PIQUA, Ohio — June 7, 1995 — Hartzell Propeller announced today that it is beginning full-scale production of its three-bladed DuPont Kevlar composite aerobatic propeller system. To date, the certified propeller system (TC pending) has undergone months of in-flight operation with Patty Wagstaff’s BF Goodrich Aerospace Extra 300. In addition, the system has been tested and incorporated into Bill Zivko’s Edge 540 aircraft as well as Jon Staudacher’s latest designs.
Monty Barrett of Barrett Performance Aircraft Engines has tested torsional inputs of the new system on engine crankshafts with impressive results.
The lighter weight composite blades dramatically reduce crankshaft stress during severe aerobatic maneuvers, and should, over the life of the system, significantly impact engine service, repair and maintenance costs. Pilots can also expect a reduction in vibration.
The Hartzell aerobatic system consists of composite blades incorporating high performance aerobatic airfoils, a strengthened shank design, a nickel erosion shield bonded to the leading edge to provide impact and erosion resistance, an aluminum hub, a new spinner, and an oil accumulator system to provide engine overspeed protection.
The accumulator system consists of a valve assembly between the engine oil supply and the governor. When the valve senses an oil pressure loss from the engine, the accumulator takes over, continuing to supply the governor with oil, and the pilot with effective propeller pitch control.
The new composite three-bladed design offers aerobatic pilots superior low speed thrust with only a minimal gain in weight. The new composite three-bladed kit weighs only 5.66 lbs. (2.57 kg) more than a comparable two-bladed aluminum system. Additional benefits of the composite system include improved tip clearance due to a shorter prop diameter, better reparability due to the easily workable composite structure, and a superior warranty.
Flight performance results are impressive. Ken Hadden of Columbus, Ohio and President of the local International Aerobatic Club has performed the initial flight testing. He noted that “… vertical penetration is fantastic and more time can be spent on down lines because of the braking effect of the three wide-chord blades.” In addition, “… topping off a line from vertical to horizontal is easier because of the added low-speed thrust of the propeller and the dramatic reduction in torque effect at high power settings.” During the flight test program, the oil accumulator system worked exceedingly well and the pilot was unable to overspeed the engine.
The new propeller system successfully completed vibration testing throughout the entire flight envelope of the Pitts S-2B test aircraft, and its Lycoming AEIO-540-D4A5 engine. Testing included analysis during high-stress maneuvers such as power on spins, snap-rolls, torque-rolls and lomcevaks.
Unlike most aerobatic propeller systems on the market today, the Hartzell system is certified and will meet similar criteria as those Hartzell composite props that have now undergone millions of flight hours on the Cessna Caravan, Beech 1900 Commuter, Shorts 360-300, CASA 212 and the Porsche Mooney PFM.
Hartzell Propeller Inc. is the world’s leading manufacturer of propeller systems enjoying 60 percent market share on turboprop airliners and 85 percent market share on corporate turboprops. The 78-year-old company is also well known for its design leadership having introduced 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.
Additional Aerobatic Aircraft with Hartzell Propellers:
Pitts S-2B, S-1T, S-1S
American Champion Decathlon
Staudacher 300 Series
Beech T34, T34C
Pilatus PC7, PC9
Siai Marchetti SF260, SF260TP