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  #1  
Old 03-19-2010, 10:31 PM
Rick RV-4 Rick RV-4 is offline
 
Join Date: Aug 2006
Posts: 221
Default Need to repitch my Sensenich?

I'm just curious what others are seeing with their Sensenich prop/RPMs at various power settings and altitudes? I have an RV-4 with an O-360, dual P Mags, and the standard Van's 85" prop.

Since adding my wheelpants and fairings to my new RV-4, I am having a lot of occurrences of hitting the 2700 RPM limit unless I pull the power back quite a bit (sometimes I have to pull it back to about 1/3 of the way). This is happening up high as well (7,500+ in altitude) - not just lower altitudes where the engine can develop full power.

At the beginning of my takeoff roll I'm showing just about 2180-2200 RPMs, increasing as I pick up speed. The numbers are pretty good - 2,200 FPM climb, and just over 200 MPH TAS. It seems like I could go a lot faster if I had more prop bite (2 - 3 inches more pitch) and could therefore be at full throttle. Anyone else run into this?

Thanks,

Rick
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  #2  
Old 03-19-2010, 11:12 PM
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Radomir Radomir is offline
 
Join Date: Jan 2005
Location: Charlotte, NC
Posts: 1,518
Default

Yeah.. it's not that uncommon... They can re-pitch it for a few hundred bucks.. A lot of prop shops around the country can do it... so it all depends on your location and what's most convenient to you.. I had an 87" Sensenich on my -7A.. it worked fine..
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  #3  
Old 03-19-2010, 11:24 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 7,804
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It's a trade off with a fixed pitch prop. Particularly on airplanes with as wide of a speed range as the RV's have.
You could re-pitch to allow you to use full throttle at 8000 and you will really scoot but I think you would be unhappy with the takeoff and climb performance.
My personal preference is for a prop pitch that gives about 2600-2650 rpm with WOT at 12,500 ft. This will give you a pitch for goo all around performance but it will require you to throttle back some at lower altitudes.
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  #4  
Old 03-20-2010, 03:11 AM
penguin penguin is offline
 
Join Date: Jan 2005
Location: England
Posts: 1,051
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You'll be surprised how much difference 1" pitch makes on the runway. You'll lose around 25rpm, which will make the take-off performance seem rather lethargic. At full throttle you'll lose around 50rpm. I would take it steadily and go 1" at a time. Any Sensenich prop can be re-pitched a total of 7" through out its life (direction doesn't matter). Should cost $100 or 200 per re-pitch, plus another $200 to get it re-painted once you're happy with the pitch.

Pete
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  #5  
Old 03-20-2010, 06:31 AM
wilddog wilddog is offline
 
Join Date: Feb 2008
Location: va.
Posts: 364
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Might want to get your tach checked first so you will be sure of what you need.
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  #6  
Old 03-20-2010, 09:06 AM
Rick RV-4 Rick RV-4 is offline
 
Join Date: Aug 2006
Posts: 221
Default Tach check

Thanks for the inputs - my TACH is electronic, so I'm fairly confident it's right (down the 10 RPM resolution).

Scott, I'll try WOT at 12,000 and see what I get . . . haven't been above 10,500 yet.

Thanks,

Rick
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  #7  
Old 03-20-2010, 09:45 AM
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turbo turbo is offline
 
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Location: Stuart, FL /Hartford, CT/Virgin Gorda,BVI
Posts: 2,992
Arrow try calling sensi and talk tp ed.

they traded me up for free from a 83 to 85 inch. they said they would recondition and sell my old prop. i had put on 900 hrs on it. i would rather do that then repitch. my prop is very thick. great unit. good luck. go for speed.
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  #8  
Old 10-23-2010, 11:56 AM
Teal35 Teal35 is offline
 
Join Date: Oct 2010
Location: Illinois
Posts: 2
Default Interested

Very interested in what you find out / decide. I have an rv-4 180 hp as well and am looking to purchase a new prop. I am considering a sensenich but, like you, am not sure what pitch to use . I am also interested in what length you went with and are you pleased with the ground clearance.

Jim
Quote:
Originally Posted by Rick RV-4 View Post
I'm just curious what others are seeing with their Sensenich prop/RPMs at various power settings and altitudes? I have an RV-4 with an O-360, dual P Mags, and the standard Van's 85" prop.

Since adding my wheelpants and fairings to my new RV-4, I am having a lot of occurrences of hitting the 2700 RPM limit unless I pull the power back quite a bit (sometimes I have to pull it back to about 1/3 of the way). This is happening up high as well (7,500+ in altitude) - not just lower altitudes where the engine can develop full power.

At the beginning of my takeoff roll I'm showing just about 2180-2200 RPMs, increasing as I pick up speed. The numbers are pretty good - 2,200 FPM climb, and just over 200 MPH TAS. It seems like I could go a lot faster if I had more prop bite (2 - 3 inches more pitch) and could therefore be at full throttle. Anyone else run into this?

Thanks,

Rick
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  #9  
Old 10-26-2010, 03:09 PM
Rick RV-4 Rick RV-4 is offline
 
Join Date: Aug 2006
Posts: 221
Default 72 by 85

Jim,

I went with the "standard" prop Van recommends for the 180 HP RV-4 (72" diameter by 85" pitch). I have the tall gear on my RV-4 and have absolutely NO problems with ground clearance. I'd be comfortable with a 74" diameter prop if I had to go that route.

I hope some day to convert to a Whirlwind RV-200 prop, but will probably keep it as is for now.

Rick
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  #10  
Old 10-31-2010, 05:56 PM
Teal35 Teal35 is offline
 
Join Date: Oct 2010
Location: Illinois
Posts: 2
Default

Quote:
Originally Posted by Rick RV-4 View Post
Jim,

I went with the "standard" prop Van recommends for the 180 HP RV-4 (72" diameter by 85" pitch). I have the tall gear on my RV-4 and have absolutely NO problems with ground clearance. I'd be comfortable with a 74" diameter prop if I had to go that route.

I hope some day to convert to a Whirlwind RV-200 prop, but will probably keep it as is for now.

Rick
Sounds Great, How did the pitch work out for you? do you know your ground static. whats cruise/ flat out speeds rpm?
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