Roll rate:
All other things being equal, roll rate varies directly with wingspan and airspeed.
Ailerons usually span 40% of the wing and 25% of the chord (10% of the wing area). The planform of the wing and the area that is affected by ailerons is important in producing the roll torque. The greater the roll torque, the faster the max roll rate will be. 2 examples:
Spitfire: Elliptical planform - minimizes roll inertia but there is little area outboard where the ailerons are, so roll torque is low and so is the roll rate.
Corsair: Slightly tapered/almost straight wing - higher inertia but faster roll rate.
A general rule of thumb to estimate roll rates...
Take the aileron deflection, multiply by the % of wing area. That will give the angle of attack change of the whole wing (figured at the mean aerodynamic chord).
20 degrees * 10% = 2 degrees
On a straight wing, the MAC is 50% of the semi-span (or half way to the wingtip). On tapered or elliptical wings, it's closer to the fuse.
Example: Span = 40', semi-span = 20', MAC =10'
A point on the MAC carves a circle 31.4' in circumference.
Use trig to figure out the velocity around that circle, depending on forward speed.
V = tan(2 degrees) * forward velocity
If the plane is flying at 200 mph, a point on the MAC is travelling at 7 mph (10.3 ft/sec).
Therefore, it will take 3 seconds to complete a roll.
