Should I Repitch A Wood Propeller?

[Geico266]

I have an 0-235-C1 on my -3. It is a whopping 108 HP @ 2,700 RPM. Red line is 2,800 RPM. Currently, I have a 68x66 wooden Sterba "cruise" prop. The "problem" is I think the prop is just a tad too much for this set up and I'm torn on what to do and I'm asking for your advice and guidance.

Sterba 68X66
Static RPM = 2,120 RPM
Take off = 2,150 RPM - 400-600 FPM climb
Max level = 2,620 (on a good day)

Max Speed is 157MPH @ 4.5 gallons per hours.

Tach is accurate. Mission of plane = Daily flyer, aerobatics, short flights around the area, short cross countries under 500 miles.

Ed Sterba says he can repitch this prop for $50 plus shipping. I am leaning towards letting him do it and taking off 4" of pitch, but I'm stuck on what to do. My calculations are I would be able to spin the prop 100-150 RPM faster getting closer to red line and 108HP and loose no speed. I could cut it down 2" also. This would help on RPM also.

My goal is to improve climb on take off, without hurting top speed. I have the old style wheel pants and I'll be changing them to the new style this winter. This would add 6 MPH.

Any thoughts from VAF crew?

[Mel]

Increasing pitch is a bit more. Any time you change pitch on a wood prop, you reduce blade area. So increasing pitch and reducing blade area sort of counteract each other.
So as long as you are reducing pitch, I would let him do it.
Reducing diameter will reduce climb performance.

[Geico266]

Originally Posted by Mel

Increasing pitch is a bit more. Any time you change pitch on a wood prop, you reduce blade area. So increasing pitch and reducing blade area sort of counteract each other.
So as long as you are reducing pitch, I would let him do it.
Reducing diameter will reduce climb performance.

Good stuff.

I found something interesting on the Sensenich web site. They recommend a 72 X 50 prop for a Pits and a Quicky with an 0-235 C1. Should I just buy a new prop and try these demensions? I guess I could have this one repitched and if I don't like it get a new one.

I hate being stuck on stupid.

[Mel]

$50 ain't much. Give it a try.

[jclark]

Originally Posted by Geico266

Good stuff.

I found something interesting on the Sensenich web site. They recommend a 72 X 50 prop for a Pits and a Quicky with an 0-235 C1. Should I just buy a new prop and try these demensions? I guess I could have this one repitched and if I don't like it get a new one.

I hate being stuck on stupid.

I would tell Ed all the details and go with what he recommends.

He is a good guy and knows his props. Numbers from OTHER props don't necessarily correlate to the results you would get with THIS prop.

James ... ~900 hours on an Ed Sterba