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Constant Speed Prop Settings

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Constant speed prop/GO-300 Cessna

« Thread started on: Oct 8th, 2004, 11:11pm »


Hello I have a Cessna P172D/GO-300 1963 Skyhawk. I would like to get the best performance from it and the best fuel economy without hurting the engine. All I have is the manifold pressure guage for the engine and a prop R.P.M. Guage. The green arc on the manifold goes from 10in. to 24in. and the green arc on the prop RPM goes from 1900 to 2500. I have had all kinds of suggestions on what to set these at for cruise but they all differ.

Can anyone please enlighten me on this issue?





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Re: Constant speed prop/GO-300 Cessna

« Reply #1 on: Nov 9th, 2004, 12:25am »


(From the 62' POH)

Adjust the Throttle and prop settings to achieve the desired speed OR fuel cunsumption at your given altitude. Does your flight need more speed or more fuel economy? At a given altitude, adjusting your throttle/prop settings for less RPM and less MP (manifold pressure) will ultimately lower your speed a bit and increase you fuel economy. You just need to be sure your not lugging the engine (Probably characterised by high MP with low RPM) They have a nice chart in the back of the book that outlines this. Maximum Horsepower and of course maximum speed is achieved with the maximum rpm and max MP at the same time.

Hope that helps a little- I guess the answer is there is no perfect setting, it all depends on your load and your desired flight parameters.


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