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  #11  
Old 10-03-2014, 11:34 AM
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Saville Saville is offline
 
Join Date: May 2014
Location: KBVY Massachusetts
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Quote:
Originally Posted by rbibb View Post
I was just pointing out that long gear legs are required to use one...
Yeah that's my point as well when I wrote:

" And I have to say that the more I look, the more an O-320, 160hp, wood prop sounds best. Unless it has long landing gear legs in which case I'd consider a bigger prop."

In other words if it has short legs then I might be inclined to go with the shorter diameter props. Longer leg? Larger dia prop.
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  #12  
Old 10-03-2014, 12:48 PM
JimRice JimRice is offline
 
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Location: Collierville, TN
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Is 68" prop the longest for use on short geared RV-4? Can a 70" be used safely?
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Jim Rice
Collierville, TN

1994 RV-4 N4WJ (Purchased/Flying)
1946 J-3 Cub N7155H (Restored/Flying)
1946 Globe Swift N3368K (Purchased Restored/Flying SOLD)
1987 Starduster Too SA-300 (Purchased/Flying/SOLD)
1994 V6STOL (Built w/dad/SOLD)

US Army Retired (still working to pay for flying)

When my ship comes in, I'll probably be at the airport.
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  #13  
Old 10-03-2014, 01:41 PM
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rbibb rbibb is offline
 
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Location: Freericksburg, VA
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Quote:
Originally Posted by Saville View Post
Yeah that's my point as well when I wrote:

" And I have to say that the more I look, the more an O-320, 160hp, wood prop sounds best. Unless it has long landing gear legs in which case I'd consider a bigger prop."

In other words if it has short legs then I might be inclined to go with the shorter diameter props. Longer leg? Larger dia prop.
Actually I was a victim of spellcheck autocorrect. What I meant to type was that the Sensenich Metal Prop (70" diameter) works fine with my short leg RV-4 so the long gear, while nice to have, is not a requirement to use that prop....
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RV-4 N144KT
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  #14  
Old 10-03-2014, 02:50 PM
Dean Pichon Dean Pichon is offline
 
Join Date: May 2006
Posts: 532
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Quote:
Originally Posted by Saville View Post

Just the other day I was looking at a C/S propped -4. The ad says it has a Hartzell HC-C2YK-1B ? 1 hung on an O-360 A1A. Nice.

But I did a search on that prop to get it's diameter and found this:

-----------------------------------------------
Hartzell HC-C2YK-1BF/F7666A-2 Propeller on 180 Hp Lycoming engines
equipped with Electronic Ignition or FADEC

The Hartzell Propeller Model HC-C2YK-1BF/F7666A-2 has been vibrationally approved per FAR23.907 on the standard production Lycoming Engine Model O-360-A1A, and similar models,rated at 180 HP at 2700 RPM with a restriction to avoid continuous operation between 2000 and 2250 RPM.
---------------------------------------------------

This came from:

https://www.vansaircraft.com/pdf/Hartzell_c2yk.pdf

There's another PDF on this here:

https://www.vansaircraft.com/pdf/Hartzell_c2yr.pdf

I'd have to investigate this further but would be a deep concern that I can't run continuously at 2100 rpm.

.
When I built my -4, I bought the engine and prop combo referenced above from Van's. It was a fairly common combo 14 or 15 years ago. I lived with the rpm restriction without any issue. I have since purchased the new "blended airfoil" prop and now run it on the same engine without rpm restrictions. According to Hartzell, it has no rpm restrictions not because it is a better match to the engine, but because no testing has been done. I'm not sure if this is better or worse than the previous combination...

Regards,
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  #15  
Old 10-03-2014, 02:50 PM
Dean Pichon Dean Pichon is offline
 
Join Date: May 2006
Posts: 532
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Quote:
Originally Posted by Saville View Post

Just the other day I was looking at a C/S propped -4. The ad says it has a Hartzell HC-C2YK-1B ? 1 hung on an O-360 A1A. Nice.

But I did a search on that prop to get it's diameter and found this:

-----------------------------------------------
Hartzell HC-C2YK-1BF/F7666A-2 Propeller on 180 Hp Lycoming engines
equipped with Electronic Ignition or FADEC

The Hartzell Propeller Model HC-C2YK-1BF/F7666A-2 has been vibrationally approved per FAR23.907 on the standard production Lycoming Engine Model O-360-A1A, and similar models,rated at 180 HP at 2700 RPM with a restriction to avoid continuous operation between 2000 and 2250 RPM.
---------------------------------------------------

This came from:

https://www.vansaircraft.com/pdf/Hartzell_c2yk.pdf

There's another PDF on this here:

https://www.vansaircraft.com/pdf/Hartzell_c2yr.pdf

I'd have to investigate this further but would be a deep concern that I can't run continuously at 2100 rpm.

.
When I built my -4, I bought the engine and prop combo referenced above from Van's. It was a fairly common combo 14 or 15 years ago. I lived with the rpm restriction without any issue. I have since purchased the new "blended airfoil" prop and now run it on the same engine without rpm restrictions. According to Hartzell, it has no rpm restrictions not because it is a better match to the engine, but because no testing has been done. I'm not sure if this is better or worse than the previous combination...

Regards,
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  #16  
Old 10-03-2014, 06:28 PM
Hangar 1271 Hangar 1271 is offline
 
Join Date: Nov 2013
Location: Orlando, FL
Posts: 94
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Thanks so much for the input. Always helpful to get the insight of experience. I searched previous threads on the subject as suggested. It is interesting to see the progression of opinions over the 9 year span of threads.
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  #17  
Old 10-09-2014, 01:35 PM
precession precession is offline
 
Join Date: Apr 2006
Posts: 146
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Quote:
Originally Posted by JimRice View Post
Is 68" prop the longest for use on short geared RV-4? Can a 70" be used safely?
Absolutely 70" works perfect on shorter gear RV-4s (I would guess better than 68).
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  #18  
Old 10-09-2014, 09:02 PM
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SMO SMO is offline
 
Join Date: Oct 2007
Location: Salmon Arm, BC
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I had a 72" Hartzell on my short-legged -4. Given this was my first taildragger and I had not flown an RV previously except for transition training, I had some interesting landings but never touched the prop.

If I were buying another -4 I would definitely get the long legged version as it is much closer to the critical AOA in the landing attitude - reduces the number of tailwheel first arrivals.
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Mark Olson
1987 RV-4 Sold
2003 Super Decathlon - Sold
F1 EVO Rocket, first flight May 31/14
First in line for the Sonex JSX-2T kit
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  #19  
Old 10-10-2014, 01:26 PM
Whitman Whitman is offline
 
Join Date: Oct 2010
Location: Allentown PA
Posts: 254
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Quote:
Originally Posted by SMO View Post

If I were buying another -4 I would definitely get the long legged version as it is much closer to the critical AOA in the landing attitude - reduces the number of tailwheel first arrivals.
I have a short legged -4 and almost every 3 point landing has the tailwheel touching first. It's not a bad thing and I believe it's the way it was designed (not sure why). With that said, the long legged version is sexy and I would buy that if possible but definitely not a deal breaker.
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