Polen Special
The Polen Special, is a homebuilt racing aircraft built to become the fastest four cylinder aircraft in the world. Development. The Polen Special, (Also known as the Polen Special II) development started in October 1967 by Dennis Polen and Darryl Usher. The project to build a fast single seat racer larger than Formula One limitations began as a retractable gear Midget Mustang modification. After reviewing engine installation shortcomings, a clean sheet design was started. The Polen Special was then designed around a Piper Comanche engine and cowling, which also had design issues with engine canting and required cowling  modifications for a single engine installation. A new clean sheet Lycoming IO-360 installation came afterward. Two sets of retractable landing gear were built and tested, but were sold to other homebuilders. Over time, the RayJay turbocharger was removed due to hunting and composite ailerons were installed. The aircraft was sold by Polen to Richard C. Keyt and has been modified several times to increase efficiency and safety. A composite rudder replaced the all-metal rudder that fluttered to destruction at 2500 engine RPM and a modern turbocharger was installed. Keyt and partner Jack Zimmanck formed the Polen Company to develop  aircraft technologies with the Polen Special as a flying testbed. A design modification called the "Stage 3" is underway incorporate further improvements. Design. The Polen Special is a low-wing monoplane with retractable conventional landing gear. The retractable gear is hydraulically operated from a T-33 sequencing valve with electric powered gear doors. The fuselage and wings are all aluminum with flush riveting. The ailerons and elevators use push-pull tubes, with cable control for the rudders. The aircraft is specifically designed to fly at high altitude on IFR routes with the pilot using supplemental oxygen to achieve maximum speed with  the turbocharged engine.