flyzone
Pre-takeoff checklist
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- Oct 10, 2014
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Flyzone
I just replaced my 45 year old propeller on my '72 Cherokee 180. I didn't really have a problem with the old prop but years ago they did say they wouldn't overhaul it due to wear limits. I finally decided to replace it as well as get a dynamic balancing which balances the prop-engine combination on the airplane.
It is hard to identify the resulting changes but they are there. In the past my engine would overspeed at full throttle to 2800 RPM (vs. 2700 red line). That is no longer the case with the max. RPM now at the red line of 2700. This is significant. If I understood it right, I read that a 1" change in pitch equals 30 RPM in engine speed. So with over 100 RPM difference that would be about 3" in pitch change.So, perhaps the old prop was whittled down to 57" which is even below climb prop territory. I have a 60" pitch prop so this should give me some more speed. I am guessing to say that I am seeing up to a +4 mph difference at low altitudes but airspeed indicator fluctuations make this an imprecise estimate at best. I'll be interested to see my results at higher altitudes and on longer trips with GPS. I will also be interested to see any difference in fuel consumption as I expect there now to be higher consumption with the same cruise RPM (usually at 2500 RPM).
I would be interested in knowing the experience of other fixed pitch prop owners of changes they have observed.
BTW, this is a $5K cost item (installed and balanced).
It is hard to identify the resulting changes but they are there. In the past my engine would overspeed at full throttle to 2800 RPM (vs. 2700 red line). That is no longer the case with the max. RPM now at the red line of 2700. This is significant. If I understood it right, I read that a 1" change in pitch equals 30 RPM in engine speed. So with over 100 RPM difference that would be about 3" in pitch change.So, perhaps the old prop was whittled down to 57" which is even below climb prop territory. I have a 60" pitch prop so this should give me some more speed. I am guessing to say that I am seeing up to a +4 mph difference at low altitudes but airspeed indicator fluctuations make this an imprecise estimate at best. I'll be interested to see my results at higher altitudes and on longer trips with GPS. I will also be interested to see any difference in fuel consumption as I expect there now to be higher consumption with the same cruise RPM (usually at 2500 RPM).
I would be interested in knowing the experience of other fixed pitch prop owners of changes they have observed.
BTW, this is a $5K cost item (installed and balanced).
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