Published: Thursday, September 12, 2013, 12:00 a.m.
The FHC's Polikarpov Po-2 is equipped with a pair of Venturi tubes, one on either side of the cockpit. Since you are all familiar with the exciting world of fluid pressure dynamics, I won't insult you with all of the minute details. The simple version is this: As air passes through the funnel-shaped constriction, its velocity and pressure increase. This manipulation of the passing air creates suction in a perpendicular tube situated just aft of the Venturi tube's smallest point. The suction system is an easy-to-maintain, cheap and simple way to spin the rotor in a vacuum-driven gyroscope located in the cockpit.