If that 50 mph is airspeed, then

force (oz) = sin(angle) * area (sq in) * mph^2 / 560

hinge moment = 25% of surface chord, or 0.5 inches in your example

Torque = force * moment

So, say for 15 degrees of deflection,

Torque = 6 oz-in

If you move the hinge line back from the leading edge, you can reduce the amount of torque needed