3 Blade prop conversions

[bnt83]

Seeing a lot of owners complain about nose heaviness lately. I see airplanes that have been converted from 2 blades to 3 blades for sale all the time, yet its kind of a turnoff to me if you gotta carry 75# in the baggage to make it handle decent.

What say you? Is ramp appeal and marginally quieter worth the additional weight and poorer handling?

 

[kgruber]

3 blade is not necessarily any quieter, for instance the 3 blade McCauley 401 is much louder than the standard 2 blade 88" seaplane prop for the Cessna 185.

3 blade is heavier, slower in cruise, much more costly to purchase and maintain. They also usually require new motor mounts to run smoothly. I regretted the change on my 185.

 

[Ted]

It completely depends on the conversion. The 4-blade props on the 340 STC reduce weight over the 3-bladers by about 50 lbs (for the engine, so two props).

For more weight and less speed, not interested.

 

[Archammer]

I will tell you that the new scimitar design, composite 3-blade Hartzell is EXTREMELY quiet on the Redhawks. Now some of that has to do with the engine, but most of it has to do with that amazing prop.

In addition to that, the composite makes the 3-blade almost the exact same weight as a standard McCauley 2-blade.


Quote directly from Hartzell:

Yes, in most installations increasing the number of blades helps to reduce noise. Cockpit noise comes from a variety of sources; engine, exhaust, air flow around the fuselage, and the propeller. Vibrations are also perceived as noise in the cockpit. In a single-engine airplane, the propeller blade wake will beat on the windshield producing noise. A 2-blade propeller produces two pressure pulses per revolution, where a 3-blade propeller will produce three smaller pulses per revolution (for the same amount of total thrust) which is inherently smoother and therefore quieter. The 3-blade propeller will generally have a smaller diameter than the 2-blade propeller that it replaces, which also reduces the tip speed and noise. In a twin-engine aircraft, the reduced diameter of the 3- blade propeller will result in less tip-generated noise and a greater clearance between the blade tip and the fuselage. Both of these characteristics will reduce cabin noise. - See more at: http://hartzellprop.com/faq/technical-questions/#sthash.huH7PMQ0.dpuf

 

[KSMooniac]

My 3-blade MT is substantially lighter than the 2-blade OEM McCauley it replaced.

No way would I ever put a metal 3-blade prop on a 4-cylinder Mooney, though.

 

[joen6171b]

On Bonanzas, the three blade helps keep the weight out front where it's needed. Most are tail heavy when loaded to gross.