January 2, 2013 – Seattle, Wash. – Working under a corporate veil of complete secrecy for the past three years, Raisbeck Engineering and Hartzell Propeller have teamed to develop and certify the first business aviation turbine propeller using practical swept-wing theory as an integral part of its design.
The effort has culminated in the FAA certification of the Raisbeck/Hartzell Swept Turbofan Propeller for the King Air 200/B200/B200GT. The new Swept Propeller has been added to Raisbeck Engineering’s Airplane Flight Manuals, making it compatible with all combinations of Raisbeck Performance Systems for these aircraft and carrying with it all these systems’ FAA-approved increased performance levels.
The swept-back design required a new Hartzell-supplied forging before production could begin. Hartzell is currently in the manufacturing cycle. For development and FAA certification flight testing, blades machined from large aluminum blocks were used. Deliveries commence March 1st, 2013 from Hartzell’s factory near Dayton, Ohio, to Raisbeck’s customers of record.
The technology behind the Swept Turbofan Propeller centers around the aerodynamic swept-wing theory, which allows for measurably lower drag on aircraft wings flying at high-subsonic Mach when swept aft. This principle has been incorporated into the new Raisbeck/Hartzell family of Turbofan Propellers, giving them an entirely new look, not previously seen outside the military anywhere in the world.
“Sexy, I’d say,” commented James Raisbeck, CEO of Raisbeck Engineering. “The overall performance improvements relative to both the OEM 3-blade and 4-blade Hartzell propellers are large, and result in greatly improved FAA-certified takeoff, climb, and landing capabilities. Their enhancement over our current Raisbeck/Hartzell Turbofan Power Props is also measurable,” he added.
Hartzell Propeller president Joe Brown applauded Hartzell’s long-term relationship with Raisbeck Engineering, going back 30 years. "Hartzell's first development with Raisbeck resulted in the Raisbeck Quiet Turbofan Propeller System for all King Air models and is still in production. Over 2600 of these Hartzell/Raisbeck propellers have been delivered to date, making this the most successful aftermarket program in Hartzell's history," he commented.
The research and design phase of the new Swept Turbofan’s development took over three years, and was led by Hartzell’s Michael Schulte and Raisbeck’s Davud Kasparov. Working together between Dayton and Seattle, they honed an attractive, efficient, evolutionary propeller. According to Schulte, “These new blades are a thing of beauty and offer the kind of rational expansion of our product development with Raisbeck Engineering that our companies have enjoyed together for the last 30 years.”
After studying multiple designs and iterations, the chosen configuration is designated the HC-D4N-3A/D9515K for the King Air 200 family. It incorporates aluminum blades and hubs to keep both weight and cost to a minimum. No shot-peening was required and ground minimum RPM remains at a low 1150. Overhaul times are a high and generous 4,000 hour/6 year cycle. Propeller diameter has been increased to 96?, a full 2? greater than Raisbeck’s current offerings for the King Air 200 family. They are a large 3? greater than the OEM propellers installed on the King Air B200 and its current production 250. Yet perceived sound levels are reduced slightly, due to the effect of blade sweep. Also, because of the new high-subsonic airfoils utilized in the design, weight remains unchanged. Much of the low-speed performance increases occur from the increased diameter, while the high-speed (and high propeller-Mach) improvements and reduction in cockpit and cabin noise are attributable to the swept-back blade design.
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