This highly modified Pitts S-2S has a 400 hp Lycoming engine and a Hartzell composite constant speed prop. So why a composite prop? Well, during tumbling maneuvers a spinning aluminum prop puts enormous gyroscopic-induced loads on a crankshaft. The lightweight composite prop reduces such loads by a factor of five.
The Pitts S2-S is the single-seat version of the Pitts S2-B. Here is a quick guide to the Pitts series of aircraft and here are some great Pitts articles by Budd Davisson.
The following companies are in the Pitts aircraft business.
Steen Aero Lab
Jim Kimball Enterprises (Requires the Flash plug-in)