3 blade McCauley VRS 2 blade Hartzell on 24-180

[Will Berninger]

Greetings fellow Comanche owners.
I have searched for hours on this site and google finding nothing so here goes:

I am new to the group but not new to the Comanche line. I have a 1961 PA24-180 with the updated Hartzell 2 blade non AD propeller. When I was searching for my 180 (not easy to find a good one!) I saw one or two with the Scimitar 3 blade McCauley props but never flew one because the airframes were just not right.
Anyway, I hear great things about that prop on the 180 and just wonder. Is the extra weight and 3rd blade actually worth the trouble?

My basis is that the scimitar 3 blade props normally tend to be 2 blade prop cruise, 3 blade prop climb, 3 blade prop vibration. Has anyone on this group changed out from the newer Hartzell to the scimitar McCauley? Or changed out from the older AD props to the 3 blade scimitar prop?

I have noticed that the STC has a larger RPM caution ban with the 3 blade prop than the 2 blade prop (other than the new 2 blade Hartzell scimitar which eliminates the RPM ban all together), and wondered if it was an issue? I have installed the McCauley on other aircraft including an Arrow which has a VERY noticeable resonance in that red arc vrs the stock Hartzell.

Forget cost, I know that part, I am wondering about actual performance improvements/weight penalty/vibration issue/maintenance needs ect on the PA24-180

As I understand it, the "Black Mac" 3 blade prop on the 250 suffers cruise speed loss but otherwise is good. This of course is not a scimitar propeller.

I have installed the Hartzell Comanche paddle prop on a 260 and the results were awesome. Perfect in every way except removal of the lower cowling

So, guess that's it. I am close to purchasing one just to know but sure hate to spend that kind of cash for an experiment.
Thanks in advance!
Will Berninger

[James Turner]

Hi Will,

I have a -180 with the old Hartzell 2 blade that likely won't pass the next overhaul. I was intending to replace it with the scimitar 2 blade when the time came.

I don't really have anything to add to your question except to ask why are you changing from the Hartzell 2 blade scimitar prop? Is it no good?

Cheers,

James.

[Will Berninger]

[Zach Grant L1011jock]

No loss in top speed, lots more static thrust for takeoff and initial climb, more efficient cruise (same speed at lower RPM on same MP), faster up high in less dense air (really becomes obvious above 10K). The caution arc is a non event as it is a "soft" restriction. It only applies if you are flying faster than 100mph indicated at less than 16" MP. It is a vibration issue but isn't imminently noticeable. I have done this mod on two different 180s with the same results. Both of these aircraft had dual exhaust. Both aircraft saw significant performance increases. Both had the stock prop before conversion. Both saw a significant reduction in noticeable cabin vibration. Some folks have reported abnormal vibration with this prop, but they all seem to have the stock exhaust, which I suspect has some sort of resonant frequency that the prop excites. I have not heard of any installation with problems lately so maybe they figured that issue out.

Zach

[Will Berninger]