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  #1  
Old 06-05-2018, 03:13 PM
raisbeck raisbeck is offline
 
Join Date: Mar 2013
Location: Laramie, WY
Posts: 7
Default 3 blade Hartzell in an RV8 with 0-360 A1A

I've got the opportunity to buy a 3-blade Hartzell (C3YR-1RF) for the RV8 we're building. We've already purchased an Aerosport 0-360 A1A for the project, and I'm wondering if anyone else has tried such a combination.

In particular:
What about the effect on CG? I know that constant speed props tend to make some 8's a little nose heavy, and this is about 14 lbs heavier yet. We're still finishing the fuselage, so I don't have any guess where the CG is going to finally fall.
Are there any harmonic problems with this combination? Again, all I have is second or third hand anecdotal information about substituting 3 blades for 2 on other airframes and engines. FWIW - the prop was recently removed from an -8, and the combination is apparently approved on the Mooney M-20C.


Any first hand experience would be welcome.
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  #2  
Old 06-06-2018, 07:05 AM
Capt Capt is offline
 
Join Date: Feb 2017
Location: Australia
Posts: 200
Default

I'm no expert and am sure someone will chime in with more tech stuff but one often hears 2 Blades are more efficient & of course cheaper to overhaul. The extra weight is obviously a concern as weight is the enemy of any aircraft especially a Vans if being used for Aero's. My 8 has the std IO360 CS & it's a sweet time tested proven combo.
About the only good thing I've heard about 3Blade is they are mostly smoother & look oh so sexy, if it's looks then 4 blade sounds about right
Looking fwd to hearing what the more experienced Vans drivers have to say:-)
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  #3  
Old 06-06-2018, 07:25 AM
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Low Pass Low Pass is offline
 
Join Date: May 2006
Location: Houston
Posts: 1,901
Default

3 blades sound much better!

But - as mentioned, they're heavier, more expensive to overhaul. The weight and larger spinning mass would be a concern to me, personally.

As for harmonics as related to that specific prop and engine combo, that's way beyond trusting an answer on an internet discussion board. Get the TCDS for the prop and examine. Then call Hartzell and discuss. They are, or used to be, very helpful discussing this issue.
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Last edited by Low Pass : 06-06-2018 at 07:31 AM.
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  #4  
Old 06-06-2018, 06:56 PM
Capt Capt is offline
 
Join Date: Feb 2017
Location: Australia
Posts: 200
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I guess at the end of the day look at what everyone else is doing, most Vans are 2 blades & popularity in numbers must mean something
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  #5  
Old 06-06-2018, 08:18 PM
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Bugsy Bugsy is offline
 
Join Date: Nov 2007
Location: Waukesha, Wisconsin
Posts: 526
Default 1 more thing

the only other thing to consider is that 3 blade is harder to get cowl on and off. But there are folks doing it.
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Paul 'Bugsy' Gardetto, Col, USAF (ret)
Milwaukee, Wisconsin (Timmerman Field)
N377KG - Flying (250 hrs)
RV-7A, Aerosport O-360, WW200RV
Advanced Flight 5400
Avidyne IFD440
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  #6  
Old 06-22-2018, 12:41 PM
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Nihon_Ni Nihon_Ni is offline
 
Join Date: Jun 2011
Location: Fredericksburg, VA
Posts: 255
Default

Quote:
Originally Posted by Bugsy View Post
the only other thing to consider is that 3 blade is harder to get cowl on and off. But there are folks doing it.
I think the issues are mostly with -8As due to the nose gear.
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Rob K
真喜志友幸
RV-8 under construction as of Sep 30, 2012
Tail kit completed on Feb 8, 2012 (180 hrs)
Wing kit mostly completed, fuselage under construction as of March 6, 2014 (750 hrs)
Paid up for 2018
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