Geometric pitch

Geometric pitch = the circumference (2 π r) of the propeller disc at the blade station multiplied by the tangent of the blade angle.

Geometric Pitch. The distance which an element of a propeller would advance in one revolution under conditions of no slip.
Gibli. A hot dry southerly wind in Tripoli, similar to the Sirocco.

effective pitch - The actual distance a propeller moves through the air in one revolution. It is the difference between the geometric pitch of the propeller and the prop slip.

At very high speeds, when you are going fast enough to over-run the geometric pitch of the propeller (so that the resultant coincides with the reference line in figure 8.4), ...

See also: Weight, Glider, Force, Flight, Glide