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2 Answers

Cruise Performance – Where to start?

Asked by: 2595 views , , , ,
General Aviation, Private Pilot, Student Pilot

Hello!

I'm struggling with the cruise performance piece of my POH for some mock cross country planning. Let's say I'm flying at 5500 and don't have a "target" speed or GPH in mind... do I just pick a power setting that sounds good and then start interpolating between 4000 and 6000? :) Like trying to aim for 65% power and then go from there? (Image should be below)

Thanks!

 

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2 Answers



  1. Jim Foley on Jul 09, 2012

    Choose an RPM setting, not a %MCP.  If you look at the chart, the %MCP is a variable and changes with altitude.  Ie, you can easily get 65% at 4,000′ but it would take a lot more work to find 65% at 6,000′.  I generally choose an RPM setting based on what I’m paying for.  If I’m renting the aircraft by the hour on a wet rate, I’d choose a higher RPM to get there the fastest.  If I’m flying somebody’s private aircraft and only paying for fuel, and not renting by the hour, I’d choose a setting that would get me the best fuel economy.  Once again, that’s just how I do it, and other people may have other methods.  Also, it’s not unheard of the have a CFI give you a constraint to work with, such a best fuel economy, or fastest time, just to get the student used to different methods of planning.  This might be something to practice as well on your own.  Since you said it’s just a mock plan, just choose any setting you want.

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  2. Aleks Udris on Jul 09, 2012

    Keep in mind that lower RPM’s reduce noise and make the ride more comfortable.  If I need the speed on a short hop, I may pick the higher RPM and endure the noise.  If I’m on a 3 hour cross country, I’m definately running a lower RPM and saving my ears (and making a medical renewal easier 🙂 .  Keep in mind, at 4000′ PA, 2600 RPM only adds 10 knots over the 2400 RPM setting.  On a 360 NM trip, that’s a difference of 16 minutes.  Not that bad for a quiet ride…

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