Air flow over wings and engine inlets greatly changes due to a number of factors, such as atmospheric conditions, speed, and the design of the surfaces. On some engines you can see mist behind the leading edge of the nacelle in front of the fan, indicative of various pressures resulting from the shape of the edge. In the same way I would guess that the shape of the pitot tube would affect the indicated airspeed- possibly at higher speeds or with a wider edge less air would enter the tube, giving an incorrect reading to the pilot. So how do various shapes affect the indicated airspeed? How about fast aircraft such as the blackbird VS common commercial aircraft VS slower aircraft like a small Cessna?