Sensenich prop engine high rpm's

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Sensenich prop engine high rpm's

Postby wingnut99 » Mon Oct 07, 2024 3:16 pm

I had to replace my damaged Prince P tip but because of a 10 month wait I ended up buying a Sensenich 54 X 62 from Sonex. I didn't have any input on the specs because it's supposed to be optimized for my 3300 Gen 4 Jabiru with a Sonex airframe. I'm seeing 3500 rpm's on takeoff and climb if I don't throttle back. WOT on my Prince never exceeded 3300 unless I was in decent and the cruise speed was 135-140 at 3000 rpm's more or less. Sonex is questioning my tachometer but I haven't touched anything that should have changed it and with the slower airspeeds I'm seeing, it seems like the prop is just not the correct pitch.
My hanger neighbor says my engine sounds like it's turning faster when I takeoff than it used to. It's unnatural for me to throttle back on takeoff but I have no other choice until I can confirm that the tach is correct or not. I'll get the engine analyzer on it and check it against my Dynon HDX next time I have the engine running. Has anyone else experienced redline rpm's with a Sonex speced Sensenich?
Thanks for taking the time. Pat Murry
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Re: Sensenich prop engine high rpm's

Postby rbarber » Mon Oct 07, 2024 5:14 pm

I have the arrangement you just mentioned. And I never see such numbers. How certain are you of your tach reading? I usually see 3000 RPM on mine

'Best,

R.
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Re: Sensenich prop engine high rpm's

Postby gammaxy » Tue Oct 08, 2024 12:42 pm

Seems unlikely the propeller would be labeled wrong, but I wonder if you can use a digital level or phone app to measure the blade pitch (and thickness and chord at say 7 inches from the tip) and compare to someone else with the same propeller? Tricky part is getting a good 0 degree reference while it's mounted on the airplane--possibly off the propeller flange or by averaging measurements from both blades.
Chris Madsen
Aerovee Sonex N256CM
Flying since September 2014
Build log: http://chrismadsen.org
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Re: Sensenich prop engine high rpm's

Postby kmacht » Tue Oct 08, 2024 5:35 pm

Where are you located? Maybe there is another sonex near by that would be willing to let you try their prop for an afternoon to see if it does the same thing.
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