Swept-wing theory leads to new King Air prop design
Taking a lesson from swept-wing military airplanes, business aircraft modification company Raisbeck Engineering and Hartzell Propeller have partnered to create a new Beech King Air 200 series propeller that dramatically boosts takeoff and climb performance over stock props. The new Raisbeck/Hartzell Swept Turbofan propeller claims a 1,000-foot reduction in takeoff performance over a 50-foot obstacle compared to stock King Air B200 props.
The new all-aluminum props are certified for the King Air 200, B200, and 200GT airplanes and can be used alone or in combination with any of Raisbeck’s many other King Air 200 airframe modifications.
Raisbeck officials say the technology behind the new propellers evolved from aerodynamic swept-wing theory, which allows for measurably lower drag on aircraft wings flying at high subsonic Mach when swept aft. The result is a 96-inch highly swept blade—three inches longer than the stock factory blades and two inches longer than Raisbeck’s existing line of King Air Power Prop replacement props, which will continue to be available. The Swept Turbofan blades are three inches longer than the current Hartzell props offered from the Beechcraft factory. Even with the greater length, the new propeller system is no heavier than the existing products.
Raisbeck engineers report that the greater diameter accounts for most of the takeoff and climb improvements, while the highly swept design accounts for a reduction in cockpit and cabin noise. Normally, larger diameter props result in increased perceived noise levels.
The new Raisbeck/Hartzell partnership to create the Swept Turbofan propellers was announced on Jan. 1, 2013. However, the project has been underway for three years, according to James Raisbeck, founder of the modifications company. The new propellers sell for $83,400 a pair from the company’s 100 dealers around the world. Shipments are scheduled to begin in March. The price is $8,900 higher than Raisbeck’s existing Power Prop line.
January 1, 2013