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Guest bfindlay

constant speed prop

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I was wondering if anyone could help with constant speed props. I'm flying the default cessna 182, baron, and caravan. I was wondering what the setting should be for best range/speed if possible. ALso it would be nice to know what the throttle should be set at. Mark

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I have no technical answer for you. Each aircraft is different in regards to the "proper" settings. I "fly" a multitude of aircraft and are very familiar with the "real" aircraft blah blah blah.............just keep the intruments in the high green (good rule to fly by).Jay

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All the information you seek should be in the checklist on the kneeboard. Here's an excerpt from the default c182:CRUISE[ ] Throttle -- 15-23" MP (press F2 or F3 as necessary)[ ] Propeller -- 2000-2400 RPM (press CTRL+F2 or CTRL+F3 as necessary)[ ] Elevator Trim -- ADJUST (with Num Lock off, press Num Pad 1 or Num Pad 7 as necessary)[ ] Rudder Trim -- ADJUST[ ] Mixture -- LEAN (press CTRL+SHIFT+F2 or CTRL+SHIFT+F3 as necessary)[ ] Cowl Flaps -- CLOSED

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I have looked at the check list, i guess what i was asking is if there is a chart or some hints as to how to adjust the throttle and propeller to get the most range. The check list only gives me limits. mark

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Saw a similar thread some months ago and kept it in note form. Here it is - an excellent discussion about CS props:"Think of the prop as a "transmission" for your airplane propeller. Just like you wouldn't use first or second gear in your car to go 75-80 mph down the freeway, in a constant speed propeller aircraft, you need to adjust your prop pitch to get the most efficient use out of your prop...In a nutshell - general for complex Cessnas:for takeoff cowl flaps openlow pitch, high RPM - (prop control - baby blue colored knob - pushed all the way in to the firewall)throttle open (black knob - pushed all the way into the firewall)After take off, establishing into climbgear-upthrottle for 25inches manifold pressureprop for 2500rpmAs you climb out and gain altitude, your manifold pressure will decrease, increase throttle to maintain 25 inches, eventually you'll be at full throttle but can't get 25 inches, at that point don't worry about it you can't do anything about manifold pressure.Transition into cruise,match manifold and rpms, e.g. 23inches, 2300 rpm.lean as necessarycowl flaps closed.When you decrease power, decrease manifold pressure first (throttle - black knob)), then decrease RPMs (prop - blue knob)When you increase power, increase RPMs first (prop control - push in), then increase manifold pressure (throttle - push in).When I'm in cruise and need to climb, I'll go ahead and go back to 2500rpm and 25", cowl flaps open.To descend, I leave the prop where it is and just decrease the throttle.Descending to land, I'll wait until I'm at idle to bring my prop back to low-pitch/high RPMs. If I'm in a powered descent to land, I'll slowly turn up the RPMs back to low-pitch/high RPMs. This is so that if I have to go around, I'll have the RPMs up before I bring the throttle back up.When you pull the prop control out, you're increasing the amount of bite the propeller takes out of the air as it goes through it, kind of like lengthening your stride if you're a runner. So as it goes roundy-roundy, it takes more of a bite out of the air.low-pitch / high RPM = like football players stair-stepping through the tires -- legs moving very fast, but not going anywhere very fasthigh-pitch / low RPM = sprinter lengthening his stride - legs moving very fast - going somewhere very fast You can mismatch your manifold pressure and rpms during cruise, the guideline is to keep the power and RPMs within the green arc of their respective gauges.If you have a prop control failure, the prop will fail to low pitch- high RPM (as if you pushed the prop control all the way in.) But you will have other problems in the event of a prop control failure as the oil that controls your prop pitch is the same oil that is used to lubricate and cool your engine cylinders, so you will also have an engine failure pretty soon afterwards. Usually a prop control failure is accompanied by a big black streak of oil all over the engine cowling - you had the oil before takeoff - it must have leaked out somewhere."

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