I think the lift formula might come in use: L=CLQSA L(lift) CL(Coefficent of lift) Q(rho or dynamic pressure) SA (Surface Area). The only place that airspeed has a factor is Q and CL. As the speed (velocity) changes, the lift changes proportionaly. Remember from the CL curve that that as airspeed is decreased lift is decreased and an increase in angle of attack must be made in order to maintain altitude (Slow flight or MCA). Sometimes the pitch increases so much with out an increase in power that a stall occurs. hope I explained this ok.
Aerobatic aircraft use symetrical airfoils, that means that they have to have a positive angle of attack to have a higher velocity over the upper surface of the airfoil, because the thickness and camber is identical along the upper and lower surfaces of the airfoil in relation to the chord line.