adamsboomer Posted October 2, 2014 Report Posted October 2, 2014 I am flying a 65 4 cylinder C with 3 blade hertzell prop. I was wondering if the RPM caution range of 2000-2250 should still be avoided? I typically fly 2300 RPM for effeciency as I am trying to get places but also build time for commercial. I tried 1800 to see what endurance provided, i didnt like being that slow. Was just curious if the 3 blade still made harmonics that need to be avoided? Thanks for the responses. Adam
Rwsavory Posted October 2, 2014 Report Posted October 2, 2014 We have the same set-up. The RPM caution range does not apply to the 3-bladed prop. We cruise either at 2300 or 2400 RPM, which seems to be a good range for noise/vibration, performance and efficiency.
carusoam Posted October 2, 2014 Report Posted October 2, 2014 There probably is a document like the STC that technically removes the yellow arc from the rpm gauge. A few dollars spent at the instrument shop can refresh the face of the device. The previous owner may have kept all the important documents in one or more places? -POH -Logs -STCs Best regards, -a-
adamsboomer Posted October 2, 2014 Author Report Posted October 2, 2014 Thanks fellas, I figured it was no longer necessary but thought I would double check. I will try 10k 2200 rpm next flight just cause I can. HAHA.
carusoam Posted October 2, 2014 Report Posted October 2, 2014 It is better to know than to assume. The limitations on the original set-up are not noticeable to ordinary pilots while flying. But, they are there for a reason...mostly expensive reasons... Best regards, -a-
1964-M20E Posted October 2, 2014 Report Posted October 2, 2014 you can always go to the manf. with all the model and s/n and ask them if you cannot find anything in the log books.
jrwilson Posted October 2, 2014 Report Posted October 2, 2014 We have the same set-up. The RPM caution range does not apply to the 3-bladed prop. We cruise either at 2300 or 2400 RPM, which seems to be a good range for noise/vibration, performance and efficiency. I have the 3 blade and it still applies, at least on the 63. I have a McCaulley prop though, so maybe that is the difference...
Guest Posted October 2, 2014 Report Posted October 2, 2014 According to the Hartzell top prop web site there is a new but different restriction and a required placard. http://hartzellprop.com/products/top-prop/mooney/m20c-g-all/ Clarence
Hank Posted October 2, 2014 Report Posted October 2, 2014 Interesting. Mine still has redline on the tach, 2000-2250, and the placard for no continuous operations below 15" between 1950 & 2350. I generally run 2300 down low, 2400 from ~4000-6500, and 2500 above that. 1
tony Posted October 3, 2014 Report Posted October 3, 2014 Hank's right, you should. Its a function of the blade passage frequency, so you just scale it down by the ratio
aaronk25 Posted October 3, 2014 Report Posted October 3, 2014 At 2200rpm at 10k are you going backwards, I mean really that's got to be SLOW.......
Cody Stallings Posted October 3, 2014 Report Posted October 3, 2014 @2200 RPM, what MP do you utilize?
adamsboomer Posted October 3, 2014 Author Report Posted October 3, 2014 Thanks for the reference materials I especially appreciate the hartzell prop website. I have never run the 2200 rpm. Right now I am running 2300rpm and 18"MP getting 135MPH level @10K I pull back to 15" for 400vvi descent clean, looks like my new setting will be 2400 in the descent to avoid that range. I am new to this plane and coming from a C152 so I don't mind slow for now. Sounds like either I have a relatively light or slick plane though as I have only noticed about 5MPH decrease per 100RPM is that around what you guys are seeing at 10K?
Hank Posted October 3, 2014 Report Posted October 3, 2014 When it's time to descend, I leave the throttle alone, push on the yoke for 500 fpm and trim the force away. That's my payback for the slow climb. 2
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