Press Releases

Propeller Achieves Results through Advanced Blended Airfoil technology

Hartzell’s new propeller for the Diamond Star DA40 increases performance, provides increased durability and meets stringent noise requirements.

PIQUA, Ohio — July 15, 2003 – Hartzell Propeller Inc. announced today the introduction of a new two-bladed propeller system for Diamond Aircraft’s DA40 Diamond Star. The propeller is a 74-inch diameter Compact series propeller. Diamond will offer this propeller on newly manufactured DA40 Diamond Stars and it is also approved for installation on any existing US or Canadian registered DA40 Diamond Stars. Working together with Diamond Aircraft Industries, this introduction is the culmination of a rapid effort by Hartzell to achieve a Supplemental Type Certification (STC). Several Diamond customers had specifically requested the availability of a metal propeller and Hartzell was selected due to their willingness to obtain the necessary STC and to achieve specific and very stringent design goals.

Diamond wanted the propeller to: improve cruise performance; have no operating restrictions; and to eliminate the current placard restricting continuous operation above 2400 rpm; all while maintaining a low noise profile. In response, Hartzell developed a new blade design specifically for the DA40 utilizing the company’s “blended airfoil” technology. The result is a propeller that offers: an improvement of 2 knots in cruise (75% power @ 5000 feet); no operating restrictions to 2700 rpm; yet remains 9 dBA below the ICAO noise limit and almost 3 dBA below the more stringent Austrian, German, and Swiss noise standards.

In order to eliminate the current operating restriction, the structural design considerations were very demanding. Most propellers installed on undamped Lycoming –360 series engines require placards to avoid operation in regions where the propeller experiences high stresses due to forced inputs from the engine. Structural tuning of the design and the use of shot peening the metal blades in order to improve fatigue strength made achievement of this goal possible.

The propeller’s extremely low noise signature was achieved despite an increase in diameter of 3 inches and an increase in engine speed of 300 rpm. This is the result of research conducted by Hartzell and the application of tools derived through its efforts in NASA’s GAP and AGATE programs. The design of the blade tip region to achieve this result has been incorporated into Hartzell “blended airfoil” technology. Up to this point, the normal avenue for reducing noise has been through increased blade count, reduced diameter and reduced engine speed. This method of noise reduction also degrades aircraft performance.

“I am proud to state that Hartzell engineering has successfully developed a design that will improve aircraft performance and still meet stringent European noise regulations,” said Mike Disbrow, Senior Vice President of Marketing & Customer Services at Hartzell.

Hartzell’s broad capability and extensive delegated authority from the FAA enabled Hartzell to complete the design of this new propeller, test it, type certify the prop, and attain STC for the aircraft in a matter of months. Hartzell was able to rely on several of it’s DER’s (Designated Engineering Representatives) and it’s in-house DOA (Delegated Option Authority) to get this new design approved and certified in time to meet Diamond’s requirement for July, 2003 deliveries.

For more information on the new propeller system for the DA40 Diamond Star, call Diamond Aircraft at 888-359-3220 or visit www.diamondair.com.

Hartzell Propeller Inc. is widely recognized as the leader in advanced propeller design and manufacturing technology. NASA has recognized Hartzell’s advanced design capability by naming it the exclusive propeller partner for its General Aviation Propulsion (GAP) program. The company has recently developed the next generation of propeller designs based upon innovative “blended airfoil” technology and is manufacturing these blades on revolutionary machining centers to provide mission optimized performance for its customers. Hartzell traces its beginnings in 1917 to a relationship with Orville Wright and was founded on the principal of Built on Honor – a tradition that continues today. For more information visit the company on the Web at www.hartzellprop.com or fax your request to Hartzell at (937) 778-4321