Originally Posted by gereed75
I spoke with a Hartzell guy at Sun and Fun. He said they started the current aluminum prop line with smaller roots, but added meat there to beef Up strength to gain structural margins with modified engines.
Talked to many Hartzell Reps at air shows. All nice but not all are same in technical department. All of their props (BA or not) have blunt (round) blade roots, to transition to hub. The extra material he is talking about is nil at root. Material they added is to address harmonics, and most likely further out towards the blade tip end not root. Even if the root has more material, the standard props still have as poor airflow adjacent to spinner. The prop blades near hub (not airfoil shaped) beat the air to death and produce little to no thrust.
Fun fact this is why the Sam James style cowl (based on MS State Engineering and NASA funded studies) have inlets as far outboard as possible away from spinner (blade root area), and this is why there is no inlet opening adjacent to spinner. The air inlet near spinner on standard Van's coals can actually flow backwards. You can block off an inch or two with out much change in cooling. It is not as effective inlet area in cruise and is more drag than effective cooling.
Raleigh, NC Area
RV-4, RV-7, ATP, CFII, MEI, 737/757/767
Last edited by gmcjetpilot : 06-24-2019 at 09:35 AM.