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Need to repitch my Sensenich?

Rick RV-4

Well Known Member
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
 
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..
 
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.
 
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
 
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
 
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.
 
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
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
 
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
 
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?
 
Prop test

I have a Sensenich wood prop pitched to 83" in my -8. Flew to 14,500 and still oversped to 2740 at WOT. Throttling back to 2700 RPM and leaning for best power resulted in TAS of 208mph @ 7.6 GPH - Thats not too bad.

I should probably repitch to peak at 2700rpm at somewhere between 11,500-12,500 for good x-cntry .

Ken
 
I have a Sensenich wood prop pitched to 83" in my -8. Flew to 14,500 and still oversped to 2740 at WOT. Throttling back to 2700 RPM and leaning for best power resulted in TAS of 208mph @ 7.6 GPH - Thats not too bad.

I should probably repitch to peak at 2700rpm at somewhere between 11,500-12,500 for good x-cntry .

Ken

I say: "If it ain't broke, ........ don't fix it!" ;)
 
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