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Guest captbulldog

flying with prop control

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Guest captbulldog

Hi, can somebody explain how to fly a plane with constant speed prop, ie the blue level? :) I don't understand how to use or how it affect the flight performance. Thanks.

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Guest pilotsim7828

Capt Bulldog;I dont Have that much time in a constant speed prop plane (only 15 hrs, Real Time) The Blue lever is the one that controls the Propeller, In which controls the angle of attack in which the prop bites in the wind If you push forward fully , the prop is in takeoff mode, And in that mode the manifold presuure will be at its fullest . BUT!!! , You must remember on take off...after leaving the groundYou must pull back on the prop lever and adjust the Throttle lever to ;25" of manifold presuuer if your in the 172 rg , And the throttle lever back to 2500 RPM`s. That is climb. Then to cruise in level flight pull the prop lever back to;18" manifold pressure , And the throttle to 2400 RPM`s Always remember to do your G,U,M,P,S check before landingG =GASU =UNDERCARRAGEM =MIXTURE RICHP =PROP FULL FORWARDS = SWITCHES Any body else Please Correct me. Jeff Akins;)

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The way I was taught, is that S stands for seatbacks erect & seat belts......... but, if you've got switches to worry about, then why not! :) I just wanted to discuss the M for Mixture Rich. While most POH's will mention "mixture rich" for landing, they'll also discuss leaning proceedures for density altitudes over 3000'. The airports close to my home are in the 4200 -4600' msl range. Here, we lean right after engine startup & never go to full rich during the landing checklist. Just richer than our higher altitude leaning. It's really evident just how much power you'll lose for a takeoff, if the engine isn't leaned during the run-up. The same goes for a go-around.L.Adamson

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Guest pilotsim7828

Hi Mr. Adamson, I know about Leaning Proceadures.The Elevation here at Kftw is 710' Msl. even on a hot day , The most Denisty is 3000'MSL Even though everyone should check thier own airport elevations ,before flight Jeff

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> Hi Mr. Adamson, > I know about Leaning Proceadures. >The Elevation here at Kftw is 710' Msl. even on a hot day , >The most Denisty is 3000'MSL > Even though everyone should check thier own airport >elevations , >before flight > Jeff Thought you might know; I just wrote it for anyone that doesn't. I've never personally descended down to a level of 710' msl myself........to see what it's like! :)L.Adamson

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Guest captbulldog

Interesting. Thanks Jeff and Larry for the insights. :)

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Guest Dean

Larry,Would that be a picture of your home built project?

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Guest captbulldog

What about the throttle and prop balance setting? I think that you could get the same airspeed with high throttle fine pitch or low throttle coarse pitch. Obviously, for the sake of effiency cruise, one would want the low throttle setting, but how does one know at what balance to achieve the most efficient setting? I assume the aircraft's POH would state this setting?

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Guest jrewing

Hi Preston,For takeoff in piston engine aircraft, you'll want the prop lever forward (full RPM) and the throttle at full (or at maximum recommended manifold pressure for a turbocharged engine). This setting assures the maximum power output.Once you've reached a safe altitude, there will be another recommended climb setting, usually a slightly lower RPM and manifold pressure to reduce strain on the engine(s).For cruise, the POH or AFM will have a table indicating RPM and manifold pressure combinations that recommended for a specific altitude and desired power output like 65% or 75% power. There is a popular rule of thumb that says you should use "square" settings for cruise, for example setting the throttle to 23" of manifold pressure and the prop to 2300 RPM. Some pilots believe that you should never use a setting that is "over square" - say 25" of MP and 2300 RPM - but this not always true. Consult the POH for recommended settings based on your cruising altitude and desired fuel ecomomy.For landing, set the props to full as part of your landing procedure so that should you need to go-around, you'll get maximum performance.High manifold pressure and low RPM settings can be very hard on a piston engine. It's like trying to go uphill in a car with a manual transmission in a high gear at a slow speed. So when changing the engine and prop settings, remember the phrase "Prop Up, Throttle Down." When you want to increase power (say to initiate a climb), set the propeller to the desired RPM setting before setting the throttle. When you want to decrease power (say to level off from a climb or initiate a descent), reduce the throttle to the desired MP setting and then set the propeller to the desired RPM. Hope that helps,John

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Regarding flight performance & advantage of constant speed props.If you take a Cessna 172 with a fixed pitch prop as an example, the prop is a compromise between a fine pitch for takeoff & a coarser pitch for cruise. In order for the engine to develope as much RPM as possible (whithin redline) which equates to horsepower, the pitch needs to be finer like low speed on a bicycle. But the fine pitch is also like low gear on a highway, which leads to high rpm, low milage & low speed. If the fixed pitch is too coarse, takeoff performance can greatly suffer, but top speed is improved. Under certain density altitude situations such as a hot day, or a high altitude airport, you need all the takeoff horsepower you can get, and an improperly pitched prop could be disasterous. That's why it's a compromise between these two settings, but never really efficient . The advantage of constant speed, is high RPM's for takeoff & low rpm/(high gear) for cruise, and settings in between. The prop can also be used for "braking action" when entering a pattern, or coming in high, by pushing the lever to fine pitch. It's kind of like putting a car into low gear to slow down, and the plane can descend with a steeper angle. The disadvantage is cost, which can be at least 5 times as much........ if not more!In most cases of GA aircraft, the prop is operated by oil pressure from a prop governor which travels to a piston in the prop hub. The oil goes to the prop through a hollow portion in the front part of the crankshaft. The blue lever is what what controls the prop governor settings. The pic below shows the hub on the front of the prop which contains the piston. The piston is connected to levers which turn each prop blade. A prop spinner will cover the hub.L.Adamson

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Guest

All this information is great stuff. When I fly the Kingair B200 in Fly, I usually use a rpm in the range of 1700 - 1800 during the climb, with max. power, but under red line. At altitude, I am ususally ~1700 rpm w/ reduced power.Would this be acceptable in a real plane?

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