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  #21  
Old 08-18-2021, 06:09 AM
BOHICA BOHICA is offline
 
Join Date: Oct 2020
Location: Austin
Posts: 48
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Quote:
Originally Posted by StressedOut View Post
I have read (with no supporting proof, to be fair) that the 3-bladed prop mated with the EXP engine is considerably smoother. Can anyone with actual experience with either the MT or Hartzell version chime in on this issue?
I would expect 3 to be quieter/smoother than a 2. Comes down to frequency of the air pushed by the prop. Three puffs of air vs two puffs of air per rotation is one way to look at it. My electrical engineering brain looks at it as a full vs half-wave rectifier.

Hartzell has an article.

https://hartzellprop.com/are-more-pr...otal%20thrust.
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  #22  
Old 08-18-2021, 11:03 AM
StressedOut StressedOut is offline
 
Join Date: Jun 2017
Location: Fullerton, CA
Posts: 161
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Quote:
Originally Posted by BOHICA View Post
I would expect 3 to be quieter/smoother than a 2. Comes down to frequency of the air pushed by the prop. Three puffs of air vs two puffs of air per rotation is one way to look at it. My electrical engineering brain looks at it as a full vs half-wave rectifier.

Hartzell has an article.

https://hartzellprop.com/are-more-pr...otal%20thrust.
Thanks for posting that link. The article was very informative. So to sum up this thread it seems like the two-bladed prop is the best value for the money. The three-bladed prop gives about the same performance but gives a smoother and slightly quieter ride. However the weight savings of the composite prop is offset slightly by the need for forward ballast to keep the CG from moving too far aft.

For me the comfort factor is significant. I also recall Flightchops’ was claiming his RV-14 had slightly better climb rate and top speed with the Hartzell 3-blade. I’ll probably go for the 3-blade composite. After all, you’re typically dropping $150K when all is said and done. What’s another $13K in the grand scheme of things?
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Art Jackson
RV-14A Kit#140433
Completed: Vertical Stab/Horizontal Stab
Scrapped: Rudder
Working on: Empennage (Elevator, Rudder #2, Aft Fuselage)
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