"The Recognized Leader in High Performance Technology"
Ram Air Recovery System
Cheyenne I, II, & IIXL
All aircraft manufactures appreciate the advantages of an aerodynamically clean airframe. Over the years, the external shape of the fuselage, wings, and cowlings have been changed and refined in a continuing effort to reduce drag and increase performance. In recent years, aeronautical engineers have given equal emphasis to the internal airflow of an airframe as an additional source of enhanced speed and efficiency. By internal airflow we mean the airflow that enters the cowling inlet and passes through ducting into the engine intakes.
Aeronautical engineers gauge the aerodynamic efficiency of the cowling and ducting by measuring how well
high velocity air at the cowling inlet is converted into static pressure around the engine's inlet. This static
pressure is generally expressed as a percentage of ram recovery. The higher the ram recovery percentage, the faster the
aircraft will go. This is because at a given ITT, there is a finite amount of energy that can be produced by
a turbo-prop engine, and this energy must be shared by the two power absorbing sections of the engine, namely
the compressor section, which compresses air for combustion and the power section, which turns the propeller.
By increasing the ram recovery to the engine inlet, less energy is used by the compressor section leaving more
energy available to drive the propeller.You may have noticed that many of the newer turbo-props feature these high efficiency cowling designs. All of the newer Beechcraft King Airs and newer Cessna turbo-props have cowlings that were designed for high ram recovery. Nearly all of the new commuter aircraft and even the Cheyenne IA and IIIA's to some extent, have them as standard equipment. The Cheyenne I's, II's, and IIXL's however, were manufactured before this technology became readily available.
Recognizing the power and value these aerodynamic improvements offer, American Aviation developed a Ram Air Recovery System specifically for the Cheyenne I, II, and IIXL.