reaction, if you like). Anything that increases the amount of energy available to be put to work, the size of the area over which it works, or the ability of the shape or angle to modify how that work is done will increase the amount of lift.
Last edited by Tinstaafl; 21st January 2011 at 19:46.