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3 Answers

Blue Line

Asked by: 1526 views ,
Private Pilot

Am a PP with ~500 hours.. have just purchased a PA27 and am prepping for my checkride.

 

Question:  If I take the plane to altitude and configure it for blue line (88kts in this plane).  Can I simply set this configuration and expect blue line elsewhere (or at least close to blue line)?

 

Also, could this be done using single engine drills?

 

Thanks,

Jeff

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3 Answers



  1. Russ Roslewski on Feb 02, 2023

    I’m not sure exactly what you’re trying to accomplish, but yes, it could be done, just as it can with any other speed. When I teach instrument flying, I teach the “by the numbers” method of setting a configuration and power and that equals a certain speed. The power settings will be a rough guide which depends on altitude, weight, temperature, etc., but it will get you close.

    And yes you could do this for single-engine flight as well.

    But why do you want to? Blue line is Vyse, which means best rate of climb, single-engine. If both engines are operating, blue line is not applicable. And if one engine is operating, the only time you’re really wanting to operate at blue line is when trying to climb – so there would be no point in having any other configuration than full power and gear/flaps up.

    If you’re single-engine and NOT trying to climb, I see no advantage to intentionally maintaining blue line IF you can go faster. Give yourself some padding so that if you do need to climb, you have some energy to convert into altitude. And if you can’t go faster than blue line, that means you’re right on the edge of being able to maintain altitude, or actually descending, and in that case you do want full power and you are pitching to maintain the airspeed at blue line, and accepting the loss of altitude.

    If you’re single-engine and intentionally descending, then there’s really no reason to artificially slow down to blue line. Let the speed build to whatever it does as you make a normal descent – when single-engine, airspeed is always your friend.

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  2. Kris Kortokrax on Feb 03, 2023

    I’m not sure you understand “Blue Line”. You quote the speed as 88 knots.

    One size does not fit all.

    Take a look at the Single Engine Rate of Climb chart in the Performance Chart section of the POH.

    88 KIAS (102 MPH) is Vyse at sea level at gross weight (5200#).
    At 4000 takeoff weight at sea level, Vyse is 78 KIAS (90 MPH).

    At 6000′ density altitude and 5200#, Vyse is 86 KIAS (99 MPH).

    I’ve often heard pilots insist on maintaining blue line on approach down to the flare. They operate based on a blue line painted on the airspeed indicator and unless at sea level and max gross weight, end up coming in too fast and floating during the flare.

    Russ,
    I can think of one situation where I would fly Vyse if not trying to climb. If the engine fails during cruise flight above the airplanes single engine absolute ceiling, flying Vyse (Drift down) would minimize the rate of altitude loss.

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  3. Russ Roslewski on Feb 03, 2023

    Kris,

    “Russ,
    I can think of one situation where I would fly Vyse if not trying to climb. If the engine fails during cruise flight above the airplanes single engine absolute ceiling, flying Vyse (Drift down) would minimize the rate of altitude loss.”

    Of course. But you wouldn’t be intentionally reducing power (setting a “configuration” as the OP asks about) in that case to maintain blue line. You’d be using maximum available power, and pitching for blue line, and accepting whatever climb or descent rate you get, since that’s all you can do. So you are “trying” to climb, it’s just resulting in a minimum descent rate. If you had extra power available above what it took to maintain altitude at blue line, you’d be using it to maintain altitude or climb. Or fly at a faster airspeed. That was my point.

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