Jeff R
Well Known Member
I am well into my flight testing but I don't think the prop I have (Sensenich 79" that Van's recommends and as supplied as part of my engine/prop package) is correct. At WOT (though at full rich), I get maybe 2,420 PRM in level flight. During takeoff, I get no more than 2,200 RPM, and this is with a fairly shallow departure (in order to keep CHT's down). This RPM makes me nervous, as Sensenich says to avoid operation between 2,150 to 2,300 RPM due to engine/prop resonances.
At a 2,300 RPM cruise with a Density Altitude of around 4,500 feet, I am indicating 120 kts with a TAS of 128 kts (148 mph). I don't have fairings, so this speed is somewhat reasonable. But, with the top RPM not very much higher than the restricted range, and with takeoff occurring in the restricted range, it would appear I have a mismatched propeller.
Any thoughts?
At a 2,300 RPM cruise with a Density Altitude of around 4,500 feet, I am indicating 120 kts with a TAS of 128 kts (148 mph). I don't have fairings, so this speed is somewhat reasonable. But, with the top RPM not very much higher than the restricted range, and with takeoff occurring in the restricted range, it would appear I have a mismatched propeller.
Any thoughts?