More Information on SynchroPulse Propellers
The all new SynchroPulse propeller, developed jointly by LoPresti Speed Merchants and the Hartzell Propeller company, has been certified by Hartzell and Approved for the Comanche 250, 260 and 260B.

This new propeller employs a fixed flap on the trailing edge of the propeller whose purpose is to ram a pulse of pressure into the inlet to the engine charge air induction system. The arrangement of the induction system and its length have been designed so that at cruise RPM, pressure pulses generated by the Flap, arrive at each of the cylinders when the intake valves are open. This synchronization provides a little supercharging which in turn provides some extra speed and efficiency.

This propeller design enhances engine performance providing more thrust and higher cruise critical altitude. The SynchroPulse action has been optimized to provide maximum effect at cruise speed and RPM.

In addition to the extra speed associated with the SynchroPulse propeller, static thrust of the propeller is 15% higher than the static thrust of the standard 2 bladed propeller (as measured on the Comanche 260s), this extra thrust is very apparent in the run-up area; with the SynchroPulse propeller, additional brake pedal pressure is required to prevent the airplane from moving. This propeller also helps during decent. "As a rule, I'm not very keen on increasing drag,: says LoPresti, "But when you come down hill, drag helps. With the SynchroPulse propeller, a customer will find that at normal descent power and indicated airspeed, the airplane will have a higher sink rate."

The propeller is the result of a technical discussion between Jim Brown, Hartzell Propeller's president, and Roy LoPresti resulting in an analytical study followed by and extensive flight test program. The SynchroPulse propellers are manufactured by Hartzell in their Piqua, Ohio, plant. The SynchroPulse propeller is featured on all LoPresti GTO Comanches. Speed Merchants is marketing Comanche GTO's that have been thoroughly modified and refurbished. GTO's cruise at speed over 200 MPH.

LoPresti Speed Merchants Gap Seals are different, (and better), than all others. Our Gap Seals are composite, not aluminum. Gap seals flex every time the flap moves. Constant flexing can lead to cracking problems. LoPresti Speed Merchants chose fiberglass for its gap seals because it has a fatigue life that is essentially infinite. Another difference is the cross section is slightly curved; this curve accelerates the boundary layer, making the flow below behave better and helps the follow the bottom surface.