PIQUA, Ohio — October 28, 1999 — Hartzell Propeller Inc. announced today that its specially designed experimental propeller system for the Lancair IV Sport Class Champion at the Reno National Championship Air Races incorporated a variety of advanced design technologies which may have future applications on high speed personal and business aircraft. The 75 inch diameter, three-bladed constant-speed propeller system featured a “Compact” aluminum hub with highly swept, wide-chord aluminum blades. The highly modified factory Lancair IV piloted by Dave Morss won the Gold race at Reno on the 19th of September at a five lap average speed of 319 MPH. The aircraft qualified at over 335 MPH on the 6.39 mile course. Both speeds were new records for the Sport Class which are production kit-built aircraft powered by reciprocating engines of 650 cu. in. or less. Sport Class racers are the second fastest class of airplanes at Reno after the Unlimiteds.
The Lancair IV was powered by a special factory prepared Continental TSIO-550 engine, designed to produce maximum power at well over 3,000 rpm. This racing application called for a prop that would maintain aerodynamic efficiency at the high airspeeds, high horsepower and extremely high prop rpm. The typical problem encountered at this flight condition are the shock waves generated by the transonic flow over the propeller blade, which greatly reduces efficiency with a significant increase in noise levels.
To overcome this design challenge, Hartzell engineers utilized ‘prop-fan’ blade technology first developed for NASA in the early 80’s but also used in some of the latest Hartzell Top Prop™ Conversions and, most recently, for NASA’s Advanced General Aviation Technology Experiments (AGATE) program. The goal of the design team was to delay the onset of shock waves by using a wide-chord, swept blade planform and thin airfoil sections which have a high critical Mach number. This design process is very similar to the design problems encountered by supersonic aircraft which utilize thin, highly swept wings.
Each of the new blades was CNC machined from one of Hartzell’s largest aluminum blade forgings which was required to accommodate the sweep. Hartzell’s ability to machine oversized forgings allows it to easily customize blades to match the performance characteristics of unique applications such as the race version of the Lancair IV. Other applications where reduced flyover and cabin noise as well as increased overall efficiency at high flight speeds are good candidates for the new technology.
Hartzell Propeller Inc. is the world’s leading manufacturer of propeller systems, well-known for its advanced engineering and manufacturing capabilities. The company is rich in aviation heritage tracing its beginnings to relationships with Orville Wright and Glenn Curtiss. Significant technical innovations include the industry’s first full-feathering propeller for light twins, the first fully reversing propellers for corporate turboprops and the industry’s first composite structure blades. Hartzell was recently selected by NASA as the exclusive propeller partner for its General Aviation Propulsion (GAP) program – developing the next generation of general aviation propulsion systems. For more information on Hartzell visit the Web at www.hartzellprop.com.