• PiperForum.com is a vibrant community of Piper owners and pilots. Our over 1,500+ active members use Piper Forum to swap technical knowledge, plan meetups and sell planes/parts. We host technical knowledge of general aviation topics and specific topics on J3-Cubs, Cherokees, Comanches, Pacers and more. In addition to an instant community of pilots for you, PiperForum.com is a library of technical topics, airplane builds, images, technical manuals, technical documents and more.

    Access to PiperForum.com is subscription based. Subscriptions are only $49.99/year or $6.99/month to gain access to this great community and unmatched library of Piper knowledge.

    Click Here to Become a Subscribing Member and Access PiperForum.com in Full!

Constant speed prop performance settings


Well-Known Member
Mar 24, 2011
Reaction score
I have an arrow that I have always flown 24"/2,400 RPM in normal cruise. Out of curiosity I started taking a look at the performance charts. I think I'm not understanding something correctly and my checkout instructor really never mentioned much on these since I always flew the 24/2400 in which I really just looked up online somewhere and others stated this is typical cruise configuration.

My understanding was that for the sake of the engine, you should always have your prop set at a higher RPM than manifold pressure to avoid excess stress on the engine. However, the POH shows performance settings of 2100 RPM with higher MP. For example a 65% power setting at a pressure altitude of 3,000 shows the setting should be 23.2" in standard temperature (ignore temperature for this discussion - also ignore the limitation my aircraft on RPM's between 2,000-2,350; this is really just for my own theoretical understanding)

Straight out of the POH it states "When selecting RPM below 2400, limiting manifold pressure for continuous operation, should be observed." Please help, what am I missing? Knowing I always fly 24"/2400 I'm not all that concerned I'm harming the engine, but the bugs the hell out of me that I don't fully understand this concept.

Latest posts